QGIS API Documentation 3.38.0-Grenoble (exported)
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qgsalgorithmrescaleraster.cpp
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1/***************************************************************************
2 qgsalgorithmrescaleraster.cpp
3 ---------------------
4 begin : July 2020
5 copyright : (C) 2020 by Alexander Bruy
6 email : alexander dot bruy at gmail dot com
7 ***************************************************************************/
8
9/***************************************************************************
10 * *
11 * This program is free software; you can redistribute it and/or modify *
12 * it under the terms of the GNU General Public License as published by *
13 * the Free Software Foundation; either version 2 of the License, or *
14 * (at your option) any later version. *
15 * *
16 ***************************************************************************/
17
18#include <limits>
19#include "math.h"
21#include "qgsrasterfilewriter.h"
22
24
25QString QgsRescaleRasterAlgorithm::name() const
26{
27 return QStringLiteral( "rescaleraster" );
28}
29
30QString QgsRescaleRasterAlgorithm::displayName() const
31{
32 return QObject::tr( "Rescale raster" );
33}
34
35QStringList QgsRescaleRasterAlgorithm::tags() const
36{
37 return QObject::tr( "raster,rescale,minimum,maximum,range" ).split( ',' );
38}
39
40QString QgsRescaleRasterAlgorithm::group() const
41{
42 return QObject::tr( "Raster analysis" );
43}
44
45QString QgsRescaleRasterAlgorithm::groupId() const
46{
47 return QStringLiteral( "rasteranalysis" );
48}
49
50QString QgsRescaleRasterAlgorithm::shortHelpString() const
51{
52 return QObject::tr( "Rescales raster layer to a new value range, while preserving the shape "
53 "(distribution) of the raster's histogram (pixel values). Input values "
54 "are mapped using a linear interpolation from the source raster's minimum "
55 "and maximum pixel values to the destination minimum and maximum pixel range.\n\n"
56 "By default the algorithm preserves the original NoData value, but there is "
57 "an option to override it." );
58}
59
60QgsRescaleRasterAlgorithm *QgsRescaleRasterAlgorithm::createInstance() const
61{
62 return new QgsRescaleRasterAlgorithm();
63}
64
65void QgsRescaleRasterAlgorithm::initAlgorithm( const QVariantMap & )
66{
67 addParameter( new QgsProcessingParameterRasterLayer( QStringLiteral( "INPUT" ), QStringLiteral( "Input raster" ) ) );
68 addParameter( new QgsProcessingParameterBand( QStringLiteral( "BAND" ), QObject::tr( "Band number" ), 1, QStringLiteral( "INPUT" ) ) );
69 addParameter( new QgsProcessingParameterNumber( QStringLiteral( "MINIMUM" ), QObject::tr( "New minimum value" ), Qgis::ProcessingNumberParameterType::Double, 0 ) );
70 addParameter( new QgsProcessingParameterNumber( QStringLiteral( "MAXIMUM" ), QObject::tr( "New maximum value" ), Qgis::ProcessingNumberParameterType::Double, 255 ) );
71 addParameter( new QgsProcessingParameterNumber( QStringLiteral( "NODATA" ), QObject::tr( "New NoData value" ), Qgis::ProcessingNumberParameterType::Double, QVariant(), true ) );
72 addParameter( new QgsProcessingParameterRasterDestination( QStringLiteral( "OUTPUT" ), QObject::tr( "Rescaled" ) ) );
73}
74
75bool QgsRescaleRasterAlgorithm::prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
76{
77 Q_UNUSED( feedback );
78
79 QgsRasterLayer *layer = parameterAsRasterLayer( parameters, QStringLiteral( "INPUT" ), context );
80 if ( !layer )
81 throw QgsProcessingException( invalidRasterError( parameters, QStringLiteral( "INPUT" ) ) );
82
83 mBand = parameterAsInt( parameters, QStringLiteral( "BAND" ), context );
84 if ( mBand < 1 || mBand > layer->bandCount() )
85 throw QgsProcessingException( QObject::tr( "Invalid band number for BAND (%1): Valid values for input raster are 1 to %2" )
86 .arg( mBand )
87 .arg( layer->bandCount() ) );
88
89 mMinimum = parameterAsDouble( parameters, QStringLiteral( "MINIMUM" ), context );
90 mMaximum = parameterAsDouble( parameters, QStringLiteral( "MAXIMUM" ), context );
91
92 mInterface.reset( layer->dataProvider()->clone() );
93
94 mCrs = layer->crs();
95 mLayerWidth = layer->width();
96 mLayerHeight = layer->height();
97 mExtent = layer->extent();
98 if ( parameters.value( QStringLiteral( "NODATA" ) ).isValid() )
99 {
100 mNoData = parameterAsDouble( parameters, QStringLiteral( "NODATA" ), context );
101 }
102 else
103 {
104 mNoData = layer->dataProvider()->sourceNoDataValue( mBand );
105 }
106
107 if ( std::isfinite( mNoData ) )
108 {
109 // Clamp nodata to float32 range, since that's the type of the raster
110 if ( mNoData < std::numeric_limits<float>::lowest() )
111 mNoData = std::numeric_limits<float>::lowest();
112 else if ( mNoData > std::numeric_limits<float>::max() )
113 mNoData = std::numeric_limits<float>::max();
114 }
115
116 mXSize = mInterface->xSize();
117 mYSize = mInterface->ySize();
118
119 return true;
120}
121
122QVariantMap QgsRescaleRasterAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
123{
124 feedback->pushInfo( QObject::tr( "Calculating raster minimum and maximum values…" ) );
125 const QgsRasterBandStats stats = mInterface->bandStatistics( mBand, Qgis::RasterBandStatistic::Min | Qgis::RasterBandStatistic::Max, QgsRectangle(), 0 );
126
127 feedback->pushInfo( QObject::tr( "Rescaling values…" ) );
128 const QString outputFile = parameterAsOutputLayer( parameters, QStringLiteral( "OUTPUT" ), context );
129 const QFileInfo fi( outputFile );
130 const QString outputFormat = QgsRasterFileWriter::driverForExtension( fi.suffix() );
131 std::unique_ptr< QgsRasterFileWriter > writer = std::make_unique< QgsRasterFileWriter >( outputFile );
132 writer->setOutputProviderKey( QStringLiteral( "gdal" ) );
133 writer->setOutputFormat( outputFormat );
134 std::unique_ptr<QgsRasterDataProvider > provider( writer->createOneBandRaster( Qgis::DataType::Float32, mXSize, mYSize, mExtent, mCrs ) );
135 if ( !provider )
136 throw QgsProcessingException( QObject::tr( "Could not create raster output: %1" ).arg( outputFile ) );
137 if ( !provider->isValid() )
138 throw QgsProcessingException( QObject::tr( "Could not create raster output %1: %2" ).arg( outputFile, provider->error().message( QgsErrorMessage::Text ) ) );
139
140 QgsRasterDataProvider *destProvider = provider.get();
141 destProvider->setEditable( true );
142 destProvider->setNoDataValue( 1, mNoData );
143
146 const int numBlocksX = static_cast< int >( std::ceil( 1.0 * mLayerWidth / blockWidth ) );
147 const int numBlocksY = static_cast< int >( std::ceil( 1.0 * mLayerHeight / blockHeight ) );
148 const int numBlocks = numBlocksX * numBlocksY;
149
150 QgsRasterIterator iter( mInterface.get() );
151 iter.startRasterRead( mBand, mLayerWidth, mLayerHeight, mExtent );
152 int iterLeft = 0;
153 int iterTop = 0;
154 int iterCols = 0;
155 int iterRows = 0;
156 std::unique_ptr< QgsRasterBlock > inputBlock;
157 while ( iter.readNextRasterPart( mBand, iterCols, iterRows, inputBlock, iterLeft, iterTop ) )
158 {
159 std::unique_ptr< QgsRasterBlock > outputBlock( new QgsRasterBlock( destProvider->dataType( 1 ), iterCols, iterRows ) );
160 feedback->setProgress( 100 * ( ( iterTop / blockHeight * numBlocksX ) + iterLeft / blockWidth ) / numBlocks );
161
162 for ( int row = 0; row < iterRows; row++ )
163 {
164 if ( feedback->isCanceled() )
165 break;
166
167 for ( int col = 0; col < iterCols; col++ )
168 {
169 bool isNoData = false;
170 const double val = inputBlock->valueAndNoData( row, col, isNoData );
171 if ( isNoData )
172 {
173 outputBlock->setValue( row, col, mNoData );
174 }
175 else
176 {
177 const double newValue = ( ( val - stats.minimumValue ) * ( mMaximum - mMinimum ) / ( stats.maximumValue - stats.minimumValue ) ) + mMinimum;
178 outputBlock->setValue( row, col, newValue );
179 }
180 }
181 }
182 destProvider->writeBlock( outputBlock.get(), mBand, iterLeft, iterTop );
183 }
184 destProvider->setEditable( false );
185
186 QVariantMap outputs;
187 outputs.insert( QStringLiteral( "OUTPUT" ), outputFile );
188 return outputs;
189}
190
@ Float32
Thirty two bit floating point (float)
bool isCanceled() const
Tells whether the operation has been canceled already.
Definition qgsfeedback.h:53
void setProgress(double progress)
Sets the current progress for the feedback object.
Definition qgsfeedback.h:61
virtual QgsRectangle extent() const
Returns the extent of the layer.
QgsCoordinateReferenceSystem crs
Definition qgsmaplayer.h:82
Contains information about the context in which a processing algorithm is executed.
Custom exception class for processing related exceptions.
Base class for providing feedback from a processing algorithm.
virtual void pushInfo(const QString &info)
Pushes a general informational message from the algorithm.
A raster band parameter for Processing algorithms.
A numeric parameter for processing algorithms.
A raster layer destination parameter, for specifying the destination path for a raster layer created ...
A raster layer parameter for processing algorithms.
The RasterBandStats struct is a container for statistics about a single raster band.
double minimumValue
The minimum cell value in the raster band.
double maximumValue
The maximum cell value in the raster band.
Raster data container.
Base class for raster data providers.
QgsRasterDataProvider * clone() const override=0
Clone itself, create deep copy.
virtual bool setNoDataValue(int bandNo, double noDataValue)
Set no data value on created dataset.
virtual double sourceNoDataValue(int bandNo) const
Value representing no data value.
bool writeBlock(QgsRasterBlock *block, int band, int xOffset=0, int yOffset=0)
Writes pixel data from a raster block into the provider data source.
Qgis::DataType dataType(int bandNo) const override=0
Returns data type for the band specified by number.
virtual bool setEditable(bool enabled)
Turns on/off editing mode of the provider.
static QString driverForExtension(const QString &extension)
Returns the GDAL driver name for a specified file extension.
Iterator for sequentially processing raster cells.
static const int DEFAULT_MAXIMUM_TILE_WIDTH
Default maximum tile width.
static const int DEFAULT_MAXIMUM_TILE_HEIGHT
Default maximum tile height.
Represents a raster layer.
int height() const
Returns the height of the (unclipped) raster.
int bandCount() const
Returns the number of bands in this layer.
QgsRasterDataProvider * dataProvider() override
Returns the source data provider.
int width() const
Returns the width of the (unclipped) raster.
A rectangle specified with double values.