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1 | /* | |
2 | * viking -- GPS Data and Topo Analyzer, Explorer, and Manager | |
3 | * | |
4 | * Copyright (C) 2003-2008, Evan Battaglia <gtoevan@gmx.net> | |
5 | * Copyright (C) 2007, Quy Tonthat <qtonthat@gmail.com> | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License as published by | |
9 | * the Free Software Foundation; either version 2 of the License, or | |
10 | * (at your option) any later version. | |
11 | * | |
12 | * This program is distributed in the hope that it will be useful, | |
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | * GNU General Public License for more details. | |
16 | * | |
17 | * You should have received a copy of the GNU General Public License | |
18 | * along with this program; if not, write to the Free Software | |
19 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
20 | * | |
21 | */ | |
22 | ||
23 | #ifdef HAVE_CONFIG_H | |
24 | #include "config.h" | |
25 | #endif | |
26 | ||
27 | #include <stdio.h> | |
28 | #ifdef HAVE_STRING_H | |
29 | #include <string.h> | |
30 | #endif | |
31 | #include <glib.h> | |
32 | #ifdef HAVE_MATH_H | |
33 | #include <math.h> | |
34 | #endif | |
35 | #ifdef HAVE_STDLIB_H | |
36 | #include <stdlib.h> | |
37 | #endif | |
38 | #include <sys/types.h> | |
39 | #include <sys/stat.h> | |
40 | #ifdef HAVE_UNISTD_H | |
41 | #include <unistd.h> | |
42 | #endif | |
43 | ||
44 | #include <glib/gstdio.h> | |
45 | #include <glib/gi18n.h> | |
46 | ||
47 | #include "compression.h" | |
48 | #include "dem.h" | |
49 | #include "file.h" | |
50 | ||
51 | /* Compatibility */ | |
52 | #if ! GLIB_CHECK_VERSION(2,22,0) | |
53 | #define g_mapped_file_unref g_mapped_file_free | |
54 | #endif | |
55 | ||
56 | #define DEM_BLOCK_SIZE 1024 | |
57 | #define GET_COLUMN(dem,n) ((VikDEMColumn *)g_ptr_array_index( (dem)->columns, (n) )) | |
58 | ||
59 | static gboolean get_double_and_continue ( gchar **buffer, gdouble *tmp, gboolean warn ) | |
60 | { | |
61 | gchar *endptr; | |
62 | *tmp = g_strtod(*buffer, &endptr); | |
63 | if ( endptr == NULL|| endptr == *buffer ) { | |
64 | if ( warn ) | |
65 | g_warning(_("Invalid DEM")); | |
66 | return FALSE; | |
67 | } | |
68 | *buffer=endptr; | |
69 | return TRUE; | |
70 | } | |
71 | ||
72 | ||
73 | static gboolean get_int_and_continue ( gchar **buffer, gint *tmp, gboolean warn ) | |
74 | { | |
75 | gchar *endptr; | |
76 | *tmp = strtol(*buffer, &endptr, 10); | |
77 | if ( endptr == NULL|| endptr == *buffer ) { | |
78 | if ( warn ) | |
79 | g_warning(_("Invalid DEM")); | |
80 | return FALSE; | |
81 | } | |
82 | *buffer=endptr; | |
83 | return TRUE; | |
84 | } | |
85 | ||
86 | static gboolean dem_parse_header ( gchar *buffer, VikDEM *dem ) | |
87 | { | |
88 | gdouble val; | |
89 | gint int_val; | |
90 | guint i; | |
91 | gchar *tmp = buffer; | |
92 | ||
93 | /* incomplete header */ | |
94 | if ( strlen(buffer) != 1024 ) | |
95 | return FALSE; | |
96 | ||
97 | /* fix Fortran-style exponentiation 1.0D5 -> 1.0E5 */ | |
98 | while (*tmp) { | |
99 | if ( *tmp=='D') | |
100 | *tmp='E'; | |
101 | tmp++; | |
102 | } | |
103 | ||
104 | /* skip name */ | |
105 | buffer += 149; | |
106 | ||
107 | /* "DEM level code, pattern code, palaimetric reference system code" -- skip */ | |
108 | get_int_and_continue(&buffer, &int_val, TRUE); | |
109 | get_int_and_continue(&buffer, &int_val, TRUE); | |
110 | get_int_and_continue(&buffer, &int_val, TRUE); | |
111 | ||
112 | /* zone */ | |
113 | get_int_and_continue(&buffer, &int_val, TRUE); | |
114 | dem->utm_zone = int_val; | |
115 | /* TODO -- southern or northern hemisphere?! */ | |
116 | dem->utm_letter = 'N'; | |
117 | ||
118 | /* skip numbers 5-19 */ | |
119 | for ( i = 0; i < 15; i++ ) { | |
120 | if ( ! get_double_and_continue(&buffer, &val, FALSE) ) { | |
121 | g_warning (_("Invalid DEM header")); | |
122 | return FALSE; | |
123 | } | |
124 | } | |
125 | ||
126 | /* number 20 -- horizontal unit code (utm/ll) */ | |
127 | get_double_and_continue(&buffer, &val, TRUE); | |
128 | dem->horiz_units = val; | |
129 | get_double_and_continue(&buffer, &val, TRUE); | |
130 | /* dem->orig_vert_units = val; now done below */ | |
131 | ||
132 | /* TODO: do this for real. these are only for 1:24k and 1:250k USGS */ | |
133 | if ( dem->horiz_units == VIK_DEM_HORIZ_UTM_METERS ) { | |
134 | dem->east_scale = 10.0; /* meters */ | |
135 | dem->north_scale = 10.0; | |
136 | dem->orig_vert_units = VIK_DEM_VERT_DECIMETERS; | |
137 | } else { | |
138 | dem->east_scale = 3.0; /* arcseconds */ | |
139 | dem->north_scale = 3.0; | |
140 | dem->orig_vert_units = VIK_DEM_VERT_METERS; | |
141 | } | |
142 | ||
143 | /* skip next */ | |
144 | get_double_and_continue(&buffer, &val, TRUE); | |
145 | ||
146 | /* now we get the four corner points. record the min and max. */ | |
147 | get_double_and_continue(&buffer, &val, TRUE); | |
148 | dem->min_east = dem->max_east = val; | |
149 | get_double_and_continue(&buffer, &val, TRUE); | |
150 | dem->min_north = dem->max_north = val; | |
151 | ||
152 | for ( i = 0; i < 3; i++ ) { | |
153 | get_double_and_continue(&buffer, &val, TRUE); | |
154 | if ( val < dem->min_east ) dem->min_east = val; | |
155 | if ( val > dem->max_east ) dem->max_east = val; | |
156 | get_double_and_continue(&buffer, &val, TRUE); | |
157 | if ( val < dem->min_north ) dem->min_north = val; | |
158 | if ( val > dem->max_north ) dem->max_north = val; | |
159 | } | |
160 | ||
161 | return TRUE; | |
162 | } | |
163 | ||
164 | static void dem_parse_block_as_cont ( gchar *buffer, VikDEM *dem, gint *cur_column, gint *cur_row ) | |
165 | { | |
166 | gint tmp; | |
167 | while ( *cur_row < GET_COLUMN(dem, *cur_column)->n_points ) { | |
168 | if ( get_int_and_continue(&buffer, &tmp,FALSE) ) { | |
169 | if ( dem->orig_vert_units == VIK_DEM_VERT_DECIMETERS ) | |
170 | GET_COLUMN(dem, *cur_column)->points[*cur_row] = (gint16) (tmp / 10); | |
171 | else | |
172 | GET_COLUMN(dem, *cur_column)->points[*cur_row] = (gint16) tmp; | |
173 | } else | |
174 | return; | |
175 | (*cur_row)++; | |
176 | } | |
177 | *cur_row = -1; /* expecting new column */ | |
178 | } | |
179 | ||
180 | static void dem_parse_block_as_header ( gchar *buffer, VikDEM *dem, gint *cur_column, gint *cur_row ) | |
181 | { | |
182 | guint n_rows; | |
183 | gint i; | |
184 | gdouble east_west, south; | |
185 | gdouble tmp; | |
186 | ||
187 | /* 1 x n_rows 1 east_west south x x x DATA */ | |
188 | ||
189 | if ( (!get_double_and_continue(&buffer, &tmp, TRUE)) || tmp != 1 ) { | |
190 | g_warning(_("Incorrect DEM Class B record: expected 1")); | |
191 | return; | |
192 | } | |
193 | ||
194 | /* don't need this */ | |
195 | if ( !get_double_and_continue(&buffer, &tmp, TRUE ) ) return; | |
196 | ||
197 | /* n_rows */ | |
198 | if ( !get_double_and_continue(&buffer, &tmp, TRUE ) ) | |
199 | return; | |
200 | n_rows = (guint) tmp; | |
201 | ||
202 | if ( (!get_double_and_continue(&buffer, &tmp, TRUE)) || tmp != 1 ) { | |
203 | g_warning(_("Incorrect DEM Class B record: expected 1")); | |
204 | return; | |
205 | } | |
206 | ||
207 | if ( !get_double_and_continue(&buffer, &east_west, TRUE) ) | |
208 | return; | |
209 | if ( !get_double_and_continue(&buffer, &south, TRUE) ) | |
210 | return; | |
211 | ||
212 | /* next three things we don't need */ | |
213 | if ( !get_double_and_continue(&buffer, &tmp, TRUE)) return; | |
214 | if ( !get_double_and_continue(&buffer, &tmp, TRUE)) return; | |
215 | if ( !get_double_and_continue(&buffer, &tmp, TRUE)) return; | |
216 | ||
217 | ||
218 | dem->n_columns ++; | |
219 | (*cur_column) ++; | |
220 | ||
221 | /* empty spaces for things before that were skipped */ | |
222 | (*cur_row) = (south - dem->min_north) / dem->north_scale; | |
223 | if ( south > dem->max_north || (*cur_row) < 0 ) | |
224 | (*cur_row) = 0; | |
225 | ||
226 | n_rows += *cur_row; | |
227 | ||
228 | g_ptr_array_add ( dem->columns, g_malloc(sizeof(VikDEMColumn)) ); | |
229 | GET_COLUMN(dem,*cur_column)->east_west = east_west; | |
230 | GET_COLUMN(dem,*cur_column)->south = south; | |
231 | GET_COLUMN(dem,*cur_column)->n_points = n_rows; | |
232 | GET_COLUMN(dem,*cur_column)->points = g_malloc(sizeof(gint16)*n_rows); | |
233 | ||
234 | /* no information for things before that */ | |
235 | for ( i = 0; i < (*cur_row); i++ ) | |
236 | GET_COLUMN(dem,*cur_column)->points[i] = VIK_DEM_INVALID_ELEVATION; | |
237 | ||
238 | /* now just continue */ | |
239 | dem_parse_block_as_cont ( buffer, dem, cur_column, cur_row ); | |
240 | ||
241 | ||
242 | } | |
243 | ||
244 | static void dem_parse_block ( gchar *buffer, VikDEM *dem, gint *cur_column, gint *cur_row ) | |
245 | { | |
246 | /* if haven't read anything or have read all items in a columns and are expecting a new column */ | |
247 | if ( *cur_column == -1 || *cur_row == -1 ) { | |
248 | dem_parse_block_as_header(buffer, dem, cur_column, cur_row); | |
249 | } else { | |
250 | dem_parse_block_as_cont(buffer, dem, cur_column, cur_row); | |
251 | } | |
252 | } | |
253 | ||
254 | static VikDEM *vik_dem_read_srtm_hgt(const gchar *file_name, const gchar *basename, gboolean zip) | |
255 | { | |
256 | gint i, j; | |
257 | VikDEM *dem; | |
258 | off_t file_size; | |
259 | gint16 *dem_mem = NULL; | |
260 | gchar *dem_file = NULL; | |
261 | const gint num_rows_3sec = 1201; | |
262 | const gint num_rows_1sec = 3601; | |
263 | gint num_rows; | |
264 | GMappedFile *mf; | |
265 | gint arcsec; | |
266 | GError *error = NULL; | |
267 | ||
268 | dem = g_malloc(sizeof(VikDEM)); | |
269 | ||
270 | dem->horiz_units = VIK_DEM_HORIZ_LL_ARCSECONDS; | |
271 | dem->orig_vert_units = VIK_DEM_VERT_DECIMETERS; | |
272 | ||
273 | /* TODO */ | |
274 | dem->min_north = atoi(basename+1) * 3600; | |
275 | dem->min_east = atoi(basename+4) * 3600; | |
276 | if ( basename[0] == 'S' ) | |
277 | dem->min_north = - dem->min_north; | |
278 | if ( basename[3] == 'W' ) | |
279 | dem->min_east = - dem->min_east; | |
280 | ||
281 | dem->max_north = 3600 + dem->min_north; | |
282 | dem->max_east = 3600 + dem->min_east; | |
283 | ||
284 | dem->columns = g_ptr_array_new(); | |
285 | dem->n_columns = 0; | |
286 | ||
287 | if ((mf = g_mapped_file_new(file_name, FALSE, &error)) == NULL) { | |
288 | g_critical(_("Couldn't map file %s: %s"), file_name, error->message); | |
289 | g_error_free(error); | |
290 | g_free(dem); | |
291 | return NULL; | |
292 | } | |
293 | file_size = g_mapped_file_get_length(mf); | |
294 | dem_file = g_mapped_file_get_contents(mf); | |
295 | ||
296 | if (zip) { | |
297 | void *unzip_mem = NULL; | |
298 | gulong ucsize; | |
299 | ||
300 | if ((unzip_mem = unzip_file(dem_file, &ucsize)) == NULL) { | |
301 | g_mapped_file_unref(mf); | |
302 | g_ptr_array_foreach ( dem->columns, (GFunc)g_free, NULL ); | |
303 | g_ptr_array_free(dem->columns, TRUE); | |
304 | g_free(dem); | |
305 | return NULL; | |
306 | } | |
307 | ||
308 | dem_mem = unzip_mem; | |
309 | file_size = ucsize; | |
310 | } | |
311 | else | |
312 | dem_mem = (gint16 *)dem_file; | |
313 | ||
314 | if (file_size == (num_rows_3sec * num_rows_3sec * sizeof(gint16))) | |
315 | arcsec = 3; | |
316 | else if (file_size == (num_rows_1sec * num_rows_1sec * sizeof(gint16))) | |
317 | arcsec = 1; | |
318 | else { | |
319 | g_warning("%s(): file %s does not have right size", __PRETTY_FUNCTION__, basename); | |
320 | g_mapped_file_unref(mf); | |
321 | g_free(dem); | |
322 | return NULL; | |
323 | } | |
324 | ||
325 | num_rows = (arcsec == 3) ? num_rows_3sec : num_rows_1sec; | |
326 | dem->east_scale = dem->north_scale = arcsec; | |
327 | ||
328 | for ( i = 0; i < num_rows; i++ ) { | |
329 | dem->n_columns++; | |
330 | g_ptr_array_add ( dem->columns, g_malloc(sizeof(VikDEMColumn)) ); | |
331 | GET_COLUMN(dem,i)->east_west = dem->min_east + arcsec*i; | |
332 | GET_COLUMN(dem,i)->south = dem->min_north; | |
333 | GET_COLUMN(dem,i)->n_points = num_rows; | |
334 | GET_COLUMN(dem,i)->points = g_malloc(sizeof(gint16)*num_rows); | |
335 | } | |
336 | ||
337 | int ent = 0; | |
338 | for ( i = (num_rows - 1); i >= 0; i-- ) { | |
339 | for ( j = 0; j < num_rows; j++ ) { | |
340 | GET_COLUMN(dem,j)->points[i] = GINT16_FROM_BE(dem_mem[ent]); | |
341 | ent++; | |
342 | } | |
343 | ||
344 | } | |
345 | ||
346 | if (zip) | |
347 | g_free(dem_mem); | |
348 | g_mapped_file_unref(mf); | |
349 | return dem; | |
350 | } | |
351 | ||
352 | #define IS_SRTM_HGT(fn) (strlen((fn))==11 && (fn)[7]=='.' && (fn)[8]=='h' && (fn)[9]=='g' && (fn)[10]=='t' && ((fn)[0]=='N' || (fn)[0]=='S') && ((fn)[3]=='E' || (fn)[3]=='W')) | |
353 | ||
354 | VikDEM *vik_dem_new_from_file(const gchar *file) | |
355 | { | |
356 | FILE *f=NULL; | |
357 | VikDEM *rv; | |
358 | gchar buffer[DEM_BLOCK_SIZE+1]; | |
359 | ||
360 | /* use to record state for dem_parse_block */ | |
361 | gint cur_column = -1; | |
362 | gint cur_row = -1; | |
363 | const gchar *basename = a_file_basename(file); | |
364 | ||
365 | if ( g_access ( file, R_OK ) != 0 ) | |
366 | return NULL; | |
367 | ||
368 | if ( (strlen(basename)==11 || ((strlen(basename) == 15) && (basename[11] == '.' && basename[12] == 'z' && basename[13] == 'i' && basename[14] == 'p'))) && | |
369 | basename[7]=='.' && basename[8]=='h' && basename[9]=='g' && basename[10]=='t' && | |
370 | (basename[0] == 'N' || basename[0] == 'S') && (basename[3] == 'E' || basename[3] =='W')) { | |
371 | gboolean is_zip_file = (strlen(basename) == 15); | |
372 | rv = vik_dem_read_srtm_hgt(file, basename, is_zip_file); | |
373 | return(rv); | |
374 | } | |
375 | ||
376 | /* Create Structure */ | |
377 | rv = g_malloc(sizeof(VikDEM)); | |
378 | ||
379 | /* Header */ | |
380 | f = g_fopen(file, "r"); | |
381 | if ( !f ) { | |
382 | g_free ( rv ); | |
383 | return NULL; | |
384 | } | |
385 | buffer[fread(buffer, 1, DEM_BLOCK_SIZE, f)] = '\0'; | |
386 | if ( ! dem_parse_header ( buffer, rv ) ) { | |
387 | g_free ( rv ); | |
388 | fclose(f); | |
389 | return NULL; | |
390 | } | |
391 | /* TODO: actually use header -- i.e. GET # OF COLUMNS EXPECTED */ | |
392 | ||
393 | rv->columns = g_ptr_array_new(); | |
394 | rv->n_columns = 0; | |
395 | ||
396 | /* Column -- Data */ | |
397 | while (! feof(f) ) { | |
398 | gchar *tmp; | |
399 | ||
400 | /* read block */ | |
401 | buffer[fread(buffer, 1, DEM_BLOCK_SIZE, f)] = '\0'; | |
402 | ||
403 | /* Fix Fortran-style exponentiation */ | |
404 | tmp = buffer; | |
405 | while (*tmp) { | |
406 | if ( *tmp=='D') | |
407 | *tmp='E'; | |
408 | tmp++; | |
409 | } | |
410 | ||
411 | dem_parse_block(buffer, rv, &cur_column, &cur_row); | |
412 | } | |
413 | ||
414 | /* TODO - class C records (right now says 'Invalid' and dies) */ | |
415 | ||
416 | fclose(f); | |
417 | f = NULL; | |
418 | ||
419 | /* 24k scale */ | |
420 | if ( rv->horiz_units == VIK_DEM_HORIZ_UTM_METERS && rv->n_columns >= 2 ) | |
421 | rv->north_scale = rv->east_scale = GET_COLUMN(rv, 1)->east_west - GET_COLUMN(rv,0)->east_west; | |
422 | ||
423 | /* FIXME bug in 10m DEM's */ | |
424 | if ( rv->horiz_units == VIK_DEM_HORIZ_UTM_METERS && rv->north_scale == 10 ) { | |
425 | rv->min_east -= 100; | |
426 | rv->min_north += 200; | |
427 | } | |
428 | ||
429 | ||
430 | return rv; | |
431 | } | |
432 | ||
433 | void vik_dem_free ( VikDEM *dem ) | |
434 | { | |
435 | guint i; | |
436 | for ( i = 0; i < dem->n_columns; i++) | |
437 | g_free ( GET_COLUMN(dem, i)->points ); | |
438 | g_ptr_array_foreach ( dem->columns, (GFunc)g_free, NULL ); | |
439 | g_ptr_array_free ( dem->columns, TRUE ); | |
440 | g_free ( dem ); | |
441 | } | |
442 | ||
443 | gint16 vik_dem_get_xy ( VikDEM *dem, guint col, guint row ) | |
444 | { | |
445 | if ( col < dem->n_columns ) | |
446 | if ( row < GET_COLUMN(dem, col)->n_points ) | |
447 | return GET_COLUMN(dem, col)->points[row]; | |
448 | return VIK_DEM_INVALID_ELEVATION; | |
449 | } | |
450 | ||
451 | gint16 vik_dem_get_east_north ( VikDEM *dem, gdouble east, gdouble north ) | |
452 | { | |
453 | gint col, row; | |
454 | ||
455 | if ( east > dem->max_east || east < dem->min_east || | |
456 | north > dem->max_north || north < dem->min_north ) | |
457 | return VIK_DEM_INVALID_ELEVATION; | |
458 | ||
459 | col = (gint) floor((east - dem->min_east) / dem->east_scale); | |
460 | row = (gint) floor((north - dem->min_north) / dem->north_scale); | |
461 | ||
462 | return vik_dem_get_xy ( dem, col, row ); | |
463 | } | |
464 | ||
465 | static gboolean dem_get_ref_points_elev_dist(VikDEM *dem, | |
466 | gdouble east, gdouble north, /* in seconds */ | |
467 | gint16 *elevs, gint16 *dists) | |
468 | { | |
469 | int i; | |
470 | int cols[4], rows[4]; | |
471 | struct LatLon ll[4]; | |
472 | struct LatLon pos; | |
473 | ||
474 | if ( east > dem->max_east || east < dem->min_east || | |
475 | north > dem->max_north || north < dem->min_north ) | |
476 | return FALSE; /* got nothing */ | |
477 | ||
478 | pos.lon = east/3600; | |
479 | pos.lat = north/3600; | |
480 | ||
481 | /* order of the data: sw, nw, ne, se */ | |
482 | /* sw */ | |
483 | cols[0] = (gint) floor((east - dem->min_east) / dem->east_scale); | |
484 | rows[0] = (gint) floor((north - dem->min_north) / dem->north_scale); | |
485 | ll[0].lon = (dem->min_east + dem->east_scale*cols[0])/3600; | |
486 | ll[0].lat = (dem->min_north + dem->north_scale*rows[0])/3600; | |
487 | /* nw */ | |
488 | cols[1] = cols[0]; | |
489 | rows[1] = rows[0] + 1; | |
490 | ll[1].lon = ll[0].lon; | |
491 | ll[1].lat = ll[0].lat + (gdouble)dem->north_scale/3600; | |
492 | /* ne */ | |
493 | cols[2] = cols[0] + 1; | |
494 | rows[2] = rows[0] + 1; | |
495 | ll[2].lon = ll[0].lon + (gdouble)dem->east_scale/3600; | |
496 | ll[2].lat = ll[0].lat + (gdouble)dem->north_scale/3600; | |
497 | /* se */ | |
498 | cols[3] = cols[0] + 1; | |
499 | rows[3] = rows[0]; | |
500 | ll[3].lon = ll[0].lon + (gdouble)dem->east_scale/3600; | |
501 | ll[3].lat = ll[0].lat; | |
502 | ||
503 | for (i = 0; i < 4; i++) { | |
504 | if ((elevs[i] = vik_dem_get_xy(dem, cols[i], rows[i])) == VIK_DEM_INVALID_ELEVATION) | |
505 | return FALSE; | |
506 | dists[i] = a_coords_latlon_diff(&pos, &ll[i]); | |
507 | } | |
508 | ||
509 | #if 0 /* debug */ | |
510 | for (i = 0; i < 4; i++) | |
511 | fprintf(stderr, "%f:%f:%d:%d ", ll[i].lat, ll[i].lon, dists[i], elevs[i]); | |
512 | fprintf(stderr, " north_scale=%f\n", dem->north_scale); | |
513 | #endif | |
514 | ||
515 | return TRUE; /* all OK */ | |
516 | } | |
517 | ||
518 | gint16 vik_dem_get_simple_interpol ( VikDEM *dem, gdouble east, gdouble north ) | |
519 | { | |
520 | int i; | |
521 | gint16 elevs[4], dists[4]; | |
522 | ||
523 | if (!dem_get_ref_points_elev_dist(dem, east, north, elevs, dists)) | |
524 | return VIK_DEM_INVALID_ELEVATION; | |
525 | ||
526 | for (i = 0; i < 4; i++) { | |
527 | if (dists[i] < 1) { | |
528 | return(elevs[i]); | |
529 | } | |
530 | } | |
531 | ||
532 | gdouble t = (gdouble)elevs[0]/dists[0] + (gdouble)elevs[1]/dists[1] + (gdouble)elevs[2]/dists[2] + (gdouble)elevs[3]/dists[3]; | |
533 | gdouble b = 1.0/dists[0] + 1.0/dists[1] + 1.0/dists[2] + 1.0/dists[3]; | |
534 | ||
535 | return(t/b); | |
536 | } | |
537 | ||
538 | gint16 vik_dem_get_shepard_interpol ( VikDEM *dem, gdouble east, gdouble north ) | |
539 | { | |
540 | int i; | |
541 | gint16 elevs[4], dists[4]; | |
542 | gint16 max_dist; | |
543 | gdouble t = 0.0; | |
544 | gdouble b = 0.0; | |
545 | ||
546 | if (!dem_get_ref_points_elev_dist(dem, east, north, elevs, dists)) | |
547 | return VIK_DEM_INVALID_ELEVATION; | |
548 | ||
549 | max_dist = 0; | |
550 | for (i = 0; i < 4; i++) { | |
551 | if (dists[i] < 1) { | |
552 | return(elevs[i]); | |
553 | } | |
554 | if (dists[i] > max_dist) | |
555 | max_dist = dists[i]; | |
556 | } | |
557 | ||
558 | gdouble tmp; | |
559 | #if 0 /* derived method by Franke & Nielson. Does not seem to work too well here */ | |
560 | for (i = 0; i < 4; i++) { | |
561 | tmp = pow((1.0*(max_dist - dists[i])/max_dist*dists[i]), 2); | |
562 | t += tmp*elevs[i]; | |
563 | b += tmp; | |
564 | } | |
565 | #endif | |
566 | ||
567 | for (i = 0; i < 4; i++) { | |
568 | tmp = pow((1.0/dists[i]), 2); | |
569 | t += tmp*elevs[i]; | |
570 | b += tmp; | |
571 | } | |
572 | ||
573 | // fprintf(stderr, "DEBUG: tmp=%f t=%f b=%f %f\n", tmp, t, b, t/b); | |
574 | ||
575 | return(t/b); | |
576 | ||
577 | } | |
578 | ||
579 | void vik_dem_east_north_to_xy ( VikDEM *dem, gdouble east, gdouble north, guint *col, guint *row ) | |
580 | { | |
581 | *col = (gint) floor((east - dem->min_east) / dem->east_scale); | |
582 | *row = (gint) floor((north - dem->min_north) / dem->north_scale); | |
583 | if ( *col < 0 ) *col = 0; | |
584 | if ( *row < 0 ) *row = 0; | |
585 | } | |
586 |