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root/radiance/ray/src/gen/gendaymtx.c
Revision: 2.39
Committed: Fri Mar 11 18:04:39 2022 UTC (2 years, 1 month ago) by greg
Content type: text/plain
Branch: MAIN
CVS Tags: rad5R4
Changes since 2.38: +3 -3 lines
Log Message:
feat(gendaymtx): Minor improvement in verbose output

File Contents

# Content
1 #ifndef lint
2 static const char RCSid[] = "$Id: gendaymtx.c,v 2.38 2020/09/11 16:50:50 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 <stdlib.h>
85 #include <ctype.h>
86 #include "platform.h"
87 #include "rtmath.h"
88 #include "rtio.h"
89 #include "color.h"
90 #include "sun.h"
91
92 char *progname; /* Program name */
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 int output = 0; /* Output type */
112
113 extern double dmax( double, double );
114 extern double CalcAirMass();
115 extern double CalcDiffuseIllumRatio( int );
116 extern double CalcDiffuseIrradiance();
117 extern double CalcDirectIllumRatio( int );
118 extern double CalcDirectIrradiance();
119 extern double CalcEccentricity();
120 extern double CalcPrecipWater( double );
121 extern double CalcRelHorzIllum( float *parr );
122 extern double CalcRelLuminance( double, double );
123 extern double CalcSkyBrightness();
124 extern double CalcSkyClearness();
125 extern int CalcSkyParamFromIllum();
126 extern int GetCategoryIndex();
127 extern void CalcPerezParam( double, double, double, int );
128 extern void CalcSkyPatchLumin( float *parr );
129 extern void ComputeSky( float *parr );
130
131 /* Degrees into radians */
132 #define DegToRad(deg) ((deg)*(PI/180.))
133
134 /* Radiuans into degrees */
135 #define RadToDeg(rad) ((rad)*(180./PI))
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, 12.01 } /* 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 /* max. # patches to spread sun into */
251 #endif
252
253 #define SUN_ANG_DEG 0.533 /* sun full-angle in degrees */
254
255 int nsuns = NSUNPATCH; /* number of sun patches to use */
256 double fixed_sun_sa = -1; /* fixed solid angle per sun? */
257
258 int verbose = 0; /* progress reports to stderr? */
259
260 int outfmt = 'a'; /* output format */
261
262 int rhsubdiv = 1; /* Reinhart sky subdivisions */
263
264 COLOR skycolor = {.96, 1.004, 1.118}; /* sky coloration */
265 COLOR suncolor = {1., 1., 1.}; /* sun color */
266 COLOR grefl = {.2, .2, .2}; /* ground reflectance */
267
268 int nskypatch; /* number of Reinhart patches */
269 float *rh_palt; /* sky patch altitudes (radians) */
270 float *rh_pazi; /* sky patch azimuths (radians) */
271 float *rh_dom; /* sky patch solid angle (sr) */
272
273 #define vector(v,alt,azi) ( (v)[1] = cos(alt), \
274 (v)[0] = (v)[1]*sin(azi), \
275 (v)[1] *= cos(azi), \
276 (v)[2] = sin(alt) )
277
278 #define rh_vector(v,i) vector(v,rh_palt[i],rh_pazi[i])
279
280 #define rh_cos(i) tsin(rh_palt[i])
281
282 #define solar_minute(jd,hr) ((24*60)*((jd)-1)+(int)((hr)*60.+.5))
283
284 extern int rh_init(void);
285 extern float * resize_dmatrix(float *mtx_data, int nsteps, int npatch);
286 extern void OutputSun(int id, int goodsun, FILE *fp, FILE *mfp);
287 extern void AddDirect(float *parr);
288
289
290 static const char *
291 getfmtname(int fmt)
292 {
293 switch (fmt) {
294 case 'a':
295 return("ascii");
296 case 'f':
297 return("float");
298 case 'd':
299 return("double");
300 }
301 return("unknown");
302 }
303
304
305 int
306 main(int argc, char *argv[])
307 {
308 char buf[256];
309 int doheader = 1; /* output header? */
310 double rotation = 0; /* site rotation (degrees) */
311 double elevation; /* site elevation (meters) */
312 int leap_day = 0; /* add leap day? */
313 int sun_hours_only = 0; /* only output sun hours? */
314 int dir_is_horiz; /* direct is meas. on horizontal? */
315 FILE *sunsfp = NULL; /* output file for individual suns */
316 FILE *modsfp = NULL; /* modifier output file */
317 float *mtx_data = NULL; /* our matrix data */
318 int avgSky = 0; /* compute average sky r.t. matrix? */
319 int ntsteps = 0; /* number of time steps */
320 int tstorage = 0; /* number of allocated time steps */
321 int nstored = 0; /* number of time steps in matrix */
322 int last_monthly = 0; /* month of last report */
323 int mo, da; /* month (1-12) and day (1-31) */
324 double hr; /* hour (local standard time) */
325 double dir, dif; /* direct and diffuse values */
326 int mtx_offset;
327 int i, j;
328
329 progname = argv[0];
330 /* get options */
331 for (i = 1; i < argc && argv[i][0] == '-'; i++)
332 switch (argv[i][1]) {
333 case 'g': /* ground reflectance */
334 grefl[0] = atof(argv[++i]);
335 grefl[1] = atof(argv[++i]);
336 grefl[2] = atof(argv[++i]);
337 break;
338 case 'v': /* verbose progress reports */
339 verbose++;
340 break;
341 case 'h': /* turn off header */
342 doheader = 0;
343 break;
344 case 'o': /* output format */
345 switch (argv[i][2]) {
346 case 'f':
347 case 'd':
348 case 'a':
349 outfmt = argv[i][2];
350 break;
351 default:
352 goto userr;
353 }
354 break;
355 case 'O': /* output type */
356 switch (argv[i][2]) {
357 case '0':
358 output = 0;
359 break;
360 case '1':
361 output = 1;
362 break;
363 default:
364 goto userr;
365 }
366 if (argv[i][3])
367 goto userr;
368 break;
369 case 'm': /* Reinhart subdivisions */
370 rhsubdiv = atoi(argv[++i]);
371 break;
372 case 'c': /* sky color */
373 skycolor[0] = atof(argv[++i]);
374 skycolor[1] = atof(argv[++i]);
375 skycolor[2] = atof(argv[++i]);
376 break;
377 case 'D': /* output suns to file */
378 if (strcmp(argv[++i], "-")) {
379 sunsfp = fopen(argv[i], "w");
380 if (sunsfp == NULL) {
381 fprintf(stderr,
382 "%s: cannot open '%s' for output\n",
383 progname, argv[i]);
384 exit(1);
385 }
386 break; /* still may output matrix */
387 }
388 sunsfp = stdout; /* sending to stdout, so... */
389 /* fall through */
390 case 'n': /* no matrix output */
391 avgSky = -1;
392 rhsubdiv = 1;
393 /* fall through */
394 case 'd': /* solar (direct) only */
395 skycolor[0] = skycolor[1] = skycolor[2] = 0;
396 grefl[0] = grefl[1] = grefl[2] = 0;
397 break;
398 case 'M': /* send sun modifiers to file */
399 if ((modsfp = fopen(argv[++i], "w")) == NULL) {
400 fprintf(stderr, "%s: cannot open '%s' for output\n",
401 progname, argv[i]);
402 exit(1);
403 }
404 break;
405 case 's': /* sky only (no direct) */
406 suncolor[0] = suncolor[1] = suncolor[2] = 0;
407 break;
408 case 'u': /* solar hours only */
409 sun_hours_only = 1;
410 break;
411 case 'r': /* rotate distribution */
412 if (argv[i][2] && argv[i][2] != 'z')
413 goto userr;
414 rotation = atof(argv[++i]);
415 break;
416 case '5': /* 5-phase calculation */
417 nsuns = 1;
418 fixed_sun_sa = PI/360.*atof(argv[++i]);
419 if (fixed_sun_sa <= 0) {
420 fprintf(stderr, "%s: missing solar disk size argument for '-5' option\n",
421 progname);
422 exit(1);
423 }
424 fixed_sun_sa *= fixed_sun_sa*PI;
425 break;
426 case 'A': /* compute average sky */
427 avgSky = 1;
428 break;
429 default:
430 goto userr;
431 }
432 if (i < argc-1)
433 goto userr;
434 if (i == argc-1 && freopen(argv[i], "r", stdin) == NULL) {
435 fprintf(stderr, "%s: cannot open '%s' for input\n",
436 progname, argv[i]);
437 exit(1);
438 }
439 if ((modsfp != NULL) & (sunsfp == NULL))
440 fprintf(stderr, "%s: warning -M output will be empty without -D\n",
441 progname);
442 if (verbose) {
443 if (i == argc-1)
444 fprintf(stderr, "%s: reading weather tape '%s'\n",
445 progname, argv[i]);
446 else
447 fprintf(stderr, "%s: reading weather tape from <stdin>\n",
448 progname);
449 }
450 /* read weather tape header */
451 if (scanf("place %[^\r\n] ", buf) != 1)
452 goto fmterr;
453 if (scanf("latitude %lf\n", &s_latitude) != 1)
454 goto fmterr;
455 if (scanf("longitude %lf\n", &s_longitude) != 1)
456 goto fmterr;
457 if (scanf("time_zone %lf\n", &s_meridian) != 1)
458 goto fmterr;
459 if (scanf("site_elevation %lf\n", &elevation) != 1)
460 goto fmterr;
461 if (scanf("weather_data_file_units %d\n", &input) != 1)
462 goto fmterr;
463 switch (input) { /* translate units */
464 case 1:
465 input = 1; /* radiometric quantities */
466 dir_is_horiz = 0; /* direct is perpendicular meas. */
467 break;
468 case 2:
469 input = 1; /* radiometric quantities */
470 dir_is_horiz = 1; /* solar measured horizontally */
471 break;
472 case 3:
473 input = 2; /* photometric quantities */
474 dir_is_horiz = 0; /* direct is perpendicular meas. */
475 break;
476 default:
477 goto fmterr;
478 }
479 rh_init(); /* initialize sky patches */
480 if (verbose) {
481 fprintf(stderr, "%s: location '%s'\n", progname, buf);
482 fprintf(stderr, "%s: (lat,long)=(%.1f,%.1f) degrees north, west\n",
483 progname, s_latitude, s_longitude);
484 if (avgSky >= 0)
485 fprintf(stderr, "%s: %d sky patches\n",
486 progname, nskypatch);
487 if (sunsfp)
488 fprintf(stderr, "%s: outputting suns to %s\n",
489 progname, sunsfp==stdout ? "stdout" : "file");
490 if (rotation != 0)
491 fprintf(stderr, "%s: rotating output %.0f degrees\n",
492 progname, rotation);
493 }
494 /* convert quantities to radians */
495 s_latitude = DegToRad(s_latitude);
496 s_longitude = DegToRad(s_longitude);
497 s_meridian = DegToRad(s_meridian);
498 /* initial allocation */
499 mtx_data = resize_dmatrix(mtx_data, tstorage=2, nskypatch);
500 /* process each time step in tape */
501 while (scanf("%d %d %lf %lf %lf\n", &mo, &da, &hr, &dir, &dif) == 5) {
502 double sda, sta;
503 int sun_in_sky;
504 /* compute solar position */
505 if ((mo == 2) & (da == 29)) {
506 julian_date = 60;
507 leap_day = 1;
508 } else
509 julian_date = jdate(mo, da) + leap_day;
510 sda = sdec(julian_date);
511 sta = stadj(julian_date);
512 altitude = salt(sda, hr+sta);
513 sun_in_sky = (altitude > -DegToRad(SUN_ANG_DEG/2.));
514 if (sun_hours_only && !sun_in_sky)
515 continue; /* skipping nighttime points */
516 azimuth = sazi(sda, hr+sta) + PI - DegToRad(rotation);
517
518 mtx_offset = 3*nskypatch*nstored;
519 nstored += !avgSky | !nstored;
520 /* make space for next row */
521 if (nstored > tstorage) {
522 tstorage += (tstorage>>1) + nstored + 7;
523 mtx_data = resize_dmatrix(mtx_data, tstorage, nskypatch);
524 }
525 ntsteps++; /* keep count of time steps */
526
527 if (dir+dif <= 1e-4) { /* effectively nighttime? */
528 if (!avgSky | !mtx_offset)
529 memset(mtx_data+mtx_offset, 0,
530 sizeof(float)*3*nskypatch);
531 /* output black sun? */
532 if (sunsfp && sun_in_sky)
533 OutputSun(solar_minute(julian_date,hr), 0,
534 sunsfp, modsfp);
535 continue;
536 }
537 if (!sun_in_sky && dir > (input==1 ? 20. : 20.*WHTEFFICACY))
538 fprintf(stderr,
539 "%s: warning - unusually bright at %.1f on %d-%d\n",
540 progname, hr, mo, da);
541 /* convert measured values */
542 if (dir_is_horiz && altitude > FTINY)
543 dir /= sin(altitude);
544 if (input == 1) {
545 dir_irrad = dir;
546 diff_irrad = dif;
547 } else /* input == 2 */ {
548 dir_illum = dir;
549 diff_illum = dif;
550 }
551 /* compute sky patch values */
552 ComputeSky(mtx_data+mtx_offset);
553 /* output sun if requested */
554 if (sunsfp && sun_in_sky)
555 OutputSun(solar_minute(julian_date,hr), 1,
556 sunsfp, modsfp);
557
558 if (avgSky < 0) /* no matrix? */
559 continue;
560
561 AddDirect(mtx_data+mtx_offset);
562 /* update cumulative sky? */
563 for (i = 3*nskypatch*(avgSky&(ntsteps>1)); i--; )
564 mtx_data[i] += mtx_data[mtx_offset+i];
565 /* monthly reporting */
566 if (verbose && mo != last_monthly)
567 fprintf(stderr, "%s: stepping through month %d...\n",
568 progname, last_monthly=mo);
569 /* note whether leap-day was given */
570 }
571 if (!ntsteps) {
572 fprintf(stderr, "%s: no valid time steps on input\n", progname);
573 exit(1);
574 }
575 /* check for junk at end */
576 while ((i = fgetc(stdin)) != EOF)
577 if (!isspace(i)) {
578 fprintf(stderr, "%s: warning - unexpected data past EOT: ",
579 progname);
580 buf[0] = i; buf[1] = '\0';
581 fgets(buf+1, sizeof(buf)-1, stdin);
582 fputs(buf, stderr); fputc('\n', stderr);
583 break;
584 }
585
586 if (avgSky < 0) /* no matrix output? */
587 goto alldone;
588
589 dif = 1./(double)ntsteps; /* average sky? */
590 for (i = 3*nskypatch*(avgSky&(ntsteps>1)); i--; )
591 mtx_data[i] *= dif;
592 /* write out matrix */
593 if (outfmt != 'a')
594 SET_FILE_BINARY(stdout);
595 #ifdef getc_unlocked
596 flockfile(stdout);
597 #endif
598 if (verbose)
599 fprintf(stderr, "%s: writing %smatrix with %d time steps...\n",
600 progname, outfmt=='a' ? "" : "binary ", nstored);
601 if (doheader) {
602 newheader("RADIANCE", stdout);
603 printargs(argc, argv, stdout);
604 printf("LATLONG= %.8f %.8f\n", RadToDeg(s_latitude),
605 -RadToDeg(s_longitude));
606 printf("NROWS=%d\n", nskypatch);
607 printf("NCOLS=%d\n", nstored);
608 printf("NCOMP=3\n");
609 if ((outfmt == 'f') | (outfmt == 'd'))
610 fputendian(stdout);
611 fputformat((char *)getfmtname(outfmt), stdout);
612 putchar('\n');
613 }
614 /* patches are rows (outer sort) */
615 for (i = 0; i < nskypatch; i++) {
616 mtx_offset = 3*i;
617 switch (outfmt) {
618 case 'a':
619 for (j = 0; j < nstored; j++) {
620 printf("%.3g %.3g %.3g\n", mtx_data[mtx_offset],
621 mtx_data[mtx_offset+1],
622 mtx_data[mtx_offset+2]);
623 mtx_offset += 3*nskypatch;
624 }
625 if (nstored > 1)
626 fputc('\n', stdout);
627 break;
628 case 'f':
629 for (j = 0; j < nstored; j++) {
630 putbinary(mtx_data+mtx_offset, sizeof(float), 3,
631 stdout);
632 mtx_offset += 3*nskypatch;
633 }
634 break;
635 case 'd':
636 for (j = 0; j < nstored; j++) {
637 double ment[3];
638 ment[0] = mtx_data[mtx_offset];
639 ment[1] = mtx_data[mtx_offset+1];
640 ment[2] = mtx_data[mtx_offset+2];
641 putbinary(ment, sizeof(double), 3, stdout);
642 mtx_offset += 3*nskypatch;
643 }
644 break;
645 }
646 if (ferror(stdout))
647 goto writerr;
648 }
649 alldone:
650 if (fflush(NULL) == EOF)
651 goto writerr;
652 if (verbose)
653 fprintf(stderr, "%s: done.\n", progname);
654 exit(0);
655 userr:
656 fprintf(stderr, "Usage: %s [-v][-h][-A][-d|-s|-n][-u][-D file [-M modfile]][-r deg][-m N][-g r g b][-c r g b][-o{f|d}][-O{0|1}] [tape.wea]\n",
657 progname);
658 exit(1);
659 fmterr:
660 fprintf(stderr, "%s: weather tape format error in header\n", progname);
661 exit(1);
662 writerr:
663 fprintf(stderr, "%s: write error on output\n", progname);
664 exit(1);
665 }
666
667 /* Return maximum of two doubles */
668 double dmax( double a, double b )
669 { return (a > b) ? a : b; }
670
671 /* Compute sky patch radiance values (modified by GW) */
672 void
673 ComputeSky(float *parr)
674 {
675 int index; /* Category index */
676 double norm_diff_illum; /* Normalized diffuse illuimnance */
677 int i;
678
679 /* Calculate atmospheric precipitable water content */
680 apwc = CalcPrecipWater(dew_point);
681
682 /* Calculate sun zenith angle (don't let it dip below horizon) */
683 /* Also limit minimum angle to keep circumsolar off zenith */
684 if (altitude <= 0.0)
685 sun_zenith = DegToRad(90.0);
686 else if (altitude >= DegToRad(87.0))
687 sun_zenith = DegToRad(3.0);
688 else
689 sun_zenith = DegToRad(90.0) - altitude;
690
691 /* Compute the inputs for the calculation of the sky distribution */
692
693 if (input == 0) /* XXX never used */
694 {
695 /* Calculate irradiance */
696 diff_irrad = CalcDiffuseIrradiance();
697 dir_irrad = CalcDirectIrradiance();
698
699 /* Calculate illuminance */
700 index = GetCategoryIndex();
701 diff_illum = diff_irrad * CalcDiffuseIllumRatio(index);
702 dir_illum = dir_irrad * CalcDirectIllumRatio(index);
703 }
704 else if (input == 1)
705 {
706 sky_brightness = CalcSkyBrightness();
707 sky_clearness = CalcSkyClearness();
708
709 /* Limit sky clearness */
710 if (sky_clearness > 11.9)
711 sky_clearness = 11.9;
712
713 /* Limit sky brightness */
714 if (sky_brightness < 0.01)
715 sky_brightness = 0.01;
716
717 /* Calculate illuminance */
718 index = GetCategoryIndex();
719 diff_illum = diff_irrad * CalcDiffuseIllumRatio(index);
720 dir_illum = dir_irrad * CalcDirectIllumRatio(index);
721 }
722 else if (input == 2)
723 {
724 /* Calculate sky brightness and clearness from illuminance values */
725 index = CalcSkyParamFromIllum();
726 }
727
728 if (output == 1) { /* hack for solar radiance */
729 diff_illum = diff_irrad * WHTEFFICACY;
730 dir_illum = dir_irrad * WHTEFFICACY;
731 }
732 /* Compute ground radiance (include solar contribution if any) */
733 parr[0] = diff_illum;
734 if (altitude > 0)
735 parr[0] += dir_illum * sin(altitude);
736 parr[2] = parr[1] = parr[0] *= (1./PI/WHTEFFICACY);
737 multcolor(parr, grefl);
738
739 if (bright(skycolor) <= 1e-4) { /* 0 sky component? */
740 memset(parr+3, 0, sizeof(float)*3*(nskypatch-1));
741 return;
742 }
743 /* Calculate Perez sky model parameters */
744 CalcPerezParam(sun_zenith, sky_clearness, sky_brightness, index);
745
746 /* Calculate sky patch luminance values */
747 CalcSkyPatchLumin(parr);
748
749 /* Calculate relative horizontal illuminance */
750 norm_diff_illum = CalcRelHorzIllum(parr);
751
752 /* Check for zero sky -- make uniform in that case */
753 if (norm_diff_illum <= FTINY) {
754 for (i = 1; i < nskypatch; i++)
755 setcolor(parr+3*i, 1., 1., 1.);
756 norm_diff_illum = PI;
757 }
758 /* Normalization coefficient */
759 norm_diff_illum = diff_illum / norm_diff_illum;
760
761 /* Apply to sky patches to get absolute radiance values */
762 for (i = 1; i < nskypatch; i++) {
763 scalecolor(parr+3*i, norm_diff_illum*(1./WHTEFFICACY));
764 multcolor(parr+3*i, skycolor);
765 }
766 }
767
768 /* Add in solar direct to nearest sky patches (GW) */
769 void
770 AddDirect(float *parr)
771 {
772 FVECT svec;
773 double near_dprod[NSUNPATCH];
774 int near_patch[NSUNPATCH];
775 double wta[NSUNPATCH], wtot;
776 int i, j, p;
777
778 if (dir_illum <= 1e-4 || bright(suncolor) <= 1e-4)
779 return;
780 /* identify nsuns closest patches */
781 if (nsuns > NSUNPATCH)
782 nsuns = NSUNPATCH;
783 else if (nsuns <= 0)
784 nsuns = 1;
785 for (i = nsuns; i--; )
786 near_dprod[i] = -1.;
787 vector(svec, altitude, azimuth);
788 for (p = 1; p < nskypatch; p++) {
789 FVECT pvec;
790 double dprod;
791 rh_vector(pvec, p);
792 dprod = DOT(pvec, svec);
793 for (i = 0; i < nsuns; i++)
794 if (dprod > near_dprod[i]) {
795 for (j = nsuns; --j > i; ) {
796 near_dprod[j] = near_dprod[j-1];
797 near_patch[j] = near_patch[j-1];
798 }
799 near_dprod[i] = dprod;
800 near_patch[i] = p;
801 break;
802 }
803 }
804 wtot = 0; /* weight by proximity */
805 for (i = nsuns; i--; )
806 wtot += wta[i] = 1./(1.002 - near_dprod[i]);
807 /* add to nearest patch radiances */
808 for (i = nsuns; i--; ) {
809 float *pdest = parr + 3*near_patch[i];
810 float val_add = wta[i] * dir_illum / (WHTEFFICACY * wtot);
811
812 val_add /= (fixed_sun_sa > 0) ? fixed_sun_sa
813 : rh_dom[near_patch[i]] ;
814 *pdest++ += val_add*suncolor[0];
815 *pdest++ += val_add*suncolor[1];
816 *pdest++ += val_add*suncolor[2];
817 }
818 }
819
820 /* Output a sun to indicated file if appropriate for this time step */
821 void
822 OutputSun(int id, int goodsun, FILE *fp, FILE *mfp)
823 {
824 double srad;
825 FVECT sv;
826
827 srad = DegToRad(SUN_ANG_DEG/2.);
828 srad = goodsun ? dir_illum/(WHTEFFICACY * PI*srad*srad) : 0;
829 vector(sv, altitude, azimuth);
830 fprintf(fp, "\nvoid light solar%d\n0\n0\n", id);
831 fprintf(fp, "3 %.3e %.3e %.3e\n", srad*suncolor[0],
832 srad*suncolor[1], srad*suncolor[2]);
833 fprintf(fp, "\nsolar%d source sun%d\n0\n0\n", id, id);
834 fprintf(fp, "4 %.6f %.6f %.6f %.4f\n", sv[0], sv[1], sv[2], SUN_ANG_DEG);
835
836 if (mfp != NULL) /* saving modifier IDs? */
837 fprintf(mfp, "solar%d\n", id);
838 }
839
840 /* Initialize Reinhart sky patch positions (GW) */
841 int
842 rh_init(void)
843 {
844 #define NROW 7
845 static const int tnaz[NROW] = {30, 30, 24, 24, 18, 12, 6};
846 const double alpha = (PI/2.)/(NROW*rhsubdiv + .5);
847 int p, i, j;
848 /* allocate patch angle arrays */
849 nskypatch = 0;
850 for (p = 0; p < NROW; p++)
851 nskypatch += tnaz[p];
852 nskypatch *= rhsubdiv*rhsubdiv;
853 nskypatch += 2;
854 rh_palt = (float *)malloc(sizeof(float)*nskypatch);
855 rh_pazi = (float *)malloc(sizeof(float)*nskypatch);
856 rh_dom = (float *)malloc(sizeof(float)*nskypatch);
857 if ((rh_palt == NULL) | (rh_pazi == NULL) | (rh_dom == NULL)) {
858 fprintf(stderr, "%s: out of memory in rh_init()\n", progname);
859 exit(1);
860 }
861 rh_palt[0] = -PI/2.; /* ground & zenith patches */
862 rh_pazi[0] = 0.;
863 rh_dom[0] = 2.*PI;
864 rh_palt[nskypatch-1] = PI/2.;
865 rh_pazi[nskypatch-1] = 0.;
866 rh_dom[nskypatch-1] = 2.*PI*(1. - cos(alpha*.5));
867 p = 1; /* "normal" patches */
868 for (i = 0; i < NROW*rhsubdiv; i++) {
869 const float ralt = alpha*(i + .5);
870 const int ninrow = tnaz[i/rhsubdiv]*rhsubdiv;
871 const float dom = 2.*PI*(sin(alpha*(i+1)) - sin(alpha*i)) /
872 (double)ninrow;
873 for (j = 0; j < ninrow; j++) {
874 rh_palt[p] = ralt;
875 rh_pazi[p] = 2.*PI * j / (double)ninrow;
876 rh_dom[p++] = dom;
877 }
878 }
879 return nskypatch;
880 #undef NROW
881 }
882
883 /* Resize daylight matrix (GW) */
884 float *
885 resize_dmatrix(float *mtx_data, int nsteps, int npatch)
886 {
887 if (mtx_data == NULL)
888 mtx_data = (float *)malloc(sizeof(float)*3*nsteps*npatch);
889 else
890 mtx_data = (float *)realloc(mtx_data,
891 sizeof(float)*3*nsteps*npatch);
892 if (mtx_data == NULL) {
893 fprintf(stderr, "%s: out of memory in resize_dmatrix(%d,%d)\n",
894 progname, nsteps, npatch);
895 exit(1);
896 }
897 return(mtx_data);
898 }
899
900 /* Determine category index */
901 int GetCategoryIndex()
902 {
903 int index; /* Loop index */
904
905 for (index = 0; index < 8; index++)
906 if ((sky_clearness >= SkyClearCat[index].lower) &&
907 (sky_clearness < SkyClearCat[index].upper))
908 break;
909
910 return index;
911 }
912
913 /* Calculate diffuse illuminance to diffuse irradiance ratio */
914
915 /* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */
916 /* Stewart. 1990. ìModeling Daylight Availability and */
917 /* Irradiance Components from Direct and Global */
918 /* Irradiance,î Solar Energy 44(5):271-289, Eqn. 7. */
919
920 double CalcDiffuseIllumRatio( int index )
921 {
922 ModelCoeff const *pnle; /* Category coefficient pointer */
923
924 /* Get category coefficient pointer */
925 pnle = &(DiffuseLumEff[index]);
926
927 return pnle->a + pnle->b * apwc + pnle->c * cos(sun_zenith) +
928 pnle->d * log(sky_brightness);
929 }
930
931 /* Calculate direct illuminance to direct irradiance ratio */
932
933 /* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */
934 /* Stewart. 1990. ìModeling Daylight Availability and */
935 /* Irradiance Components from Direct and Global */
936 /* Irradiance,î Solar Energy 44(5):271-289, Eqn. 8. */
937
938 double CalcDirectIllumRatio( int index )
939 {
940 ModelCoeff const *pnle; /* Category coefficient pointer */
941
942 /* Get category coefficient pointer */
943 pnle = &(DirectLumEff[index]);
944
945 /* Calculate direct illuminance from direct irradiance */
946
947 return dmax((pnle->a + pnle->b * apwc + pnle->c * exp(5.73 *
948 sun_zenith - 5.0) + pnle->d * sky_brightness),
949 0.0);
950 }
951
952 /* Calculate sky brightness */
953
954 /* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */
955 /* Stewart. 1990. ìModeling Daylight Availability and */
956 /* Irradiance Components from Direct and Global */
957 /* Irradiance,î Solar Energy 44(5):271-289, Eqn. 2. */
958
959 double CalcSkyBrightness()
960 {
961 return diff_irrad * CalcAirMass() / (DC_SolarConstantE *
962 CalcEccentricity());
963 }
964
965 /* Calculate sky clearness */
966
967 /* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */
968 /* Stewart. 1990. ìModeling Daylight Availability and */
969 /* Irradiance Components from Direct and Global */
970 /* Irradiance,î Solar Energy 44(5):271-289, Eqn. 1. */
971
972 double CalcSkyClearness()
973 {
974 double sz_cubed; /* Sun zenith angle cubed */
975
976 /* Calculate sun zenith angle cubed */
977 sz_cubed = sun_zenith*sun_zenith*sun_zenith;
978
979 return ((diff_irrad + dir_irrad) / diff_irrad + 1.041 *
980 sz_cubed) / (1.0 + 1.041 * sz_cubed);
981 }
982
983 /* Calculate diffuse horizontal irradiance from Perez sky brightness */
984
985 /* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */
986 /* Stewart. 1990. ìModeling Daylight Availability and */
987 /* Irradiance Components from Direct and Global */
988 /* Irradiance,î Solar Energy 44(5):271-289, Eqn. 2 */
989 /* (inverse). */
990
991 double CalcDiffuseIrradiance()
992 {
993 return sky_brightness * DC_SolarConstantE * CalcEccentricity() /
994 CalcAirMass();
995 }
996
997 /* Calculate direct normal irradiance from Perez sky clearness */
998
999 /* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */
1000 /* Stewart. 1990. ìModeling Daylight Availability and */
1001 /* Irradiance Components from Direct and Global */
1002 /* Irradiance,î Solar Energy 44(5):271-289, Eqn. 1 */
1003 /* (inverse). */
1004
1005 double CalcDirectIrradiance()
1006 {
1007 return CalcDiffuseIrradiance() * ((sky_clearness - 1.0) * (1 + 1.041
1008 * sun_zenith*sun_zenith*sun_zenith));
1009 }
1010
1011 /* Calculate sky brightness and clearness from illuminance values */
1012 int CalcSkyParamFromIllum()
1013 {
1014 double test1 = 0.1;
1015 double test2 = 0.1;
1016 int counter = 0;
1017 int index = 0; /* Category index */
1018
1019 /* Convert illuminance to irradiance */
1020 diff_irrad = diff_illum * DC_SolarConstantE /
1021 (DC_SolarConstantL * 1000.0);
1022 dir_irrad = dir_illum * DC_SolarConstantE /
1023 (DC_SolarConstantL * 1000.0);
1024
1025 /* Calculate sky brightness and clearness */
1026 sky_brightness = CalcSkyBrightness();
1027 sky_clearness = CalcSkyClearness();
1028
1029 /* Limit sky clearness */
1030 if (sky_clearness > 12.0)
1031 sky_clearness = 12.0;
1032
1033 /* Limit sky brightness */
1034 if (sky_brightness < 0.01)
1035 sky_brightness = 0.01;
1036
1037 while (((fabs(diff_irrad - test1) > 10.0) ||
1038 (fabs(dir_irrad - test2) > 10.0)) && !(counter == 5))
1039 {
1040 test1 = diff_irrad;
1041 test2 = dir_irrad;
1042 counter++;
1043
1044 /* Convert illuminance to irradiance */
1045 index = GetCategoryIndex();
1046 diff_irrad = diff_illum / CalcDiffuseIllumRatio(index);
1047 dir_irrad = CalcDirectIllumRatio(index);
1048 if (dir_irrad > 0.1)
1049 dir_irrad = dir_illum / dir_irrad;
1050
1051 /* Calculate sky brightness and clearness */
1052 sky_brightness = CalcSkyBrightness();
1053 sky_clearness = CalcSkyClearness();
1054
1055 /* Limit sky clearness */
1056 if (sky_clearness > 12.0)
1057 sky_clearness = 12.0;
1058
1059 /* Limit sky brightness */
1060 if (sky_brightness < 0.01)
1061 sky_brightness = 0.01;
1062 }
1063
1064 return GetCategoryIndex();
1065 }
1066
1067 /* Calculate relative luminance */
1068
1069 /* Reference: Perez, R., R. Seals, and J. Michalsky. 1993. */
1070 /* ìAll-Weather Model for Sky Luminance Distribution - */
1071 /* Preliminary Configuration and Validation,î Solar Energy */
1072 /* 50(3):235-245, Eqn. 1. */
1073
1074 double CalcRelLuminance( double gamma, double zeta )
1075 {
1076 return (1.0 + perez_param[0] * exp(perez_param[1] / cos(zeta))) *
1077 (1.0 + perez_param[2] * exp(perez_param[3] * gamma) +
1078 perez_param[4] * cos(gamma) * cos(gamma));
1079 }
1080
1081 /* Calculate Perez sky model parameters */
1082
1083 /* Reference: Perez, R., R. Seals, and J. Michalsky. 1993. */
1084 /* ìAll-Weather Model for Sky Luminance Distribution - */
1085 /* Preliminary Configuration and Validation,î Solar Energy */
1086 /* 50(3):235-245, Eqns. 6 - 8. */
1087
1088 void CalcPerezParam( double sz, double epsilon, double delta,
1089 int index )
1090 {
1091 double x[5][4]; /* Coefficents a, b, c, d, e */
1092 int i, j; /* Loop indices */
1093
1094 /* Limit sky brightness */
1095 if (epsilon > 1.065 && epsilon < 2.8)
1096 {
1097 if (delta < 0.2)
1098 delta = 0.2;
1099 }
1100
1101 /* Get Perez coefficients */
1102 for (i = 0; i < 5; i++)
1103 for (j = 0; j < 4; j++)
1104 x[i][j] = PerezCoeff[index][4 * i + j];
1105
1106 if (index != 0)
1107 {
1108 /* Calculate parameter a, b, c, d and e (Eqn. 6) */
1109 for (i = 0; i < 5; i++)
1110 perez_param[i] = x[i][0] + x[i][1] * sz + delta * (x[i][2] +
1111 x[i][3] * sz);
1112 }
1113 else
1114 {
1115 /* Parameters a, b and e (Eqn. 6) */
1116 perez_param[0] = x[0][0] + x[0][1] * sz + delta * (x[0][2] +
1117 x[0][3] * sz);
1118 perez_param[1] = x[1][0] + x[1][1] * sz + delta * (x[1][2] +
1119 x[1][3] * sz);
1120 perez_param[4] = x[4][0] + x[4][1] * sz + delta * (x[4][2] +
1121 x[4][3] * sz);
1122
1123 /* Parameter c (Eqn. 7) */
1124 perez_param[2] = exp(pow(delta * (x[2][0] + x[2][1] * sz),
1125 x[2][2])) - x[2][3];
1126
1127 /* Parameter d (Eqn. 8) */
1128 perez_param[3] = -exp(delta * (x[3][0] + x[3][1] * sz)) +
1129 x[3][2] + delta * x[3][3];
1130 }
1131 }
1132
1133 /* Calculate relative horizontal illuminance (modified by GW) */
1134
1135 /* Reference: Perez, R., R. Seals, and J. Michalsky. 1993. */
1136 /* ìAll-Weather Model for Sky Luminance Distribution - */
1137 /* Preliminary Configuration and Validation,î Solar Energy */
1138 /* 50(3):235-245, Eqn. 3. */
1139
1140 double CalcRelHorzIllum( float *parr )
1141 {
1142 int i;
1143 double rh_illum = 0.0; /* Relative horizontal illuminance */
1144
1145 for (i = 1; i < nskypatch; i++)
1146 rh_illum += parr[3*i+1] * rh_cos(i) * rh_dom[i];
1147
1148 return rh_illum;
1149 }
1150
1151 /* Calculate earth orbit eccentricity correction factor */
1152
1153 /* Reference: Sen, Z. 2008. Solar Energy Fundamental and Modeling */
1154 /* Techniques. Springer, p. 72. */
1155
1156 double CalcEccentricity()
1157 {
1158 double day_angle; /* Day angle (radians) */
1159 double E0; /* Eccentricity */
1160
1161 /* Calculate day angle */
1162 day_angle = (julian_date - 1.0) * (2.0 * PI / 365.0);
1163
1164 /* Calculate eccentricity */
1165 E0 = 1.00011 + 0.034221 * cos(day_angle) + 0.00128 * sin(day_angle)
1166 + 0.000719 * cos(2.0 * day_angle) + 0.000077 * sin(2.0 *
1167 day_angle);
1168
1169 return E0;
1170 }
1171
1172 /* Calculate atmospheric precipitable water content */
1173
1174 /* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */
1175 /* Stewart. 1990. ìModeling Daylight Availability and */
1176 /* Irradiance Components from Direct and Global */
1177 /* Irradiance,î Solar Energy 44(5):271-289, Eqn. 3. */
1178
1179 /* Note: The default surface dew point temperature is 11 deg. C */
1180 /* (52 deg. F). Typical values are: */
1181
1182 /* Celsius Fahrenheit Human Perception */
1183 /* > 24 > 75 Extremely uncomfortable */
1184 /* 21 - 24 70 - 74 Very humid */
1185 /* 18 - 21 65 - 69 Somewhat uncomfortable */
1186 /* 16 - 18 60 - 64 OK for most people */
1187 /* 13 - 16 55 - 59 Comfortable */
1188 /* 10 - 12 50 - 54 Very comfortable */
1189 /* < 10 < 49 A bit dry for some */
1190
1191 double CalcPrecipWater( double dpt )
1192 { return exp(0.07 * dpt - 0.075); }
1193
1194 /* Calculate relative air mass */
1195
1196 /* Reference: Kasten, F. 1966. "A New Table and Approximation Formula */
1197 /* for the Relative Optical Air Mass," Arch. Meteorol. */
1198 /* Geophys. Bioklimataol. Ser. B14, pp. 206-233. */
1199
1200 /* Note: More sophisticated relative air mass models are */
1201 /* available, but they differ significantly only for */
1202 /* sun zenith angles greater than 80 degrees. */
1203
1204 double CalcAirMass()
1205 {
1206 return (1.0 / (cos(sun_zenith) + 0.15 * pow(93.885 -
1207 RadToDeg(sun_zenith), -1.253)));
1208 }
1209
1210 /* Calculate Perez All-Weather sky patch luminances (modified by GW) */
1211
1212 /* NOTE: The sky patches centers are determined in accordance with the */
1213 /* BRE-IDMP sky luminance measurement procedures. (See for example */
1214 /* Mardaljevic, J. 2001. "The BRE-IDMP Dataset: A New Benchmark */
1215 /* for the Validation of Illuminance Prediction Techniques," */
1216 /* Lighting Research & Technology 33(2):117-136.) */
1217
1218 void CalcSkyPatchLumin( float *parr )
1219 {
1220 int i;
1221 double aas; /* Sun-sky point azimuthal angle */
1222 double sspa; /* Sun-sky point angle */
1223 double zsa; /* Zenithal sun angle */
1224
1225 for (i = 1; i < nskypatch; i++)
1226 {
1227 /* Calculate sun-sky point azimuthal angle */
1228 aas = fabs(rh_pazi[i] - azimuth);
1229
1230 /* Calculate zenithal sun angle */
1231 zsa = PI * 0.5 - rh_palt[i];
1232
1233 /* Calculate sun-sky point angle (Equation 8-20) */
1234 sspa = acos(cos(sun_zenith) * cos(zsa) + sin(sun_zenith) *
1235 sin(zsa) * cos(aas));
1236
1237 /* Calculate patch luminance */
1238 parr[3*i] = CalcRelLuminance(sspa, zsa);
1239 if (parr[3*i] < 0) parr[3*i] = 0;
1240 parr[3*i+2] = parr[3*i+1] = parr[3*i];
1241 }
1242 }