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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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mhugent
mhugent committed Nov 6, 2009
1 parent b63be1d commit 7f5ac8c56bc75c9bcf5f4b0ea487e78cd8b1ba4b
@@ -25,6 +25,7 @@ SET(QGIS_ANALYSIS_SRCS
raster/qgsaspectfilter.cpp
raster/qgstotalcurvaturefilter.cpp
vector/qgsgeometryanalyzer.cpp
vector/qgszonalstatistics.cpp
)

SET(QGIS_ANALYSIS_MOC_HDRS
@@ -93,7 +94,7 @@ INSTALL(TARGETS qgis_analysis

# Added by Tim to install headers

SET(QGIS_ANALYSIS_HDRS vector/qgsgeometryanalyzer.h
SET(QGIS_ANALYSIS_HDRS vector/qgsgeometryanalyzer.h vector/qgszonalstatistics.h
)

INSTALL(CODE "MESSAGE(\"Installing ANALYSIS headers...\")")
@@ -0,0 +1,252 @@
/***************************************************************************
qgszonalstatistics.cpp - description
----------------------------
begin : August 29th, 2009
copyright : (C) 2009 by Marco Hugentobler
email : marco at hugis dot net
***************************************************************************/

/***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************/

#include "qgszonalstatistics.h"
#include "qgsgeometry.h"
#include "qgsvectordataprovider.h"
#include "qgsvectorlayer.h"
#include "gdal.h"
#include "cpl_string.h"
#include <QProgressDialog>

QgsZonalStatistics::QgsZonalStatistics(QgsVectorLayer* polygonLayer, const QString& rasterFile, const QString& attributePrefix, int rasterBand): \
mRasterFilePath(rasterFile), mRasterBand(rasterBand), mPolygonLayer(polygonLayer), mAttributePrefix(attributePrefix), mInputNodataValue( -1 )
{

}

QgsZonalStatistics::QgsZonalStatistics(): mRasterBand(0), mPolygonLayer(0)
{

}

QgsZonalStatistics::~QgsZonalStatistics()
{

}

int QgsZonalStatistics::calculateStatistics(QProgressDialog* p)
{
if(!mPolygonLayer || !mPolygonLayer->geometryType() == QGis::Polygon)
{
return 1;
}

QgsVectorDataProvider* vectorProvider = mPolygonLayer->dataProvider();
if(!vectorProvider)
{
return 2;
}

//open the raster layer and the raster band
GDALAllRegister();
GDALDatasetH inputDataset = GDALOpen(mRasterFilePath.toLocal8Bit().data(), GA_ReadOnly );
if ( inputDataset == NULL )
{
return 3;
}

if ( GDALGetRasterCount( inputDataset ) < (mRasterBand - 1) )
{
GDALClose( inputDataset );
return 4;
}

GDALRasterBandH rasterBand = GDALGetRasterBand( inputDataset, mRasterBand );
if ( rasterBand == NULL )
{
GDALClose( inputDataset );
return 5;
}
mInputNodataValue = GDALGetRasterNoDataValue( rasterBand, NULL );

//get geometry info about raster layer
int nCellsX = GDALGetRasterXSize( inputDataset );
int nCellsY = GDALGetRasterYSize( inputDataset );
double geoTransform[6];
if ( GDALGetGeoTransform( inputDataset, geoTransform ) != CE_None )
{
GDALClose( inputDataset );
return 6;
}
double cellsizeX = geoTransform[1];
if(cellsizeX < 0)
{
cellsizeX = -cellsizeX;
}
double cellsizeY = geoTransform[5];
if(cellsizeY < 0)
{
cellsizeY = -cellsizeY;
}
QgsRectangle rasterBBox(geoTransform[0], geoTransform[3] - (nCellsY * cellsizeY), geoTransform[0] + (nCellsX * cellsizeX), geoTransform[3]);

//add the new count, sum, mean fields to the provider
QList<QgsField> newFieldList;
QgsField countField(mAttributePrefix + "count", QVariant::Int);
QgsField sumField(mAttributePrefix + "sum", QVariant::Double);
QgsField meanField(mAttributePrefix + "mean", QVariant::Double);
newFieldList.push_back(countField);
newFieldList.push_back(sumField);
newFieldList.push_back(meanField);
if(!vectorProvider->addAttributes( newFieldList ))
{
return 7;
}

//index of the new fields
int countIndex = vectorProvider->fieldNameIndex(mAttributePrefix + "count");
int sumIndex = vectorProvider->fieldNameIndex(mAttributePrefix + "sum");
int meanIndex = vectorProvider->fieldNameIndex(mAttributePrefix + "mean");

if (countIndex == -1 || sumIndex == -1 || meanIndex == -1)
{
return 8;
}

//progress dialog
long featureCount = vectorProvider->featureCount();
if(p)
{
p->setMaximum(featureCount);
}


//iterate over each polygon
vectorProvider->select(QgsAttributeList(), QgsRectangle(), true, false);
vectorProvider->rewind();
QgsFeature f;
double count = 0;
double sum = 0;
double mean = 0;
float* scanLine;
int featureCounter = 0;
//x- and y- coordinate of current cell
double cellCenterX = 0;
double cellCenterY = 0;
QgsPoint currentCellCenter;

while(vectorProvider->nextFeature(f))
{
if(p)
{
p->setValue(featureCounter);
}

if(p && p->wasCanceled())
{
break;
}

QgsGeometry* featureGeometry = f.geometry();
if(!featureGeometry)
{
++featureCounter;
continue;
}

int offsetX, offsetY, nCellsX, nCellsY;
if(cellInfoForBBox(rasterBBox, featureGeometry->boundingBox(), cellsizeX, cellsizeY, offsetX, offsetY, nCellsX, nCellsY) != 0)
{
++featureCounter;
continue;
}

scanLine = ( float * ) CPLMalloc( sizeof( float ) * nCellsX );
cellCenterY = rasterBBox.yMaximum() - offsetY * cellsizeY - cellsizeY / 2;
count = 0;
sum = 0;
float currentValue;

for(int i = 0; i < nCellsY; ++i)
{
GDALRasterIO( rasterBand, GF_Read, offsetX, offsetY + i, nCellsX, 1, scanLine, nCellsX, 1, GDT_Float32, 0, 0 );
cellCenterX = rasterBBox.xMinimum() + offsetX * cellsizeX + cellsizeX / 2;
for(int j = 0; j < nCellsX; ++j)
{
currentCellCenter = QgsPoint(cellCenterX, cellCenterY);
if(featureGeometry->contains(&currentCellCenter))
{
if(scanLine[j] != mInputNodataValue) //don't consider nodata values
{
sum += scanLine[j];
++count;
}
}
cellCenterX += cellsizeX;
}
cellCenterY -= cellsizeY;
}

if(count == 0)
{
mean = 0;
}
else
{
mean = sum / count;
}

//write the new AEY value to the vector data provider
QgsChangedAttributesMap changeMap;
QgsAttributeMap changeAttributeMap;
changeAttributeMap.insert(countIndex, QVariant(count));
changeAttributeMap.insert(sumIndex, QVariant(sum));
changeAttributeMap.insert(meanIndex, QVariant(mean));
changeMap.insert(f.id(), changeAttributeMap);
vectorProvider->changeAttributeValues(changeMap);

CPLFree(scanLine);
++featureCounter;
}

if(p)
{
p->setValue(featureCount);
}

GDALClose( inputDataset );
return 0;
}

int QgsZonalStatistics::cellInfoForBBox(const QgsRectangle& rasterBBox, const QgsRectangle& featureBBox, double cellSizeX, double cellSizeY, \
int& offsetX, int& offsetY, int& nCellsX, int& nCellsY) const
{
//get intersecting bbox
QgsRectangle intersectBox = rasterBBox.intersect(&featureBBox);
if(intersectBox.isEmpty())
{
nCellsX = 0; nCellsY = 0; offsetX = 0; offsetY = 0;
return 0;
}

//get offset in pixels in x- and y- direction
offsetX = (int)( (intersectBox.xMinimum() - rasterBBox.xMinimum()) / cellSizeX);
offsetY = (int)( (rasterBBox.yMaximum() - intersectBox.yMaximum()) / cellSizeY);

int maxColumn = (int) ( (intersectBox.xMaximum() - rasterBBox.xMinimum()) / cellSizeX) + 1;
int maxRow = (int) ( (rasterBBox.yMaximum() - intersectBox.yMinimum()) / cellSizeY ) + 1;

nCellsX = maxColumn - offsetX;
nCellsY = maxRow - offsetY;

return 0;
}




@@ -0,0 +1,54 @@
/***************************************************************************
qgszonalstatistics.h - description
----------------------------
begin : August 29th, 2009
copyright : (C) 2009 by Marco Hugentobler
email : marco at hugis dot net
***************************************************************************/

/***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************/

#ifndef QGSZONALSTATISTICS_H
#define QGSZONALSTATISTICS_H

#include "qgsrectangle.h"
#include <QString>

class QgsVectorLayer;
class QProgressDialog;

/**A class that calculates raster statistics (count, sum, mean) for a polygon or multipolygon layer and appends the results as attributes*/
class ANALYSIS_EXPORT QgsZonalStatistics
{
public:
QgsZonalStatistics(QgsVectorLayer* polygonLayer, const QString& rasterFile, const QString& attributePrefix = "", int rasterBand = 1);
~QgsZonalStatistics();

/**Starts the calculation
@return 0 in case of success*/
int calculateStatistics(QProgressDialog* p);

private:
QgsZonalStatistics();
/**Analysis what cells need to be considered to cover the bounding box of a feature
@return 0 in case of success*/
int cellInfoForBBox(const QgsRectangle& rasterBBox, const QgsRectangle& featureBBox, double cellSizeX, double cellSizeY, \
int& offsetX, int& offsetY, int& nCellsX, int& nCellsY) const;

QString mRasterFilePath;
/**Raster band to calculate statistics from (defaults to 1)*/
int mRasterBand;
QgsVectorLayer* mPolygonLayer;
QString mAttributePrefix;
/**The nodata value of the input layer*/
float mInputNodataValue;
};

#endif // QGSZONALSTATISTICS_H

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