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133 lines
5.9 KiB
Python
133 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
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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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#get parameters
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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)['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)['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.pendingFields().toList(), QGis.WKBPolygon, 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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