QGIS API Documentation 3.37.0-Master (684a802617f)
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qgsrelief.cpp
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1/***************************************************************************
2 qgsrelief.cpp - description
3 ---------------------------
4 begin : November 2011
5 copyright : (C) 2011 by Marco Hugentobler
6 email : marco dot hugentobler at sourcepole dot ch
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 "qgsgdalutils.h"
19#include "qgslogger.h"
20#include "qgsrelief.h"
21#include "qgsaspectfilter.h"
22#include "qgshillshadefilter.h"
23#include "qgsslopefilter.h"
24#include "qgsfeedback.h"
25#include "qgis.h"
26#include "cpl_string.h"
27#include "qgsogrutils.h"
28#include <cfloat>
29
30#include <QVector>
31#include <QColor>
32#include <QFile>
33#include <QTextStream>
34
35QgsRelief::QgsRelief( const QString &inputFile, const QString &outputFile, const QString &outputFormat )
36 : mInputFile( inputFile )
37 , mOutputFile( outputFile )
38 , mOutputFormat( outputFormat )
39 , mSlopeFilter( std::make_unique< QgsSlopeFilter >( inputFile, outputFile, outputFormat ) )
40 , mAspectFilter( std::make_unique< QgsAspectFilter > ( inputFile, outputFile, outputFormat ) )
41 , mHillshadeFilter285( std::make_unique< QgsHillshadeFilter >( inputFile, outputFile, outputFormat, 285, 30 ) )
42 , mHillshadeFilter300( std::make_unique< QgsHillshadeFilter >( inputFile, outputFile, outputFormat, 300, 30 ) )
43 , mHillshadeFilter315( std::make_unique< QgsHillshadeFilter >( inputFile, outputFile, outputFormat, 315, 30 ) )
44{
45 /*mReliefColors = calculateOptimizedReliefClasses();
46 setDefaultReliefColors();*/
47}
48
49QgsRelief::~QgsRelief() = default;
50
52{
53 mReliefColors.clear();
54}
55
57{
58 mReliefColors.push_back( color );
59}
60
61void QgsRelief::setDefaultReliefColors()
62{
64 addReliefColorClass( ReliefColor( QColor( 9, 176, 76 ), 0, 200 ) );
65 addReliefColorClass( ReliefColor( QColor( 20, 228, 128 ), 200, 500 ) );
66 addReliefColorClass( ReliefColor( QColor( 167, 239, 153 ), 500, 1000 ) );
67 addReliefColorClass( ReliefColor( QColor( 218, 188, 143 ), 1000, 2000 ) );
68 addReliefColorClass( ReliefColor( QColor( 233, 158, 91 ), 2000, 4000 ) );
69 addReliefColorClass( ReliefColor( QColor( 255, 255, 255 ), 4000, 9000 ) );
70}
71
73{
74 //open input file
75 int xSize, ySize;
76 const gdal::dataset_unique_ptr inputDataset = openInputFile( xSize, ySize );
77 if ( !inputDataset )
78 {
79 return 1; //opening of input file failed
80 }
81
82 //output driver
83 GDALDriverH outputDriver = openOutputDriver();
84 if ( !outputDriver )
85 {
86 return 2;
87 }
88
89 gdal::dataset_unique_ptr outputDataset = openOutputFile( inputDataset.get(), outputDriver );
90 if ( !outputDataset )
91 {
92 return 3; //create operation on output file failed
93 }
94
95 //initialize dependency filters with cell sizes
96 mHillshadeFilter285->setCellSizeX( mCellSizeX );
97 mHillshadeFilter285->setCellSizeY( mCellSizeY );
98 mHillshadeFilter285->setZFactor( mZFactor );
99 mHillshadeFilter300->setCellSizeX( mCellSizeX );
100 mHillshadeFilter300->setCellSizeY( mCellSizeY );
101 mHillshadeFilter300->setZFactor( mZFactor );
102 mHillshadeFilter315->setCellSizeX( mCellSizeX );
103 mHillshadeFilter315->setCellSizeY( mCellSizeY );
104 mHillshadeFilter315->setZFactor( mZFactor );
105 mSlopeFilter->setCellSizeX( mCellSizeX );
106 mSlopeFilter->setCellSizeY( mCellSizeY );
107 mSlopeFilter->setZFactor( mZFactor );
108 mAspectFilter->setCellSizeX( mCellSizeX );
109 mAspectFilter->setCellSizeY( mCellSizeY );
110 mAspectFilter->setZFactor( mZFactor );
111
112 //open first raster band for reading (operation is only for single band raster)
113 GDALRasterBandH rasterBand = GDALGetRasterBand( inputDataset.get(), 1 );
114 if ( !rasterBand )
115 {
116 return 4;
117 }
118 mInputNodataValue = GDALGetRasterNoDataValue( rasterBand, nullptr );
119 mSlopeFilter->setInputNodataValue( mInputNodataValue );
120 mAspectFilter->setInputNodataValue( mInputNodataValue );
121 mHillshadeFilter285->setInputNodataValue( mInputNodataValue );
122 mHillshadeFilter300->setInputNodataValue( mInputNodataValue );
123 mHillshadeFilter315->setInputNodataValue( mInputNodataValue );
124
125 GDALRasterBandH outputRedBand = GDALGetRasterBand( outputDataset.get(), 1 );
126 GDALRasterBandH outputGreenBand = GDALGetRasterBand( outputDataset.get(), 2 );
127 GDALRasterBandH outputBlueBand = GDALGetRasterBand( outputDataset.get(), 3 );
128
129 if ( !outputRedBand || !outputGreenBand || !outputBlueBand )
130 {
131 return 5;
132 }
133 //try to set -9999 as nodata value
134 GDALSetRasterNoDataValue( outputRedBand, -9999 );
135 GDALSetRasterNoDataValue( outputGreenBand, -9999 );
136 GDALSetRasterNoDataValue( outputBlueBand, -9999 );
137 mOutputNodataValue = GDALGetRasterNoDataValue( outputRedBand, nullptr );
138 mSlopeFilter->setOutputNodataValue( mOutputNodataValue );
139 mAspectFilter->setOutputNodataValue( mOutputNodataValue );
140 mHillshadeFilter285->setOutputNodataValue( mOutputNodataValue );
141 mHillshadeFilter300->setOutputNodataValue( mOutputNodataValue );
142 mHillshadeFilter315->setOutputNodataValue( mOutputNodataValue );
143
144 if ( ySize < 3 ) //we require at least three rows (should be true for most datasets)
145 {
146 return 6;
147 }
148
149 //keep only three scanlines in memory at a time
150 float *scanLine1 = ( float * ) CPLMalloc( sizeof( float ) * xSize );
151 float *scanLine2 = ( float * ) CPLMalloc( sizeof( float ) * xSize );
152 float *scanLine3 = ( float * ) CPLMalloc( sizeof( float ) * xSize );
153
154 unsigned char *resultRedLine = ( unsigned char * ) CPLMalloc( sizeof( unsigned char ) * xSize );
155 unsigned char *resultGreenLine = ( unsigned char * ) CPLMalloc( sizeof( unsigned char ) * xSize );
156 unsigned char *resultBlueLine = ( unsigned char * ) CPLMalloc( sizeof( unsigned char ) * xSize );
157
158 bool resultOk;
159
160 //values outside the layer extent (if the 3x3 window is on the border) are sent to the processing method as (input) nodata values
161 for ( int i = 0; i < ySize; ++i )
162 {
163 if ( feedback )
164 {
165 feedback->setProgress( 100.0 * i / static_cast< double >( ySize ) );
166 }
167
168 if ( feedback && feedback->isCanceled() )
169 {
170 break;
171 }
172
173 if ( i == 0 )
174 {
175 //fill scanline 1 with (input) nodata for the values above the first row and feed scanline2 with the first row
176 for ( int a = 0; a < xSize; ++a )
177 {
178 scanLine1[a] = mInputNodataValue;
179 }
180 if ( GDALRasterIO( rasterBand, GF_Read, 0, 0, xSize, 1, scanLine2, xSize, 1, GDT_Float32, 0, 0 ) != CE_None )
181 {
182 QgsDebugError( QStringLiteral( "Raster IO Error" ) );
183 }
184 }
185 else
186 {
187 //normally fetch only scanLine3 and release scanline 1 if we move forward one row
188 CPLFree( scanLine1 );
189 scanLine1 = scanLine2;
190 scanLine2 = scanLine3;
191 scanLine3 = ( float * ) CPLMalloc( sizeof( float ) * xSize );
192 }
193
194 if ( i == ySize - 1 ) //fill the row below the bottom with nodata values
195 {
196 for ( int a = 0; a < xSize; ++a )
197 {
198 scanLine3[a] = mInputNodataValue;
199 }
200 }
201 else
202 {
203 if ( GDALRasterIO( rasterBand, GF_Read, 0, i + 1, xSize, 1, scanLine3, xSize, 1, GDT_Float32, 0, 0 ) != CE_None )
204 {
205 QgsDebugError( QStringLiteral( "Raster IO Error" ) );
206 }
207 }
208
209 for ( int j = 0; j < xSize; ++j )
210 {
211 if ( j == 0 )
212 {
213 resultOk = processNineCellWindow( &mInputNodataValue, &scanLine1[j], &scanLine1[j + 1], &mInputNodataValue, &scanLine2[j], \
214 &scanLine2[j + 1], &mInputNodataValue, &scanLine3[j], &scanLine3[j + 1], \
215 &resultRedLine[j], &resultGreenLine[j], &resultBlueLine[j] );
216 }
217 else if ( j == xSize - 1 )
218 {
219 resultOk = processNineCellWindow( &scanLine1[j - 1], &scanLine1[j], &mInputNodataValue, &scanLine2[j - 1], &scanLine2[j], \
220 &mInputNodataValue, &scanLine3[j - 1], &scanLine3[j], &mInputNodataValue, \
221 &resultRedLine[j], &resultGreenLine[j], &resultBlueLine[j] );
222 }
223 else
224 {
225 resultOk = processNineCellWindow( &scanLine1[j - 1], &scanLine1[j], &scanLine1[j + 1], &scanLine2[j - 1], &scanLine2[j], \
226 &scanLine2[j + 1], &scanLine3[j - 1], &scanLine3[j], &scanLine3[j + 1], \
227 &resultRedLine[j], &resultGreenLine[j], &resultBlueLine[j] );
228 }
229
230 if ( !resultOk )
231 {
232 resultRedLine[j] = mOutputNodataValue;
233 resultGreenLine[j] = mOutputNodataValue;
234 resultBlueLine[j] = mOutputNodataValue;
235 }
236 }
237
238 if ( GDALRasterIO( outputRedBand, GF_Write, 0, i, xSize, 1, resultRedLine, xSize, 1, GDT_Byte, 0, 0 ) != CE_None )
239 {
240 QgsDebugError( QStringLiteral( "Raster IO Error" ) );
241 }
242 if ( GDALRasterIO( outputGreenBand, GF_Write, 0, i, xSize, 1, resultGreenLine, xSize, 1, GDT_Byte, 0, 0 ) != CE_None )
243 {
244 QgsDebugError( QStringLiteral( "Raster IO Error" ) );
245 }
246 if ( GDALRasterIO( outputBlueBand, GF_Write, 0, i, xSize, 1, resultBlueLine, xSize, 1, GDT_Byte, 0, 0 ) != CE_None )
247 {
248 QgsDebugError( QStringLiteral( "Raster IO Error" ) );
249 }
250 }
251
252 if ( feedback )
253 {
254 feedback->setProgress( 100 );
255 }
256
257 CPLFree( resultRedLine );
258 CPLFree( resultBlueLine );
259 CPLFree( resultGreenLine );
260 CPLFree( scanLine1 );
261 CPLFree( scanLine2 );
262 CPLFree( scanLine3 );
263
264 if ( feedback && feedback->isCanceled() )
265 {
266 //delete the dataset without closing (because it is faster)
267 gdal::fast_delete_and_close( outputDataset, outputDriver, mOutputFile );
268 return 7;
269 }
270
271 return 0;
272}
273
274bool QgsRelief::processNineCellWindow( float *x1, float *x2, float *x3, float *x4, float *x5, float *x6, float *x7, float *x8, float *x9,
275 unsigned char *red, unsigned char *green, unsigned char *blue )
276{
277 //1. component: color and hillshade from 300 degrees
278 int r = 0;
279 int g = 0;
280 int b = 0;
281
282 const float hillShadeValue300 = mHillshadeFilter300->processNineCellWindow( x1, x2, x3, x4, x5, x6, x7, x8, x9 );
283 if ( hillShadeValue300 != mOutputNodataValue )
284 {
285 if ( !setElevationColor( *x5, &r, &g, &b ) )
286 {
287 r = hillShadeValue300;
288 g = hillShadeValue300;
289 b = hillShadeValue300;
290 }
291 else
292 {
293 r = r / 2.0 + hillShadeValue300 / 2.0;
294 g = g / 2.0 + hillShadeValue300 / 2.0;
295 b = b / 2.0 + hillShadeValue300 / 2.0;
296 }
297 }
298
299 //2. component: hillshade and slope
300 const float hillShadeValue315 = mHillshadeFilter315->processNineCellWindow( x1, x2, x3, x4, x5, x6, x7, x8, x9 );
301 const float slope = mSlopeFilter->processNineCellWindow( x1, x2, x3, x4, x5, x6, x7, x8, x9 );
302 if ( hillShadeValue315 != mOutputNodataValue && slope != mOutputNodataValue )
303 {
304 int r2, g2, b2;
305 if ( slope > 15 )
306 {
307 r2 = 0 / 2.0 + hillShadeValue315 / 2.0;
308 g2 = 0 / 2.0 + hillShadeValue315 / 2.0;
309 b2 = 0 / 2.0 + hillShadeValue315 / 2.0;
310 }
311 else if ( slope >= 1 )
312 {
313 const int slopeValue = 255 - ( slope / 15.0 * 255.0 );
314 r2 = slopeValue / 2.0 + hillShadeValue315 / 2.0;
315 g2 = slopeValue / 2.0 + hillShadeValue315 / 2.0;
316 b2 = slopeValue / 2.0 + hillShadeValue315 / 2.0;
317 }
318 else
319 {
320 r2 = hillShadeValue315;
321 g2 = hillShadeValue315;
322 b2 = hillShadeValue315;
323 }
324
325 //combine with r,g,b with 70 percentage coverage
326 r = r * 0.7 + r2 * 0.3;
327 g = g * 0.7 + g2 * 0.3;
328 b = b * 0.7 + b2 * 0.3;
329 }
330
331 //3. combine yellow aspect with 10% transparency, illumination from 285 degrees
332 const float hillShadeValue285 = mHillshadeFilter285->processNineCellWindow( x1, x2, x3, x4, x5, x6, x7, x8, x9 );
333 const float aspect = mAspectFilter->processNineCellWindow( x1, x2, x3, x4, x5, x6, x7, x8, x9 );
334 if ( hillShadeValue285 != mOutputNodataValue && aspect != mOutputNodataValue )
335 {
336 double angle_diff = std::fabs( 285 - aspect );
337 if ( angle_diff > 180 )
338 {
339 angle_diff -= 180;
340 }
341
342 int r3, g3, b3;
343 if ( angle_diff < 90 )
344 {
345 const int aspectVal = ( 1 - std::cos( angle_diff * M_PI / 180 ) ) * 255;
346 r3 = 0.5 * 255 + hillShadeValue315 * 0.5;
347 g3 = 0.5 * 255 + hillShadeValue315 * 0.5;
348 b3 = 0.5 * aspectVal + hillShadeValue315 * 0.5;
349 }
350 else //white
351 {
352 r3 = 0.5 * 255 + hillShadeValue315 * 0.5;
353 g3 = 0.5 * 255 + hillShadeValue315 * 0.5;
354 b3 = 0.5 * 255 + hillShadeValue315 * 0.5;
355 }
356
357 r = r3 * 0.1 + r * 0.9;
358 g = g3 * 0.1 + g * 0.9;
359 b = b3 * 0.1 + b * 0.9;
360 }
361
362 *red = ( unsigned char )r;
363 *green = ( unsigned char )g;
364 *blue = ( unsigned char )b;
365 return true;
366}
367
368bool QgsRelief::setElevationColor( double elevation, int *red, int *green, int *blue )
369{
370 QList< ReliefColor >::const_iterator reliefColorIt = mReliefColors.constBegin();
371 for ( ; reliefColorIt != mReliefColors.constEnd(); ++reliefColorIt )
372 {
373 if ( elevation >= reliefColorIt->minElevation && elevation <= reliefColorIt->maxElevation )
374 {
375 const QColor &c = reliefColorIt->color;
376 *red = c.red();
377 *green = c.green();
378 *blue = c.blue();
379
380 return true;
381 }
382 }
383 return false;
384}
385
386//duplicated from QgsNineCellFilter. Todo: make common base class
387gdal::dataset_unique_ptr QgsRelief::openInputFile( int &nCellsX, int &nCellsY )
388{
389 gdal::dataset_unique_ptr inputDataset( GDALOpen( mInputFile.toUtf8().constData(), GA_ReadOnly ) );
390 if ( inputDataset )
391 {
392 nCellsX = GDALGetRasterXSize( inputDataset.get() );
393 nCellsY = GDALGetRasterYSize( inputDataset.get() );
394
395 //we need at least one band
396 if ( GDALGetRasterCount( inputDataset.get() ) < 1 )
397 {
398 return nullptr;
399 }
400 }
401 return inputDataset;
402}
403
404GDALDriverH QgsRelief::openOutputDriver()
405{
406 //open driver
407 GDALDriverH outputDriver = GDALGetDriverByName( mOutputFormat.toLocal8Bit().data() );
408
409 if ( !outputDriver )
410 {
411 return outputDriver; //return nullptr, driver does not exist
412 }
413
414 if ( !QgsGdalUtils::supportsRasterCreate( outputDriver ) )
415 {
416 return nullptr; //driver exist, but it does not support the create operation
417 }
418
419 return outputDriver;
420}
421
422gdal::dataset_unique_ptr QgsRelief::openOutputFile( GDALDatasetH inputDataset, GDALDriverH outputDriver )
423{
424 if ( !inputDataset )
425 {
426 return nullptr;
427 }
428
429 const int xSize = GDALGetRasterXSize( inputDataset );
430 const int ySize = GDALGetRasterYSize( inputDataset );
431
432 //open output file
433 char **papszOptions = nullptr;
434
435 //use PACKBITS compression for tiffs by default
436 papszOptions = CSLSetNameValue( papszOptions, "COMPRESS", "PACKBITS" );
437
438 //create three band raster (red, green, blue)
439 gdal::dataset_unique_ptr outputDataset( GDALCreate( outputDriver, mOutputFile.toUtf8().constData(), xSize, ySize, 3, GDT_Byte, papszOptions ) );
440 CSLDestroy( papszOptions );
441 papszOptions = nullptr;
442
443 if ( !outputDataset )
444 {
445 return nullptr;
446 }
447
448 //get geotransform from inputDataset
449 double geotransform[6];
450 if ( GDALGetGeoTransform( inputDataset, geotransform ) != CE_None )
451 {
452 return nullptr;
453 }
454 GDALSetGeoTransform( outputDataset.get(), geotransform );
455
456 //make sure mCellSizeX and mCellSizeY are always > 0
457 mCellSizeX = geotransform[1];
458 if ( mCellSizeX < 0 )
459 {
460 mCellSizeX = -mCellSizeX;
461 }
462 mCellSizeY = geotransform[5];
463 if ( mCellSizeY < 0 )
464 {
465 mCellSizeY = -mCellSizeY;
466 }
467
468 const char *projection = GDALGetProjectionRef( inputDataset );
469 GDALSetProjection( outputDataset.get(), projection );
470
471 return outputDataset;
472}
473
474//this function is mainly there for debugging
476{
477 int nCellsX, nCellsY;
478 const gdal::dataset_unique_ptr inputDataset = openInputFile( nCellsX, nCellsY );
479 if ( !inputDataset )
480 {
481 return false;
482 }
483
484 //open first raster band for reading (elevation raster is always single band)
485 GDALRasterBandH elevationBand = GDALGetRasterBand( inputDataset.get(), 1 );
486 if ( !elevationBand )
487 {
488 return false;
489 }
490
491 //1. get minimum and maximum of elevation raster -> 252 elevation classes
492 int minOk, maxOk;
493 double minMax[2];
494 minMax[0] = GDALGetRasterMinimum( elevationBand, &minOk );
495 minMax[1] = GDALGetRasterMaximum( elevationBand, &maxOk );
496
497 if ( !minOk || !maxOk )
498 {
499 GDALComputeRasterMinMax( elevationBand, true, minMax );
500 }
501
502 //2. go through raster cells and get frequency of classes
503
504 //store elevation frequency in 256 elevation classes
505 double frequency[252] = {0};
506 const double frequencyClassRange = ( minMax[1] - minMax[0] ) / 252.0;
507
508 float *scanLine = ( float * ) CPLMalloc( sizeof( float ) * nCellsX );
509 int elevationClass = -1;
510
511 for ( int i = 0; i < nCellsY; ++i )
512 {
513 if ( GDALRasterIO( elevationBand, GF_Read, 0, i, nCellsX, 1,
514 scanLine, nCellsX, 1, GDT_Float32,
515 0, 0 ) != CE_None )
516 {
517 QgsDebugError( QStringLiteral( "Raster IO Error" ) );
518 }
519
520 for ( int j = 0; j < nCellsX; ++j )
521 {
522 elevationClass = frequencyClassForElevation( scanLine[j], minMax[0], frequencyClassRange );
523 if ( elevationClass >= 0 && elevationClass < 252 )
524 {
525 frequency[elevationClass] += 1.0;
526 }
527 }
528 }
529
530 CPLFree( scanLine );
531
532 //log10 transformation for all frequency values
533 for ( int i = 0; i < 252; ++i )
534 {
535 frequency[i] = std::log10( frequency[i] );
536 }
537
538 //write out frequency values to csv file for debugging
539 QFile outFile( file );
540 if ( !outFile.open( QIODevice::WriteOnly | QIODevice::Truncate ) )
541 {
542 return false;
543 }
544
545 QTextStream outstream( &outFile );
546#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
547 outstream.setCodec( "UTF-8" );
548#endif
549 for ( int i = 0; i < 252; ++i )
550 {
551 outstream << QString::number( i ) + ',' + QString::number( frequency[i] ) << Qt::endl;
552 }
553 outFile.close();
554 return true;
555}
556
557QList< QgsRelief::ReliefColor > QgsRelief::calculateOptimizedReliefClasses()
558{
559 QList< QgsRelief::ReliefColor > resultList;
560
561 int nCellsX, nCellsY;
562 const gdal::dataset_unique_ptr inputDataset = openInputFile( nCellsX, nCellsY );
563 if ( !inputDataset )
564 {
565 return resultList;
566 }
567
568 //open first raster band for reading (elevation raster is always single band)
569 GDALRasterBandH elevationBand = GDALGetRasterBand( inputDataset.get(), 1 );
570 if ( !elevationBand )
571 {
572 return resultList;
573 }
574
575 //1. get minimum and maximum of elevation raster -> 252 elevation classes
576 int minOk, maxOk;
577 double minMax[2];
578 minMax[0] = GDALGetRasterMinimum( elevationBand, &minOk );
579 minMax[1] = GDALGetRasterMaximum( elevationBand, &maxOk );
580
581 if ( !minOk || !maxOk )
582 {
583 GDALComputeRasterMinMax( elevationBand, true, minMax );
584 }
585
586 //2. go through raster cells and get frequency of classes
587
588 //store elevation frequency in 256 elevation classes
589 double frequency[252] = {0};
590 const double frequencyClassRange = ( minMax[1] - minMax[0] ) / 252.0;
591
592 float *scanLine = ( float * ) CPLMalloc( sizeof( float ) * nCellsX );
593 int elevationClass = -1;
594
595 for ( int i = 0; i < nCellsY; ++i )
596 {
597 if ( GDALRasterIO( elevationBand, GF_Read, 0, i, nCellsX, 1,
598 scanLine, nCellsX, 1, GDT_Float32,
599 0, 0 ) != CE_None )
600 {
601 QgsDebugError( QStringLiteral( "Raster IO Error" ) );
602 }
603 for ( int j = 0; j < nCellsX; ++j )
604 {
605 elevationClass = frequencyClassForElevation( scanLine[j], minMax[0], frequencyClassRange );
606 elevationClass = std::max( std::min( elevationClass, 251 ), 0 );
607 frequency[elevationClass] += 1.0;
608 }
609 }
610
611 CPLFree( scanLine );
612
613 //log10 transformation for all frequency values
614 for ( int i = 0; i < 252; ++i )
615 {
616 frequency[i] = std::log10( frequency[i] );
617 }
618
619 //start with 9 uniformly distributed classes
620 QList<int> classBreaks;
621 classBreaks.append( 0 );
622 classBreaks.append( 28 );
623 classBreaks.append( 56 );
624 classBreaks.append( 84 );
625 classBreaks.append( 112 );
626 classBreaks.append( 140 );
627 classBreaks.append( 168 );
628 classBreaks.append( 196 );
629 classBreaks.append( 224 );
630 classBreaks.append( 252 );
631
632 for ( int i = 0; i < 10; ++i )
633 {
634 optimiseClassBreaks( classBreaks, frequency );
635 }
636
637 //debug, print out all the classbreaks
638 for ( int i = 0; i < classBreaks.size(); ++i )
639 {
640 qWarning( "%d", classBreaks[i] );
641 }
642
643 //set colors according to optimised class breaks
644 QVector<QColor> colorList;
645 colorList.reserve( 9 );
646 colorList.push_back( QColor( 7, 165, 144 ) );
647 colorList.push_back( QColor( 12, 221, 162 ) );
648 colorList.push_back( QColor( 33, 252, 183 ) );
649 colorList.push_back( QColor( 247, 252, 152 ) );
650 colorList.push_back( QColor( 252, 196, 8 ) );
651 colorList.push_back( QColor( 252, 166, 15 ) );
652 colorList.push_back( QColor( 175, 101, 15 ) );
653 colorList.push_back( QColor( 255, 133, 92 ) );
654 colorList.push_back( QColor( 204, 204, 204 ) );
655
656 resultList.reserve( classBreaks.size() );
657 for ( int i = 1; i < classBreaks.size(); ++i )
658 {
659 const double minElevation = minMax[0] + classBreaks[i - 1] * frequencyClassRange;
660 const double maxElevation = minMax[0] + classBreaks[i] * frequencyClassRange;
661 resultList.push_back( QgsRelief::ReliefColor( colorList.at( i - 1 ), minElevation, maxElevation ) );
662 }
663
664 return resultList;
665}
666
667void QgsRelief::optimiseClassBreaks( QList<int> &breaks, double *frequencies )
668{
669 const int nClasses = breaks.size() - 1;
670 double *a = new double[nClasses]; //slopes
671 double *b = new double[nClasses]; //y-offsets
672
673 for ( int i = 0; i < nClasses; ++i )
674 {
675 //get all the values between the class breaks into input
676 QList< QPair < int, double > > regressionInput;
677 regressionInput.reserve( breaks.at( i + 1 ) - breaks.at( i ) );
678 for ( int j = breaks.at( i ); j < breaks.at( i + 1 ); ++j )
679 {
680 regressionInput.push_back( qMakePair( j, frequencies[j] ) );
681 }
682
683 double aParam, bParam;
684 if ( !regressionInput.isEmpty() && calculateRegression( regressionInput, aParam, bParam ) )
685 {
686 a[i] = aParam;
687 b[i] = bParam;
688 }
689 else
690 {
691 a[i] = 0;
692 b[i] = 0; //better default value
693 }
694 }
695
696 const QList<int> classesToRemove;
697
698 //shift class boundaries or eliminate classes which fall together
699 for ( int i = 1; i < nClasses ; ++i )
700 {
701 if ( breaks[i] == breaks[ i - 1 ] )
702 {
703 continue;
704 }
705
706 if ( qgsDoubleNear( a[i - 1 ], a[i] ) )
707 {
708 continue;
709 }
710 else
711 {
712 int newX = ( b[i - 1] - b[ i ] ) / ( a[ i ] - a[ i - 1 ] );
713
714 if ( newX <= breaks[i - 1] )
715 {
716 newX = breaks[i - 1];
717 // classesToRemove.push_back( i );//remove this class later as it falls together with the preceding one
718 }
719 else if ( i < nClasses - 1 && newX >= breaks[i + 1] )
720 {
721 newX = breaks[i + 1];
722 // classesToRemove.push_back( i );//remove this class later as it falls together with the next one
723 }
724
725 breaks[i] = newX;
726 }
727 }
728
729 for ( int i = classesToRemove.size() - 1; i >= 0; --i )
730 {
731 breaks.removeAt( classesToRemove.at( i ) );
732 }
733
734 delete[] a;
735 delete[] b;
736}
737
738int QgsRelief::frequencyClassForElevation( double elevation, double minElevation, double elevationClassRange )
739{
740 return ( elevation - minElevation ) / elevationClassRange;
741}
742
743bool QgsRelief::calculateRegression( const QList< QPair < int, double > > &input, double &a, double &b )
744{
745 double xMean, yMean;
746 double xSum = 0;
747 double ySum = 0;
748 QList< QPair < int, double > >::const_iterator inputIt = input.constBegin();
749 for ( ; inputIt != input.constEnd(); ++inputIt )
750 {
751 xSum += inputIt->first;
752 ySum += inputIt->second;
753 }
754 xMean = xSum / input.size();
755 yMean = ySum / input.size();
756
757 double sumCounter = 0;
758 double sumDenominator = 0;
759 inputIt = input.constBegin();
760 for ( ; inputIt != input.constEnd(); ++inputIt )
761 {
762 sumCounter += ( ( inputIt->first - xMean ) * ( inputIt->second - yMean ) );
763 sumDenominator += ( ( inputIt->first - xMean ) * ( inputIt->first - xMean ) );
764 }
765
766 a = sumCounter / sumDenominator;
767 b = yMean - a * xMean;
768
769 return true;
770}
771
Calculates aspect values in a window of 3x3 cells based on first order derivatives in x- and y- direc...
Base class for feedback objects to be used for cancellation of something running in a worker thread.
Definition qgsfeedback.h:44
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
static bool supportsRasterCreate(GDALDriverH driver)
Reads whether a driver supports GDALCreate() for raster purposes.
A hillshade filter.
void clearReliefColors()
Definition qgsrelief.cpp:51
bool exportFrequencyDistributionToCsv(const QString &file)
Write frequency of elevation values to file for manual inspection.
QgsRelief(const QString &inputFile, const QString &outputFile, const QString &outputFormat)
Definition qgsrelief.cpp:35
QList< QgsRelief::ReliefColor > calculateOptimizedReliefClasses()
Calculates class breaks according with the method of Buenzli (2011) using an iterative algorithm for ...
int processRaster(QgsFeedback *feedback=nullptr)
Starts the calculation, reads from mInputFile and stores the result in mOutputFile.
Definition qgsrelief.cpp:72
void addReliefColorClass(const QgsRelief::ReliefColor &color)
Definition qgsrelief.cpp:56
Calculates slope values in a window of 3x3 cells based on first order derivatives in x- and y- direct...
void CORE_EXPORT fast_delete_and_close(dataset_unique_ptr &dataset, GDALDriverH driver, const QString &path)
Performs a fast close of an unwanted GDAL dataset handle by deleting the underlying data store.
std::unique_ptr< std::remove_pointer< GDALDatasetH >::type, GDALDatasetCloser > dataset_unique_ptr
Scoped GDAL dataset.
As part of the API refactoring and improvements which landed in the Processing API was substantially reworked from the x version This was done in order to allow much of the underlying Processing framework to be ported into c
bool qgsDoubleNear(double a, double b, double epsilon=4 *std::numeric_limits< double >::epsilon())
Compare two doubles (but allow some difference)
Definition qgis.h:5445
void * GDALDatasetH
#define QgsDebugError(str)
Definition qgslogger.h:38