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root/radiance/ray/src/gen/gendaymtx.c
Revision: 2.6
Committed: Fri Jan 25 23:17:31 2013 UTC (11 years, 2 months ago) by greg
Content type: text/plain
Branch: MAIN
Changes since 2.5: +9 -7 lines
Log Message:
Fixed NaN output from non-zero illuminance before dawn or after sunset

File Contents

# Content
1 #ifndef lint
2 static const char RCSid[] = "$Id: gendaymtx.c,v 2.5 2013/01/20 01:16:49 greg Exp $";
3 #endif
4 /*
5 * gendaymtx.c
6 *
7 * Generate a daylight matrix based on Perez Sky Model.
8 *
9 * Most of this code is borrowed (see copyright below) from Ian Ashdown's
10 * excellent re-implementation of Jean-Jacques Delaunay's gendaylit.c
11 *
12 * Created by Greg Ward on 1/16/13.
13 */
14
15 /*********************************************************************
16 *
17 * H32_gendaylit.CPP - Perez Sky Model Calculation
18 *
19 * Version: 1.00A
20 *
21 * History: 09/10/01 - Created.
22 * 11/10/08 - Modified for Unix compilation.
23 * 11/10/12 - Fixed conditional __max directive.
24 * 1/11/13 - Tweaks and optimizations (G.Ward)
25 *
26 * Compilers: Microsoft Visual C/C++ Professional V10.0
27 *
28 * Author: Ian Ashdown, P.Eng.
29 * byHeart Consultants Limited
30 * 620 Ballantree Road
31 * West Vancouver, B.C.
32 * Canada V7S 1W3
33 * e-mail: [email protected]
34 *
35 * References: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R.
36 * Stewart. 1990. ìModeling Daylight Availability and
37 * Irradiance Components from Direct and Global
38 * Irradiance,î Solar Energy 44(5):271-289.
39 *
40 * Perez, R., R. Seals, and J. Michalsky. 1993.
41 * ìAll-Weather Model for Sky Luminance Distribution -
42 * Preliminary Configuration and Validation,î Solar Energy
43 * 50(3):235-245.
44 *
45 * Perez, R., R. Seals, and J. Michalsky. 1993. "ERRATUM to
46 * All-Weather Model for Sky Luminance Distribution -
47 * Preliminary Configuration and Validation,î Solar Energy
48 * 51(5):423.
49 *
50 * NOTE: This program is a completely rewritten version of
51 * gendaylit.c written by Jean-Jacques Delaunay (1994).
52 *
53 * Copyright 2009-2012 byHeart Consultants Limited. All rights
54 * reserved.
55 *
56 * Redistribution and use in source and binary forms, with or without
57 * modification, are permitted for personal and commercial purposes
58 * provided that redistribution of source code must retain the above
59 * copyright notice, this list of conditions and the following
60 * disclaimer:
61 *
62 * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESSED OR IMPLIED
63 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
64 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
65 * DISCLAIMED. IN NO EVENT SHALL byHeart Consultants Limited OR
66 * ITS EMPLOYEES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
67 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
68 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
69 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
70 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
71 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
72 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
73 * POSSIBILITY OF SUCH DAMAGE.
74 *
75 *********************************************************************/
76
77 /* Zenith is along the Z-axis */
78 /* X-axis points east */
79 /* Y-axis points north */
80 /* azimuth is measured as degrees or radians east of North */
81
82 /* Include files */
83 #define _USE_MATH_DEFINES
84 #include <stdio.h>
85 #include <stdlib.h>
86 #include <string.h>
87 #include <ctype.h>
88 #include "rtmath.h"
89 #include "color.h"
90
91 char *progname; /* Program name */
92 char errmsg[128]; /* Error message buffer */
93 const double DC_SolarConstantE = 1367.0; /* Solar constant W/m^2 */
94 const double DC_SolarConstantL = 127.5; /* Solar constant klux */
95
96 double altitude; /* Solar altitude (radians) */
97 double azimuth; /* Solar azimuth (radians) */
98 double apwc; /* Atmospheric precipitable water content */
99 double dew_point = 11.0; /* Surface dew point temperature (deg. C) */
100 double diff_illum; /* Diffuse illuminance */
101 double diff_irrad; /* Diffuse irradiance */
102 double dir_illum; /* Direct illuminance */
103 double dir_irrad; /* Direct irradiance */
104 int julian_date; /* Julian date */
105 double perez_param[5]; /* Perez sky model parameters */
106 double sky_brightness; /* Sky brightness */
107 double sky_clearness; /* Sky clearness */
108 double solar_rad; /* Solar radiance */
109 double sun_zenith; /* Sun zenith angle (radians) */
110 int input = 0; /* Input type */
111
112 extern double dmax( double, double );
113 extern double CalcAirMass();
114 extern double CalcDiffuseIllumRatio( int );
115 extern double CalcDiffuseIrradiance();
116 extern double CalcDirectIllumRatio( int );
117 extern double CalcDirectIrradiance();
118 extern double CalcEccentricity();
119 extern double CalcPrecipWater( double );
120 extern double CalcRelHorzIllum( float *parr );
121 extern double CalcRelLuminance( double, double );
122 extern double CalcSkyBrightness();
123 extern double CalcSkyClearness();
124 extern int CalcSkyParamFromIllum();
125 extern int GetCategoryIndex();
126 extern void CalcPerezParam( double, double, double, int );
127 extern void CalcSkyPatchLumin( float *parr );
128 extern void ComputeSky( float *parr );
129
130 /* Degrees into radians */
131 #define DegToRad(deg) ((deg)*(PI/180.))
132
133 /* Radiuans into degrees */
134 #define RadToDeg(rad) ((rad)*(180./PI))
135
136
137 /* Perez sky model coefficients */
138
139 /* Reference: Perez, R., R. Seals, and J. Michalsky, 1993. "All- */
140 /* Weather Model for Sky Luminance Distribution - */
141 /* Preliminary Configuration and Validation," Solar */
142 /* Energy 50(3):235-245, Table 1. */
143
144 static const double PerezCoeff[8][20] =
145 {
146 /* Sky clearness (epsilon): 1.000 to 1.065 */
147 { 1.3525, -0.2576, -0.2690, -1.4366, -0.7670,
148 0.0007, 1.2734, -0.1233, 2.8000, 0.6004,
149 1.2375, 1.0000, 1.8734, 0.6297, 0.9738,
150 0.2809, 0.0356, -0.1246, -0.5718, 0.9938 },
151 /* Sky clearness (epsilon): 1.065 to 1.230 */
152 { -1.2219, -0.7730, 1.4148, 1.1016, -0.2054,
153 0.0367, -3.9128, 0.9156, 6.9750, 0.1774,
154 6.4477, -0.1239, -1.5798, -0.5081, -1.7812,
155 0.1080, 0.2624, 0.0672, -0.2190, -0.4285 },
156 /* Sky clearness (epsilon): 1.230 to 1.500 */
157 { -1.1000, -0.2515, 0.8952, 0.0156, 0.2782,
158 -0.1812, - 4.5000, 1.1766, 24.7219, -13.0812,
159 -37.7000, 34.8438, -5.0000, 1.5218, 3.9229,
160 -2.6204, -0.0156, 0.1597, 0.4199, -0.5562 },
161 /* Sky clearness (epsilon): 1.500 to 1.950 */
162 { -0.5484, -0.6654, -0.2672, 0.7117, 0.7234,
163 -0.6219, -5.6812, 2.6297, 33.3389, -18.3000,
164 -62.2500, 52.0781, -3.5000, 0.0016, 1.1477,
165 0.1062, 0.4659, -0.3296, -0.0876, -0.0329 },
166 /* Sky clearness (epsilon): 1.950 to 2.800 */
167 { -0.6000, -0.3566, -2.5000, 2.3250, 0.2937,
168 0.0496, -5.6812, 1.8415, 21.0000, -4.7656 ,
169 -21.5906, 7.2492, -3.5000, -0.1554, 1.4062,
170 0.3988, 0.0032, 0.0766, -0.0656, -0.1294 },
171 /* Sky clearness (epsilon): 2.800 to 4.500 */
172 { -1.0156, -0.3670, 1.0078, 1.4051, 0.2875,
173 -0.5328, -3.8500, 3.3750, 14.0000, -0.9999,
174 -7.1406, 7.5469, -3.4000, -0.1078, -1.0750,
175 1.5702, -0.0672, 0.4016, 0.3017, -0.4844 },
176 /* Sky clearness (epsilon): 4.500 to 6.200 */
177 { -1.0000, 0.0211, 0.5025, -0.5119, -0.3000,
178 0.1922, 0.7023, -1.6317, 19.0000, -5.0000,
179 1.2438, -1.9094, -4.0000, 0.0250, 0.3844,
180 0.2656, 1.0468, -0.3788, -2.4517, 1.4656 },
181 /* Sky clearness (epsilon): 6.200 to ... */
182 { -1.0500, 0.0289, 0.4260, 0.3590, -0.3250,
183 0.1156, 0.7781, 0.0025, 31.0625, -14.5000,
184 -46.1148, 55.3750, -7.2312, 0.4050, 13.3500,
185 0.6234, 1.5000, -0.6426, 1.8564, 0.5636 }
186 };
187
188 /* Perez irradiance component model coefficients */
189
190 /* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */
191 /* Stewart. 1990. ìModeling Daylight Availability and */
192 /* Irradiance Components from Direct and Global */
193 /* Irradiance,î Solar Energy 44(5):271-289. */
194
195 typedef struct
196 {
197 double lower; /* Lower bound */
198 double upper; /* Upper bound */
199 } CategoryBounds;
200
201 /* Perez sky clearness (epsilon) categories (Table 1) */
202 static const CategoryBounds SkyClearCat[8] =
203 {
204 { 1.000, 1.065 }, /* Overcast */
205 { 1.065, 1.230 },
206 { 1.230, 1.500 },
207 { 1.500, 1.950 },
208 { 1.950, 2.800 },
209 { 2.800, 4.500 },
210 { 4.500, 6.200 },
211 { 6.200, 12.00 } /* Clear */
212 };
213
214 /* Luminous efficacy model coefficients */
215 typedef struct
216 {
217 double a;
218 double b;
219 double c;
220 double d;
221 } ModelCoeff;
222
223 /* Diffuse luminous efficacy model coefficients (Table 4, Eqn. 7) */
224 static const ModelCoeff DiffuseLumEff[8] =
225 {
226 { 97.24, -0.46, 12.00, -8.91 },
227 { 107.22, 1.15, 0.59, -3.95 },
228 { 104.97, 2.96, -5.53, -8.77 },
229 { 102.39, 5.59, -13.95, -13.90 },
230 { 100.71, 5.94, -22.75, -23.74 },
231 { 106.42, 3.83, -36.15, -28.83 },
232 { 141.88, 1.90, -53.24, -14.03 },
233 { 152.23, 0.35, -45.27, -7.98 }
234 };
235
236 /* Direct luminous efficacy model coefficients (Table 4, Eqn. 8) */
237 static const ModelCoeff DirectLumEff[8] =
238 {
239 { 57.20, -4.55, -2.98, 117.12 },
240 { 98.99, -3.46, -1.21, 12.38 },
241 { 109.83, -4.90, -1.71, -8.81 },
242 { 110.34, -5.84, -1.99, -4.56 },
243 { 106.36, -3.97, -1.75, -6.16 },
244 { 107.19, -1.25, -1.51, -26.73 },
245 { 105.75, 0.77, -1.26, -34.44 },
246 { 101.18, 1.58, -1.10, -8.29 }
247 };
248
249 #ifndef NSUNPATCH
250 #define NSUNPATCH 4 /* # patches to spread sun into */
251 #endif
252
253 extern int jdate(int month, int day);
254 extern double stadj(int jd);
255 extern double sdec(int jd);
256 extern double salt(double sd, double st);
257 extern double sazi(double sd, double st);
258 /* sun calculation constants */
259 extern double s_latitude;
260 extern double s_longitude;
261 extern double s_meridian;
262
263 int verbose = 0; /* progress reports to stderr? */
264
265 int outfmt = 'a'; /* output format */
266
267 int rhsubdiv = 1; /* Reinhart sky subdivisions */
268
269 COLOR skycolor = {.96, 1.004, 1.118}; /* sky coloration */
270 COLOR suncolor = {1., 1., 1.}; /* sun color */
271 COLOR grefl = {.2, .2, .2}; /* ground reflectance */
272
273 int nskypatch; /* number of Reinhart patches */
274 float *rh_palt; /* sky patch altitudes (radians) */
275 float *rh_pazi; /* sky patch azimuths (radians) */
276 float *rh_dom; /* sky patch solid angle (sr) */
277
278 #define vector(v,alt,azi) ( (v)[1] = tcos(alt), \
279 (v)[0] = (v)[1]*tsin(azi), \
280 (v)[1] *= tcos(azi), \
281 (v)[2] = tsin(alt) )
282
283 #define rh_vector(v,i) vector(v,rh_palt[i],rh_pazi[i])
284
285 #define rh_cos(i) tsin(rh_palt[i])
286
287 extern int rh_init(void);
288 extern float * resize_dmatrix(float *mtx_data, int nsteps, int npatch);
289 extern void AddDirect(float *parr);
290
291 int
292 main(int argc, char *argv[])
293 {
294 char buf[256];
295 double elevation; /* site elevation (meters) */
296 int dir_is_horiz; /* direct is meas. on horizontal? */
297 float *mtx_data = NULL; /* our matrix data */
298 int ntsteps = 0; /* number of rows in matrix */
299 int last_monthly = 0; /* month of last report */
300 int mo, da; /* month (1-12) and day (1-31) */
301 double hr; /* hour (local standard time) */
302 double dir, dif; /* direct and diffuse values */
303 int mtx_offset;
304 int i, j;
305
306 progname = argv[0];
307 /* get options */
308 for (i = 1; i < argc && argv[i][0] == '-'; i++)
309 switch (argv[i][1]) {
310 case 'g': /* ground reflectance */
311 grefl[0] = atof(argv[++i]);
312 grefl[1] = atof(argv[++i]);
313 grefl[2] = atof(argv[++i]);
314 break;
315 case 'v': /* verbose progress reports */
316 verbose++;
317 break;
318 case 'o': /* output format */
319 switch (argv[i][2]) {
320 case 'f':
321 case 'd':
322 case 'a':
323 outfmt = argv[i][2];
324 break;
325 default:
326 goto userr;
327 }
328 break;
329 case 'm': /* Reinhart subdivisions */
330 rhsubdiv = atoi(argv[++i]);
331 break;
332 case 'c': /* sky color */
333 skycolor[0] = atof(argv[++i]);
334 skycolor[1] = atof(argv[++i]);
335 skycolor[2] = atof(argv[++i]);
336 break;
337 case 'd': /* solar (direct) only */
338 skycolor[0] = skycolor[1] = skycolor[2] = 0;
339 if (suncolor[1] <= 1e-4)
340 suncolor[0] = suncolor[1] = suncolor[2] = 1;
341 break;
342 case 's': /* sky only (no direct) */
343 suncolor[0] = suncolor[1] = suncolor[2] = 0;
344 if (skycolor[1] <= 1e-4)
345 skycolor[0] = skycolor[1] = skycolor[2] = 1;
346 break;
347 default:
348 goto userr;
349 }
350 if (i < argc-1)
351 goto userr;
352 if (i == argc-1 && freopen(argv[i], "r", stdin) == NULL) {
353 fprintf(stderr, "%s: cannot open '%s' for input\n",
354 progname, argv[i]);
355 exit(1);
356 }
357 if (verbose) {
358 if (i == argc-1)
359 fprintf(stderr, "%s: reading weather tape '%s'\n",
360 progname, argv[i]);
361 else
362 fprintf(stderr, "%s: reading weather tape from <stdin>\n",
363 progname);
364 }
365 /* read weather tape header */
366 if (scanf("place %[^\r\n] ", buf) != 1)
367 goto fmterr;
368 if (scanf("latitude %lf\n", &s_latitude) != 1)
369 goto fmterr;
370 if (scanf("longitude %lf\n", &s_longitude) != 1)
371 goto fmterr;
372 if (scanf("time_zone %lf\n", &s_meridian) != 1)
373 goto fmterr;
374 if (scanf("site_elevation %lf\n", &elevation) != 1)
375 goto fmterr;
376 if (scanf("weather_data_file_units %d\n", &input) != 1)
377 goto fmterr;
378 switch (input) { /* translate units */
379 case 1:
380 input = 1; /* radiometric quantities */
381 dir_is_horiz = 0; /* direct is perpendicular meas. */
382 break;
383 case 2:
384 input = 1; /* radiometric quantities */
385 dir_is_horiz = 1; /* solar measured horizontally */
386 break;
387 case 3:
388 input = 2; /* photometric quantities */
389 dir_is_horiz = 0; /* direct is perpendicular meas. */
390 break;
391 default:
392 goto fmterr;
393 }
394 rh_init(); /* initialize sky patches */
395 if (verbose) {
396 fprintf(stderr, "%s: location '%s'\n", progname, buf);
397 fprintf(stderr, "%s: (lat,long)=(%.1f,%.1f) degrees north, west\n",
398 progname, s_latitude, s_longitude);
399 fprintf(stderr, "%s: %d sky patches per time step\n",
400 progname, nskypatch);
401 }
402 /* convert quantities to radians */
403 s_latitude = DegToRad(s_latitude);
404 s_longitude = DegToRad(s_longitude);
405 s_meridian = DegToRad(s_meridian);
406 /* process each time step in tape */
407 while (scanf("%d %d %lf %lf %lf\n", &mo, &da, &hr, &dir, &dif) == 5) {
408 double sda, sta;
409 /* make space for next time step */
410 mtx_offset = 3*nskypatch*ntsteps++;
411 mtx_data = resize_dmatrix(mtx_data, ntsteps, nskypatch);
412 if (dif <= 1e-4) {
413 memset(mtx_data+mtx_offset, 0, sizeof(float)*3*nskypatch);
414 continue;
415 }
416 if (verbose && mo != last_monthly)
417 fprintf(stderr, "%s: stepping through month %d...\n",
418 progname, last_monthly=mo);
419 /* compute solar position */
420 julian_date = jdate(mo, da);
421 sda = sdec(julian_date);
422 sta = stadj(julian_date);
423 altitude = salt(sda, hr+sta);
424 azimuth = sazi(sda, hr+sta) + PI;
425 /* convert measured values */
426 if (dir_is_horiz && altitude > 0.)
427 dir /= sin(altitude);
428 if (input == 1) {
429 dir_irrad = dir;
430 diff_irrad = dif;
431 } else /* input == 2 */ {
432 dir_illum = dir;
433 diff_illum = dif;
434 }
435 /* compute sky patch values */
436 ComputeSky(mtx_data+mtx_offset);
437 AddDirect(mtx_data+mtx_offset);
438 }
439 /* check for junk at end */
440 while ((i = fgetc(stdin)) != EOF)
441 if (!isspace(i)) {
442 fprintf(stderr, "%s: warning - unexpected data past EOT: ",
443 progname);
444 buf[0] = i; buf[1] = '\0';
445 fgets(buf+1, sizeof(buf)-1, stdin);
446 fputs(buf, stderr); fputc('\n', stderr);
447 break;
448 }
449 /* write out matrix */
450 #ifdef getc_unlocked
451 flockfile(stdout);
452 #endif
453 if (verbose)
454 fprintf(stderr, "%s: writing %smatrix with %d time steps...\n",
455 progname, outfmt=='a' ? "" : "binary ", ntsteps);
456 /* patches are rows (outer sort) */
457 for (i = 0; i < nskypatch; i++) {
458 mtx_offset = 3*i;
459 switch (outfmt) {
460 case 'a':
461 for (j = 0; j < ntsteps; j++) {
462 printf("%.3g %.3g %.3g\n", mtx_data[mtx_offset],
463 mtx_data[mtx_offset+1],
464 mtx_data[mtx_offset+2]);
465 mtx_offset += 3*nskypatch;
466 }
467 if (ntsteps > 1)
468 fputc('\n', stdout);
469 break;
470 case 'f':
471 for (j = 0; j < ntsteps; j++) {
472 fwrite(mtx_data+mtx_offset, sizeof(float), 3,
473 stdout);
474 mtx_offset += 3*nskypatch;
475 }
476 break;
477 case 'd':
478 for (j = 0; j < ntsteps; j++) {
479 double ment[3];
480 ment[0] = mtx_data[mtx_offset];
481 ment[1] = mtx_data[mtx_offset+1];
482 ment[2] = mtx_data[mtx_offset+2];
483 fwrite(ment, sizeof(double), 3, stdout);
484 mtx_offset += 3*nskypatch;
485 }
486 break;
487 }
488 if (ferror(stdout))
489 goto writerr;
490 }
491 if (fflush(stdout) == EOF)
492 goto writerr;
493 if (verbose)
494 fprintf(stderr, "%s: done.\n", progname);
495 exit(0);
496 userr:
497 fprintf(stderr, "Usage: %s [-v][-d|-s][-m N][-g r g b][-c r g b][-o{f|d}] [tape.wea]\n",
498 progname);
499 exit(1);
500 fmterr:
501 fprintf(stderr, "%s: input weather tape format error\n", progname);
502 exit(1);
503 writerr:
504 fprintf(stderr, "%s: write error on output\n", progname);
505 exit(1);
506 }
507
508 /* Return maximum of two doubles */
509 double dmax( double a, double b )
510 { return (a > b) ? a : b; }
511
512 /* Compute sky patch radiance values (modified by GW) */
513 void
514 ComputeSky(float *parr)
515 {
516 int index; /* Category index */
517 double norm_diff_illum; /* Normalized diffuse illuimnance */
518 double zlumin; /* Zenith luminance */
519 int i;
520
521 /* Calculate atmospheric precipitable water content */
522 apwc = CalcPrecipWater(dew_point);
523
524 /* Calculate sun zenith angle (don't let it dip below horizon) */
525 /* Also limit minimum angle to keep circumsolar off zenith */
526 if (altitude <= 0.0)
527 sun_zenith = DegToRad(90.0);
528 else if (altitude >= DegToRad(87.0))
529 sun_zenith = DegToRad(3.0);
530 else
531 sun_zenith = DegToRad(90.0) - altitude;
532
533 /* Compute the inputs for the calculation of the sky distribution */
534
535 if (input == 0) /* XXX never used */
536 {
537 /* Calculate irradiance */
538 diff_irrad = CalcDiffuseIrradiance();
539 dir_irrad = CalcDirectIrradiance();
540
541 /* Calculate illuminance */
542 index = GetCategoryIndex();
543 diff_illum = diff_irrad * CalcDiffuseIllumRatio(index);
544 dir_illum = dir_irrad * CalcDirectIllumRatio(index);
545 }
546 else if (input == 1)
547 {
548 sky_brightness = CalcSkyBrightness();
549 sky_clearness = CalcSkyClearness();
550
551 /* Calculate illuminance */
552 index = GetCategoryIndex();
553 diff_illum = diff_irrad * CalcDiffuseIllumRatio(index);
554 dir_illum = dir_irrad * CalcDirectIllumRatio(index);
555 }
556 else if (input == 2)
557 {
558 /* Calculate sky brightness and clearness from illuminance values */
559 index = CalcSkyParamFromIllum();
560 }
561
562 if (bright(skycolor) <= 1e-4) { /* 0 sky component? */
563 memset(parr, 0, sizeof(float)*3*nskypatch);
564 return;
565 }
566 /* Compute ground radiance (include solar contribution if any) */
567 parr[0] = diff_illum;
568 if (altitude > 0)
569 parr[0] += dir_illum * sin(altitude);
570 parr[2] = parr[1] = parr[0] *= (1./PI/WHTEFFICACY);
571 multcolor(parr, grefl);
572
573 /* Calculate Perez sky model parameters */
574 CalcPerezParam(sun_zenith, sky_clearness, sky_brightness, index);
575
576 /* Calculate sky patch luminance values */
577 CalcSkyPatchLumin(parr);
578
579 /* Calculate relative horizontal illuminance */
580 norm_diff_illum = CalcRelHorzIllum(parr);
581
582 /* Normalization coefficient */
583 norm_diff_illum = diff_illum / norm_diff_illum;
584
585 /* Calculate relative zenith luminance */
586 zlumin = CalcRelLuminance(sun_zenith, 0.0);
587
588 /* Calculate absolute zenith illuminance */
589 zlumin *= norm_diff_illum;
590
591 /* Apply to sky patches to get absolute radiance values */
592 for (i = 1; i < nskypatch; i++) {
593 scalecolor(parr+3*i, zlumin*(1./WHTEFFICACY));
594 multcolor(parr+3*i, skycolor);
595 }
596 }
597
598 /* Add in solar direct to nearest sky patches (GW) */
599 void
600 AddDirect(float *parr)
601 {
602 FVECT svec;
603 double near_dprod[NSUNPATCH];
604 int near_patch[NSUNPATCH];
605 double wta[NSUNPATCH], wtot;
606 int i, j, p;
607
608 if (dir_illum <= 1e-4 || bright(suncolor) <= 1e-4)
609 return;
610 /* identify NSUNPATCH closest patches */
611 for (i = NSUNPATCH; i--; )
612 near_dprod[i] = -1.;
613 vector(svec, altitude, azimuth);
614 for (p = 1; p < nskypatch; p++) {
615 FVECT pvec;
616 double dprod;
617 rh_vector(pvec, p);
618 dprod = DOT(pvec, svec);
619 for (i = 0; i < NSUNPATCH; i++)
620 if (dprod > near_dprod[i]) {
621 for (j = NSUNPATCH; --j > i; ) {
622 near_dprod[j] = near_dprod[j-1];
623 near_patch[j] = near_patch[j-1];
624 }
625 near_dprod[i] = dprod;
626 near_patch[i] = p;
627 break;
628 }
629 }
630 wtot = 0; /* weight by proximity */
631 for (i = NSUNPATCH; i--; )
632 wtot += wta[i] = 1./(1.002 - near_dprod[i]);
633 /* add to nearest patch radiances */
634 for (i = NSUNPATCH; i--; ) {
635 float *pdest = parr + 3*near_patch[i];
636 float val_add = wta[i] * dir_illum /
637 (WHTEFFICACY * wtot * rh_dom[near_patch[i]]);
638 *pdest++ += val_add*suncolor[0];
639 *pdest++ += val_add*suncolor[1];
640 *pdest++ += val_add*suncolor[2];
641 }
642 }
643
644 /* Initialize Reinhart sky patch positions (GW) */
645 int
646 rh_init(void)
647 {
648 #define NROW 7
649 static const int tnaz[NROW] = {30, 30, 24, 24, 18, 12, 6};
650 const double alpha = (PI/2.)/(NROW*rhsubdiv + .5);
651 int p, i, j;
652 /* allocate patch angle arrays */
653 nskypatch = 0;
654 for (p = 0; p < NROW; p++)
655 nskypatch += tnaz[p];
656 nskypatch *= rhsubdiv*rhsubdiv;
657 nskypatch += 2;
658 rh_palt = (float *)malloc(sizeof(float)*nskypatch);
659 rh_pazi = (float *)malloc(sizeof(float)*nskypatch);
660 rh_dom = (float *)malloc(sizeof(float)*nskypatch);
661 if ((rh_palt == NULL) | (rh_pazi == NULL) | (rh_dom == NULL)) {
662 fprintf(stderr, "%s: out of memory in rh_init()\n", progname);
663 exit(1);
664 }
665 rh_palt[0] = -PI/2.; /* ground & zenith patches */
666 rh_pazi[0] = 0.;
667 rh_dom[0] = 2.*PI;
668 rh_palt[nskypatch-1] = PI/2.;
669 rh_pazi[nskypatch-1] = 0.;
670 rh_dom[nskypatch-1] = 2.*PI*(1. - cos(alpha*.5));
671 p = 1; /* "normal" patches */
672 for (i = 0; i < NROW*rhsubdiv; i++) {
673 const float ralt = alpha*(i + .5);
674 const int ninrow = tnaz[i/rhsubdiv]*rhsubdiv;
675 const float dom = 2.*PI*(sin(alpha*(i+1)) - sin(alpha*i)) /
676 (double)ninrow;
677 for (j = 0; j < ninrow; j++) {
678 rh_palt[p] = ralt;
679 rh_pazi[p] = 2.*PI * j / (double)ninrow;
680 rh_dom[p++] = dom;
681 }
682 }
683 return nskypatch;
684 #undef NROW
685 }
686
687 /* Resize daylight matrix (GW) */
688 float *
689 resize_dmatrix(float *mtx_data, int nsteps, int npatch)
690 {
691 if (mtx_data == NULL)
692 mtx_data = (float *)malloc(sizeof(float)*3*nsteps*npatch);
693 else
694 mtx_data = (float *)realloc(mtx_data,
695 sizeof(float)*3*nsteps*npatch);
696 if (mtx_data == NULL) {
697 fprintf(stderr, "%s: out of memory in resize_dmatrix(%d,%d)\n",
698 progname, nsteps, npatch);
699 exit(1);
700 }
701 return(mtx_data);
702 }
703
704 /* Determine category index */
705 int GetCategoryIndex()
706 {
707 int index; /* Loop index */
708
709 for (index = 0; index < 8; index++)
710 if ((sky_clearness >= SkyClearCat[index].lower) &&
711 (sky_clearness < SkyClearCat[index].upper))
712 break;
713
714 return index;
715 }
716
717 /* Calculate diffuse illuminance to diffuse irradiance ratio */
718
719 /* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */
720 /* Stewart. 1990. ìModeling Daylight Availability and */
721 /* Irradiance Components from Direct and Global */
722 /* Irradiance,î Solar Energy 44(5):271-289, Eqn. 7. */
723
724 double CalcDiffuseIllumRatio( int index )
725 {
726 ModelCoeff const *pnle; /* Category coefficient pointer */
727
728 /* Get category coefficient pointer */
729 pnle = &(DiffuseLumEff[index]);
730
731 return pnle->a + pnle->b * apwc + pnle->c * cos(sun_zenith) +
732 pnle->d * log(sky_brightness);
733 }
734
735 /* Calculate direct illuminance to direct irradiance ratio */
736
737 /* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */
738 /* Stewart. 1990. ìModeling Daylight Availability and */
739 /* Irradiance Components from Direct and Global */
740 /* Irradiance,î Solar Energy 44(5):271-289, Eqn. 8. */
741
742 double CalcDirectIllumRatio( int index )
743 {
744 ModelCoeff const *pnle; /* Category coefficient pointer */
745
746 /* Get category coefficient pointer */
747 pnle = &(DirectLumEff[index]);
748
749 /* Calculate direct illuminance from direct irradiance */
750
751 return dmax((pnle->a + pnle->b * apwc + pnle->c * exp(5.73 *
752 sun_zenith - 5.0) + pnle->d * sky_brightness),
753 0.0);
754 }
755
756 /* Calculate sky brightness */
757
758 /* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */
759 /* Stewart. 1990. ìModeling Daylight Availability and */
760 /* Irradiance Components from Direct and Global */
761 /* Irradiance,î Solar Energy 44(5):271-289, Eqn. 2. */
762
763 double CalcSkyBrightness()
764 {
765 return diff_irrad * CalcAirMass() / (DC_SolarConstantE *
766 CalcEccentricity());
767 }
768
769 /* Calculate sky clearness */
770
771 /* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */
772 /* Stewart. 1990. ìModeling Daylight Availability and */
773 /* Irradiance Components from Direct and Global */
774 /* Irradiance,î Solar Energy 44(5):271-289, Eqn. 1. */
775
776 double CalcSkyClearness()
777 {
778 double sz_cubed; /* Sun zenith angle cubed */
779
780 /* Calculate sun zenith angle cubed */
781 sz_cubed = pow(sun_zenith, 3.0);
782
783 return ((diff_irrad + dir_irrad) / diff_irrad + 1.041 *
784 sz_cubed) / (1.0 + 1.041 * sz_cubed);
785 }
786
787 /* Calculate diffuse horizontal irradiance from Perez sky brightness */
788
789 /* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */
790 /* Stewart. 1990. ìModeling Daylight Availability and */
791 /* Irradiance Components from Direct and Global */
792 /* Irradiance,î Solar Energy 44(5):271-289, Eqn. 2 */
793 /* (inverse). */
794
795 double CalcDiffuseIrradiance()
796 {
797 return sky_brightness * DC_SolarConstantE * CalcEccentricity() /
798 CalcAirMass();
799 }
800
801 /* Calculate direct normal irradiance from Perez sky clearness */
802
803 /* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */
804 /* Stewart. 1990. ìModeling Daylight Availability and */
805 /* Irradiance Components from Direct and Global */
806 /* Irradiance,î Solar Energy 44(5):271-289, Eqn. 1 */
807 /* (inverse). */
808
809 double CalcDirectIrradiance()
810 {
811 return CalcDiffuseIrradiance() * ((sky_clearness - 1.0) * (1 + 1.041
812 * pow(sun_zenith, 3.0)));
813 }
814
815 /* Calculate sky brightness and clearness from illuminance values */
816 int CalcSkyParamFromIllum()
817 {
818 double test1 = 0.1;
819 double test2 = 0.1;
820 int counter = 0;
821 int index = 0; /* Category index */
822
823 /* Convert illuminance to irradiance */
824 diff_irrad = diff_illum * DC_SolarConstantE /
825 (DC_SolarConstantL * 1000.0);
826 dir_irrad = dir_illum * DC_SolarConstantE /
827 (DC_SolarConstantL * 1000.0);
828
829 /* Calculate sky brightness and clearness */
830 sky_brightness = CalcSkyBrightness();
831 sky_clearness = CalcSkyClearness();
832
833 /* Limit sky clearness */
834 if (sky_clearness > 12.0)
835 sky_clearness = 12.0;
836
837 /* Limit sky brightness */
838 if (sky_brightness < 0.05)
839 sky_brightness = 0.01;
840
841 while (((fabs(diff_irrad - test1) > 10.0) ||
842 (fabs(dir_irrad - test2) > 10.0)) && !(counter == 5))
843 {
844 test1 = diff_irrad;
845 test2 = dir_irrad;
846 counter++;
847
848 /* Convert illuminance to irradiance */
849 index = GetCategoryIndex();
850 diff_irrad = diff_illum / CalcDiffuseIllumRatio(index);
851 dir_irrad = dir_illum / CalcDirectIllumRatio(index);
852
853 /* Calculate sky brightness and clearness */
854 sky_brightness = CalcSkyBrightness();
855 sky_clearness = CalcSkyClearness();
856
857 /* Limit sky clearness */
858 if (sky_clearness > 12.0)
859 sky_clearness = 12.0;
860
861 /* Limit sky brightness */
862 if (sky_brightness < 0.05)
863 sky_brightness = 0.01;
864 }
865
866 return GetCategoryIndex();
867 }
868
869 /* Calculate relative luminance */
870
871 /* Reference: Perez, R., R. Seals, and J. Michalsky. 1993. */
872 /* ìAll-Weather Model for Sky Luminance Distribution - */
873 /* Preliminary Configuration and Validation,î Solar Energy */
874 /* 50(3):235-245, Eqn. 1. */
875
876 double CalcRelLuminance( double gamma, double zeta )
877 {
878 return (1.0 + perez_param[0] * exp(perez_param[1] / cos(zeta))) *
879 (1.0 + perez_param[2] * exp(perez_param[3] * gamma) +
880 perez_param[4] * cos(gamma) * cos(gamma));
881 }
882
883 /* Calculate Perez sky model parameters */
884
885 /* Reference: Perez, R., R. Seals, and J. Michalsky. 1993. */
886 /* ìAll-Weather Model for Sky Luminance Distribution - */
887 /* Preliminary Configuration and Validation,î Solar Energy */
888 /* 50(3):235-245, Eqns. 6 - 8. */
889
890 void CalcPerezParam( double sz, double epsilon, double delta,
891 int index )
892 {
893 double x[5][4]; /* Coefficents a, b, c, d, e */
894 int i, j; /* Loop indices */
895
896 /* Limit sky brightness */
897 if (epsilon > 1.065 && epsilon < 2.8)
898 {
899 if (delta < 0.2)
900 delta = 0.2;
901 }
902
903 /* Get Perez coefficients */
904 for (i = 0; i < 5; i++)
905 for (j = 0; j < 4; j++)
906 x[i][j] = PerezCoeff[index][4 * i + j];
907
908 if (index != 0)
909 {
910 /* Calculate parameter a, b, c, d and e (Eqn. 6) */
911 for (i = 0; i < 5; i++)
912 perez_param[i] = x[i][0] + x[i][1] * sz + delta * (x[i][2] +
913 x[i][3] * sz);
914 }
915 else
916 {
917 /* Parameters a, b and e (Eqn. 6) */
918 perez_param[0] = x[0][0] + x[0][1] * sz + delta * (x[0][2] +
919 x[0][3] * sz);
920 perez_param[1] = x[1][0] + x[1][1] * sz + delta * (x[1][2] +
921 x[1][3] * sz);
922 perez_param[4] = x[4][0] + x[4][1] * sz + delta * (x[4][2] +
923 x[4][3] * sz);
924
925 /* Parameter c (Eqn. 7) */
926 perez_param[2] = exp(pow(delta * (x[2][0] + x[2][1] * sz),
927 x[2][2])) - x[2][3];
928
929 /* Parameter d (Eqn. 8) */
930 perez_param[3] = -exp(delta * (x[3][0] + x[3][1] * sz)) +
931 x[3][2] + delta * x[3][3];
932 }
933 }
934
935 /* Calculate relative horizontal illuminance (modified by GW) */
936
937 /* Reference: Perez, R., R. Seals, and J. Michalsky. 1993. */
938 /* ìAll-Weather Model for Sky Luminance Distribution - */
939 /* Preliminary Configuration and Validation,î Solar Energy */
940 /* 50(3):235-245, Eqn. 3. */
941
942 double CalcRelHorzIllum( float *parr )
943 {
944 int i;
945 double rh_illum = 0.0; /* Relative horizontal illuminance */
946
947 for (i = 1; i < nskypatch; i++)
948 rh_illum += parr[3*i+1] * rh_cos(i);
949
950 return rh_illum * (2.0 * PI / (nskypatch-1));
951 }
952
953 /* Calculate earth orbit eccentricity correction factor */
954
955 /* Reference: Sen, Z. 2008. Solar Energy Fundamental and Modeling */
956 /* Techniques. Springer, p. 72. */
957
958 double CalcEccentricity()
959 {
960 double day_angle; /* Day angle (radians) */
961 double E0; /* Eccentricity */
962
963 /* Calculate day angle */
964 day_angle = (julian_date - 1.0) * (2.0 * PI / 365.0);
965
966 /* Calculate eccentricity */
967 E0 = 1.00011 + 0.034221 * cos(day_angle) + 0.00128 * sin(day_angle)
968 + 0.000719 * cos(2.0 * day_angle) + 0.000077 * sin(2.0 *
969 day_angle);
970
971 return E0;
972 }
973
974 /* Calculate atmospheric precipitable water content */
975
976 /* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */
977 /* Stewart. 1990. ìModeling Daylight Availability and */
978 /* Irradiance Components from Direct and Global */
979 /* Irradiance,î Solar Energy 44(5):271-289, Eqn. 3. */
980
981 /* Note: The default surface dew point temperature is 11 deg. C */
982 /* (52 deg. F). Typical values are: */
983
984 /* Celsius Fahrenheit Human Perception */
985 /* > 24 > 75 Extremely uncomfortable */
986 /* 21 - 24 70 - 74 Very humid */
987 /* 18 - 21 65 - 69 Somewhat uncomfortable */
988 /* 16 - 18 60 - 64 OK for most people */
989 /* 13 - 16 55 - 59 Comfortable */
990 /* 10 - 12 50 - 54 Very comfortable */
991 /* < 10 < 49 A bit dry for some */
992
993 double CalcPrecipWater( double dpt )
994 { return exp(0.07 * dpt - 0.075); }
995
996 /* Calculate relative air mass */
997
998 /* Reference: Kasten, F. 1966. "A New Table and Approximation Formula */
999 /* for the Relative Optical Air Mass," Arch. Meteorol. */
1000 /* Geophys. Bioklimataol. Ser. B14, pp. 206-233. */
1001
1002 /* Note: More sophisticated relative air mass models are */
1003 /* available, but they differ significantly only for */
1004 /* sun zenith angles greater than 80 degrees. */
1005
1006 double CalcAirMass()
1007 {
1008 return (1.0 / (cos(sun_zenith) + 0.15 * pow(93.885 -
1009 RadToDeg(sun_zenith), -1.253)));
1010 }
1011
1012 /* Calculate Perez All-Weather sky patch luminances (modified by GW) */
1013
1014 /* NOTE: The sky patches centers are determined in accordance with the */
1015 /* BRE-IDMP sky luminance measurement procedures. (See for example */
1016 /* Mardaljevic, J. 2001. "The BRE-IDMP Dataset: A New Benchmark */
1017 /* for the Validation of Illuminance Prediction Techniques," */
1018 /* Lighting Research & Technology 33(2):117-136.) */
1019
1020 void CalcSkyPatchLumin( float *parr )
1021 {
1022 int i;
1023 double aas; /* Sun-sky point azimuthal angle */
1024 double sspa; /* Sun-sky point angle */
1025 double zsa; /* Zenithal sun angle */
1026
1027 for (i = 1; i < nskypatch; i++)
1028 {
1029 /* Calculate sun-sky point azimuthal angle */
1030 aas = fabs(rh_pazi[i] - azimuth);
1031
1032 /* Calculate zenithal sun angle */
1033 zsa = PI * 0.5 - rh_palt[i];
1034
1035 /* Calculate sun-sky point angle (Equation 8-20) */
1036 sspa = acos(cos(sun_zenith) * cos(zsa) + sin(sun_zenith) *
1037 sin(zsa) * cos(aas));
1038
1039 /* Calculate patch luminance */
1040 parr[3*i] = CalcRelLuminance(sspa, zsa);
1041 if (parr[3*i] < 0) parr[3*i] = 0;
1042 parr[3*i+2] = parr[3*i+1] = parr[3*i];
1043 }
1044 }