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mhugent
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Added zonal statistics class to analysis lib
git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@11931 c8812cc2-4d05-0410-92ff-de0c093fc19c
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‎src/analysis/CMakeLists.txt

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Original file line numberDiff line numberDiff line change
@@ -25,6 +25,7 @@ SET(QGIS_ANALYSIS_SRCS
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raster/qgsaspectfilter.cpp
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raster/qgstotalcurvaturefilter.cpp
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vector/qgsgeometryanalyzer.cpp
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vector/qgszonalstatistics.cpp
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)
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SET(QGIS_ANALYSIS_MOC_HDRS
@@ -93,7 +94,7 @@ INSTALL(TARGETS qgis_analysis
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# Added by Tim to install headers
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SET(QGIS_ANALYSIS_HDRS vector/qgsgeometryanalyzer.h
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SET(QGIS_ANALYSIS_HDRS vector/qgsgeometryanalyzer.h vector/qgszonalstatistics.h
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)
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INSTALL(CODE "MESSAGE(\"Installing ANALYSIS headers...\")")

‎src/analysis/vector/qgszonalstatistics.cpp

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/***************************************************************************
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qgszonalstatistics.cpp - description
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----------------------------
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begin : August 29th, 2009
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copyright : (C) 2009 by Marco Hugentobler
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email : marco at hugis dot net
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***************************************************************************/
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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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#include "qgszonalstatistics.h"
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#include "qgsgeometry.h"
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#include "qgsvectordataprovider.h"
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#include "qgsvectorlayer.h"
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#include "gdal.h"
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#include "cpl_string.h"
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#include <QProgressDialog>
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QgsZonalStatistics::QgsZonalStatistics(QgsVectorLayer* polygonLayer, const QString& rasterFile, const QString& attributePrefix, int rasterBand): \
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mRasterFilePath(rasterFile), mRasterBand(rasterBand), mPolygonLayer(polygonLayer), mAttributePrefix(attributePrefix), mInputNodataValue( -1 )
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{
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}
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QgsZonalStatistics::QgsZonalStatistics(): mRasterBand(0), mPolygonLayer(0)
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{
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}
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QgsZonalStatistics::~QgsZonalStatistics()
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{
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}
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int QgsZonalStatistics::calculateStatistics(QProgressDialog* p)
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{
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if(!mPolygonLayer || !mPolygonLayer->geometryType() == QGis::Polygon)
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{
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return 1;
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}
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QgsVectorDataProvider* vectorProvider = mPolygonLayer->dataProvider();
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if(!vectorProvider)
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{
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return 2;
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}
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//open the raster layer and the raster band
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GDALAllRegister();
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GDALDatasetH inputDataset = GDALOpen(mRasterFilePath.toLocal8Bit().data(), GA_ReadOnly );
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if ( inputDataset == NULL )
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{
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return 3;
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}
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if ( GDALGetRasterCount( inputDataset ) < (mRasterBand - 1) )
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{
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GDALClose( inputDataset );
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return 4;
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}
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GDALRasterBandH rasterBand = GDALGetRasterBand( inputDataset, mRasterBand );
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if ( rasterBand == NULL )
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{
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GDALClose( inputDataset );
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return 5;
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}
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mInputNodataValue = GDALGetRasterNoDataValue( rasterBand, NULL );
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//get geometry info about raster layer
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int nCellsX = GDALGetRasterXSize( inputDataset );
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int nCellsY = GDALGetRasterYSize( inputDataset );
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double geoTransform[6];
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if ( GDALGetGeoTransform( inputDataset, geoTransform ) != CE_None )
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{
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GDALClose( inputDataset );
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return 6;
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}
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double cellsizeX = geoTransform[1];
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if(cellsizeX < 0)
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{
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cellsizeX = -cellsizeX;
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}
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double cellsizeY = geoTransform[5];
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if(cellsizeY < 0)
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{
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cellsizeY = -cellsizeY;
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}
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QgsRectangle rasterBBox(geoTransform[0], geoTransform[3] - (nCellsY * cellsizeY), geoTransform[0] + (nCellsX * cellsizeX), geoTransform[3]);
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//add the new count, sum, mean fields to the provider
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QList<QgsField> newFieldList;
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QgsField countField(mAttributePrefix + "count", QVariant::Int);
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QgsField sumField(mAttributePrefix + "sum", QVariant::Double);
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QgsField meanField(mAttributePrefix + "mean", QVariant::Double);
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newFieldList.push_back(countField);
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newFieldList.push_back(sumField);
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newFieldList.push_back(meanField);
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if(!vectorProvider->addAttributes( newFieldList ))
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{
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return 7;
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}
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//index of the new fields
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int countIndex = vectorProvider->fieldNameIndex(mAttributePrefix + "count");
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int sumIndex = vectorProvider->fieldNameIndex(mAttributePrefix + "sum");
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int meanIndex = vectorProvider->fieldNameIndex(mAttributePrefix + "mean");
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if (countIndex == -1 || sumIndex == -1 || meanIndex == -1)
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{
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return 8;
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}
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//progress dialog
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long featureCount = vectorProvider->featureCount();
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if(p)
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{
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p->setMaximum(featureCount);
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}
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//iterate over each polygon
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vectorProvider->select(QgsAttributeList(), QgsRectangle(), true, false);
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vectorProvider->rewind();
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QgsFeature f;
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double count = 0;
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double sum = 0;
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double mean = 0;
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float* scanLine;
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int featureCounter = 0;
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//x- and y- coordinate of current cell
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double cellCenterX = 0;
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double cellCenterY = 0;
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QgsPoint currentCellCenter;
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while(vectorProvider->nextFeature(f))
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{
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if(p)
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{
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p->setValue(featureCounter);
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}
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if(p && p->wasCanceled())
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{
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break;
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}
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QgsGeometry* featureGeometry = f.geometry();
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if(!featureGeometry)
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{
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++featureCounter;
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continue;
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}
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int offsetX, offsetY, nCellsX, nCellsY;
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if(cellInfoForBBox(rasterBBox, featureGeometry->boundingBox(), cellsizeX, cellsizeY, offsetX, offsetY, nCellsX, nCellsY) != 0)
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{
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++featureCounter;
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continue;
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}
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scanLine = ( float * ) CPLMalloc( sizeof( float ) * nCellsX );
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cellCenterY = rasterBBox.yMaximum() - offsetY * cellsizeY - cellsizeY / 2;
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count = 0;
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sum = 0;
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float currentValue;
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for(int i = 0; i < nCellsY; ++i)
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{
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GDALRasterIO( rasterBand, GF_Read, offsetX, offsetY + i, nCellsX, 1, scanLine, nCellsX, 1, GDT_Float32, 0, 0 );
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cellCenterX = rasterBBox.xMinimum() + offsetX * cellsizeX + cellsizeX / 2;
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for(int j = 0; j < nCellsX; ++j)
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{
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currentCellCenter = QgsPoint(cellCenterX, cellCenterY);
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if(featureGeometry->contains(&currentCellCenter))
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{
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if(scanLine[j] != mInputNodataValue) //don't consider nodata values
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{
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sum += scanLine[j];
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++count;
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}
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}
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cellCenterX += cellsizeX;
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}
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cellCenterY -= cellsizeY;
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}
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if(count == 0)
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{
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mean = 0;
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}
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else
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{
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mean = sum / count;
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}
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//write the new AEY value to the vector data provider
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QgsChangedAttributesMap changeMap;
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QgsAttributeMap changeAttributeMap;
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changeAttributeMap.insert(countIndex, QVariant(count));
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changeAttributeMap.insert(sumIndex, QVariant(sum));
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changeAttributeMap.insert(meanIndex, QVariant(mean));
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changeMap.insert(f.id(), changeAttributeMap);
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vectorProvider->changeAttributeValues(changeMap);
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CPLFree(scanLine);
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++featureCounter;
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}
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if(p)
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{
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p->setValue(featureCount);
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}
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GDALClose( inputDataset );
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return 0;
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}
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int QgsZonalStatistics::cellInfoForBBox(const QgsRectangle& rasterBBox, const QgsRectangle& featureBBox, double cellSizeX, double cellSizeY, \
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int& offsetX, int& offsetY, int& nCellsX, int& nCellsY) const
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{
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//get intersecting bbox
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QgsRectangle intersectBox = rasterBBox.intersect(&featureBBox);
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if(intersectBox.isEmpty())
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{
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nCellsX = 0; nCellsY = 0; offsetX = 0; offsetY = 0;
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return 0;
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}
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//get offset in pixels in x- and y- direction
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offsetX = (int)( (intersectBox.xMinimum() - rasterBBox.xMinimum()) / cellSizeX);
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offsetY = (int)( (rasterBBox.yMaximum() - intersectBox.yMaximum()) / cellSizeY);
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int maxColumn = (int) ( (intersectBox.xMaximum() - rasterBBox.xMinimum()) / cellSizeX) + 1;
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int maxRow = (int) ( (rasterBBox.yMaximum() - intersectBox.yMinimum()) / cellSizeY ) + 1;
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nCellsX = maxColumn - offsetX;
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nCellsY = maxRow - offsetY;
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return 0;
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}
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‎src/analysis/vector/qgszonalstatistics.h

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/***************************************************************************
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qgszonalstatistics.h - description
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----------------------------
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begin : August 29th, 2009
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copyright : (C) 2009 by Marco Hugentobler
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email : marco at hugis dot net
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***************************************************************************/
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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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#ifndef QGSZONALSTATISTICS_H
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#define QGSZONALSTATISTICS_H
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#include "qgsrectangle.h"
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#include <QString>
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class QgsVectorLayer;
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class QProgressDialog;
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/**A class that calculates raster statistics (count, sum, mean) for a polygon or multipolygon layer and appends the results as attributes*/
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class ANALYSIS_EXPORT QgsZonalStatistics
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{
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public:
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QgsZonalStatistics(QgsVectorLayer* polygonLayer, const QString& rasterFile, const QString& attributePrefix = "", int rasterBand = 1);
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~QgsZonalStatistics();
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/**Starts the calculation
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@return 0 in case of success*/
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int calculateStatistics(QProgressDialog* p);
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private:
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QgsZonalStatistics();
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/**Analysis what cells need to be considered to cover the bounding box of a feature
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@return 0 in case of success*/
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int cellInfoForBBox(const QgsRectangle& rasterBBox, const QgsRectangle& featureBBox, double cellSizeX, double cellSizeY, \
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int& offsetX, int& offsetY, int& nCellsX, int& nCellsY) const;
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QString mRasterFilePath;
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/**Raster band to calculate statistics from (defaults to 1)*/
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int mRasterBand;
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QgsVectorLayer* mPolygonLayer;
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QString mAttributePrefix;
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/**The nodata value of the input layer*/
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float mInputNodataValue;
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};
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#endif // QGSZONALSTATISTICS_H

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