QgsRasterBandStats QgsRasterInterface::bandStatistics( int theBandNo,
int theStats,
const QgsRectangle & theExtent,
int theSampleSize )
{
QgsDebugMsg( QString( "theBandNo = %1 theStats = %2 theSampleSize = %3" ).arg( theBandNo ).arg( theStats ).arg( theSampleSize ) );
// TODO: null values set on raster layer!!!
QgsRasterBandStats myRasterBandStats;
initStatistics( myRasterBandStats, theBandNo, theStats, theExtent, theSampleSize );
foreach ( QgsRasterBandStats stats, mStatistics )
{
if ( stats.contains( myRasterBandStats ) )
{
QgsDebugMsg( "Using cached statistics." );
return stats;
}
}
QgsRectangle myExtent = myRasterBandStats.extent;
int myWidth = myRasterBandStats.width;
int myHeight = myRasterBandStats.height;
//int myDataType = dataType( theBandNo );
int myXBlockSize = xBlockSize();
int myYBlockSize = yBlockSize();
if ( myXBlockSize == 0 ) // should not happen, but happens
{
myXBlockSize = 500;
}
if ( myYBlockSize == 0 ) // should not happen, but happens
{
myYBlockSize = 500;
}
int myNXBlocks = ( myWidth + myXBlockSize - 1 ) / myXBlockSize;
int myNYBlocks = ( myHeight + myYBlockSize - 1 ) / myYBlockSize;
double myXRes = myExtent.width() / myWidth;
double myYRes = myExtent.height() / myHeight;
// TODO: progress signals
// used by single pass stdev
double myMean = 0;
double mySumOfSquares = 0;
bool myFirstIterationFlag = true;
for ( int myYBlock = 0; myYBlock < myNYBlocks; myYBlock++ )
{
for ( int myXBlock = 0; myXBlock < myNXBlocks; myXBlock++ )
{
QgsDebugMsg( QString( "myYBlock = %1 myXBlock = %2" ).arg( myYBlock ).arg( myXBlock ) );
int myBlockWidth = qMin( myXBlockSize, myWidth - myXBlock * myXBlockSize );
int myBlockHeight = qMin( myYBlockSize, myHeight - myYBlock * myYBlockSize );
double xmin = myExtent.xMinimum() + myXBlock * myXBlockSize * myXRes;
double xmax = xmin + myBlockWidth * myXRes;
double ymin = myExtent.yMaximum() - myYBlock * myYBlockSize * myYRes;
double ymax = ymin - myBlockHeight * myYRes;
QgsRectangle myPartExtent( xmin, ymin, xmax, ymax );
QgsRasterBlock* blk = block( theBandNo, myPartExtent, myBlockWidth, myBlockHeight );
// Collect the histogram counts.
for ( qgssize i = 0; i < (( qgssize ) myBlockHeight ) * myBlockWidth; i++ )
{
if ( blk->isNoData( i ) ) continue; // NULL
double myValue = blk->value( i );
myRasterBandStats.sum += myValue;
myRasterBandStats.elementCount++;
if ( myFirstIterationFlag )
{
myFirstIterationFlag = false;
myRasterBandStats.minimumValue = myValue;
myRasterBandStats.maximumValue = myValue;
}
else
{
if ( myValue < myRasterBandStats.minimumValue )
{
myRasterBandStats.minimumValue = myValue;
}
if ( myValue > myRasterBandStats.maximumValue )
{
myRasterBandStats.maximumValue = myValue;
}
}
// Single pass stdev
double myDelta = myValue - myMean;
myMean += myDelta / myRasterBandStats.elementCount;
mySumOfSquares += myDelta * ( myValue - myMean );
}
delete blk;
}
}
myRasterBandStats.range = myRasterBandStats.maximumValue - myRasterBandStats.minimumValue;
myRasterBandStats.mean = myRasterBandStats.sum / myRasterBandStats.elementCount;
myRasterBandStats.sumOfSquares = mySumOfSquares; // OK with single pass?
// stdDev may differ from GDAL stats, because GDAL is using naive single pass
// algorithm which is more error prone (because of rounding errors)
// Divide result by sample size - 1 and get square root to get stdev
myRasterBandStats.stdDev = sqrt( mySumOfSquares / ( myRasterBandStats.elementCount - 1 ) );
QgsDebugMsg( "************ STATS **************" );
QgsDebugMsg( QString( "MIN %1" ).arg( myRasterBandStats.minimumValue ) );
QgsDebugMsg( QString( "MAX %1" ).arg( myRasterBandStats.maximumValue ) );
QgsDebugMsg( QString( "RANGE %1" ).arg( myRasterBandStats.range ) );
QgsDebugMsg( QString( "MEAN %1" ).arg( myRasterBandStats.mean ) );
QgsDebugMsg( QString( "STDDEV %1" ).arg( myRasterBandStats.stdDev ) );
myRasterBandStats.statsGathered = QgsRasterBandStats::All;
mStatistics.append( myRasterBandStats );
return myRasterBandStats;
}
QgsRasterHistogram QgsRasterInterface::histogram( int theBandNo,
int theBinCount,
double theMinimum, double theMaximum,
const QgsRectangle & theExtent,
int theSampleSize,
bool theIncludeOutOfRange )
{
QgsDebugMsg( QString( "theBandNo = %1 theBinCount = %2 theMinimum = %3 theMaximum = %4 theSampleSize = %5" ).arg( theBandNo ).arg( theBinCount ).arg( theMinimum ).arg( theMaximum ).arg( theSampleSize ) );
QgsRasterHistogram myHistogram;
initHistogram( myHistogram, theBandNo, theBinCount, theMinimum, theMaximum, theExtent, theSampleSize, theIncludeOutOfRange );
// Find cached
foreach ( QgsRasterHistogram histogram, mHistograms )
{
if ( histogram == myHistogram )
{
QgsDebugMsg( "Using cached histogram." );
return histogram;
}
}
int myBinCount = myHistogram.binCount;
int myWidth = myHistogram.width;
int myHeight = myHistogram.height;
QgsRectangle myExtent = myHistogram.extent;
myHistogram.histogramVector.resize( myBinCount );
int myXBlockSize = xBlockSize();
int myYBlockSize = yBlockSize();
if ( myXBlockSize == 0 ) // should not happen, but happens
{
myXBlockSize = 500;
}
if ( myYBlockSize == 0 ) // should not happen, but happens
{
myYBlockSize = 500;
}
int myNXBlocks = ( myWidth + myXBlockSize - 1 ) / myXBlockSize;
int myNYBlocks = ( myHeight + myYBlockSize - 1 ) / myYBlockSize;
double myXRes = myExtent.width() / myWidth;
double myYRes = myExtent.height() / myHeight;
double myMinimum = myHistogram.minimum;
double myMaximum = myHistogram.maximum;
// To avoid rounding errors
// TODO: check this
double myerval = ( myMaximum - myMinimum ) / myHistogram.binCount;
myMinimum -= 0.1 * myerval;
myMaximum += 0.1 * myerval;
QgsDebugMsg( QString( "binCount = %1 myMinimum = %2 myMaximum = %3" ).arg( myHistogram.binCount ).arg( myMinimum ).arg( myMaximum ) );
double myBinSize = ( myMaximum - myMinimum ) / myBinCount;
// TODO: progress signals
for ( int myYBlock = 0; myYBlock < myNYBlocks; myYBlock++ )
{
for ( int myXBlock = 0; myXBlock < myNXBlocks; myXBlock++ )
{
int myBlockWidth = qMin( myXBlockSize, myWidth - myXBlock * myXBlockSize );
int myBlockHeight = qMin( myYBlockSize, myHeight - myYBlock * myYBlockSize );
double xmin = myExtent.xMinimum() + myXBlock * myXBlockSize * myXRes;
double xmax = xmin + myBlockWidth * myXRes;
double ymin = myExtent.yMaximum() - myYBlock * myYBlockSize * myYRes;
double ymax = ymin - myBlockHeight * myYRes;
QgsRectangle myPartExtent( xmin, ymin, xmax, ymax );
QgsRasterBlock* blk = block( theBandNo, myPartExtent, myBlockWidth, myBlockHeight );
// Collect the histogram counts.
for ( qgssize i = 0; i < (( qgssize ) myBlockHeight ) * myBlockWidth; i++ )
{
if ( blk->isNoData( i ) )
{
continue; // NULL
}
double myValue = blk->value( i );
int myBinIndex = static_cast <int>( qFloor(( myValue - myMinimum ) / myBinSize ) ) ;
if (( myBinIndex < 0 || myBinIndex > ( myBinCount - 1 ) ) && !theIncludeOutOfRange )
{
continue;
}
if ( myBinIndex < 0 ) myBinIndex = 0;
if ( myBinIndex > ( myBinCount - 1 ) ) myBinIndex = myBinCount - 1;
myHistogram.histogramVector[myBinIndex] += 1;
myHistogram.nonNullCount++;
}
delete blk;
}
}
myHistogram.valid = true;
mHistograms.append( myHistogram );
#ifdef QGISDEBUG
QString hist;
for ( int i = 0; i < qMin( myHistogram.histogramVector.size(), 500 ); i++ )
{
hist += QString::number( myHistogram.histogramVector.value( i ) ) + " ";
}
QgsDebugMsg( "Histogram (max first 500 bins): " + hist );
#endif
return myHistogram;
}
QgsRasterBandStats QgsRasterDataProvider::bandStatistics( int theBandNo )
{
double myNoDataValue = noDataValue();
QgsRasterBandStats myRasterBandStats;
myRasterBandStats.elementCount = 0; // because we'll be counting only VALID pixels later
myRasterBandStats.bandName = generateBandName( theBandNo );
myRasterBandStats.bandNumber = theBandNo;
int myDataType = dataType( theBandNo );
int myNXBlocks, myNYBlocks, myXBlockSize, myYBlockSize;
myXBlockSize = xBlockSize();
myYBlockSize = yBlockSize();
myNXBlocks = ( xSize() + myXBlockSize - 1 ) / myXBlockSize;
myNYBlocks = ( ySize() + myYBlockSize - 1 ) / myYBlockSize;
void *myData = CPLMalloc( myXBlockSize * myYBlockSize * ( dataTypeSize( theBandNo ) / 8 ) );
// unfortunately we need to make two passes through the data to calculate stddev
bool myFirstIterationFlag = true;
int myBandXSize = xSize();
int myBandYSize = ySize();
for ( int iYBlock = 0; iYBlock < myNYBlocks; iYBlock++ )
{
for ( int iXBlock = 0; iXBlock < myNXBlocks; iXBlock++ )
{
int nXValid, nYValid;
readBlock( theBandNo, iXBlock, iYBlock, myData );
// Compute the portion of the block that is valid
// for partial edge blocks.
if (( iXBlock + 1 ) * myXBlockSize > myBandXSize )
nXValid = myBandXSize - iXBlock * myXBlockSize;
else
nXValid = myXBlockSize;
if (( iYBlock + 1 ) * myYBlockSize > myBandYSize )
nYValid = myBandYSize - iYBlock * myYBlockSize;
else
nYValid = myYBlockSize;
// Collect the histogram counts.
for ( int iY = 0; iY < nYValid; iY++ )
{
for ( int iX = 0; iX < nXValid; iX++ )
{
double myValue = readValue( myData, myDataType, iX + ( iY * myXBlockSize ) );
//QgsDebugMsg ( QString ( "%1 %2 value %3" ).arg (iX).arg(iY).arg( myValue ) );
if ( mValidNoDataValue && ( qAbs( myValue - myNoDataValue ) <= TINY_VALUE ) )
{
continue; // NULL
}
myRasterBandStats.sum += myValue;
++myRasterBandStats.elementCount;
//only use this element if we have a non null element
if ( myFirstIterationFlag )
{
//this is the first iteration so initialise vars
myFirstIterationFlag = false;
myRasterBandStats.minimumValue = myValue;
myRasterBandStats.maximumValue = myValue;
} //end of true part for first iteration check
else
{
//this is done for all subsequent iterations
if ( myValue < myRasterBandStats.minimumValue )
{
myRasterBandStats.minimumValue = myValue;
}
if ( myValue > myRasterBandStats.maximumValue )
{
myRasterBandStats.maximumValue = myValue;
}
} //end of false part for first iteration check
}
}
} //end of column wise loop
} //end of row wise loop
//end of first pass through data now calculate the range
myRasterBandStats.range = myRasterBandStats.maximumValue - myRasterBandStats.minimumValue;
//calculate the mean
myRasterBandStats.mean = myRasterBandStats.sum / myRasterBandStats.elementCount;
//for the second pass we will get the sum of the squares / mean
for ( int iYBlock = 0; iYBlock < myNYBlocks; iYBlock++ )
{
for ( int iXBlock = 0; iXBlock < myNXBlocks; iXBlock++ )
{
int nXValid, nYValid;
readBlock( theBandNo, iXBlock, iYBlock, myData );
// Compute the portion of the block that is valid
// for partial edge blocks.
if (( iXBlock + 1 ) * myXBlockSize > myBandXSize )
nXValid = myBandXSize - iXBlock * myXBlockSize;
else
nXValid = myXBlockSize;
if (( iYBlock + 1 ) * myYBlockSize > myBandYSize )
nYValid = myBandYSize - iYBlock * myYBlockSize;
else
nYValid = myYBlockSize;
// Collect the histogram counts.
for ( int iY = 0; iY < nYValid; iY++ )
{
for ( int iX = 0; iX < nXValid; iX++ )
{
double myValue = readValue( myData, myDataType, iX + ( iY * myXBlockSize ) );
//QgsDebugMsg ( "myValue = " + QString::number(myValue) );
if ( mValidNoDataValue && ( qAbs( myValue - myNoDataValue ) <= TINY_VALUE ) )
{
continue; // NULL
}
myRasterBandStats.sumOfSquares += static_cast < double >
( pow( myValue - myRasterBandStats.mean, 2 ) );
}
}
} //end of column wise loop
} //end of row wise loop
//divide result by sample size - 1 and get square root to get stdev
myRasterBandStats.stdDev = static_cast < double >( sqrt( myRasterBandStats.sumOfSquares /
( myRasterBandStats.elementCount - 1 ) ) );
#ifdef QGISDEBUG
QgsLogger::debug( "************ STATS **************", 1, __FILE__, __FUNCTION__, __LINE__ );
QgsLogger::debug( "VALID NODATA", mValidNoDataValue, 1, __FILE__, __FUNCTION__, __LINE__ );
QgsLogger::debug( "NULL", noDataValue() , 1, __FILE__, __FUNCTION__, __LINE__ );
QgsLogger::debug( "MIN", myRasterBandStats.minimumValue, 1, __FILE__, __FUNCTION__, __LINE__ );
QgsLogger::debug( "MAX", myRasterBandStats.maximumValue, 1, __FILE__, __FUNCTION__, __LINE__ );
QgsLogger::debug( "RANGE", myRasterBandStats.range, 1, __FILE__, __FUNCTION__, __LINE__ );
QgsLogger::debug( "MEAN", myRasterBandStats.mean, 1, __FILE__, __FUNCTION__, __LINE__ );
QgsLogger::debug( "STDDEV", myRasterBandStats.stdDev, 1, __FILE__, __FUNCTION__, __LINE__ );
#endif
CPLFree( myData );
myRasterBandStats.statsGathered = true;
return myRasterBandStats;
}
