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nyalldawsonnyalldawson
committedAug 30, 2017
[FEATURE] New algorithm for creating vector layer from raster layer's extent
Allows creation of a new vector layer with a single feature containing a raster layer's extent. Previously this was only possible for vector layers.
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ltr-3_40final-3_0_0
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‎python/plugins/processing/algs/help/qgis.yaml

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@@ -402,12 +402,14 @@ qgis:polygoncentroids: >
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NOTE: This algorithm is deprecated and the generic "centroids" algorithm (which works for line and multi geometry layers) should be used instead.
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qgis:polygonfromlayerextent: >
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This algorithm takes a vector layer and generates a new one with the minimum bounding box (rectangle with N-S orientation) that covers all the input features.
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As an alternative, the output layer can contain not just a single bounding box, but one for each input feature, representing the bounding box of each of them.
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qgis:polygonfromrasterextent: >
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This algorithm takes a raster layer and generates a vector layer containing a feature with the minimum bounding box that covers the raster layer's extent.
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qgis:polygonize: >
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This algorithm takes a lines layer and creates a polygon layer, with polygons generated from the lines in the input layer.
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‎python/plugins/processing/algs/qgis/ExtentFromRasterLayer.py

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# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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ExtentFromRasterLayer.py
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---------------------
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Date : August 2017
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Copyright : (C) 2017 by Nyall Dawson
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Email : nyall dot dawson at gmail dot com
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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__ = 'Nyall Dawson'
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__date__ = 'August 2017'
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__copyright__ = '(C) 2017, Nyall Dawson'
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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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import os
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from qgis.PyQt.QtGui import QIcon
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from qgis.PyQt.QtCore import QVariant
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from qgis.core import (QgsField,
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QgsFeatureSink,
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QgsPointXY,
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QgsGeometry,
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QgsFeature,
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QgsWkbTypes,
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QgsProcessing,
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QgsProcessingParameterRasterLayer,
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QgsProcessingParameterFeatureSink,
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QgsFields)
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from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
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pluginPath = os.path.split(os.path.split(os.path.dirname(__file__))[0])[0]
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class ExtentFromRasterLayer(QgisAlgorithm):
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INPUT = 'INPUT'
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OUTPUT = 'OUTPUT'
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def icon(self):
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return QIcon(os.path.join(pluginPath, 'images', 'ftools', 'layer_extent.png'))
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def tags(self):
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return self.tr('extent,envelope,bounds,bounding,boundary,layer').split(',')
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def group(self):
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return self.tr('Raster tools')
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def __init__(self):
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super().__init__()
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def initAlgorithm(self, config=None):
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self.addParameter(QgsProcessingParameterRasterLayer(self.INPUT, self.tr('Input layer')))
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self.addParameter(QgsProcessingParameterFeatureSink(self.OUTPUT, self.tr('Extent'), type=QgsProcessing.TypeVectorPolygon))
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def name(self):
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return 'polygonfromrasterextent'
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def displayName(self):
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return self.tr('Polygon from raster extent')
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def processAlgorithm(self, parameters, context, feedback):
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raster = self.parameterAsRasterLayer(parameters, self.INPUT, context)
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fields = QgsFields()
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fields.append(QgsField('MINX', QVariant.Double))
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fields.append(QgsField('MINY', QVariant.Double))
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fields.append(QgsField('MAXX', QVariant.Double))
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fields.append(QgsField('MAXY', QVariant.Double))
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fields.append(QgsField('CNTX', QVariant.Double))
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fields.append(QgsField('CNTY', QVariant.Double))
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fields.append(QgsField('AREA', QVariant.Double))
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fields.append(QgsField('PERIM', QVariant.Double))
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fields.append(QgsField('HEIGHT', QVariant.Double))
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fields.append(QgsField('WIDTH', QVariant.Double))
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(sink, dest_id) = self.parameterAsSink(parameters, self.OUTPUT, context,
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fields, QgsWkbTypes.Polygon, raster.crs())
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self.layerExtent(raster, sink, feedback)
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return {self.OUTPUT: dest_id}
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def layerExtent(self, raster, sink, feedback):
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rect = raster.extent()
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geometry = QgsGeometry.fromRect(rect)
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minx = rect.xMinimum()
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miny = rect.yMinimum()
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maxx = rect.xMaximum()
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maxy = rect.yMaximum()
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height = rect.height()
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width = rect.width()
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cntx = minx + width / 2.0
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cnty = miny + height / 2.0
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area = width * height
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perim = 2 * width + 2 * height
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feat = QgsFeature()
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feat.setGeometry(geometry)
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attrs = [
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minx,
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miny,
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maxx,
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maxy,
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cntx,
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cnty,
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area,
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perim,
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height,
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width,
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]
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feat.setAttributes(attrs)
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sink.addFeature(feat, QgsFeatureSink.FastInsert)

‎python/plugins/processing/algs/qgis/QGISAlgorithmProvider.py

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@@ -70,6 +70,7 @@
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from .ExportGeometryInfo import ExportGeometryInfo
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from .ExtendLines import ExtendLines
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from .ExtentFromLayer import ExtentFromLayer
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from .ExtentFromRasterLayer import ExtentFromRasterLayer
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from .ExtractNodes import ExtractNodes
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from .ExtractSpecificNodes import ExtractSpecificNodes
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from .FieldPyculator import FieldsPyculator
@@ -222,6 +223,7 @@ def getAlgs(self):
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ExportGeometryInfo(),
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ExtendLines(),
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ExtentFromLayer(),
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ExtentFromRasterLayer(),
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ExtractNodes(),
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ExtractSpecificNodes(),
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FieldsCalculator(),

‎python/plugins/processing/tests/testdata/expected/raster_extent.gfs

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<GMLFeatureClassList>
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<GMLFeatureClass>
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<Name>raster_extent</Name>
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<ElementPath>raster_extent</ElementPath>
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<!--POLYGON-->
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<GeometryType>3</GeometryType>
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<SRSName>EPSG:4326</SRSName>
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<DatasetSpecificInfo>
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<FeatureCount>1</FeatureCount>
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<ExtentXMin>18.66630</ExtentXMin>
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<ExtentXMax>18.70360</ExtentXMax>
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<ExtentYMin>45.77670</ExtentYMin>
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<ExtentYMax>45.81170</ExtentYMax>
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</DatasetSpecificInfo>
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<PropertyDefn>
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<Name>MINX</Name>
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<ElementPath>MINX</ElementPath>
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<Type>Real</Type>
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</PropertyDefn>
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<PropertyDefn>
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<Name>MINY</Name>
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<ElementPath>MINY</ElementPath>
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<Type>Real</Type>
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</PropertyDefn>
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<PropertyDefn>
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<Name>MAXX</Name>
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<ElementPath>MAXX</ElementPath>
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<Type>Real</Type>
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</PropertyDefn>
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<PropertyDefn>
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<Name>MAXY</Name>
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<ElementPath>MAXY</ElementPath>
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<Type>Real</Type>
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</PropertyDefn>
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<PropertyDefn>
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<Name>CNTX</Name>
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<ElementPath>CNTX</ElementPath>
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<Type>Real</Type>
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</PropertyDefn>
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<PropertyDefn>
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<Name>CNTY</Name>
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<ElementPath>CNTY</ElementPath>
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<Type>Real</Type>
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</PropertyDefn>
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<PropertyDefn>
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<Name>AREA</Name>
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<ElementPath>AREA</ElementPath>
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<Type>Real</Type>
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</PropertyDefn>
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<PropertyDefn>
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<Name>PERIM</Name>
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<ElementPath>PERIM</ElementPath>
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<Type>Real</Type>
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</PropertyDefn>
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<PropertyDefn>
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<Name>HEIGHT</Name>
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<ElementPath>HEIGHT</ElementPath>
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<Type>Real</Type>
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</PropertyDefn>
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<PropertyDefn>
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<Name>WIDTH</Name>
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<ElementPath>WIDTH</ElementPath>
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<Type>Real</Type>
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</PropertyDefn>
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</GMLFeatureClass>
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</GMLFeatureClassList>

‎python/plugins/processing/tests/testdata/expected/raster_extent.gml

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<?xml version="1.0" encoding="utf-8" ?>
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<ogr:FeatureCollection
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation=""
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xmlns:ogr="http://ogr.maptools.org/"
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xmlns:gml="http://www.opengis.net/gml">
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<gml:boundedBy>
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<gml:Box>
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<gml:coord><gml:X>18.6662979442</gml:X><gml:Y>45.7767014376</gml:Y></gml:coord>
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<gml:coord><gml:X>18.7035979442</gml:X><gml:Y>45.8117014376</gml:Y></gml:coord>
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</gml:Box>
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</gml:boundedBy>
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<gml:featureMember>
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<ogr:raster_extent fid="raster_extent.0">
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<ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>18.6662979442,45.7767014376 18.7035979442,45.7767014376 18.7035979442,45.8117014376 18.6662979442,45.8117014376 18.6662979442,45.7767014376</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
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<ogr:MINX>18.6662979442</ogr:MINX>
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<ogr:MINY>45.7767014376</ogr:MINY>
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<ogr:MAXX>18.7035979442</ogr:MAXX>
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<ogr:MAXY>45.8117014376</ogr:MAXY>
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<ogr:CNTX>18.6849479442</ogr:CNTX>
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<ogr:CNTY>45.7942014376</ogr:CNTY>
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<ogr:AREA>0.00130549999999981</ogr:AREA>
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<ogr:PERIM>0.14459999999999</ogr:PERIM>
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<ogr:HEIGHT>0.0349999999999966</ogr:HEIGHT>
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<ogr:WIDTH>0.0372999999999983</ogr:WIDTH>
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</ogr:raster_extent>
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</gml:featureMember>
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</ogr:FeatureCollection>

‎python/plugins/processing/tests/testdata/qgis_algorithm_tests.yaml

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@@ -3228,3 +3228,14 @@ tests:
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OUTPUT:
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name: expected/execute_sql.gml
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type: vector
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- algorithm: qgis:polygonfromrasterextent
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name: Polygon from raster extent
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params:
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INPUT:
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name: dem.tif
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type: raster
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results:
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OUTPUT:
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name: expected\raster_extent.gml
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type: vector

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