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qgsrelief.cpp
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qgsrelief.cpp
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/***************************************************************************
qgsrelief.cpp - description
---------------------------
begin : November 2011
copyright : (C) 2011 by Marco Hugentobler
email : marco dot hugentobler at sourcepole dot ch
***************************************************************************/
/***************************************************************************
* *
* 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 "qgsrelief.h"
#include "qgsaspectfilter.h"
#include "qgshillshadefilter.h"
#include "qgsslopefilter.h"
#include "qgis.h"
#include "cpl_string.h"
#include <QProgressDialog>
#include <cfloat>
#include <QFile>
#include <QTextStream>
#if defined(GDAL_VERSION_NUM) && GDAL_VERSION_NUM >= 1800
#define TO8(x) (x).toUtf8().constData()
#else
#define TO8(x) (x).toLocal8Bit().constData()
#endif
QgsRelief::QgsRelief( const QString& inputFile, const QString& outputFile, const QString& outputFormat ): \
mInputFile( inputFile ), mOutputFile( outputFile ), mOutputFormat( outputFormat ), mZFactor( 1.0 )
{
mSlopeFilter = new QgsSlopeFilter( inputFile, outputFile, outputFormat );
mAspectFilter = new QgsAspectFilter( inputFile, outputFile, outputFormat );
mHillshadeFilter285 = new QgsHillshadeFilter( inputFile, outputFile, outputFormat, 285, 30 );
mHillshadeFilter300 = new QgsHillshadeFilter( inputFile, outputFile, outputFormat, 300, 30 );
mHillshadeFilter315 = new QgsHillshadeFilter( inputFile, outputFile, outputFormat, 315, 30 );
/*mReliefColors = calculateOptimizedReliefClasses();
setDefaultReliefColors();*/
}
QgsRelief::~QgsRelief()
{
delete mSlopeFilter;
delete mAspectFilter;
delete mHillshadeFilter285;
delete mHillshadeFilter300;
delete mHillshadeFilter315;
}
void QgsRelief::clearReliefColors()
{
mReliefColors.clear();
}
void QgsRelief::addReliefColorClass( const ReliefColor& color )
{
mReliefColors.push_back( color );
}
void QgsRelief::setDefaultReliefColors()
{
clearReliefColors();
addReliefColorClass( ReliefColor( QColor( 9, 176, 76 ), 0, 200 ) );
addReliefColorClass( ReliefColor( QColor( 20, 228, 128 ), 200, 500 ) );
addReliefColorClass( ReliefColor( QColor( 167, 239, 153 ), 500, 1000 ) );
addReliefColorClass( ReliefColor( QColor( 218, 188, 143 ), 1000, 2000 ) );
addReliefColorClass( ReliefColor( QColor( 233, 158, 91 ), 2000, 4000 ) );
addReliefColorClass( ReliefColor( QColor( 255, 255, 255 ), 4000, 9000 ) );
}
int QgsRelief::processRaster( QProgressDialog* p )
{
//open input file
int xSize, ySize;
GDALDatasetH inputDataset = openInputFile( xSize, ySize );
if ( inputDataset == NULL )
{
return 1; //opening of input file failed
}
//output driver
GDALDriverH outputDriver = openOutputDriver();
if ( outputDriver == 0 )
{
return 2;
}
GDALDatasetH outputDataset = openOutputFile( inputDataset, outputDriver );
if ( outputDataset == NULL )
{
return 3; //create operation on output file failed
}
//initialize dependency filters with cell sizes
mHillshadeFilter285->setCellSizeX( mCellSizeX );
mHillshadeFilter285->setCellSizeY( mCellSizeY );
mHillshadeFilter285->setZFactor( mZFactor );
mHillshadeFilter300->setCellSizeX( mCellSizeX );
mHillshadeFilter300->setCellSizeY( mCellSizeY );
mHillshadeFilter300->setZFactor( mZFactor );
mHillshadeFilter315->setCellSizeX( mCellSizeX );
mHillshadeFilter315->setCellSizeY( mCellSizeY );
mHillshadeFilter315->setZFactor( mZFactor );
mSlopeFilter->setCellSizeX( mCellSizeX );
mSlopeFilter->setCellSizeY( mCellSizeY );
mSlopeFilter->setZFactor( mZFactor );
mAspectFilter->setCellSizeX( mCellSizeX );
mAspectFilter->setCellSizeY( mCellSizeY );
mAspectFilter->setZFactor( mZFactor );
//open first raster band for reading (operation is only for single band raster)
GDALRasterBandH rasterBand = GDALGetRasterBand( inputDataset, 1 );
if ( rasterBand == NULL )
{
GDALClose( inputDataset );
GDALClose( outputDataset );
return 4;
}
mInputNodataValue = GDALGetRasterNoDataValue( rasterBand, NULL );
mSlopeFilter->setInputNodataValue( mInputNodataValue );
mAspectFilter->setInputNodataValue( mInputNodataValue );
mHillshadeFilter285->setInputNodataValue( mInputNodataValue );
mHillshadeFilter300->setInputNodataValue( mInputNodataValue );
mHillshadeFilter315->setInputNodataValue( mInputNodataValue );
GDALRasterBandH outputRedBand = GDALGetRasterBand( outputDataset, 1 );
GDALRasterBandH outputGreenBand = GDALGetRasterBand( outputDataset, 2 );
GDALRasterBandH outputBlueBand = GDALGetRasterBand( outputDataset, 3 );
if ( outputRedBand == NULL || outputGreenBand == NULL || outputBlueBand == NULL )
{
GDALClose( inputDataset );
GDALClose( outputDataset );
return 5;
}
//try to set -9999 as nodata value
GDALSetRasterNoDataValue( outputRedBand, -9999 );
GDALSetRasterNoDataValue( outputGreenBand, -9999 );
GDALSetRasterNoDataValue( outputBlueBand, -9999 );
mOutputNodataValue = GDALGetRasterNoDataValue( outputRedBand, NULL );
mSlopeFilter->setOutputNodataValue( mOutputNodataValue );
mAspectFilter->setOutputNodataValue( mOutputNodataValue );
mHillshadeFilter285->setOutputNodataValue( mOutputNodataValue );
mHillshadeFilter300->setOutputNodataValue( mOutputNodataValue );
mHillshadeFilter315->setOutputNodataValue( mOutputNodataValue );
if ( ySize < 3 ) //we require at least three rows (should be true for most datasets)
{
GDALClose( inputDataset );
GDALClose( outputDataset );
return 6;
}
//keep only three scanlines in memory at a time
float* scanLine1 = ( float * ) CPLMalloc( sizeof( float ) * xSize );
float* scanLine2 = ( float * ) CPLMalloc( sizeof( float ) * xSize );
float* scanLine3 = ( float * ) CPLMalloc( sizeof( float ) * xSize );
int* resultRedLine = ( int * ) CPLMalloc( sizeof( int ) * xSize );
int* resultGreenLine = ( int * ) CPLMalloc( sizeof( int ) * xSize );
int* resultBlueLine = ( int * ) CPLMalloc( sizeof( int ) * xSize );
if ( p )
{
p->setMaximum( ySize );
}
bool resultOk;
//values outside the layer extent (if the 3x3 window is on the border) are sent to the processing method as (input) nodata values
for ( int i = 0; i < ySize; ++i )
{
if ( p )
{
p->setValue( i );
}
if ( p && p->wasCanceled() )
{
break;
}
if ( i == 0 )
{
//fill scanline 1 with (input) nodata for the values above the first row and feed scanline2 with the first row
for ( int a = 0; a < xSize; ++a )
{
scanLine1[a] = mInputNodataValue;
}
GDALRasterIO( rasterBand, GF_Read, 0, 0, xSize, 1, scanLine2, xSize, 1, GDT_Float32, 0, 0 );
}
else
{
//normally fetch only scanLine3 and release scanline 1 if we move forward one row
CPLFree( scanLine1 );
scanLine1 = scanLine2;
scanLine2 = scanLine3;
scanLine3 = ( float * ) CPLMalloc( sizeof( float ) * xSize );
}
if ( i == ySize - 1 ) //fill the row below the bottom with nodata values
{
for ( int a = 0; a < xSize; ++a )
{
scanLine3[a] = mInputNodataValue;
}
}
else
{
GDALRasterIO( rasterBand, GF_Read, 0, i + 1, xSize, 1, scanLine3, xSize, 1, GDT_Float32, 0, 0 );
}
for ( int j = 0; j < xSize; ++j )
{
if ( j == 0 )
{
resultOk = processNineCellWindow( &mInputNodataValue, &scanLine1[j], &scanLine1[j+1], &mInputNodataValue, &scanLine2[j], \
&scanLine2[j+1], &mInputNodataValue, &scanLine3[j], &scanLine3[j+1], \
&resultRedLine[j], &resultGreenLine[j], &resultBlueLine[j] );
}
else if ( j == xSize - 1 )
{
resultOk = processNineCellWindow( &scanLine1[j-1], &scanLine1[j], &mInputNodataValue, &scanLine2[j-1], &scanLine2[j], \
&mInputNodataValue, &scanLine3[j-1], &scanLine3[j], &mInputNodataValue, \
&resultRedLine[j], &resultGreenLine[j], &resultBlueLine[j] );
}
else
{
resultOk = processNineCellWindow( &scanLine1[j-1], &scanLine1[j], &scanLine1[j+1], &scanLine2[j-1], &scanLine2[j], \
&scanLine2[j+1], &scanLine3[j-1], &scanLine3[j], &scanLine3[j+1], \
&resultRedLine[j], &resultGreenLine[j], &resultBlueLine[j] );
}
if ( !resultOk )
{
resultRedLine[j] = mOutputNodataValue;
resultGreenLine[j] = mOutputNodataValue;
resultBlueLine[j] = mOutputNodataValue;
}
}
GDALRasterIO( outputRedBand, GF_Write, 0, i, xSize, 1, resultRedLine, xSize, 1, GDT_Int32, 0, 0 );
GDALRasterIO( outputGreenBand, GF_Write, 0, i, xSize, 1, resultGreenLine, xSize, 1, GDT_Int32, 0, 0 );
GDALRasterIO( outputBlueBand, GF_Write, 0, i, xSize, 1, resultBlueLine, xSize, 1, GDT_Int32, 0, 0 );
}
if ( p )
{
p->setValue( ySize );
}
CPLFree( resultRedLine );
CPLFree( resultBlueLine );
CPLFree( resultGreenLine );
CPLFree( scanLine1 );
CPLFree( scanLine2 );
CPLFree( scanLine3 );
GDALClose( inputDataset );
if ( p && p->wasCanceled() )
{
//delete the dataset without closing (because it is faster)
GDALDeleteDataset( outputDriver, mOutputFile.toLocal8Bit().data() );
return 7;
}
GDALClose( outputDataset );
return 0;
}
bool QgsRelief::processNineCellWindow( float* x1, float* x2, float* x3, float* x4, float* x5, float* x6, float* x7, float* x8, float* x9,
int* red, int* green, int* blue )
{
//1. component: colour and hillshade from 300 degrees
int r = 0;
int g = 0;
int b = 0;
float hillShadeValue300 = mHillshadeFilter300->processNineCellWindow( x1, x2, x3, x4, x5, x6, x7, x8, x9 );
if ( hillShadeValue300 != mOutputNodataValue )
{
if ( !setElevationColor( *x5, &r, &g, &b ) )
{
r = hillShadeValue300;
g = hillShadeValue300;
b = hillShadeValue300;
}
else
{
r = r / 2.0 + hillShadeValue300 / 2.0;
g = g / 2.0 + hillShadeValue300 / 2.0;
b = b / 2.0 + hillShadeValue300 / 2.0;
}
}
//2. component: hillshade and slope
float hillShadeValue315 = mHillshadeFilter315->processNineCellWindow( x1, x2, x3, x4, x5, x6, x7, x8, x9 );
float slope = mSlopeFilter->processNineCellWindow( x1, x2, x3, x4, x5, x6, x7, x8, x9 );
if ( hillShadeValue315 != mOutputNodataValue && slope != mOutputNodataValue )
{
int r2, g2, b2;
if ( slope > 15 )
{
r2 = 0 / 2.0 + hillShadeValue315 / 2.0;
g2 = 0 / 2.0 + hillShadeValue315 / 2.0;
b2 = 0 / 2.0 + hillShadeValue315 / 2.0;
}
else if ( slope >= 1 )
{
int slopeValue = 255 - ( slope / 15.0 * 255.0 );
r2 = slopeValue / 2.0 + hillShadeValue315 / 2.0;
g2 = slopeValue / 2.0 + hillShadeValue315 / 2.0;
b2 = slopeValue / 2.0 + hillShadeValue315 / 2.0;
}
else
{
r2 = hillShadeValue315; g2 = hillShadeValue315; b2 = hillShadeValue315;
}
//combine with r,g,b with 70 percentage coverage
r = r * 0.7 + r2 * 0.3;
g = g * 0.7 + g2 * 0.3;
b = b * 0.7 + b2 * 0.3;
}
//3. combine yellow aspect with 10% transparency, illumination from 285 degrees
float hillShadeValue285 = mHillshadeFilter285->processNineCellWindow( x1, x2, x3, x4, x5, x6, x7, x8, x9 );
float aspect = mAspectFilter->processNineCellWindow( x1, x2, x3, x4, x5, x6, x7, x8, x9 );
if ( hillShadeValue285 != mOutputNodataValue && aspect != mOutputNodataValue )
{
double angle_diff = qAbs( 285 - aspect );
if ( angle_diff > 180 )
{
angle_diff -= 180;
}
int r3, g3, b3;
if ( angle_diff < 90 )
{
int aspectVal = ( 1 - cos( angle_diff * M_PI / 180 ) ) * 255;
r3 = 0.5 * 255 + hillShadeValue315 * 0.5;
g3 = 0.5 * 255 + hillShadeValue315 * 0.5;
b3 = 0.5 * aspectVal + hillShadeValue315 * 0.5;
}
else //white
{
r3 = 0.5 * 255 + hillShadeValue315 * 0.5;
g3 = 0.5 * 255 + hillShadeValue315 * 0.5;
b3 = 0.5 * 255 + hillShadeValue315 * 0.5;
}
r = r3 * 0.1 + r * 0.9;
g = g3 * 0.1 + g * 0.9;
b = b3 * 0.1 + b * 0.9;
}
*red = r;
*green = g;
*blue = b;
return true;
}
bool QgsRelief::setElevationColor( double elevation, int* red, int* green, int* blue )
{
QList< ReliefColor >::const_iterator reliefColorIt = mReliefColors.constBegin();
for ( ; reliefColorIt != mReliefColors.constEnd(); ++reliefColorIt )
{
if ( elevation >= reliefColorIt->minElevation && elevation <= reliefColorIt->maxElevation )
{
const QColor& c = reliefColorIt->color;
*red = c.red();
*green = c.green();
*blue = c.blue();
return true;
}
}
return false;
}
//duplicated from QgsNineCellFilter. Todo: make common base class
GDALDatasetH QgsRelief::openInputFile( int& nCellsX, int& nCellsY )
{
GDALDatasetH inputDataset = GDALOpen( TO8( mInputFile ), GA_ReadOnly );
if ( inputDataset != NULL )
{
nCellsX = GDALGetRasterXSize( inputDataset );
nCellsY = GDALGetRasterYSize( inputDataset );
//we need at least one band
if ( GDALGetRasterCount( inputDataset ) < 1 )
{
GDALClose( inputDataset );
return NULL;
}
}
return inputDataset;
}
GDALDriverH QgsRelief::openOutputDriver()
{
char **driverMetadata;
//open driver
GDALDriverH outputDriver = GDALGetDriverByName( mOutputFormat.toLocal8Bit().data() );
if ( outputDriver == NULL )
{
return outputDriver; //return NULL, driver does not exist
}
driverMetadata = GDALGetMetadata( outputDriver, NULL );
if ( !CSLFetchBoolean( driverMetadata, GDAL_DCAP_CREATE, false ) )
{
return NULL; //driver exist, but it does not support the create operation
}
return outputDriver;
}
GDALDatasetH QgsRelief::openOutputFile( GDALDatasetH inputDataset, GDALDriverH outputDriver )
{
if ( inputDataset == NULL )
{
return NULL;
}
int xSize = GDALGetRasterXSize( inputDataset );
int ySize = GDALGetRasterYSize( inputDataset );;
//open output file
char **papszOptions = NULL;
//use PACKBITS compression for tiffs by default
papszOptions = CSLSetNameValue( papszOptions, "COMPRESS", "PACKBITS" );
//create three band raster (reg, green, blue)
GDALDatasetH outputDataset = GDALCreate( outputDriver, mOutputFile.toLocal8Bit().data(), xSize, ySize, 3, GDT_Int32, papszOptions );
if ( outputDataset == NULL )
{
return outputDataset;
}
//get geotransform from inputDataset
double geotransform[6];
if ( GDALGetGeoTransform( inputDataset, geotransform ) != CE_None )
{
GDALClose( outputDataset );
return NULL;
}
GDALSetGeoTransform( outputDataset, geotransform );
//make sure mCellSizeX and mCellSizeY are always > 0
mCellSizeX = geotransform[1];
if ( mCellSizeX < 0 )
{
mCellSizeX = -mCellSizeX;
}
mCellSizeY = geotransform[5];
if ( mCellSizeY < 0 )
{
mCellSizeY = -mCellSizeY;
}
const char* projection = GDALGetProjectionRef( inputDataset );
GDALSetProjection( outputDataset, projection );
return outputDataset;
}
//this function is mainly there for debugging
bool QgsRelief::exportFrequencyDistributionToCsv( const QString& file )
{
int nCellsX, nCellsY;
GDALDatasetH inputDataset = openInputFile( nCellsX, nCellsY );
if ( inputDataset == NULL )
{
return false;
}
//open first raster band for reading (elevation raster is always single band)
GDALRasterBandH elevationBand = GDALGetRasterBand( inputDataset, 1 );
if ( elevationBand == NULL )
{
GDALClose( inputDataset );
return false;
}
//1. get minimum and maximum of elevation raster -> 252 elevation classes
int minOk, maxOk;
double minMax[2];
minMax[0] = GDALGetRasterMinimum( elevationBand, &minOk );
minMax[1] = GDALGetRasterMaximum( elevationBand, &maxOk );
if ( !minOk || !maxOk )
{
GDALComputeRasterMinMax( elevationBand, TRUE, minMax );
}
//2. go through raster cells and get frequency of classes
//store elevation frequency in 256 elevation classes
double frequency[252];
double frequencyClassRange = ( minMax[1] - minMax[0] ) / 252.0;
//initialize to zero
for ( int i = 0; i < 252; ++i )
{
frequency[i] = 0;
}
float* scanLine = ( float * ) CPLMalloc( sizeof( float ) * nCellsX );
int elevationClass = -1;
for ( int i = 0; i < nCellsY; ++i )
{
GDALRasterIO( elevationBand, GF_Read, 0, i, nCellsX, 1,
scanLine, nCellsX, 1, GDT_Float32,
0, 0 );
for ( int j = 0; j < nCellsX; ++j )
{
elevationClass = frequencyClassForElevation( scanLine[j], minMax[0], frequencyClassRange );
if ( elevationClass >= 0 )
{
frequency[elevationClass] += 1.0;
}
}
}
CPLFree( scanLine );
//log10 transformation for all frequency values
for ( int i = 0; i < 252; ++i )
{
frequency[i] = log10( frequency[i] );
}
//write out frequency values to csv file for debugging
QFile outFile( file );
if ( !outFile.open( QIODevice::WriteOnly ) )
{
return false;
}
QTextStream outstream( &outFile );
for ( int i = 0; i < 252; ++i )
{
outstream << QString::number( i ) + "," + QString::number( frequency[i] ) << endl;
}
outFile.close();
return true;
}
QList< QgsRelief::ReliefColor > QgsRelief::calculateOptimizedReliefClasses()
{
QList< QgsRelief::ReliefColor > resultList;
int nCellsX, nCellsY;
GDALDatasetH inputDataset = openInputFile( nCellsX, nCellsY );
if ( inputDataset == NULL )
{
return resultList;
}
//open first raster band for reading (elevation raster is always single band)
GDALRasterBandH elevationBand = GDALGetRasterBand( inputDataset, 1 );
if ( elevationBand == NULL )
{
GDALClose( inputDataset );
return resultList;
}
//1. get minimum and maximum of elevation raster -> 252 elevation classes
int minOk, maxOk;
double minMax[2];
minMax[0] = GDALGetRasterMinimum( elevationBand, &minOk );
minMax[1] = GDALGetRasterMaximum( elevationBand, &maxOk );
if ( !minOk || !maxOk )
{
GDALComputeRasterMinMax( elevationBand, TRUE, minMax );
}
//2. go through raster cells and get frequency of classes
//store elevation frequency in 256 elevation classes
double frequency[252];
double frequencyClassRange = ( minMax[1] - minMax[0] ) / 252.0;
//initialize to zero
for ( int i = 0; i < 252; ++i )
{
frequency[i] = 0;
}
float* scanLine = ( float * ) CPLMalloc( sizeof( float ) * nCellsX );
int elevationClass = -1;
for ( int i = 0; i < nCellsY; ++i )
{
GDALRasterIO( elevationBand, GF_Read, 0, i, nCellsX, 1,
scanLine, nCellsX, 1, GDT_Float32,
0, 0 );
for ( int j = 0; j < nCellsX; ++j )
{
elevationClass = frequencyClassForElevation( scanLine[j], minMax[0], frequencyClassRange );
if ( elevationClass < 0 )
{
elevationClass = 0;
}
else if ( elevationClass >= 252 )
{
elevationClass = 251;
}
frequency[elevationClass] += 1.0;
}
}
CPLFree( scanLine );
//log10 transformation for all frequency values
for ( int i = 0; i < 252; ++i )
{
frequency[i] = log10( frequency[i] );
}
//start with 9 uniformly distributed classes
QList<int> classBreaks;
classBreaks.append( 0 );
classBreaks.append( 28 );
classBreaks.append( 56 );
classBreaks.append( 84 );
classBreaks.append( 112 );
classBreaks.append( 140 );
classBreaks.append( 168 );
classBreaks.append( 196 );
classBreaks.append( 224 );
classBreaks.append( 252 );
for ( int i = 0; i < 10; ++i )
{
optimiseClassBreaks( classBreaks, frequency );
}
//debug, print out all the classbreaks
for ( int i = 0; i < classBreaks.size(); ++i )
{
qWarning( "%d", classBreaks[i] );
}
//set colors according to optimised class breaks
QList<QColor> colorList;
colorList.push_back( QColor( 7, 165, 144 ) );
colorList.push_back( QColor( 12, 221, 162 ) );
colorList.push_back( QColor( 33, 252, 183 ) );
colorList.push_back( QColor( 247, 252, 152 ) );
colorList.push_back( QColor( 252, 196, 8 ) );
colorList.push_back( QColor( 252, 166, 15 ) );
colorList.push_back( QColor( 175, 101, 15 ) );
colorList.push_back( QColor( 255, 133, 92 ) );
colorList.push_back( QColor( 204, 204, 204 ) );
for ( int i = 1; i < classBreaks.size(); ++i )
{
double minElevation = minMax[0] + classBreaks[i - 1] * frequencyClassRange;
double maxElevation = minMax[0] + classBreaks[i] * frequencyClassRange;
resultList.push_back( QgsRelief::ReliefColor( colorList.at( i - 1 ), minElevation, maxElevation ) );
}
return resultList;
}
void QgsRelief::optimiseClassBreaks( QList<int>& breaks, double* frequencies )
{
int nClasses = breaks.size() - 1;
double* a = new double[nClasses]; //slopes
double* b = new double[nClasses]; //y-offsets
for ( int i = 0; i < nClasses; ++i )
{
//get all the values between the class breaks into input
QList< QPair < int, double > > regressionInput;
for ( int j = breaks.at( i ); j < breaks.at( i + 1 ); ++j )
{
regressionInput.push_back( qMakePair( j, frequencies[j] ) );
}
double aParam, bParam;
if ( regressionInput.size() > 0 && calculateRegression( regressionInput, aParam, bParam ) )
{
a[i] = aParam;
b[i] = bParam;
}
else
{
a[i] = 0;
b[i] = 0; //better default value
}
}
QList<int> classesToRemove;
//shift class boundaries or eliminate classes which fall together
for ( int i = 1; i < nClasses ; ++i )
{
if ( breaks[i] == breaks[ i - 1 ] )
{
continue;
}
if ( doubleNear( a[i - 1 ], a[i] ) )
{
continue;
}
else
{
int newX = ( b[i - 1] - b[ i ] ) / ( a[ i ] - a[ i - 1 ] );
if ( newX <= breaks[i - 1] )
{
newX = breaks[i - 1];
// classesToRemove.push_back( i );//remove this class later as it falls together with the preceding one
}
else if ( i < nClasses - 1 && newX >= breaks[i + 1] )
{
newX = breaks[i + 1];
// classesToRemove.push_back( i );//remove this class later as it falls together with the next one
}
breaks[i] = newX;
}
}
for ( int i = classesToRemove.size() - 1; i >= 0; --i )
{
breaks.removeAt( classesToRemove.at( i ) );
}
delete[] a;
delete[] b;
}
int QgsRelief::frequencyClassForElevation( double elevation, double minElevation, double elevationClassRange )
{
return ( elevation - minElevation ) / elevationClassRange;
}
bool QgsRelief::calculateRegression( const QList< QPair < int, double > >& input, double& a, double& b )
{
double xMean, yMean;
double xSum = 0;
double ySum = 0;
QList< QPair < int, double > >::const_iterator inputIt = input.constBegin();
for ( ; inputIt != input.constEnd(); ++inputIt )
{
xSum += inputIt->first;
ySum += inputIt->second;
}
xMean = xSum / input.size();
yMean = ySum / input.size();
double sumCounter = 0;
double sumDenominator = 0;
inputIt = input.constBegin();
for ( ; inputIt != input.constEnd(); ++inputIt )
{
sumCounter += (( inputIt->first - xMean ) * ( inputIt->second - yMean ) );
sumDenominator += (( inputIt->first - xMean ) * ( inputIt->first - xMean ) );
}
a = sumCounter / sumDenominator;
b = yMean - a * xMean;
return true;
}