WSL/SLF GitLab Repository

DEMObject.cc 42.9 KB
Newer Older
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
/***********************************************************************************/
/*  Copyright 2009 WSL Institute for Snow and Avalanche Research    SLF-DAVOS      */
/***********************************************************************************/
/* This file is part of MeteoIO.
    MeteoIO is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    MeteoIO is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with MeteoIO.  If not, see <http://www.gnu.org/licenses/>.
*/
18
#include <cmath>
19
#include <limits.h>
20

21
#include <meteoio/dataClasses/DEMObject.h>
22
#include <meteoio/MathOptim.h>
23
#include <meteoio/meteoLaws/Meteoconst.h> //for math constants
24

25
26
27
28
29
30
31
32
33
34
35
36
/**
* @file DEMObject.cc
* @brief implementation of the DEMBoject class
*/

using namespace std;

namespace mio {

/**
* @brief Default constructor.
* Initializes all variables to 0, except lat/long which are initialized to IOUtils::nodata
37
* @param i_algorithm specify the default algorithm to use for slope computation (default=DFLT)
38
*/
39
40
DEMObject::DEMObject(const slope_type& i_algorithm)
           : Grid2DObject(), slope(), azi(), curvature(), Nx(), Ny(), Nz(),
41
42
             min_altitude(Cst::dbl_max), min_slope(Cst::dbl_max), min_curvature(Cst::dbl_max),
             max_altitude(Cst::dbl_min), max_slope(Cst::dbl_min), max_curvature(Cst::dbl_min),
43
44
45
             CalculateSlope(&DEMObject::CalculateCorripio),
             update_flag(INT_MAX), dflt_algorithm(i_algorithm),
             slope_failures(0), curvature_failures(0)
46
{
47
	setDefaultAlgorithm(i_algorithm);
48
49
50
51
}

/**
* @brief Constructor that sets variables.
Mathias Bavay's avatar
Mathias Bavay committed
52
53
54
* @param i_ncols number of colums in the grid2D
* @param i_nrows number of rows in the grid2D
* @param i_cellsize value for cellsize in grid2D
55
56
* @param i_llcorner lower lower corner point
* @param i_algorithm specify the default algorithm to use for slope computation (default=DFLT)
57
*/
Mathias Bavay's avatar
Mathias Bavay committed
58
DEMObject::DEMObject(const size_t& i_ncols, const size_t& i_nrows,
59
                     const double& i_cellsize, const Coords& i_llcorner, const slope_type& i_algorithm)
60
61
           : Grid2DObject(i_ncols, i_nrows, i_cellsize, i_llcorner),
             slope(), azi(), curvature(), Nx(), Ny(), Nz(),
62
63
             min_altitude(Cst::dbl_max), min_slope(Cst::dbl_max), min_curvature(Cst::dbl_max),
             max_altitude(Cst::dbl_min), max_slope(Cst::dbl_min), max_curvature(Cst::dbl_min),
64
65
66
             CalculateSlope(&DEMObject::CalculateCorripio),
             update_flag(INT_MAX), dflt_algorithm(i_algorithm),
             slope_failures(0), curvature_failures(0)
67
{
68
	setDefaultAlgorithm(i_algorithm);
69
70
71
72
}

/**
* @brief Constructor that sets variables.
Mathias Bavay's avatar
Mathias Bavay committed
73
* @param i_cellsize value for cellsize in grid2D
74
* @param i_llcorner lower lower corner point
Mathias Bavay's avatar
Mathias Bavay committed
75
76
* @param i_altitude grid2D of elevations
* @param i_update also update slope/normals/curvatures and their min/max? (default=true)
77
* @param i_algorithm specify the default algorithm to use for slope computation (default=DFLT)
78
*/
79
DEMObject::DEMObject(const double& i_cellsize, const Coords& i_llcorner, const Array2D<double>& i_altitude,
80
                     const bool& i_update, const slope_type& i_algorithm)
81
           : Grid2DObject(i_cellsize, i_llcorner, i_altitude),
82
             slope(), azi(), curvature(), Nx(), Ny(), Nz(),
83
84
             min_altitude(Cst::dbl_max), min_slope(Cst::dbl_max), min_curvature(Cst::dbl_max),
             max_altitude(Cst::dbl_min), max_slope(Cst::dbl_min), max_curvature(Cst::dbl_min),
85
86
87
             CalculateSlope(&DEMObject::CalculateCorripio),
             update_flag(INT_MAX), dflt_algorithm(i_algorithm),
             slope_failures(0), curvature_failures(0)
88
{
89
90
	setDefaultAlgorithm(i_algorithm);
	if(i_update==false) {
91
92
		updateAllMinMax();
	} else {
93
		update(i_algorithm);
94
95
96
97
98
	}
}

/**
* @brief Constructor that sets variables from a Grid2DObject
Mathias Bavay's avatar
Mathias Bavay committed
99
100
* @param i_dem grid contained in a Grid2DObject
* @param i_update also update slope/normals/curvatures and their min/max? (default=true)
101
* @param i_algorithm specify the default algorithm to use for slope computation (default=DFLT)
102
*/
103
DEMObject::DEMObject(const Grid2DObject& i_dem, const bool& i_update, const slope_type& i_algorithm)
104
           : Grid2DObject(i_dem.cellsize, i_dem.llcorner, i_dem.grid2D),
105
             slope(), azi(), curvature(), Nx(), Ny(), Nz(),
106
107
             min_altitude(Cst::dbl_max), min_slope(Cst::dbl_max), min_curvature(Cst::dbl_max),
             max_altitude(Cst::dbl_min), max_slope(Cst::dbl_min), max_curvature(Cst::dbl_min),
108
109
110
             CalculateSlope(&DEMObject::CalculateCorripio),
             update_flag(INT_MAX), dflt_algorithm(i_algorithm),
             slope_failures(0), curvature_failures(0)
111
{
112
113
	setDefaultAlgorithm(i_algorithm);
	if(i_update==false) {
114
115
		updateAllMinMax();
	} else {
116
		update(i_algorithm);
117
118
119
120
	}
}

/**
121
* @brief Constructor that sets variables from a subset of another DEMObject,
122
* given an origin (X,Y) (first index being 0) and a number of columns and rows
Mathias Bavay's avatar
Mathias Bavay committed
123
124
125
126
127
128
* @param i_dem dem contained in a DEMDObject
* @param i_nx X coordinate of the new origin
* @param i_ny Y coordinate of the new origin
* @param i_ncols number of columns for the subset dem
* @param i_nrows number of rows for the subset dem
* @param i_update also update slope/normals/curvatures and their min/max? (default=true)
129
* @param i_algorithm specify the default algorithm to use for slope computation (default=DFLT)
130
*/
Mathias Bavay's avatar
Mathias Bavay committed
131
132
DEMObject::DEMObject(const DEMObject& i_dem, const size_t& i_nx, const size_t& i_ny,
                     const size_t& i_ncols, const size_t& i_nrows,
133
                     const bool& i_update, const slope_type& i_algorithm)
134
135
           : Grid2DObject(i_dem, i_nx,i_ny, i_ncols,i_nrows),
             slope(), azi(), curvature(), Nx(), Ny(), Nz(),
136
137
             min_altitude(Cst::dbl_max), min_slope(Cst::dbl_max), min_curvature(Cst::dbl_max),
             max_altitude(Cst::dbl_min), max_slope(Cst::dbl_min), max_curvature(Cst::dbl_min),
138
139
140
             CalculateSlope(&DEMObject::CalculateCorripio),
             update_flag(i_dem.update_flag), dflt_algorithm(i_algorithm),
             slope_failures(0), curvature_failures(0)
141
{
142
	if ((i_ncols==0) || (i_nrows==0)) {
143
144
		throw InvalidArgumentException("requesting a subset of 0 columns or rows for DEMObject", AT);
	}
145

146
	//handling of the update properties
147
148
	setDefaultAlgorithm(i_algorithm);
	if(i_update==true) {
149
150
		//if the object is in automatic update, then we only process the arrays according to
		//the update_flag
151
		update(i_algorithm);
152
153
154
	} else {
		//if the object is NOT in automatic update, we manually copy all non-empty arrays
		//from the original set
Mathias Bavay's avatar
Mathias Bavay committed
155
		size_t nx, ny;
156

157
		i_dem.slope.size(nx, ny);
158
		if(nx>0 && ny>0) {
159
			slope.subset(i_dem.slope,i_nx,i_ny, i_ncols,i_nrows);
160
		}
161
		i_dem.azi.size(nx, ny);
162
		if(nx>0 && ny>0) {
163
			azi.subset(i_dem.azi,i_nx,i_ny, i_ncols,i_nrows);
164
		}
165
		i_dem.curvature.size(nx, ny);
166
		if(nx>0 && ny>0) {
167
			curvature.subset(i_dem.curvature,i_nx,i_ny, i_ncols,i_nrows);
168
		}
169
		i_dem.Nx.size(nx, ny);
170
		if(nx>0 && ny>0) {
171
			Nx.subset(i_dem.Nx,i_nx,i_ny, i_ncols,i_nrows);
172
		}
173
		i_dem.Ny.size(nx, ny);
174
		if(nx>0 && ny>0) {
175
			Ny.subset(i_dem.Ny,i_nx,i_ny, i_ncols,i_nrows);
176
		}
177
		i_dem.Nz.size(nx, ny);
178
		if(nx>0 && ny>0) {
179
			Nz.subset(i_dem.Nz,i_nx,i_ny, i_ncols,i_nrows);
180
181
182
		}

		updateAllMinMax();
183
184
185
	}
}

186
187
188
189
190
191
192
193
194
195
196
197
198
199
/**
* @brief Set the properties that will be calculated by the object when updating
* The following properties can be turned on/off: slope/azimuth and/or normals, and/or curvatures.
* Flags are combined using the binary "|" operator.
* @param in_update_flag parameters to update
*/
void DEMObject::setUpdatePpt(const update_type& in_update_flag) {
	update_flag = in_update_flag;
}

/**
* @brief Get the properties that will be calculated by the object when updating
* @return combination of flags set with the binary "|" operator
*/
200
int DEMObject::getUpdatePpt() const {
201
202
203
	return update_flag;
}

204
205
/**
* @brief Force the computation of the local slope, azimuth, normal vector and curvature.
206
* It has to be called manually since it can require some time to compute. Without this call,
207
* the above mentionned parameters are NOT up to date.
Mathias Bavay's avatar
Mathias Bavay committed
208
* @param algorithm algorithm to use for computing slope, azimuth and normals
209
210
*/
void DEMObject::update(const slope_type& algorithm) {
211
//This method recomputes the attributes that are not read as parameters
212
213
214
//(such as slope, azimuth, normal vector)

	// Creating tables
215
	if(update_flag&SLOPE) {
216
217
		slope.resize(getNx(), getNy());
		azi.resize(getNx(), getNy());
218
219
	}
	if(update_flag&CURVATURE) {
220
		curvature.resize(getNx(), getNy());
221
222
	}
	if(update_flag&NORMAL) {
223
224
225
		Nx.resize(getNx(), getNy());
		Ny.resize(getNx(), getNy());
		Nz.resize(getNx(), getNy());
226
	}
227
228
229
230
231
232
233

	CalculateAziSlopeCurve(algorithm);
	updateAllMinMax();
}

/**
* @brief Force the computation of the local slope, azimuth, normal vector and curvature.
234
* It has to be called manually since it can require some time to compute. Without this call,
235
* the above mentionned parameters are NOT up to date.
Mathias Bavay's avatar
Mathias Bavay committed
236
* @param algorithm algorithm to use for computing slope, azimuth and normals
237
238
239
240
241
242
* it is either:
* - HICK that uses the maximum downhill slope method (Dunn and Hickey, 1998)
* - FLEMING uses a 4 neighbors algorithm (Fleming and Hoffer, 1979)
* - CORRIPIO that uses the surface normal vector using the two triangle method given in Corripio (2002)
* and the eight-neighbor algorithm of Horn (1981) for border cells.
* - D8 uses CORRIPIO but discretizes the resulting azimuth to 8 cardinal directions and the slope is rounded to the nearest degree. Curvature and normals are left untouched.
243
*
244
245
246
* The azimuth is always computed using the Hodgson (1998) algorithm.
*/
void DEMObject::update(const std::string& algorithm) {
247
//This method recomputes the attributes that are not read as parameters
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
//(such as slope, azimuth, normal vector)
	slope_type type;

	if(algorithm.compare("HICK")==0) {
		type=HICK;
	} else if(algorithm.compare("FLEMING")==0) {
		type=FLEM;
	} else if(algorithm.compare("HORN")==0) {
		type=HORN;
	} else if(algorithm.compare("CORRIPIO")==0) {
		type=CORR;
	} else if(algorithm.compare("D8")==0) {
		type=D8;
	} else if(algorithm.compare("DEFAULT")==0) {
		type=DFLT;
	} else {
		throw InvalidArgumentException("Chosen slope algorithm " + algorithm + " not available", AT);
	}
266

267
268
269
270
271
	update(type);
}

/**
* @brief Sets the default slope calculation algorithm
272
* @param i_algorithm specify the default algorithm to use for slope computation
273
*/
274
void DEMObject::setDefaultAlgorithm(const slope_type& i_algorithm) {
275
//This method MUST be called by each constructor!
276
	if(i_algorithm==DFLT) {
277
278
		dflt_algorithm = CORR;
	} else {
279
		dflt_algorithm = i_algorithm;
280
281
282
	}
}

283
284
285
286
287
288
289
/**
* @brief Get the default slope calculation algorithm
* @return default algorithm to use for slope computation
*/
int DEMObject::getDefaultAlgorithm() const {
	return dflt_algorithm;
}
290
291
/**
* @brief Recomputes the min/max of altitude, slope and curvature
292
* It return +/- std::numeric_limits\<double\>\:\:max() for a given parameter if its grid was empty/undefined
293
294
295
*/
void DEMObject::updateAllMinMax() {
//updates the min/max parameters of all 2D tables
296
	if(update_flag&SLOPE) {
297
298
		min_slope = slope.getMin();
		max_slope = slope.getMax();
299
300
	}
	if(update_flag&CURVATURE) {
301
302
		min_curvature = curvature.getMin();
		max_curvature = curvature.getMax();
303
304
	}

305
306
	min_altitude = grid2D.getMin();
	max_altitude = grid2D.getMax();
307
308
309
310
311
312
313
314
315
}

/**
* @brief Prints the list of points that have an elevation different than nodata but no slope or curvature
* Such points can happen if they are surrounded by too many points whose elevation is nodata
* If no such points exist, it prints nothing.
*/
void DEMObject::printFailures() {
	bool header=true;
316
317
	const size_t ncols = getNx();
	const size_t nrows = getNy();
318

319
	if(update_flag&SLOPE) {
Mathias Bavay's avatar
Mathias Bavay committed
320
321
		for ( size_t j = 0; j < nrows; j++ ) {
			for ( size_t i = 0; i < ncols; i++ ) {
322
323
				if((slope(i,j)==IOUtils::nodata) && (grid2D(i,j)!=IOUtils::nodata)) {
					if(header==true) {
324
325
						cerr << "[i] DEM slope could not be computed at the following points \n";
						cerr << "[i]\tGrid Point\tElevation\tSlope\n";
326
327
						header=false;
					}
328
					cerr << "[i]\t(" << i << "," << j << ")" << "\t\t" << grid2D(i,j) << "\t\t" << slope(i,j) << "\n";
329
330
331
332
333
334
				}
			}
		}
	}

	if(update_flag&CURVATURE) {
Mathias Bavay's avatar
Mathias Bavay committed
335
336
		for ( size_t j = 0; j < nrows; j++ ) {
			for ( size_t i = 0; i < ncols; i++ ) {
337
338
				if((curvature(i,j)==IOUtils::nodata) && (grid2D(i,j)!=IOUtils::nodata)) {
					if(header==true) {
339
340
						cerr << "[i] DEM curvature could not be computed at the following points \n";
						cerr << "[i]\tGrid Point\tElevation\tCurvature\n";
341
342
						header=false;
					}
343
					cerr << "[i]\t(" << i << "," << j << ")" << "\t\t" << grid2D(i,j) << "\t\t" <<  curvature(i,j) << "\n";
344
345
346
347
348
				}
			}
		}
	}
	if(header==false) {
349
		cerr << std::endl;
350
351
352
353
354
355
356
357
358
359
360
361
362
363
	}
}

/**
* @brief Clean up the DEM Object
* When computing the slope and curvature, it is possible to get points where the elevation is known
* but where no slope/azimuth/normals/curvature could be computed. This method sets the elevation to nodata for such points,
* so that latter use of the DEM would be simpler (simply test the elevation in order to know if the point can be used
* and it guarantees that all other informations are available).If the slope/azimuth/normals/curvature tables were manually updated, this method will NOT perform any work (it requires the count of slopes/curvature failures to be greater than zero)
*
* IMPORTANT: calling this method DOES change the table of elevations!
*/
void DEMObject::sanitize() {
	if(slope_failures>0 || curvature_failures>0) {
364
365
366
		const size_t ncols = getNx();
		const size_t nrows = getNy();

Mathias Bavay's avatar
Mathias Bavay committed
367
368
		for ( size_t j = 0; j < nrows; j++ ) {
			for ( size_t i = 0; i < ncols; i++ ) {
369
370
371
372
373
374
375
376
377
				if(update_flag&SLOPE) {
					if((slope(i,j)==IOUtils::nodata) && (grid2D(i,j)!=IOUtils::nodata)) {
						grid2D(i,j) = IOUtils::nodata;
					}
				}
				if(update_flag&CURVATURE) {
					if((curvature(i,j)==IOUtils::nodata) && (grid2D(i,j)!=IOUtils::nodata)) {
						grid2D(i,j) = IOUtils::nodata;
					}
378
379
380
381
382
383
				}
			}
		}
	}
}

384
385
386
387
388
/**
* @brief Computes the hillshade for the dem
* This "fake illumination" method is used to better show the relief on maps.
* @param elev elevation (in degrees) of the source of light
* @param azimuth azimuth (in degrees) of the source of light
389
* @return hillshade grid that containing the illumination
390
391
*
*/
392
Grid2DObject DEMObject::getHillshade(const double& elev, const double& azimuth) const
393
394
395
396
397
398
{
	if(slope.isEmpty() || azi.isEmpty())
		throw InvalidArgumentException("Hillshade computation requires slope and azimuth!", AT);

	const double zenith_rad = (90.-elev)*Cst::to_rad;
	const double azimuth_rad = azimuth*Cst::to_rad;
399
400
401
402
	const size_t ncols = getNx();
	const size_t nrows = getNy();

	Grid2DObject hillshade(ncols, nrows, cellsize, llcorner);
403
404
405
406
407
408
409
410
411
412
413
414
415
416

	for ( size_t j = 0; j < nrows; j++ ) {
		for ( size_t i = 0; i < ncols; i++ ) {
			const double alt = grid2D(i,j);
			const double sl = slope(i,j);
			const double az = azi(i,j);
			if(alt!=IOUtils::nodata && sl!=IOUtils::nodata && az!=IOUtils::nodata) {
				const double sl_rad = sl*Cst::to_rad;
				const double tmp = cos(zenith_rad) * cos(sl_rad) + sin(zenith_rad) * sin(sl_rad) * cos(azimuth_rad-az*Cst::to_rad);
				hillshade(i,j) = (tmp>=0.)? tmp : 0.;
			} else
				hillshade(i,j) = IOUtils::nodata;
		}
	}
417
418

	return hillshade;
419
420
}

421
422
423
424
425
426
427
428
429
430
431
/**
* @brief Computes the horizontal distance between two points in a metric grid
* @param xcoord1 east coordinate of the first point
* @param ycoord1 north coordinate of the first point
* @param xcoord2 east coordinate of the second point
* @param ycoord2 north coordinate of the second point
* @return horizontal distance in meters
*
*/
double DEMObject::horizontalDistance(const double& xcoord1, const double& ycoord1, const double& xcoord2, const double& ycoord2)
{
432
	return sqrt( Optim::pow2(xcoord2-xcoord1) + Optim::pow2(ycoord2-ycoord1) );
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
}

/**
* @brief Computes the horizontal distance between two points in a metric grid
* @param point1 first point (ie: origin)
* @param point2 second point (ie: destination)
* @return horizontal distance in meters
*
*/
double DEMObject::horizontalDistance(Coords point1, const Coords& point2)
{
	if(point1.isSameProj(point2)==false) {
		point1.copyProj(point2);
	}
	return horizontalDistance(point1.getEasting(), point1.getNorthing(),
448
	                          point2.getEasting(), point2.getNorthing() );
449
450
451
452
453
454
455
456
457
458
459
460
461
}


/**
* @brief Returns the distance *following the terrain* between two coordinates
* @param point1 first point (ie: origin)
* @param point2 second point (ie: destination)
* @return distance following the terrain in meters
*
*/
double DEMObject::terrainDistance(Coords point1, const Coords& point2) {
	std::vector<GRID_POINT_2D> vec_points;
	double distance=0.;
Mathias Bavay's avatar
Mathias Bavay committed
462
	size_t last_point=0; //point 0 is always the starting point
463
464
465
466
467
468
469

	//Checking that both points use the same projection is done in getPointsBetween()
	getPointsBetween(point1, point2, vec_points);
	if(vec_points.size()<=1) {
		return 0.;
	}

Mathias Bavay's avatar
Mathias Bavay committed
470
471
472
473
474
	for(size_t ii=1; ii<vec_points.size(); ii++) {
		const size_t ix1=vec_points[last_point].ix;
		const size_t iy1=vec_points[last_point].iy;
		const size_t ix2=vec_points[ii].ix;
		const size_t iy2=vec_points[ii].iy;
475
476
477
478
479
480

		if(grid2D(ix2,iy2)!=IOUtils::nodata) {
			if(grid2D(ix1,iy1)!=IOUtils::nodata) {
				//distance += sqrt( pow2((ix2-ix1)*cellsize) + pow2((iy2-iy1)*cellsize) + pow2(grid2D(ix2,iy2)-grid2D(ix1,iy1)) );
				const double z1=grid2D(ix1,iy1);
				const double z2=grid2D(ix2,iy2);
481
482
483
				const double tmpx=Optim::pow2((double)(ix2-ix1)*cellsize);
				const double tmpy=Optim::pow2((double)(iy2-iy1)*cellsize);
				const double tmpz=Optim::pow2(z2-z1);
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
				distance += sqrt( tmpx + tmpy + tmpz );
			}
			last_point = ii;
		}
	}

	return distance;
}

/**
* @brief Returns a list of grid points that are on the straight line between two coordinates
* @param point1 first point (ie: origin)
* @param point2 second point (ie: destination)
* @param vec_points vector of points that are in between
*
*/
void DEMObject::getPointsBetween(Coords point1, Coords point2, std::vector<GRID_POINT_2D>& vec_points) {

	if(point1.isSameProj(point2)==false) {
		point1.copyProj(point2);
	}

	if(point1.getEasting() > point2.getEasting()) {
		//we want xcoord1<xcoord2, so we swap the two points
		const Coords tmp = point1;
		point1 = point2;
		point2 = tmp;
	}

	//extension of the line segment (pts1, pts2) along the X axis
	const int ix1 = (int)floor( (point1.getEasting() - llcorner.getEasting())/cellsize );
	const int iy1 = (int)floor( (point1.getNorthing() - llcorner.getNorthing())/cellsize );
	const int ix2 = (int)floor( (point2.getEasting() - llcorner.getEasting())/cellsize );
	const int iy2 = (int)floor( (point2.getNorthing() - llcorner.getNorthing())/cellsize );

	if(ix1==ix2) {
		//special case of vertical alignement
521
		for(int iy=min(iy1,iy2); iy<=max(iy1,iy2); iy++) {
522
523
524
525
526
527
528
529
530
531
532
533
534
535
			GRID_POINT_2D pts;
			pts.ix = ix1;
			pts.iy = iy;
			vec_points.push_back(pts);
		}
	} else {
		//normal case
		//equation of the line between the two points
		const double a = ((double)(iy2-iy1)) / ((double)(ix2-ix1));
		const double b = (double)iy1 - a * (double)ix1;

		for(int ix=ix1; ix<=ix2; ix++) {
			//extension of the line segment (ix, ix+1) along the Y axis
			int y1 = (int)floor( a*(double)ix+b );
536
			//const int y2 = min( (int)floor( a*((double)ix+1)+b ) , iy2);
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
			int y2 = (int)floor( a*((double)ix+1)+b );
			if(ix==ix2 && y1==iy2) {
				//we don't want to overshoot when reaching the target cell
				y2 = y1;
			}

			if(y1>y2) {
				//we want y1<y2, so we swap the two coordinates
				const int ytemp=y1;
				y1=y2; y2=ytemp;
			}

			for(int iy=y1; iy<=y2; iy++) {
				GRID_POINT_2D pts;
				pts.ix = ix;
				pts.iy = iy;
				//make sure we only return points within the dem
554
				if(ix>0 && ix<(signed)getNx() && iy>0 && iy<(signed)getNy()) {
555
556
557
558
559
560
561
					vec_points.push_back(pts);
				}
			}
		}
	}
}

562
563
564
565
566
567
568
/**
* @brief Returns a list of grid points that are on the straight line between two coordinates
* @param point the origin point
* @param bearing direction given by a compass bearing
* @param vec_points vector of points that are between point and the edge of the dem following direction given by bearing
*
*/
569
570
void DEMObject::getPointsBetween(const Coords& point, const double& bearing, std::vector<GRID_POINT_2D>& vec_points) {
	//equation of the line between for a point (x0,y0) and a bearing
571
572
	const double x0 = (point.getEasting() - llcorner.getEasting())/cellsize;
	const double y0 = (point.getNorthing() - llcorner.getNorthing())/cellsize;
573
574
	const double bear=fmod(bearing+360., 360.); //this should not be needed, but as safety...
	const double a = tan( IOUtils::bearing_to_angle(bear) ); //to get trigonometric angle
575
	const double b = y0 - a * x0;
576

577
578
579
	//looking which point is on the limit of the grid and not outside
	Coords pointlim;
	pointlim.copyProj(llcorner); //we use the same projection parameters as the DEM
580
581
582
583

	//define the boundaries according to the quadrant we are in
	double xlim, ylim;
	if(bear>=0. && bear<90.) {
584
585
		xlim = (double)(getNx()-1);
		ylim = (double)(getNy()-1);
586
	} else if (bear>=90. && bear<180.) {
587
		xlim = (double)(getNx()-1);
588
589
590
591
592
593
		ylim = 0.;
	} else if (bear>=180. && bear<270.) {
		xlim = 0.;
		ylim = 0.;
	} else {
		xlim = 0.;
594
		ylim = (double)(getNy()-1);
595
596
597
598
599
600
601
602
603
	}

	//calculate the two possible intersections between the bearing line and the boundaries
	const double y2 = a * xlim + b;
	const double x2 = (ylim - b) / (a + 1e-12);

	//Find out which point is the first intersect and take it as our destination point
	if(bear>=90. && bear<270.) {
		if (y2 >= ylim)
604
605
606
        		pointlim.setXY((xlim*cellsize)+llcorner.getEasting(),(y2*cellsize)+llcorner.getNorthing() , IOUtils::nodata);
		else
        		pointlim.setXY((x2*cellsize)+llcorner.getEasting(),(ylim*cellsize)+llcorner.getNorthing() , IOUtils::nodata);
607
	} else {
608
609
610
611
612
		if (y2 <= ylim)
        		pointlim.setXY((xlim*cellsize)+llcorner.getEasting(),(y2*cellsize)+llcorner.getNorthing() , IOUtils::nodata);
		else
        		pointlim.setXY((x2*cellsize)+llcorner.getEasting(),(ylim*cellsize)+llcorner.getNorthing() , IOUtils::nodata);
	}
613

614
	if(gridify(pointlim)==false) {
615
		std::ostringstream tmp;
616
617
		tmp << "[E] Wrong destination point calculated for bearing " << bearing;
		throw InvalidArgumentException(tmp.str(), AT);
618
619
	}

620
621
	getPointsBetween(point, pointlim, vec_points);
	//HACK BUG : for bearing=160 -> both start and end points are missing from the list!!
622
623
624
625
626
627
628
629
630
631
632
}

/**
* @brief Returns the horizon from a given point looking toward a given bearing
* @param point the origin point
* @param bearing direction given by a compass bearing
* @return angle above the horizontal (in deg)
*
*/
double DEMObject::getHorizon(const Coords& point, const double& bearing) {

633
	std::vector<Grid2DObject::GRID_POINT_2D> vec_points;
634
635
	getPointsBetween(point, bearing, vec_points);

636
637
638
639
	//Starting point
	const int ix0 = (int)point.getGridI();
	const int iy0 = (int)point.getGridJ();
	const double height0 = grid2D(ix0,iy0);
640

641
	//going through every point and looking for the highest tangent (which is also the highest angle)
642
	double max_tangent = 0.;
Mathias Bavay's avatar
Mathias Bavay committed
643
	for (size_t ii=0; ii < vec_points.size(); ii++) {
644
645
646
647
648
649
650
651
652
		const int ix = (int)vec_points[ii].ix;
		const int iy = (int)vec_points[ii].iy;
		const double delta_height = grid2D(ix, iy) - height0;
		const double x_distance = (double)(ix - ix0) * cellsize;
		const double y_distance = (double)(iy - iy0) * cellsize;
		const double distance = sqrt(x_distance * x_distance + y_distance * y_distance);
		const double tangent = (delta_height / distance);

		if(tangent > max_tangent) max_tangent = tangent;
653
654
	}

655
	//returning the angle matching the highest tangent
656
	return ( atan(max_tangent)*Cst::to_deg );
657
658
659
660
661
662
663
664
665
}

/**
* @brief Returns the horizon from a given point looking 360 degrees around by increments
* @param point the origin point
* @param increment to the bearing between two angles
* @param horizon vector of heights above a given angle
*
*/
666
667
668
669
670
671
void DEMObject::getHorizon(const Coords& point, const double& increment, std::vector<double>& horizon)
{
	for(double bearing=0.0; bearing <360.; bearing += increment) {
		const double alpha = getHorizon(point, bearing * Cst::PI/180.);
		horizon.push_back(alpha);
	}
672
673
}

674
675
676
void DEMObject::CalculateAziSlopeCurve(slope_type algorithm) {
//This computes the slope and the aspect at a given cell as well as the x and y components of the normal vector
	double A[4][4]; //table to store neigbouring heights: 3x3 matrix but we want to start at [1][1]
677
	                //we use matrix notation: A[y][x]
678
679
680
681
682
683
	if(algorithm==DFLT) {
		algorithm = dflt_algorithm;
	}

	slope_failures = curvature_failures = 0;
	if(algorithm==HICK) {
684
		CalculateSlope = &DEMObject::CalculateHick;
685
	} else if(algorithm==HORN) {
686
		CalculateSlope = &DEMObject::CalculateHorn;
687
	} else if(algorithm==CORR) {
688
		CalculateSlope = &DEMObject::CalculateCorripio;
689
	} else if(algorithm==FLEM) {
690
691
692
693
694
695
696
697
		CalculateSlope = &DEMObject::CalculateFleming;
	} else if(algorithm==D8) {
		CalculateSlope = &DEMObject::CalculateHick;
	} else {
		throw InvalidArgumentException("Chosen slope algorithm not available", AT);
	}

	//Now, calculate the parameters using the previously defined function pointer
698
699
	for ( size_t j = 0; j < getNy(); j++ ) {
		for ( size_t i = 0; i < getNx(); i++ ) {
700
701
			if( grid2D(i,j) == IOUtils::nodata ) {
				if(update_flag&SLOPE) {
702
					slope(i,j) = azi(i,j) = IOUtils::nodata;
703
704
				}
				if(update_flag&CURVATURE) {
705
					curvature(i,j) = IOUtils::nodata;
706
707
				}
				if(update_flag&NORMAL) {
708
					Nx(i,j) = Ny(i,j) = Nz(i,j) = IOUtils::nodata;
709
710
711
				}
			} else {
				getNeighbours(i, j, A);
712
				double new_slope, new_Nx, new_Ny, new_Nz;
713
				(this->*CalculateSlope)(A, new_slope, new_Nx, new_Ny, new_Nz);
714
715
				const double new_azi = CalculateAspect(new_Nx, new_Ny, new_Nz, new_slope);
				const double new_curvature = getCurvature(A);
716
				if(update_flag&SLOPE) {
717
718
					slope(i,j) = new_slope;
					azi(i,j) = new_azi;
719
720
				}
				if(update_flag&CURVATURE) {
721
					curvature(i,j) = new_curvature;
722
723
				}
				if(update_flag&NORMAL) {
724
725
726
					Nx(i,j) = new_Nx;
					Ny(i,j) = new_Ny;
					Nz(i,j) = new_Nz;
727
728
729
				}
			}
		}
730
731
732
	}

	if((update_flag&SLOPE) && (algorithm==D8)) { //extra processing required: discretization
733
734
		for ( size_t j = 0; j < getNy(); j++ ) {
			for ( size_t i = 0; i < getNx(); i++ ) {
735
736
737
738
739
740
741
742
743
744
745
746
					//TODO: process flats by an extra algorithm
					if(azi(i,j)!=IOUtils::nodata)
						azi(i,j) = fmod(floor( (azi(i,j)+22.5)/45. )*45., 360.);
					if(slope(i,j)!=IOUtils::nodata)
						slope(i,j) = floor( slope(i,j)+0.5 );
			}
		}
	}

	//Inform the user is some points have unexpectidly not been computed
	//(ie: there was an altitude but some parameters could not be computed)
	if(slope_failures>0 || curvature_failures>0) {
747
		cerr << "[W] DEMObject: " << slope_failures << " point(s) have an elevation but no slope, " << curvature_failures << " point(s) have an elevation but no curvature." << std::endl;
748
749
750
751
	}

} // end of CalculateAziSlope

752
double DEMObject::CalculateAspect(const double& o_Nx, const double& o_Ny, const double& o_Nz, const double& o_slope, const double no_slope) {
753
754
755
756
//Calculates the aspect at a given point knowing its normal vector and slope
//(direction of the normal pointing out of the surface, clockwise from north)
//This azimuth calculation is similar to Hodgson (1998)
//local_nodata is the value that we want to give to the aspect of points that don't have a slope
757
//The value is a bearing (ie: deg, clockwise, 0=North)
758

759
	if(o_Nx==IOUtils::nodata || o_Ny==IOUtils::nodata || o_Nz==IOUtils::nodata || o_slope==IOUtils::nodata) {
760
761
762
		return IOUtils::nodata;
	}

763
764
765
	if ( o_slope > 0. ) { //there is some slope
		if ( o_Nx == 0. ) { //no E-W slope, so it is purely N-S
			if ( o_Ny < 0. ) {
766
				return(180.); // south facing
767
			} else {
768
				return (0.); // north facing
769
770
			}
		} else { //there is a E-W slope
771
772
			if ( o_Nx > 0. ) {
				return (90. - atan(o_Ny/o_Nx)*Cst::to_deg);
773
			} else {
774
				return (270. - atan(o_Ny/o_Nx)*Cst::to_deg);
775
776
777
778
779
780
781
782
			}
		}
	} else { // if slope = 0
		return (no_slope);          // undefined or plain surface
	}
}


783
void DEMObject::CalculateHick(double A[4][4], double& o_slope, double& o_Nx, double& o_Ny, double& o_Nz) {
784
785
786
787
788
789
//This calculates the surface normal vector using the steepest slope method (Dunn and Hickey, 1998):
//the steepest slope found in the eight cells surrounding (i,j) is given to be the slope in (i,j)
//Beware, sudden steps could happen
	const double smax = steepestGradient(A); //steepest local gradient

	if(smax==IOUtils::nodata) {
790
791
792
793
		o_slope = IOUtils::nodata;
		o_Nx = IOUtils::nodata;
		o_Ny = IOUtils::nodata;
		o_Nz = IOUtils::nodata;
794
795
		slope_failures++;
	} else {
796
		o_slope = atan(smax)*Cst::to_deg;
797
798
799
800
801
802

		//Nx and Ny: x and y components of the normal pointing OUT of the surface
		if ( smax > 0. ) { //ie: there is some slope
			double dx_sum, dy_sum;
			surfaceGradient(dx_sum, dy_sum, A);
			if(dx_sum==IOUtils::nodata || dy_sum==IOUtils::nodata) {
803
804
805
				o_Nx = IOUtils::nodata;
				o_Ny = IOUtils::nodata;
				o_Nz = IOUtils::nodata;
806
807
				slope_failures++;
			} else {
808
809
810
				o_Nx = -1.0 * dx_sum / (2. * cellsize);	//Nx=-dz/dx
				o_Ny = -1.0 * dy_sum / (2. * cellsize);	//Ny=-dz/dy
				o_Nz = 1.;				//Nz=1 (normalized by definition of Nx and Ny)
811
812
			}
		} else { //ie: there is no slope
813
814
815
			o_Nx = 0.;
			o_Ny = 0.;
			o_Nz = 1.;
816
817
818
819
		}
	}
}

820
void DEMObject::CalculateFleming(double A[4][4], double& o_slope, double& o_Nx, double& o_Ny, double& o_Nz) {
821
822
//This calculates the surface normal vector using method by Fleming and Hoffer (1979)
	if(A[2][1]!=IOUtils::nodata && A[2][3]!=IOUtils::nodata && A[3][2]!=IOUtils::nodata && A[1][2]!=IOUtils::nodata) {
823
824
825
826
		o_Nx = 0.5 * (A[2][1] - A[2][3]) / cellsize;
		o_Ny = 0.5 * (A[3][2] - A[1][2]) / cellsize;
		o_Nz = 1.;
		o_slope = atan( sqrt(o_Nx*o_Nx+o_Ny*o_Ny) ) * Cst::to_deg;
827
	} else {
828
		CalculateHick(A, o_slope, o_Nx, o_Ny, o_Nz);
829
830
831
	}
}

832
void DEMObject::CalculateHorn(double A[4][4], double& o_slope, double& o_Nx, double& o_Ny, double& o_Nz) {
833
834
835
836
837
//This calculates the slope using the two eight neighbors method given in Horn (1981)
//This is also the algorithm used by ArcGIS
	if ( A[1][1]!=IOUtils::nodata && A[1][2]!=IOUtils::nodata && A[1][3]!=IOUtils::nodata &&
	     A[2][1]!=IOUtils::nodata && A[2][2]!=IOUtils::nodata && A[2][3]!=IOUtils::nodata &&
	     A[3][1]!=IOUtils::nodata && A[3][2]!=IOUtils::nodata && A[3][3]!=IOUtils::nodata) {
838
839
840
		o_Nx = ((A[3][3]+2.*A[2][3]+A[1][3]) - (A[3][1]+2.*A[2][1]+A[1][1])) / (8.*cellsize);
		o_Ny = ((A[1][3]+2.*A[1][2]+A[1][1]) - (A[3][3]+2.*A[3][2]+A[3][1])) / (8.*cellsize);
		o_Nz = 1.;
841
842
843

		//There is no difference between slope = acos(n_z/|n|) and slope = atan(sqrt(sx*sx+sy*sy))
		//slope = acos( (Nz / sqrt( Nx*Nx + Ny*Ny + Nz*Nz )) );
844
		o_slope = atan( sqrt(o_Nx*o_Nx+o_Ny*o_Ny) ) * Cst::to_deg;
845
846
	} else {
		//steepest slope method (Dunn and Hickey, 1998)
847
		CalculateHick(A, o_slope, o_Nx, o_Ny, o_Nz);
848
849
850
	}
}

851
void DEMObject::CalculateCorripio(double A[4][4], double& o_slope, double& o_Nx, double& o_Ny, double& o_Nz) {
852
853
854
855
856
//This calculates the surface normal vector using the two triangle method given in Corripio (2003) but cell centered instead of node centered (ie using a 3x3 grid instead of 2x2)
	if ( A[1][1]!=IOUtils::nodata && A[1][3]!=IOUtils::nodata && A[3][1]!=IOUtils::nodata && A[3][3]!=IOUtils::nodata) {
		// See Corripio (2003), knowing that here we normalize the result (divided by Nz=cellsize*cellsize) and that we are cell centered instead of node centered
		o_Nx = (A[3][1] + A[1][1] - A[3][3] - A[1][3]) / (2.*2.*cellsize);
		o_Ny = (A[3][1] - A[1][1] + A[3][3] - A[1][3]) / (2.*2.*cellsize);
857
		o_Nz = 1.;
858
859
		//There is no difference between slope = acos(n_z/|n|) and slope = atan(sqrt(sx*sx+sy*sy))
		//slope = acos( (Nz / sqrt( Nx*Nx + Ny*Ny + Nz*Nz )) );
860
		o_slope = atan( sqrt(o_Nx*o_Nx+o_Ny*o_Ny) ) * Cst::to_deg;
861
862
	} else {
		//steepest slope method (Dunn and Hickey, 1998)
863
		CalculateHick(A, o_slope, o_Nx, o_Ny, o_Nz);
864
865
866
867
868
869
870
871
872
873
874
875
876
	}
}

double DEMObject::getCurvature(double A[4][4]) {
//This methode computes the curvature of a specific cell
	if(A[2][2]!=IOUtils::nodata) {
		const double Zwe   = avgHeight(A[2][1], A[2][2], A[2][3]);
		const double Zsn   = avgHeight(A[1][2], A[2][2], A[3][2]);
		const double Zswne = avgHeight(A[3][1], A[2][2], A[1][3]);
		const double Znwse = avgHeight(A[1][1], A[2][2], A[3][3]);

		const double sqrt2 = sqrt(2.);
		double sum=0.;
Mathias Bavay's avatar
Mathias Bavay committed
877
		size_t count=0;
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895

		if(Zwe!=IOUtils::nodata) {
			sum += 0.5*(A[2][2]-Zwe);
			count++;
		}
		if(Zsn!=IOUtils::nodata) {
			sum += 0.5*(A[2][2]-Zsn);
			count++;
		}
		if(Zswne!=IOUtils::nodata) {
			sum += 0.5*(A[2][2]-Zswne)/sqrt2;
			count++;
		}
		if(Znwse!=IOUtils::nodata) {
			sum += 0.5*(A[2][2]-Znwse)/sqrt2;
			count++;
		}

Mathias Bavay's avatar
Mathias Bavay committed
896
		if(count != 0.) return 1./(double)count * sum;
897
898
899
900
901
902
903
904
905
906
907
908
	}
	curvature_failures++;
	return IOUtils::nodata;
}

double DEMObject::steepestGradient(double A[4][4]) {
//best effort to calculate the local steepest gradient
	double smax=-1.;		//maximum slope of all neighboring slopes
	const double sqrt2=sqrt(2.);	//the weight of the 4 corner cells is increased by sqrt(2)

	if(A[2][2]!=IOUtils::nodata) {
		if(A[1][1]!=IOUtils::nodata)
909
			smax = max( smax, fabs(A[2][2] - A[1][1])/(cellsize*sqrt2) );
910
		if(A[1][2]!=IOUtils::nodata)
911
			smax = max( smax, fabs(A[2][2] - A[1][2])/(cellsize) );
912
		if(A[1][3]!=IOUtils::nodata)
913
			smax = max( smax, fabs(A[2][2] - A[1][3])/(cellsize*sqrt2) );
914
		if(A[2][1]!=IOUtils::nodata)
915
			smax = max( smax, fabs(A[2][2] - A[2][1])/(cellsize) );
916
		if(A[2][3]!=IOUtils::nodata)
917
			smax = max( smax, fabs(A[2][2] - A[2][3])/(cellsize) );
918
		if(A[3][1]!=IOUtils::nodata)
919
			smax = max( smax, fabs(A[2][2] - A[3][1])/(cellsize*sqrt2) );
920
		if(A[3][2]!=IOUtils::nodata)
921
			smax = max( smax, fabs(A[2][2] - A[3][2])/(cellsize) );
922
		if(A[3][3]!=IOUtils::nodata)
923
			smax = max( smax, fabs(A[2][2] - A[3][3])/(cellsize*sqrt2) );
924
925
926
927
928
929
930
931
932
933
	}

	if(smax<0.)
		return IOUtils::nodata;
	return smax;
}

double DEMObject::lineGradient(const double& A1, const double& A2, const double& A3) {
//best effort to calculate the local gradient
	if(A3!=IOUtils::nodata && A1!=IOUtils::nodata) {
934
		return A3 - A1;
935
936
	} else {
		if(A2!=IOUtils::nodata) {
937
			if(A3!=IOUtils::nodata)
938
				return (A3 - A2)*2.;
939
			if(A1!=IOUtils::nodata)
940
				return (A2 - A1)*2.;
941
942
943
		}
	}

944
	return IOUtils::nodata;
945
946
947
948
949
}

double DEMObject::fillMissingGradient(const double& delta1, const double& delta2) {
//If a gradient could not be computed, try to fill it with some neighboring value
	if(delta1!=IOUtils::nodata && delta2!=IOUtils::nodata) {
950
		return 0.5*(delta1+delta2);
951
	} else {
952
953
		if(delta1!=IOUtils::nodata) return delta1;
		if(delta2!=IOUtils::nodata) return delta2;
954
955
	}

956
	return IOUtils::nodata;
957
958
959
960
}

void DEMObject::surfaceGradient(double& dx_sum, double& dy_sum, double A[4][4]) {
//Compute the gradient for a given cell (i,j) accross its eight surrounding cells (Horn, 1981)
961
962
963
	double dx1 = lineGradient(A[3][1], A[3][2], A[3][3]);
	double dx2 = lineGradient(A[2][1], A[2][2], A[2][3]);
	double dx3 = lineGradient(A[1][1], A[1][2], A[1][3]);
964

965
966
967
	double dy1 = lineGradient(A[3][1], A[2][1], A[1][1]);
	double dy2 = lineGradient(A[3][2], A[2][2], A[1][2]);
	double dy3 = lineGradient(A[3][3], A[2][3], A[1][3]);
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000

	//now trying to fill whatever could not be filled...
	if(dx1==IOUtils::nodata) dx1 = fillMissingGradient(dx2, dx3);
	if(dx2==IOUtils::nodata) dx2 = fillMissingGradient(dx1, dx3);
	if(dx3==IOUtils::nodata) dx3 = fillMissingGradient(dx1, dx2);
	if(dy1==IOUtils::nodata) dy1 = fillMissingGradient(dy2, dy3);
	if(dy2==IOUtils::nodata) dy2 = fillMissingGradient(dy1, dy3);
	if(dy3==IOUtils::nodata) dy3 = fillMissingGradient(dy1, dy2);

	if(dx1!=IOUtils::nodata && dy1!=IOUtils::nodata) {
		// principal axis twice to emphasize height difference in that direction
		dx_sum = (dx1 + 2.*dx2 + dx3) * 0.25;
		dy_sum = (dy1 + 2.*dy2 + dy3) * 0.25;
	} else {
		//if dx1==nodata, this also means that dx2==nodata and dx3==nodata
		//(otherwise, dx1 would have received a copy of either dx2 or dx3)
		dx_sum = IOUtils::nodata;
		dy_sum = IOUtils::nodata;
	}
}

double DEMObject::avgHeight(const double& z1, const double &z2, const double& z3) {
//this safely computes the average height accross a vector

	if(z1!=IOUtils::nodata && z3!=IOUtils::nodata) {
		return 0.5*(z1+z3);
	}
	if(z1!=IOUtils::nodata && z2!=IOUtils::nodata) {
		return 0.5*(z1+z2);
	}
	if(z3!=IOUtils::nodata && z2!=IOUtils::nodata) {
		return 0.5*(z3+z2);
	}
For faster browsing, not all history is shown. View entire blame