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06c4b07222
Since the layer has more complete knowledge of the crs (ie, when provider could not determine crs and user has selected it from the list), and also better knowledge of layer fields (virtual fields, joined fields) we should use these rather than the provider methods.
138 lines
5.9 KiB
Python
138 lines
5.9 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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ConcaveHull.py
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---------------------
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Date : May 2014
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Copyright : (C) 2012 by Piotr Pociask
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Email : piotr dot pociask at gis-support dot pl
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***************************************************************************
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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***************************************************************************
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"""
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__author__ = 'Piotr Pociask'
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__date__ = 'May 2014'
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__copyright__ = '(C) 2014, Piotr Pociask'
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# This will get replaced with a git SHA1 when you do a git archive
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__revision__ = '$Format:%H$'
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from qgis.core import Qgis, QgsFeatureRequest, QgsFeature, QgsGeometry, QgsWkbTypes
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from processing.core.GeoAlgorithm import GeoAlgorithm
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from processing.core.parameters import ParameterVector
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from processing.core.parameters import ParameterNumber
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from processing.core.parameters import ParameterBoolean
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from processing.core.outputs import OutputVector
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from processing.tools import dataobjects
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import processing
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from math import sqrt
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class ConcaveHull(GeoAlgorithm):
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INPUT = 'INPUT'
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ALPHA = 'ALPHA'
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HOLES = 'HOLES'
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NO_MULTIGEOMETRY = 'NO_MULTIGEOMETRY'
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OUTPUT = 'OUTPUT'
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def defineCharacteristics(self):
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self.name, self.i18n_name = self.trAlgorithm('Concave hull')
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self.group, self.i18n_group = self.trAlgorithm('Vector geometry tools')
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self.addParameter(ParameterVector(ConcaveHull.INPUT,
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self.tr('Input point layer'), [ParameterVector.VECTOR_TYPE_POINT]))
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self.addParameter(ParameterNumber(self.ALPHA,
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self.tr('Threshold (0-1, where 1 is equivalent with Convex Hull)'),
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0, 1, 0.3))
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self.addParameter(ParameterBoolean(self.HOLES,
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self.tr('Allow holes'), True))
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self.addParameter(ParameterBoolean(self.NO_MULTIGEOMETRY,
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self.tr('Split multipart geometry into singleparts geometries'), False))
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self.addOutput(OutputVector(ConcaveHull.OUTPUT, self.tr('Concave hull')))
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def processAlgorithm(self, progress):
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layer = dataobjects.getObjectFromUri(self.getParameterValue(ConcaveHull.INPUT))
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alpha = self.getParameterValue(self.ALPHA)
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holes = self.getParameterValue(self.HOLES)
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no_multigeom = self.getParameterValue(self.NO_MULTIGEOMETRY)
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# Delaunay triangulation from input point layer
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progress.setText(self.tr('Creating Delaunay triangles...'))
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delone_triangles = processing.runalg("qgis:delaunaytriangulation", layer, None, progress=None)['OUTPUT']
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delaunay_layer = processing.getObject(delone_triangles)
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# Get max edge length from Delaunay triangles
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progress.setText(self.tr('Computing edges max length...'))
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features = delaunay_layer.getFeatures()
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counter = 50. / delaunay_layer.featureCount()
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lengths = []
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edges = {}
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for feat in features:
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line = feat.geometry().asPolygon()[0]
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for i in range(len(line) - 1):
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lengths.append(sqrt(line[i].sqrDist(line[i + 1])))
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edges[feat.id()] = max(lengths[-3:])
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progress.setPercentage(feat.id() * counter)
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max_length = max(lengths)
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# Get features with longest edge longer than alpha*max_length
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progress.setText(self.tr('Removing features...'))
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counter = 50. / len(edges)
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i = 0
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ids = []
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for id, max_len in edges.iteritems():
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if max_len > alpha * max_length:
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ids.append(id)
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progress.setPercentage(50 + i * counter)
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i += 1
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# Remove features
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delaunay_layer.setSelectedFeatures(ids)
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delaunay_layer.startEditing()
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delaunay_layer.deleteSelectedFeatures()
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delaunay_layer.commitChanges()
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# Dissolve all Delaunay triangles
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progress.setText(self.tr('Dissolving Delaunay triangles...'))
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dissolved = processing.runalg("qgis:dissolve", delaunay_layer,
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True, None, None, progress=None)['OUTPUT']
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dissolved_layer = processing.getObject(dissolved)
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# Save result
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progress.setText(self.tr('Saving data...'))
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feat = QgsFeature()
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dissolved_layer.getFeatures(QgsFeatureRequest().setFilterFid(0)).nextFeature(feat)
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writer = self.getOutputFromName(self.OUTPUT).getVectorWriter(
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layer.fields().toList(), QgsWkbTypes.Polygon, layer.crs())
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geom = feat.geometry()
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if no_multigeom and geom.isMultipart():
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# Only singlepart geometries are allowed
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geom_list = geom.asMultiPolygon()
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for single_geom_list in geom_list:
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single_feature = QgsFeature()
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single_geom = QgsGeometry.fromPolygon(single_geom_list)
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if not holes:
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# Delete holes
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deleted = True
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while deleted:
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deleted = single_geom.deleteRing(1)
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single_feature.setGeometry(single_geom)
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writer.addFeature(single_feature)
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else:
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# Multipart geometries are allowed
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if not holes:
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# Delete holes
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deleted = True
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while deleted:
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deleted = geom.deleteRing(1)
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writer.addFeature(feat)
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del writer
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