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Zonal statistics: avoid access to pixels outside the raster. Fixes ti… 
…cket #6624
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@mhugent
mhugent committed Nov 10, 2012
1 parent e899021 commit 8914e7d
Showing 1 changed file with 52 additions and 131 deletions.
183 src/analysis/vector/qgszonalstatistics.cpp
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@@ -87,8 +87,8 @@ int QgsZonalStatistics::calculateStatistics( QProgressDialog* p )
mInputNodataValue = GDALGetRasterNoDataValue( rasterBand, NULL );

//get geometry info about raster layer
int nCellsX = GDALGetRasterXSize( inputDataset );
int nCellsY = GDALGetRasterYSize( inputDataset );
int nCellsXGDAL = GDALGetRasterXSize( inputDataset );
int nCellsYGDAL = GDALGetRasterYSize( inputDataset );
double geoTransform[6];
if ( GDALGetGeoTransform( inputDataset, geoTransform ) != CE_None )
{
@@ -105,7 +105,8 @@ int QgsZonalStatistics::calculateStatistics( QProgressDialog* p )
{
cellsizeY = -cellsizeY;
}
QgsRectangle rasterBBox( geoTransform[0], geoTransform[3] - ( nCellsY * cellsizeY ), geoTransform[0] + ( nCellsX * cellsizeX ), geoTransform[3] );
QgsRectangle rasterBBox( geoTransform[0], geoTransform[3] - ( nCellsYGDAL * cellsizeY ),
geoTransform[0] + ( nCellsXGDAL * cellsizeX ), geoTransform[3] );

//add the new count, sum, mean fields to the provider
QList<QgsField> newFieldList;
@@ -145,7 +146,6 @@ int QgsZonalStatistics::calculateStatistics( QProgressDialog* p )

while ( vectorProvider->nextFeature( f ) )
{
qWarning( "%d", featureCounter );
if ( p )
{
p->setValue( featureCounter );
@@ -163,15 +163,32 @@ int QgsZonalStatistics::calculateStatistics( QProgressDialog* p )
continue;
}

QgsRectangle featureRect = featureGeometry->boundingBox().intersect( &rasterBBox );
if ( featureRect.isEmpty() )
{
++featureCounter;
continue;
}

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

statisticsFromMiddlePointTest_improved( rasterBand, featureGeometry, offsetX, offsetY, nCellsX, nCellsY, cellsizeX, cellsizeY,
rasterBBox, sum, count );
//avoid access to cells outside of the raster (may occur because of rounding)
if (( offsetX + nCellsX ) > nCellsXGDAL )
{
nCellsX = nCellsXGDAL - offsetX;
}
if (( offsetY + nCellsY ) > nCellsYGDAL )
{
nCellsY = nCellsYGDAL - offsetY;
}

statisticsFromMiddlePointTest( rasterBand, featureGeometry, offsetX, offsetY, nCellsX, nCellsY, cellsizeX, cellsizeY,
rasterBBox, sum, count );

if ( count <= 1 )
{
@@ -246,21 +263,44 @@ void QgsZonalStatistics::statisticsFromMiddlePointTest( void* band, QgsGeometry*
int pixelOffsetY, int nCellsX, int nCellsY, double cellSizeX, double cellSizeY, const QgsRectangle& rasterBBox, double& sum, double& count )
{
double cellCenterX, cellCenterY;
QgsPoint currentCellCenter;

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

GEOSGeometry* polyGeos = poly->asGeos();
if ( !polyGeos )
{
return;
}

const GEOSPreparedGeometry* polyGeosPrepared = GEOSPrepare( poly->asGeos() );
if ( !polyGeosPrepared )
{
return;
}

GEOSCoordSequence* cellCenterCoords = 0;
GEOSGeometry* currentCellCenter = 0;

for ( int i = 0; i < nCellsY; ++i )
{
GDALRasterIO( band, GF_Read, pixelOffsetX, pixelOffsetY + i, nCellsX, 1, scanLine, nCellsX, 1, GDT_Float32, 0, 0 );
if ( GDALRasterIO( band, GF_Read, pixelOffsetX, pixelOffsetY + i, nCellsX, 1, scanLine, nCellsX, 1, GDT_Float32, 0, 0 )
!= CPLE_None )
{
continue;
}
cellCenterX = rasterBBox.xMinimum() + pixelOffsetX * cellSizeX + cellSizeX / 2;
for ( int j = 0; j < nCellsX; ++j )
{
currentCellCenter = QgsPoint( cellCenterX, cellCenterY );
if ( poly->contains( &currentCellCenter ) )
GEOSGeom_destroy( currentCellCenter );
cellCenterCoords = GEOSCoordSeq_create( 1, 2 );
GEOSCoordSeq_setX( cellCenterCoords, 0, cellCenterX );
GEOSCoordSeq_setY( cellCenterCoords, 0, cellCenterY );
currentCellCenter = GEOSGeom_createPoint( cellCenterCoords );

if ( GEOSPreparedContains( polyGeosPrepared, currentCellCenter ) )
{
if ( scanLine[j] != mInputNodataValue ) //don't consider nodata values
{
@@ -273,6 +313,7 @@ void QgsZonalStatistics::statisticsFromMiddlePointTest( void* band, QgsGeometry*
cellCenterY -= cellSizeY;
}
CPLFree( scanLine );
GEOSPreparedGeom_destroy( polyGeosPrepared );
}

void QgsZonalStatistics::statisticsFromPreciseIntersection( void* band, QgsGeometry* poly, int pixelOffsetX,
@@ -319,124 +360,4 @@ void QgsZonalStatistics::statisticsFromPreciseIntersection( void* band, QgsGeome
CPLFree( pixelData );
}

void QgsZonalStatistics::statisticsFromMiddlePointTest_improved( void* band, QgsGeometry* poly, int pixelOffsetX, int pixelOffsetY, int nCellsX, int nCellsY,
double cellSizeX, double cellSizeY, const QgsRectangle& rasterBBox, double& sum, double& count )
{
double cellCenterX, cellCenterY;
QgsPoint currentCellCenter;

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

for ( int i = 0; i < nCellsY; ++i )
{
GDALRasterIO( band, GF_Read, pixelOffsetX, pixelOffsetY + i, nCellsX, 1, scanLine, nCellsX, 1, GDT_Float32, 0, 0 );
cellCenterX = rasterBBox.xMinimum() + pixelOffsetX * cellSizeX + cellSizeX / 2;

//do intersection of scanline with geometry
GEOSCoordSequence* scanLineSequence = GEOSCoordSeq_create( 2, 2 );
GEOSCoordSeq_setX( scanLineSequence, 0, cellCenterX );
GEOSCoordSeq_setY( scanLineSequence, 0, cellCenterY );
GEOSCoordSeq_setX( scanLineSequence, 1, cellCenterX + nCellsX * cellSizeX );
GEOSCoordSeq_setY( scanLineSequence, 1, cellCenterY );
GEOSGeometry* scanLineGeos = GEOSGeom_createLineString( scanLineSequence ); //todo: delete
GEOSGeometry* polyGeos = poly->asGeos();
GEOSGeometry* scanLineIntersection = GEOSIntersection( scanLineGeos, polyGeos );
GEOSGeom_destroy( scanLineGeos );
if ( !scanLineIntersection )
{
cellCenterY -= cellSizeY;
continue;
}

//debug
//char* scanLineIntersectionType = GEOSGeomType( scanLineIntersection );

int numGeoms = GEOSGetNumGeometries( scanLineIntersection );
if ( numGeoms < 1 )
{
GEOSGeom_destroy( scanLineIntersection );
cellCenterY -= cellSizeY;
continue;
}

QList<double> scanLineList;
double currentValue;
GEOSGeometry* currentGeom = 0;
for ( int z = 0; z < numGeoms; ++z )
{
if ( numGeoms == 1 )
{
currentGeom = scanLineIntersection;
}
else
{
currentGeom = GEOSGeom_clone( GEOSGetGeometryN( scanLineIntersection, z ) );
}
const GEOSCoordSequence* scanLineCoordSequence = GEOSGeom_getCoordSeq( currentGeom );
if ( !scanLineCoordSequence )
{
//error
}
unsigned int scanLineIntersectionSize;
GEOSCoordSeq_getSize( scanLineCoordSequence, &scanLineIntersectionSize );
if ( !scanLineCoordSequence || scanLineIntersectionSize < 2 || ( scanLineIntersectionSize & 1 ) )
{
//error
}
for ( unsigned int k = 0; k < scanLineIntersectionSize; ++k )
{
GEOSCoordSeq_getX( scanLineCoordSequence, k, &currentValue );
scanLineList.push_back( currentValue );
}

if ( numGeoms != 1 )
{
GEOSGeom_destroy( currentGeom );
}
}
GEOSGeom_destroy( scanLineIntersection );
qSort( scanLineList );

if ( scanLineList.size() < 1 )
{
cellCenterY -= cellSizeY;
continue;
}

int listPlace = -1;
for ( int j = 0; j < nCellsX; ++j )
{
//currentCellCenter = QgsPoint( cellCenterX, cellCenterY );

//instead of doing a contained test every time, find the place of scanLineList and check if even / odd
if ( listPlace >= scanLineList.size() - 1 )
{
break;
}
if ( cellCenterX >= scanLineList.at( listPlace + 1 ) )
{
++listPlace;
if ( listPlace >= scanLineList.size() )
{
break;
}
}
if ( listPlace >= 0 && listPlace < ( scanLineList.size() - 1 ) && !( listPlace & 1 ) )
{
if ( scanLine[j] != mInputNodataValue ) //don't consider nodata values
{
sum += scanLine[j];
++count;
}
}
cellCenterX += cellSizeX;
}
cellCenterY -= cellSizeY;
}
CPLFree( scanLine );
}


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