+
+
+
+QGIS User Guide
+ | 
+ PDF |
+
+
+
Version 0.1 (Moroz)
-
-
Introduction
+
+
+
+
+ |
+Introduction
+ | |
+
+
+ | | |
+
+
+
+
Quantum GIS (QGIS) is designed to be a Geographic Information System (GIS)
built for Linux/Unix. QGIS currently offers basic support for vector, raster, and database formats.
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+
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-
Current Features
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+
+
+
+ |
+Current Features
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+ | | |
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@@ -139,37 +231,78 @@ built for Linux/Unix. QGIS currently offers basic support for vector, raster, an
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Getting Started
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+Getting Started
+ | |
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+
+ | | |
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+
+
-
This section gives you a quick overview of running QGIS and examining data in
+
This section gives you a quick overview of running QGIS and examining data
available on the QGIS web page.
-
-
Installation
-
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+
+
+
+ |
+Installation
+ | |
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+ | | |
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+
+
Installation of QGIS is documented in the Installation Guide.
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-
-
Starting QGIS
-
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+
+
+
+ |
+Sample Data
+ | |
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+ | | |
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+
+
+
If you do not have any GIS data, you can obtain a dataset for Alaska (which will be used as the
+ basis for the examples and screenshots provided in this document) from the
+ the QGIS web site
+
+
+
+
+
+
+ |
+Starting QGIS
+ | |
+
+
+ | | |
+
+
+
Assuming the QGIS is installed in the PATH, you can start QGIS by typing:
qgis.
-
- When QGIS starts, an empty window is displayed as shown below.
- 
-
-
-
Note
-
Your window decorations (title bar, etc.) may appear different depending on your operating system
- and window manager
-
In addition, you can start QGIS by specifying one or more datafiles on the commandline. For example,
assuming you are in your data directory, you could start QGIS with two shapefiles and a raster file set to
@@ -180,76 +313,346 @@ built for Linux/Unix. QGIS currently offers basic support for vector, raster, an
+
+
Note
+
Your window decorations (title bar, etc.) may appear different depending on your operating system
+ and window manager
+
+
+
+
+
+
+ |
+The QGIS main window
+ | |
+
+
+ | | |
+
+
+
+
+ When QGIS starts, an empty window is displayed as shown below.
+
+
+
The QGIS main window is divided into five areas:
+
+
+- The menu bar
+
+- The tool bar
+
+- The map legend
+
+- The map view
+
+- The status bar
+
+
+
These five parts of the main QGIS are described in more detail in the following sections
+
+
The QGIS menu bar
+
The menu bar provides access to various QGIS features using a standard windows
+ heirachical menu.
+
The File Menu:
+
+
+-
+
- Open a previously saved project.
+
+-
+
- Save the current project.
+
+-
+
- Save project under a new file name.
+
+-
+
- Export your current project as a mapserver
+ map file. Note that not all mapserver features are available in the exported mapfile.
+
+-
+
- Exit the QGIS application.
+
+
+
The View Menu:
+
+
+-
+
- Add one or more layers
+ stored in a PostgreSQL/Postgis geodatabase to the map view.
+
+-
+
- Add one or more layers
+ stored on disk as shapefiles to the map view.
+
+-
+
- Add one or more raster layers
+ to the map view.
+
+
+
The Tools Menu:
+
+
+-
+
- This opens a dialog
+ that allows you to manage (load and unload) which plugins are used in QGIS.
+
+-
+
- This option connects
+ over the internet to the QGIS server to find out what the latest available version is. No
+ personal data is sent to the QGIS server.
+
+-
+
- Global configuration options
+ for the QGIS application.
+
+
+
The Help Menu:
+
+
+-
+
- This opens the help documentation
+ you are reading right now!.
+
+-
+
- Clicking this menu option will
+ take you to the QGIS internet home page using your preferred browser.
+
+-
+
- This will take you to the Sourceforge.net
+ project page for QGIS.
+
+-
+
- Click here to find out some useful information
+ about the current version of QGIS you are using. If you want to frighten yourself silly, take a
+ look at the Contributors tab to see all the hardworking elves behind the QGIS effort.
+
+
+
+
The QGIS toolbars
+
QGIS has toolbars that provide quick access to commonly used functions. These are:
+
+
+-
+
- Start a new QGIS project. If you
+ already have a project ope, you will be asked if you would like to save the existing one first.
+
+-
+ - Open a previously saved project.
+
+-
+ - Save the current project.
+
+-
+ - Save project under a new file name.
+
+-
+ - Add one or more layers
+ stored in a PostgreSQL/Postgis geodatabase to the map view.
+
+-
+ - Add one or more layers
+ stored on disk as shapefiles to the map view.
+
+-
+ - Add one or more raster layers
+ to the map view.
+
+-
+
- Reload the current map view (refreshes display)
+
+-
+
- Zoom in the map display by dragging a rectangle
+
+-
+
- Zoom out of the map display by dragging a rectangle.
+ Dragging a small rectangle will zoom out a long way, dragging a large rectangle will zoom out a little way.
+
+-
+
- Zoom out until all features in all map layers
+ are visible.
+
+-
+
- Zoom to fit all selected features in the
+ map view.
+
+-
+
- Pan in the map display area.
+
+-
+
- Zoom to last extents.
+
+-
+
- Show information about a feature (applies only to vector data).
+
+-
+
- Select features in the map display (applies only to vector data).
+
+-
+
- Show the attribute table for the selected layer (applies only to vector data).
+
+
+
+
The QGIS map legend
+
The map legend area is used to set the visibility and z-ordering of layers.
+ Z-ordering means that layers listed nearer the top of the legend are drawn over
+ layers listed lower down in the legend. The checkbox in each legend entry can be useed
+ to show/hire that layer.
+
+
The QGIS map view
+
This is the 'business end' of QGIS - maps are displayed in this area! The map
+ displayed in this window will depend on the vector and raster layers you have chosen
+ to load (see sections that follow for more info on this). The map view can be panned (shifting
+ to focus of the map display to another region), zoomed in and out, and supports various other
+ actions as described in the toolbar description above.
+
The map view and the legend are tightly bound to each other - the maps in view
+ reflect changes you make in the legend area.
+
+
The QGIS map status bar
+
The status bar shows you your current position in map coordinate (e.g. meters or decimal
+ degress) as the mouse pointer is moved accross the map view.
+
-
-
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Working with vector data
-
-
-
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Loading vector data
+
+
+
+
+ |
+Working with vector data
+ | |
+
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+ | | |
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+Loading vector data
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+ | | |
+
+
+
To load one or more shapefiles, click on the Add Layer button
- 
.
+
.
The Select one or more layers to add dialog box will be displayed.
- 
+
Navigate to the directory where the shapefiles reside. Select one or
more files and click ok to load them.
When QGIS loads a layer, it assigns a random color to it as shown
below.
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+
Obviously QGIS's choice of colors is not very pleasing in this case.
-
-
-
Changing Symbology
-
+
+
+
+
+ |
+Changing Symbology
+ | |
+
+
+ | | |
+
+
+
To make the layer more appealing, open the Layer Properties
dialog by right-clicking on a layer name
in the table of contents (left side of the QGIS window) and
- selecting Properties.
+ selecting Properties.
+
If you like, change the display name of the layer by editing
+ the Display name field.
-
+
+
Click on the Legend
+ tab to display the current symbols used for the layer
- If you like, change the display name of the layer by editing
- the Display name field. Click on the Symbology
- tab and click on the Outline color and Fill color
+
+
+
Click on the Outline color and Fill color
and select a new color from the color chooser. You can also change the
line width if desired.
-
+
After making the changes, click Ok to apply the changes to
the layer. Note that the alaska layer has been renamed to Alaska and the
color has been changed to a light green:
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+
-
-
-
Identifying a Feature
-
+
+
+
+
+ |
+Identifying a Feature
+ | |
+
+
+ | | |
+
+
+
+
QGIS provides a useful tool ( - the 'identify' tool) that allows you to click on a vector feature (
+ point, line or polygon) and view information about that feautre. The information displayed is
+ retrieved from the Postgres database (in the case of Postgis layers) or from the .dbf file
+ associated with the shapefile you are insecting.
+
-
-
Working with raster data
-
-
-
-
What is raster data?
+
+
+
+
+ |
+Working with raster data
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+
+
+ | | |
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+What is raster data?
+ | |
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+ | | |
+
+
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Raster data in GIS are matrices of discrete cells that represent features on, above or below the earth's surface. Each
cell in the raster grid is the same size, and cells are usually rectangular (in QGIS they will always be rectangular.
Typical raster datasets include 'remote sensing' data (such as aerial photography and satellite imagery) and modelled data
@@ -259,11 +662,20 @@ built for Linux/Unix. QGIS currently offers basic support for vector, raster, an
In GIS, a raster layer would have geopositioning data associated with it which will allow it to be positioned
correctly in the map display to allow other vector and raster data to be overlayed with it. QGIS, can read this
geopositioning data to facilitate properly displaying map overlays.
-
-
-
Raster formats supported in QGIS.
-
+
+
+
+
+ |
+Raster formats supported in QGIS.
+ | |
+
+
+ | | |
+
+
+
QGIS supports a number of different raster formats. Currently tested formats include:
@@ -285,19 +697,37 @@ built for Linux/Unix. QGIS currently offers basic support for vector, raster, an
Because the raster implmentation in QGIS is based on the GDAL abstraction library, orther raster formats implemented
in GDAL are also likely to work, but have not yet been tested. See
the GDAL Raster Formats page for more details.
-
-
-
Loading raster data in QGIS
-
+
+
+
+
+ |
+Loading raster data in QGIS
+ | |
+
+
+ | | |
+
+
+
Raster layers are loaded either by clicking on the icon
or by selecting the View->Add Raster Layer menu option. More than one layer can be loaded at the same time
by holding down the Control key and clicking on multiple items in the file dialog.
-
-
-
Symbolisation and properties for raster layers
-
+
+
+
+
+ |
+Symbolisation and properties for raster layers
+ | |
+
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+ | | |
+
+
+
Symbolisation of raster layers is achieved by right clicking on a raster layer legend entry and choosing 'properties':
on the popup menu that appears:
@@ -305,13 +735,15 @@ built for Linux/Unix. QGIS currently offers basic support for vector, raster, an
On the properties dialog for rasters you will see there are three tabs:
-
+
The general properties tab
-
+
The legend tab displays basic information aboug the selected raster - including its
+ dimensions (in pixels) and its display name in the legend.
+
The symbology properties tab
@@ -348,63 +780,126 @@ built for Linux/Unix. QGIS currently offers basic support for vector, raster, an
QGIS has the capability to invert the colours in a given layer so that light
- colors become dark (and dark colors become light).
-
QGIS has the capability to invert the colours in a given layer so that light
- colors become dark (and dark colors become light).
-
QGIS has the capability to invert the colours in a given layer so that light
- colors become dark (and dark colors become light).
-
+ colors become dark (and dark colors become light). Use the 'Invert Color Map' checkbox
+ to enable / disable this behaviour.
+
QGIS has the capability to display each raster layer at varying transparency levels. Use
+ the transparency slider to indicate to what extent the underlying layers (if any) should
+ be visible though the current raster layer.
+
QGIS has the capability to restrict the data displayed to show only cells whose values are
+ within a given number of standard diviations of the mean for the layer. This is useful
+ when you have one or two cells with abnormally high values in a raster grid that are having a
+ negative impact on the rendering of the raster. This option is only available for pseudocolor
+ images.
+
The raster statistics properties tab
+
This tab displays statistics about each band in the current raster layer. Statistics are
+ gathered on a 'need to know' basis, so it may well be that a given layer's statistics have
+ not yet been collected.
+
Statistics for a layer are gathered when pseudocolor rendering is selected and the 'apply'
+ button is pressed.
+
+
Note
+
Gathering statistics for a layer can be time consuming. Please be patient while
+ QGIS examines your data!
+
-
-
Identifying a Feature
+
+
+
+
+ |
+Creating a QGIS mime type
+ | |
+
+
+ | | |
+
+
+
+
+
If you are a KDE user, you can create a mime type that associates GIS files with QGIS. This is useful
+ because it allows you to click on a shapefile (for example) in konqueror and the file will be loaded in a
+ new instance of QGIS.
+
+
+
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+
+
+
+
+
+ |
+Acknowledgments
+ | |
+
+
+ | | |
+
+
+
+
+
+
+
Hosting for the QGIS project is generously provided by Sourceforge.
+
-
+
+
Please see the Help->About->Contributors for a list of people who have donated their time to the QGIS project.
+
+
-
by Gary Sherman, Tim Sutton
-
