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QGIS/design/docs/qgis_design.lyx
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#LyX 1.3 created this file. For more info see http://www.lyx.org/
\lyxformat 221
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\language american
\inputencoding latin1
\fontscheme default
\graphics default
\float_placement !ht
\paperfontsize default
\spacing single
\papersize Default
\paperpackage a4
\use_geometry 0
\use_amsmath 0
\use_natbib 0
\use_numerical_citations 0
\paperorientation portrait
\secnumdepth 3
\tocdepth 3
\paragraph_separation indent
\defskip medskip
\quotes_language english
\quotes_times 2
\papercolumns 1
\papersides 1
\paperpagestyle fancy
\layout Title
Quantum GIS Design Document
\layout Author
Mark Coletti
\layout Standard
\begin_inset LatexCommand \tableofcontents{}
\end_inset
\layout Standard
\begin_inset FloatList figure
\end_inset
\layout Standard
\begin_inset FloatList table
\end_inset
\layout Chapter
Introduction
\layout Standard
This document describes the requirements and design for Quantum GIS (QGIS),
a desktop GIS application for Linux and Unix.
This document presents use cases, high-level class diagrams, and additional
information about the design and implementaion of QGIS.
\layout Standard
QGIS is hosted on SourceForge at http://qgis.sourceforge.net.
The current release of QGIS is a viewer with a minimal feature set, including
loading data (shapefiles and PostgreSQL layers), browsing, and identifying
features.
\layout Standard
The design outlined in this document represents the next phase of QGIS developme
nt, which will move the application to a flexible and extensible platform
for working with spatial data.
\layout Standard
Note that it's presumed that the reader is familiar with C++, object-oriented
design, and UML.
\layout Chapter
Requirements
\layout Section
Organization
\layout Standard
This section describes the functional requirements of Quantum GIS.
First, a general overview of capabilities of QGIS is given; this is followed
by sections that refine that requirement description by analyzing the users
(actors) and possible use-cases.
\layout Section
General Requirements
\layout Standard
QGIS will provide GIS functionality somewhere between a simple viewer and
an industrial strength application.
Some of the major design requirements include:
\layout Itemize
Ability to render and browse data in many formats:
\begin_deeper
\layout Itemize
Spatio-temporal data using a feature-centric model
\layout Itemize
Shapefiles
\layout Itemize
PostgreSQL / PostGIS layers
\layout Itemize
Raster
\end_deeper
\layout Itemize
Support for Geography Markup Language (GML)
\layout Itemize
Support for Web Feature Service (WFS)
\layout Itemize
Edit PostgreSQL / PostGIS layers
\layout Itemize
Perform analytical operations
\begin_deeper
\layout Itemize
Buffer
\layout Itemize
Spatial selections (touching, contained-by, overlapping, etc.)
\end_deeper
\layout Itemize
Extensible plugin interface
\begin_deeper
\layout Itemize
All major functionality is provided via plugins
\end_deeper
\layout Section
Actors
\layout Standard
The viewer requirements are driven by how it is to be used.
Before the exact nature of this use can be discussed, it's important to
first identifiy the types of users (
\begin_inset Quotes eld
\end_inset
actors
\begin_inset Quotes erd
\end_inset
in design parlance).
After all, each type of user will approach the viewer with different goals,
each of which will have to be effectable in the viewer.
\layout Standard
There are five different actors relevent to the viewer.
They are the
\begin_inset Quotes eld
\end_inset
Casual User
\begin_inset Quotes erd
\end_inset
,
\begin_inset Quotes eld
\end_inset
Casual GIS User
\begin_inset Quotes erd
\end_inset
,
\begin_inset Quotes eld
\end_inset
Home GIS User
\begin_inset Quotes erd
\end_inset
,
\begin_inset Quotes eld
\end_inset
Earth Science Information Center help desk staffer
\begin_inset Quotes erd
\end_inset
, and
\begin_inset Quotes eld
\end_inset
GIS professional
\begin_inset Quotes erd
\end_inset
.
\begin_inset ERT
status Collapsed
\layout Standard
Figure~
\backslash
ref{fig:actors}
\end_inset
depicts these roles and their relationship.
\begin_inset Float figure
wide false
collapsed false
\layout Caption
\begin_inset Graphics
\end_inset
\end_inset
\layout Standard
\begin_inset Float figure
wide true
collapsed false
\layout Standard
\align center
\begin_inset Graphics
filename actors.eps
display grayscale
width 100col%
subcaptionText "Actor"
\end_inset
\layout Caption
\begin_inset LatexCommand \label{fig:actors}
\end_inset
SDTS Viewer actor roles and their relationships
\end_inset
\layout Subsection
Casual User
\layout Standard
The casual user would infrequently use the viewer and would possess at most
a modicum of GIS knowledge.
They may only have a single SDTS dataset to view.
They would want to quickly view a given area and perhaps print what they
see.
They also may wish to verify SDTS data integrity by looking at it.
\layout Subsection
Home GIS User
\layout Standard
A
\begin_inset Quotes eld
\end_inset
Home GIS User
\begin_inset Quotes erd
\end_inset
is a type of
\begin_inset Quotes eld
\end_inset
Casual User
\begin_inset Quotes erd
\end_inset
that would be a lay person that is perhaps interested in viewing geospatial
data of special interest, say of the area where they live.
They are curious to see what the data looks like, or may intend to use
images in, say, a personal web site.
It's important that they be able to easily save what they see into a standard
format or to print on their printer.
They would use the viewer infrequently.
They, too, would also use the viewer to verify that their data is correct.
They would not necessarily know a lot about GIS.
\layout Subsection
Casual GIS User
\layout Standard
Another
\begin_inset Quotes eld
\end_inset
Casual User
\begin_inset Quotes erd
\end_inset
is the
\begin_inset Quotes eld
\end_inset
Casual GIS User,
\begin_inset Quotes erd
\end_inset
who would be a professional that has occasional use of geospatial data.
They probably don't have any high-end GIS tools.
They may be a graphic artist that wishes to generate quick images for a
company banner, or an engineer that wants to print out a rough map of a
transportation grid.
They also would want to quickly verify the correctness of data.
\layout Subsection
Educator
\layout Standard
A teacher or professor may use the browser as a tool to educate students
about geography or GIS related topics.
\layout Subsection
ESIC help desk staffer
\layout Standard
The ESIC answers SDTS related questions from USGS customers.
Occasionally these questions require a staffer to pull up the same dataset
that the client is using to insure its quality or to find a particular
feature for the client.
The staffer would frequently use the viewer in their work.
The staffer may also print metadata or an image to fax to a client; alternative
ly they may wish to save this same information into a format suitable for
sending via e-mail.
A staffer may also wish to quickly restore a
\begin_inset Quotes eld
\end_inset
browsing state;
\begin_inset Quotes erd
\end_inset
that is, being able to load a dataset and restore a previous view of that
dataset.
\layout Standard
Note that this isn't a principal use case as obviously the ESIC staffers
will be a minority of the type of users; moreover the focus for the viewer
is clearly targeted to both the casual and professional user.
However it is not only possible that ESIC related use cases will overlap
use cases derived from other roles and thus emphasize their relative importance
, but that use cases specific to ESIC personnel may also serendipitously
prove to be useful to those other roles.
\layout Subsection
GIS Professional
\layout Standard
A GIS professional would presumably have high-grade GIS tools, such as Arcinfo,
available to them.
However, they may want to view a dataset prior to converting it to a proprietar
y format to insure that they have the correct data and that it's error-free.
This role is similar to an ESIC staffer as the GIS professional would also
want to perform identical tasks; that is, they also wish to check a dataset's
integrity and quickly find a particular feature.
Naturally the GIS professional would have a great deal of GIS related knowledge.
They may use the browser frequently.
\layout Section
Use Cases
\layout Standard
This section describes the use cases that the viewer will have to address,
and naturally are driven by one or more actor roles.
The following use cases will be described in more detail in the following
sections:
\layout Itemize
buffer features
\layout Itemize
select features based on relationship to other features
\begin_deeper
\layout Itemize
touching
\layout Itemize
contained
\layout Itemize
overlapping
\end_deeper
\layout Itemize
browseData
\begin_deeper
\layout Itemize
zoom
\begin_deeper
\layout Itemize
zoom full
\layout Itemize
zoom selected
\layout Itemize
pan
\end_deeper
\end_deeper
\layout Itemize
loadData
\layout Itemize
union
\layout Itemize
intersect
\layout Itemize
merge
\layout Itemize
identify
\layout Itemize
edit data
\layout Itemize
findFeature
\layout Itemize
getHelp
\layout Itemize
setPreferences
\layout Itemize
saveProject
\layout Itemize
restoreProject
\layout Itemize
exportData
\layout Itemize
saveImage
\layout Itemize
print
\begin_deeper
\layout Itemize
printImage
\layout Itemize
printMetadata
\layout Itemize
printFeatureInformation
\end_deeper
\layout Standard
\begin_inset Float figure
wide true
collapsed false
\layout Standard
\align center
\begin_inset Graphics
filename usecases.eps
display grayscale
width 100text%
\end_inset
\layout Caption
\begin_inset LatexCommand \label{fig:useCases}
\end_inset
SDTS viewer use cases
\end_inset
\begin_inset ERT
status Collapsed
\layout Standard
Figure~
\backslash
ref{fig:useCases}
\end_inset
shows all the use cases and their respective relationships.
There are three driving use cases, which are highlighted in the figure:
verifyData, saveImage, and print.
That is, the user will have one or more of these use cases as goals when
using the browser.
\layout Subsection
browseData
\layout Standard
This is the most important use case -- that is, being able to examine a
given SDTS dataset.
This includes viewing different parts of the data, querying features, and
examining attendant metadata.
\begin_inset ERT
status Collapsed
\layout Standard
Table~
\backslash
ref{table:browsecase}
\end_inset
shows the general steps for browseData.
\begin_inset Float table
wide false
collapsed false
\layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="5" columns="2">
<features>
<column alignment="center" valignment="top" leftline="true" width="0pt">
<column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
User Intentions
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
System Response
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Change View
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Redisplay View
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
<<extension point>>
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
[continue until done]
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
</lyxtabular>
\end_inset
\layout Caption
\begin_inset LatexCommand \label{table:browsecase}
\end_inset
browseData Use Case
\end_inset
\begin_inset Quotes eld
\end_inset
Change View
\begin_inset Quotes erd
\end_inset
means changing the view point, or toggling the visibility of a feature
type, a portion of the data, or a thematic layer.
The marked extension point is for the verifyData, saveViewContext, and
saveImage use cases.
\layout Subsubsection
pan
\layout Standard
If only a subset of the data is rendered in the main window and the user
wishes to see data that is in another area, then the user could use the
pan use case to render the other area of interest.
\layout Standard
\begin_inset Float table
wide false
collapsed false
\layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="3" columns="2">
<features>
<column alignment="center" valignment="top" leftline="true" width="0pt">
<column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
User Intentions
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
System Response
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Select new area
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Redisplay View
\end_inset
</cell>
</row>
</lyxtabular>
\end_inset
\layout Caption
\begin_inset LatexCommand \label{table:pan}
\end_inset
pan Use Case
\end_inset
\layout Subsubsection
zoom
\layout Standard
This is similar to the pan use case that what data is rendered in the main
window is changed.
However, instead of moving the area covered by the main window to another
part of the data set, the size of the covered area is changed instead.
\layout Standard
\begin_inset Float table
wide false
collapsed false
\layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="3" columns="2">
<features>
<column alignment="center" valignment="top" leftline="true" width="0pt">
<column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
User Intentions
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
System Response
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Select new area
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Redisplay View
\end_inset
</cell>
</row>
</lyxtabular>
\end_inset
\layout Caption
\begin_inset LatexCommand \label{table:zoom}
\end_inset
zoom Use Case
\end_inset
\layout Subsection
findFeature
\layout Standard
This use case, as shown in
\begin_inset ERT
status Collapsed
\layout Standard
table~
\backslash
ref{table:findFeature}
\end_inset
, denotes where a user is looking for a specific entity within an SDTS dataset.
\layout Standard
\begin_inset Float table
wide false
collapsed false
\layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="3" columns="2">
<features>
<column alignment="center" valignment="top" leftline="true" width="0pt">
<column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
User Intentions
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
System Response
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Select Feature
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Show Feature
\end_inset
</cell>
</row>
</lyxtabular>
\end_inset
\layout Caption
\begin_inset LatexCommand \label{table:findFeature}
\end_inset
findFeature Use Case
\end_inset
findFeature extends the browseData use case in that a user can locate a
specific feature by browsing for it.
Alternatively the user should be able to directly express their search
for a particular feature.
\layout Subsection
loadData
\layout Standard
\begin_inset ERT
status Collapsed
\layout Standard
Table~
\backslash
ref{table:loadData}
\end_inset
show the semantics for the loadData use case, where a user loads a specific
SDTS dataset.
\layout Standard
\begin_inset Float table
wide false
collapsed false
\layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="5" columns="2">
<features>
<column alignment="center" valignment="top" leftline="true" width="0pt">
<column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
User Intentions
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
System Response
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Find CATD file
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\lang english
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Allow for file system navigationto locate SDTS catalog file(i.e., a CATD module)
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Load data
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\lang english
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Open and read in appropriate modules
\end_inset
</cell>
</row>
</lyxtabular>
\end_inset
\layout Caption
\begin_inset LatexCommand \label{table:loadData}
\end_inset
loadData Use Case
\end_inset
\layout Subsection
print
\layout Standard
This use case is a generalization of the printFeatureInformation, printMetaData,
and printImage use cases, and is shown in
\begin_inset ERT
status Collapsed
\layout Standard
table~
\backslash
ref{table:print}
\end_inset
.
\layout Standard
\begin_inset Float table
wide false
collapsed false
\layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="7" columns="2">
<features>
<column alignment="center" valignment="top" leftline="true" width="0pt">
<column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
User Intentions
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
System Response
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Select Something
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Show that Something
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Choose Output Target
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Remember Output Target
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Print
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Print to Output Target
\end_inset
</cell>
</row>
</lyxtabular>
\end_inset
\layout Caption
\begin_inset LatexCommand \label{table:print}
\end_inset
print Use Case
\end_inset
\layout Subsection
printImage
\layout Standard
\begin_inset ERT
status Collapsed
\layout Standard
Table~
\backslash
ref{table:printImage}
\end_inset
describes where a user wishes to print out part or all of a given dataset.
That is, the user will print a copy of a rendered SDTS dataset to a file
or a printer.
\layout Standard
\begin_inset Float table
wide false
collapsed false
\layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="7" columns="2">
<features>
<column alignment="center" valignment="top" leftline="true" width="0pt">
<column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
User Intentions
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
System Response
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Select Data
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Show Data
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Choose Output Target
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Remember Output Target
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Print
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Print to Target
\end_inset
</cell>
</row>
</lyxtabular>
\end_inset
\layout Caption
\begin_inset LatexCommand \label{table:printImage}
\end_inset
printImage Use Case
\end_inset
\layout Subsection
printMetadata
\layout Standard
\begin_inset ERT
status Collapsed
\layout Standard
Table~
\backslash
ref{table:printMetaData}
\end_inset
shows where the user wants to print out some or all of the dataset's metadata.
\layout Standard
\begin_inset Float table
wide false
collapsed false
\layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="7" columns="2">
<features>
<column alignment="center" valignment="top" leftline="true" width="0pt">
<column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
User Intentions
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
System Response
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Select Metadata
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Show Metadata
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Choose Output Target
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Remember Output Target
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Print
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Print to Target
\end_inset
</cell>
</row>
</lyxtabular>
\end_inset
\layout Caption
\begin_inset LatexCommand \label{table:printMetaData}
\end_inset
printMetaData Use Case
\end_inset
\layout Subsection
printFeatureInformation
\layout Standard
This use case entails finding a given feature and printing its metadata
to a file or printer and is depicted in
\begin_inset ERT
status Collapsed
\layout Standard
table~
\backslash
ref{table:printFeatureInformation}
\end_inset
.
\begin_inset Float table
wide false
collapsed false
\layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="7" columns="2">
<features>
<column alignment="center" valignment="top" leftline="true" width="0pt">
<column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
User Intentions
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
System Response
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Select Feature
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Show Feature
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Choose Output Target
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Remember Output Target
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Print
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Print to Target
\end_inset
</cell>
</row>
</lyxtabular>
\end_inset
\layout Caption
\begin_inset LatexCommand \label{table:printFeatureInformation}
\end_inset
printFeatureInformation Use Case
\end_inset
\layout Subsection
verifyData
\layout Standard
Here, the user wants to ensure that they got the correct data and that the
data isn't damaged or corrupted in some way.
\begin_inset ERT
status Collapsed
\layout Standard
Table~
\backslash
ref{table:verifyData}
\end_inset
details the use case steps.
\begin_inset Float table
wide false
collapsed false
\layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="4" columns="2">
<features>
<column alignment="center" valignment="top" leftline="true" width="0pt">
<column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
User Intentions
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
System Response
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Load Data
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Read Data
\end_inset
</cell>
</row>
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
[insure data is valid]
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
</lyxtabular>
\end_inset
\layout Caption
\begin_inset LatexCommand \label{table:verifyData}
\end_inset
verifyData Use Case
\end_inset
This extends the browseData use case in that the user may browse the data
to insure its fidelity.
A user may also use findFeature to verify data -- that is, a missing feature
may indicate an erroneous data set.
\layout Subsection
saveImage
\layout Standard
This use case entails taking the current view and saving it in a common
graphic format, such as GIF, PNG, or JPEG and is shown in
\begin_inset ERT
status Collapsed
\layout Standard
table~
\backslash
ref{table:saveImage}
\end_inset
.
Although a user can presumably take a screen snapshot, crop it, and save
it into a specific format, some of the user roles would lack these skills
and available tools.
(E.g.
the Casual GIS User) Even those users that did have the right tools and
knowledge would find it convenient to save what they see into a file using
the viewer itself.
\layout Standard
\begin_inset Float table
wide false
collapsed false
\layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="7" columns="2">
<features>
<column alignment="center" valignment="top" leftline="true" width="0pt">
<column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
User Intentions
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
System Response
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Select Format
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Remember Format
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Select Target
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Remember Target
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Save View
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Write View to Target in Format
\end_inset
</cell>
</row>
</lyxtabular>
\end_inset
\layout Caption
\begin_inset LatexCommand \label{table:saveImage}
\end_inset
saveImage Use Case
\end_inset
The format will obviously be one of the previously mentioned formats.
However the target could be a file or even a printer; if the latter, then
the format is more-or-less irrelevent, so this implies that saving a view
to a file or sending to a printer are mutually exclusive.
\layout Subsection
restoreViewContext
\layout Standard
Occasionally a user will want to look at the same data more than once; moreover
they may want to return to the last view location.
That is, they desire to return the viewer to a previous state.
Although they can manually do so, restoring the viewers
\begin_inset Quotes eld
\end_inset
browse state
\begin_inset Quotes erd
\end_inset
can be laborious and is not guaranteed to restore
\emph on
\emph default
an
\emph on
exact
\emph default
view.
The restoreViewContext use case allows a previous view context to be restored
and is shown in
\begin_inset ERT
status Collapsed
\layout Standard
table~
\backslash
ref{table:restoreViewContext}
\end_inset
.
\layout Standard
\begin_inset Float table
wide false
collapsed false
\layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="5" columns="2">
<features>
<column alignment="center" valignment="top" leftline="true" width="0pt">
<column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
User Intentions
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
System Response
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Select Target
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Remember Target
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Load Context
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Restore Context from Target
\end_inset
</cell>
</row>
</lyxtabular>
\end_inset
\layout Caption
\begin_inset LatexCommand \label{table:restoreViewContext}
\end_inset
restoreViewContext Use Case
\end_inset
\layout Subsection
saveViewContext
\layout Standard
\begin_inset ERT
status Collapsed
\layout Standard
Table~
\backslash
ref{table:saveViewContext}
\end_inset
shows the use case that is implied in the previous section.
After all, if there's a way to restore a view, then there must be a view
saving mechainism.
\begin_inset Float table
wide false
collapsed false
\layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="5" columns="2">
<features>
<column alignment="center" valignment="top" leftline="true" width="0pt">
<column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
User Intentions
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
System Response
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Select Target
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Remember Target
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Save Context
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Write Context to Target
\end_inset
</cell>
</row>
</lyxtabular>
\end_inset
\layout Caption
\begin_inset LatexCommand \label{table:saveViewContext}
\end_inset
saveViewContext
\end_inset
\layout Subsection
getHelp
\layout Standard
Though we'd like to think that the viewer will be intuitive, there will
be times when the user needs to learn how to do something within the viewer
-- or to see if a given functionality is even available.
The getHelp use case addresses these needs, and the semantics are show
in
\begin_inset ERT
status Collapsed
\layout Standard
table~
\backslash
ref{table:getHelp}
\end_inset
.
\layout Standard
\begin_inset Float figure
wide false
collapsed false
\layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="3" columns="2">
<features>
<column alignment="center" valignment="top" leftline="true" width="0pt">
<column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
User Intentions
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
System Response
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Ask for Help
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Display Help
\end_inset
</cell>
</row>
</lyxtabular>
\end_inset
\layout Caption
\begin_inset LatexCommand \label{table:getHelp}
\end_inset
getHelp use case semantics
\end_inset
\layout Subsection
setPreferences
\layout Standard
This use case allows the user to tailor how the view is rendered.
For example, they can set what is shown, what colors are used for what,
and how lines are drawn.
There are three general use case types of preferences, setVisible, setRasterAtt
ributes, setLineAttributes, which are detailed in the next three sub-sections.
They all follow the general semantics shown in
\begin_inset ERT
status Collapsed
\layout Standard
table~
\backslash
ref{table:setPreferences}
\end_inset
.
\layout Standard
\begin_inset Float table
wide false
collapsed false
\layout Standard
\align center
\begin_inset Tabular
<lyxtabular version="3" rows="5" columns="2">
<features>
<column alignment="center" valignment="top" leftline="true" width="0pt">
<column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
User Intentions
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
System Response
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Select Viewer Attribute
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Acknowledge Selection
\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
Set Attribute Value
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
</row>
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text
\layout Standard
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text
\layout Standard
Re-render with Changed Value
\end_inset
</cell>
</row>
</lyxtabular>
\end_inset
\layout Caption
\begin_inset LatexCommand \label{table:setPreferences}
\end_inset
setPreferences general use case
\end_inset
\layout Subsubsection
setVisible
\layout Standard
The user may wish to exclude some things from being shown to better see
other details.
Here the user can toggle some dataset entity's visibility.
This could be a specific type of feature or entire thematic layers.
\layout Subsubsection
setRasterAttributes
\layout Standard
The user can set how raster data is rendered.
The following raster attributes can be set:
\layout Itemize
shading model
\begin_deeper
\layout Itemize
flat
\layout Itemize
gouroud
\end_deeper
\layout Itemize
color scheme
\begin_deeper
\layout Itemize
rgb
\layout Itemize
gray scale
\layout Itemize
hsv
\layout Itemize
tailorable
\end_deeper
\layout Itemize
contrast
\layout Itemize
brightness
\layout Itemize
level of detail
\layout Subsubsection
setVectorAttributes
\layout Standard
The user can set how line data is displayed and assign specific line types
to certain vector-based features.
The following line attributes can be set:
\layout Itemize
color
\layout Itemize
thickness
\layout Itemize
type
\begin_deeper
\layout Itemize
solid
\layout Itemize
dashed
\layout Itemize
tailored
\end_deeper
\layout Itemize
anti-aliased
\layout Chapter
Design
\layout Section
User Interface Design
\layout Standard
This chapter describes the viewer's user interface.
Each use-case should have one or more GUI components, the one notable use
case being verifyData.
That use case is supported by the findFeature and browseData use cases,
as show in
\begin_inset ERT
status Collapsed
\layout Standard
figure~
\backslash
ref{fig:useCases}
\end_inset
.
First we show the main application interface, and then the contents of
the top-level menus.
Then we address each use case's user-interface implementation.
\layout Subsection
Main application interface
\layout Standard
\begin_inset ERT
status Collapsed
\layout Standard
Figure~
\backslash
ref{fig:mainUI}
\end_inset
shows what the top level application interface looks like.
It's divided into a menu bar, toolbar, status bar, and display area.
The menu bar is the top-most component, and contains the file, edit, view,
and help sub-menus.
Immediately below the menu bar is the toolbar, which provides short-cuts
for commonly used functions.
The user can open a dataset, save an image or view context, view information
about the current dataset, or get help on any of the interface components.
The bottom-most component is the status bar where menu item explanatory
text is displayed.
\layout Standard
\begin_inset Float figure
wide false
collapsed false
\layout Standard
\align center
\begin_inset Graphics
filename main.eps
display grayscale
width 100col%
\end_inset
\layout Caption
\begin_inset LatexCommand \label{fig:mainUI}
\end_inset
Main user interface
\end_inset
\layout Subsection
File menu
\layout Standard
\begin_inset ERT
status Collapsed
\layout Standard
Figure~
\backslash
ref{fig:fileMenuUI}
\end_inset
shows the file menu.
It has menu entries for creating a new view, opening a dataset, saving
the current view, or saving the view as an image, closing the current dataset,
printing the dataset, and exiting the application.
Not that all of these support alternative key stroke access as well as
accelerator keys.
\layout Standard
\begin_inset Float figure
wide false
collapsed false
\layout Standard
\align center
\begin_inset Graphics
filename mainmenu.eps
display color
\end_inset
\layout Caption
\begin_inset LatexCommand \label{fig:fileMenuUI}
\end_inset
File menu contents
\end_inset
\layout Subsection
Edit menu
\layout Standard
\begin_inset ERT
status Collapsed
\layout Standard
Figure~
\backslash
ref{fig:editMenuUI}
\end_inset
shows the edit menu.
Currently the only entry is to set the browser's preferences.
Note that it, too, has single keystroke access and an accelerator key.
\layout Standard
\begin_inset Float figure
wide false
collapsed false
\layout Standard
\align center
\begin_inset Graphics
filename editmenu.eps
display color
\end_inset
\layout Caption
\begin_inset LatexCommand \label{fig:editMenuUI}
\end_inset
Edit menu contents
\end_inset
\layout Subsection
View menu
\layout Standard
The view menu, as shown in
\begin_inset ERT
status Collapsed
\layout Standard
figure~
\backslash
ref{fig:viewMenuUI}
\end_inset
, has entries for toggling the display of the toolbar and status bar.
The
\begin_inset Quotes eld
\end_inset
Detail
\begin_inset Quotes erd
\end_inset
item invokes the dataset information display dialog.
\begin_inset Float figure
wide false
collapsed false
\layout Standard
\align center
\begin_inset Graphics
filename viewmenu.eps
display color
\end_inset
\layout Caption
\begin_inset LatexCommand \label{fig:viewMenuUI}
\end_inset
View menu contents
\end_inset
\layout Subsection
loadData
\layout Standard
\begin_inset LatexCommand \label{section:loadData}
\end_inset
Each SDTS dataset is comprised of modules of which one contains a manifest
of all its modules, including itself.
This module is the Catalog/Directory module which the standard dictates
must have the mnemonic
\begin_inset Quotes eld
\end_inset
CATD
\begin_inset Quotes erd
\end_inset
somewhere in its file name.
The CATD module is a convenient way of locating the rest of the dataset's
files; each CATD record contains a file name and the corresponding module
type.
So, we can use the CATD module as a means of opening any other files we
need, and also can offer hints on the type of data we'll be reading.
That is, we can deterimine
\emph on
a priori
\emph default
whether we'll be reading raster or vector data (or both) by the presence
of raster or vector related module listings in a CATD module.
\layout Standard
\begin_inset ERT
status Collapsed
\layout Standard
Figure~
\backslash
ref{fig:loadData}
\end_inset
shows what the loadData file dialog should look like.
Note that the
\begin_inset Quotes eld
\end_inset
File type
\begin_inset Quotes erd
\end_inset
field will have
\begin_inset Quotes eld
\end_inset
SDTS
\begin_inset Quotes erd
\end_inset
and will have a regular expression suitable to match CATD modules.
(I.e., a case insenstive
\begin_inset Quotes eld
\end_inset
*catd*ddf) There is a second file type that can be loaded, one for restoring
a view context; its corresponding file name regular expression is
\begin_inset Quotes eld
\end_inset
*.svc
\begin_inset Quotes erd
\end_inset
.
View contexts are further explained in
\begin_inset ERT
status Collapsed
\layout Standard
section~
\backslash
ref{section:viewContext}
\end_inset
.
\layout Standard
\begin_inset Float figure
wide false
collapsed false
\layout Standard
\align center
\begin_inset Graphics
filename loadData.eps
display grayscale
width 97text%
\end_inset
\layout Caption
\begin_inset LatexCommand \label{fig:loadData}
\end_inset
Prototype for file dialog to load a SDTS dataset
\end_inset
\layout Standard
This dialog can be invoked in one of the following way.
\layout Itemize
From the top level
\begin_inset Quotes eld
\end_inset
File
\begin_inset Quotes erd
\end_inset
menu's
\begin_inset Quotes eld
\end_inset
Open
\begin_inset Quotes erd
\end_inset
entry
\layout Itemize
The accelerator key sequence
\begin_inset Quotes eld
\end_inset
Alt-F, 'O'
\begin_inset Quotes erd
\end_inset
\layout Itemize
Clicking the folder icon on the main menu bar
\layout Standard
A previously loaded dataset can be accessed in a list of the last five documents
from the main
\begin_inset Quotes eld
\end_inset
File
\begin_inset Quotes erd
\end_inset
menu
\layout Subsection
saveImage
\layout Standard
\begin_inset LatexCommand \label{section:saveImage}
\end_inset
Once invoked, a dialog similar to
\begin_inset ERT
status Collapsed
\layout Standard
figure~
\backslash
ref{fig:loadData}
\end_inset
is displayed.
The user can the following image file types from the
\begin_inset Quotes eld
\end_inset
File Type
\begin_inset Quotes erd
\end_inset
field: GIF, JPEG, and PNG.
Note that this same dialog will be used in
\begin_inset Quotes eld
\end_inset
saveViewContext
\begin_inset Quotes erd
\end_inset
; the user selects a file type of
\begin_inset Quotes eld
\end_inset
View Context
\begin_inset Quotes erd
\end_inset
instead of GIF, JPEG, or PNG.
\layout Standard
This dialog can be invoked by:
\layout Itemize
From the top level
\begin_inset Quotes eld
\end_inset
File
\begin_inset Quotes erd
\end_inset
menu's
\begin_inset Quotes eld
\end_inset
Save As
\begin_inset Quotes erd
\end_inset
entry
\layout Itemize
The accelerator key sequence of
\begin_inset Quotes eld
\end_inset
Alt-F, 'S'
\begin_inset Quotes erd
\end_inset
\layout Itemize
The accelerator key sequence of
\begin_inset Quotes eld
\end_inset
Control-S
\begin_inset Quotes erd
\end_inset
\layout Itemize
Clicking the floppy disk icon on the main menu bar
\layout Subsection
print
\layout Standard
There are three different types of things for a user to print.
First, the current data as seen in the view port.
Second, a specific feature.
And, thirdly, metadata either for the entire dataset, or some subset thereof.
\layout Standard
All of these functions are available through the print dialog;
\begin_inset ERT
status Collapsed
\layout Standard
figure~
\backslash
ref{fig:print}
\end_inset
shows a mock-up of this dialog.
\layout Standard
Note that there's a functional overlap between this use case and the saveImage
use case.
That is, one can print an image to a file with this dialog, which is semantical
ly identical to saveImage.
However, users may find the notion of using a print dialog to save an image
unintuitive, so this functionality will be in both places.
\layout Standard
\begin_inset Float figure
wide false
collapsed false
\layout Standard
\align center
\begin_inset Graphics
filename qprintdlg-m.eps
display grayscale
width 95text%
\end_inset
\layout Caption
\begin_inset LatexCommand \label{fig:print}
\end_inset
print dialog
\end_inset
\layout Standard
The print dialog is accessible the following ways:
\layout Itemize
As the
\begin_inset Quotes eld
\end_inset
print
\begin_inset Quotes erd
\end_inset
option from the main window's
\begin_inset Quotes eld
\end_inset
File
\begin_inset Quotes erd
\end_inset
menu
\layout Itemize
clicking on the printer icon on the main menu bar
\layout Itemize
The accelerator key sequence
\begin_inset Quotes eld
\end_inset
Control-P
\begin_inset Quotes erd
\end_inset
\layout Subsubsection
printImage
\layout Standard
The print dialog shall have an option that specifies whether you want the
view window contents to be printed.
\layout Subsubsection
printFeature
\layout Standard
The print dialog shall have an option that specifies whether you want selected
features printed.
This ties in to the printMetaData use case implementation.
That is, do you want to print the feature
\emph on
image
\emph default
, its metadata, or both?
\layout Subsubsection
printMetaData
\layout Standard
This is covered in the previous section.
\layout Subsection
browseData
\layout Standard
\begin_inset LatexCommand \label{section:browseData}
\end_inset
The main view window of the viewer renders all or part of the dataset.
The user can pan by moving the pan wheels located at the left and bottom
of the render area.
The left wheel controls vertical movement and the bottom wheel controls
horizontal movement.
The arrow keys can also be used to move the view point up, down, left,
or right.
\layout Standard
Zooming is done spinning the zoom wheel, located on the right side of the
render area.
Alternatively, the keypad '+' and '-' keys will zoom in and out of the
image, respectively.
\layout Subsection
findFeature
\layout Standard
\begin_inset LatexCommand \label{section:findFeature}
\end_inset
This use case is implemented in a separate dialog.
It shall be comprised of a list of features identified in the current dataset.
It will also allow the user to search for a particular feature by name;
they will enter a string and press a
\begin_inset Quotes eld
\end_inset
search
\begin_inset Quotes erd
\end_inset
button.
Any matching features will be highlighted in the list.
\layout Standard
Clicking on any of the listed features will display that feature's detailed
information.
\layout Standard
The user can also use this dialog to have the display view shifted to were
the feature is located.
\layout Standard
Also, metadata for features selected by the mouse while the viewer is in
pick mode can be shown.
\layout Standard
(Should this be an alternative means for setting vector attributes? This
would save the user from using a separate dialog.)
\layout Subsection
saveViewContext
\layout Standard
\begin_inset LatexCommand \label{section:viewContext}
\end_inset
A
\begin_inset Quotes eld
\end_inset
view context
\begin_inset Quotes erd
\end_inset
contains the following browser state information:
\layout Itemize
current dataset
\layout Itemize
visible layers
\layout Itemize
viewpoint position and attitude
\layout Itemize
miscellaneous view settings (e.g., line color, rendering options, etc.)
\layout Standard
Saving this information allows the user to quickly return to a particular
\begin_inset Quotes eld
\end_inset
view
\begin_inset Quotes erd
\end_inset
of a given SDTS dataset, thus saving the time needed to open the dataset,
navigate to a particular point, set the view perspective, turning on or
off layers, and setting viewer options.
\layout Standard
This information is saved from the same file dialog used by the
\begin_inset Quotes eld
\end_inset
saveImage
\begin_inset Quotes erd
\end_inset
use case implementation.
As mentioned in
\begin_inset ERT
status Collapsed
\layout Standard
section~
\backslash
ref{section:saveImage}
\end_inset
, the user selects a
\begin_inset Quotes eld
\end_inset
view context
\begin_inset Quotes erd
\end_inset
file type in the save dialog, and sets the file name and directory.
Invoking
\begin_inset Quotes eld
\end_inset
save
\begin_inset Quotes erd
\end_inset
writes the context to the given file.
\layout Subsection
restoreViewContext
\layout Standard
This use case shares the loadData use case implementation as described in
\begin_inset ERT
status Collapsed
\layout Standard
section~
\backslash
ref{section:loadData}
\end_inset
.
\layout Subsection
getHelp
\layout Standard
The user can get help through a variety of means.
First, all the main menu bar icons will have terse tooltip text that explains
that button's function; this tooltip text will automatically display when
the user hovers the mouse cursor over the button's image for more than
a few seconds.
Secondly, each menu item has explanatory text that is displayed as the
user navigates through the menu system; this text is displayed at the bottom
of the main window.
\begin_inset Foot
collapsed true
\layout Standard
On the other hand, Constantine has stated he dislikes this as the user may
not notice help text displayed clear at the other end of where their eyes
are focused; i.e., they're looking at the top where the menus are and so
fail to see helpful text being displayed at the bottom.
I'm toying with the notion of displaying menu item help text at the
\emph on
top
\emph default
, but am still vacillating.
After all, this does violate a GUI idiom, albeit one that may need to change.)
\end_inset
Thirdly, there is a more sophisticated, hierarchically organized help system
that has its own dialog, which will be available via the following:
\layout Itemize
by selecting the
\begin_inset Quotes eld
\end_inset
Help
\begin_inset Quotes erd
\end_inset
item on the main window bar
\layout Itemize
by clicking the question mark icon on the main window bar
\layout Subsection
setPreferences
\layout Standard
\begin_inset LatexCommand \label{section:setPreferences}
\end_inset
There are three categories of viewer preferences.
That is, there are those that affect vector objects, raster objects, and
viewer specific states.
(The last being for such things as toggling use of anti-aliasing.)
\layout Standard
The viewer specific states can be modified directly from the main menu bar
under the edit menu's
\begin_inset Quotes eld
\end_inset
Preferences
\begin_inset Quotes erd
\end_inset
item.
This invokes a preferences dialog that has entries where browser options
can be set.
\layout Standard
\begin_inset Float figure
wide false
collapsed false
\layout Standard
\align center
\begin_inset Graphics
filename theme.eps
display color
width 100col%
\end_inset
\layout Caption
\begin_inset LatexCommand \label{fig:theme}
\end_inset
dataset details dialog mockup
\end_inset
\layout Subsubsection
setVisible
\layout Standard
A user can toggle a layer's visibility using the
\begin_inset Quotes eld
\end_inset
detail
\begin_inset Quotes erd
\end_inset
dialog, which is shown in figure
\begin_inset LatexCommand \ref[ref:fig:theme]{fig:theme}
\end_inset
.
However, the user may wish to toggle individual objects.
This would be done through the features dialog.
The user first needs to select the object or objects that they wish to
hide or show.
They can do this either by directly picking the object in the main window
by clicking on it, or by finding and selecting the object in the features
dialog.
Once the object is selected, they can toggle its visibility by checking
or unchecking a
\begin_inset Quotes eld
\end_inset
visibility
\begin_inset Quotes erd
\end_inset
attribute.
\layout Subsubsection
setRasterAttributes
\layout Standard
Double-clicking on a raster layer in the
\begin_inset Quotes eld
\end_inset
Details
\begin_inset Quotes erd
\end_inset
dialog will invoke the raster attributes dialog.
If the raster layer is for a DEM, the user can select color and shading
models used to render the scene.
For other raster types (e.g., DOQs), the user can set contrast and brightness.
\layout Subsubsection
setVectorAttributes
\layout Standard
A vector attributes dialog is invoked by double-clicking on a vector layer
in the layers dialog.
The use can set line color and types in this dialog.
\layout Section
Top level design
\layout Standard
From the most coarse grained persepctive, the SDTS viewer is comprised of
a few packages the most important being the package for the core viewer
functionality.
That package isn't alone, though.
The viewer package relies on several external packages.
The viewer will need to read SDTS data, be able to manipulate that data
in the geography domain, and be able to render that data; each of these
needs has one or more corresponding packages as depicted in
\begin_inset ERT
status Collapsed
\layout Standard
figure~
\backslash
ref{fig:packages}
\end_inset
and is shown in the following:
\layout Itemize
The sdts++ package is responsible for providing SDTS reading functionality
\layout Itemize
The GIS tools package will contain such functions as projection transformations
and coordinate conversions
\layout Itemize
The Coin Open Inventor 3D graphics C++ Toolkit package, which also provides
a Qt compliant interface
\layout Itemize
The Qt GUI C++ toolkit
\layout Itemize
OpenGL is an open standard for 3D object manipulation and rendering
\begin_inset Float figure
wide false
collapsed false
\layout Standard
\align center
\begin_inset Graphics
filename packages.eps
display color
width 100col%
\end_inset
\layout Caption
\begin_inset LatexCommand \label{fig:packages}
\end_inset
top-level packages
\end_inset
Each of these three packages will be discussed in more detail in the following
sections.
After that, the remainder of this chapter will focus on the main viewer
package.
\layout Subsection
sdts++
\layout Standard
sdts++ is a free, open-source C++ toolkit for reading and writing SDTS data.
We'll be using sdts++ to read SDTS datasets.
\layout Subsection
GIS tools
\layout Standard
Rendering the data correctly implies that some form of GIS functionality
exists.
This would include any spatial data transforms and other operators.
\layout Subsection
Coin Open Inventor C++ toolkit
\layout Standard
Open Inventor is another industry standard for a C++ library for manipulating
2D and 3D objects.
Open Inventor employs OpenGL.
\layout Subsection
OpenGL
\layout Standard
OpenGL is an industry standard in 2D and 3D object modelling and rendering,
and is available for both Microsoft Windows and X/Windows platforms.
\layout Subsection
Qt
\layout Standard
Qt is a C++ GUI toolkit that works on both Microsoft Windows and X/Windows
platforms.
Moreover, it provides for OpenGL interaction, which can either be used
directly, or through the Coin Open Inventor toolkit.
\layout Subsection
viewer
\layout Standard
The viewer design uses a variant of the Model-View-Controller (MVC) paradigm.
The MVC architecture dictates that the data is contained in a Model component,
a View gives a unique rendering of that data, and a Controller is responsible
for handling user events.
\begin_inset ERT
status Collapsed
\layout Standard
Figure~
\backslash
ref{fig:staticDesign}
\end_inset
shows the browser's version of the MVC architecture.
The View component is implemented in an SdtsviewerView class.
The Model component is implemented in the SdtsviewerDoc class.
The Controller, as in most implementations, is not an explicit class; instead
the top level class, Sdtsviewer and the View component, SdtsviewerView,
handle user generated events such as mouse movements and pressed keys and
translate those into changes in the rendered view.
Since this is a browser and not an editor, the Model component only changes
when data is loaded; after that, the data is immutable.
\layout Standard
Sdtsviewer is the top level widget, and provides the functionality of QMainWindo
w.
That is, it implements the top level menus, toolbar, and a main rendering
area.
It also contains a SdtsviewerDoc (i.e., the model) and a SdtsviewerView (i.e.,
the viewer).
The SdtsviewerView inherits from the Coin Open Inventor Qt widget, SoQtFullView
er.
This widget provides for a main render area for the Open Inventor scenegraph
that contains the actual 3D objects corresponding to SDTS spatial objects.
In turn, it provides a pop-up menu that one can use to tailor how the scene
is rendered and the spin-wheel widgets that are used to pan and zoom the
view.
SdtsviewerDoc inherits from QObject to take advantage of Qt's signal/slot
mechanism.
In this case, this is to implement the Observer design pattern such that
view's can be notified when the data changes.
(In this case, when data is loaded.
There should be no further changes after that.)
\layout Standard
SdtsviewerDoc has a Dataset object.
This object contains all the spatial and meta data for a given dataset.
SdtsviewerDoc uses an SDTSImporter object to populate its Dataset object.
\layout Standard
\begin_inset Float figure
wide false
collapsed false
\layout Standard
\align center
\begin_inset Graphics
filename design1.eps
display color
width 100col%
\end_inset
\layout Caption
\begin_inset LatexCommand \label{fig:staticDesign}
\end_inset
static top-level design
\end_inset
The Dataset object, in addition to containing certain metadata, contains
Layer objects; each of these Layer objects represents a thematic sub-set
of the current SDTS dataset.
(E.g., hydrography, hysography, transportation, etc.) These Layer objects
can, in turn, represent vector or raster data; and, in the case of raster
data, raster images or heightfields.
A dataset also contains attributes and features; they aren't bound to a
particular layer because some features may easily belong to more than one
layer.
A feature is a manifestation of some attribute.
(Not really.
I have to really think hard about how to adequately handle features and
attributes.
The current design needs a lot of work on attributes and features.) The
Dataset class is associated with an Open Inventor scenegraph that contains
all the Open Inventor spatial objects that represent SDTS spatial objects.
The scene graph contains an SoNodeKit for each of these spatial objects.
(We decided to use an SoNodeKit instead of an SoNode because it's possible
to change the rendering attribute of a specific node.
However, we don't want to incur the resource penalty of putting SoAttribute
objects in front of every SoNode since that would be a waste of resources;
and manually adding them in when we DID want to change how a specific feature
was rendered would be a pain.
Fortunately SoNodeKits do all that for us.
We can change how a specific node kit is rendered without having an impact
on any other nodes.
We can also group transform attributes for collections of spatial objects.)
A Layer is going to have a relationship with a specific SoNodeKit; i.e.,
it wil be its entry point in the general scenegraph.
That is, each Layer corresponds to a sub-tree in the scenegraph; and so
each Layer has a handle on the root SoNodeKit in that subtree.
The SDTSImporter, naturally, populates a Dataset with Layers, Features,
Attributes, and the corresponding Scenegraph with spatial objects in the
form of SoNodeKit objects.
\begin_inset ERT
status Collapsed
\layout Standard
Figure~
\backslash
ref{fig:datasetDesign}
\end_inset
depicts these classes and their relationships.
\begin_inset Float figure
wide false
collapsed false
\layout Standard
\align center
\begin_inset Graphics
filename staticdesign.eps
display color
width 100col%
\end_inset
\layout Caption
\begin_inset LatexCommand \label{fig:datasetDesign}
\end_inset
Detailed Dataset class design
\end_inset
foo
\layout Subsubsection
loadData implementation
\layout Standard
\begin_inset Float figure
wide false
collapsed false
\layout Standard
\align center
\begin_inset Graphics
filename loadDataDiagram.eps
display grayscale
width 100col%
\end_inset
\layout Caption
\begin_inset LatexCommand \label{fig:loadDataColloboration}
\end_inset
loadData colloboration diagram
\end_inset
\the_end
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