src/gen/gensky.c

/* Copyright (c) 1992 Regents of the University of California */

#ifndef lint
static char SCCSid[] = "$SunId$ LBL";
#endif

/*
 *  gensky.c - program to generate sky functions.
 *              Our zenith is along the Z-axis, the X-axis
 *              points east, and the Y-axis points north.
 *              Radiance is in watts/steradian/sq. meter.
 *
 *     3/26/86
 */

#include  <stdio.h>

#include  <math.h>

#include  "color.h"

extern char  *strcpy(), *strcat(), *malloc();
extern double  stadj(), sdec(), sazi(), salt();

#define  PI             3.141592654

#define  DOT(v1,v2)     (v1[0]*v2[0]+v1[1]*v2[1]+v1[2]*v2[2])

#define  S_CLEAR        1
#define  S_OVER         2
#define  S_UNIF         3
#define  S_INTER        4

#define  overcast       (skytype==S_OVER|skytype==S_UNIF)

double  normsc();
                                        /* sun calculation constants */
extern double  s_latitude;
extern double  s_longitude;
extern double  s_meridian;
                                        /* required values */
int  month, day;                                /* date */
double  hour;                                   /* time */
int  tsolar;                                    /* 0=standard, 1=solar */
double  altitude, azimuth;                      /* or solar angles */
                                        /* default values */
int  skytype = S_CLEAR;                         /* sky type */
int  dosun = 1;
double  zenithbr = 0.0;
int     u_zenith = 0;                           /* -1=irradiance, 1=radiance */
double  turbidity = 2.75;
double  gprefl = 0.2;
                                        /* computed values */
double  sundir[3];
double  groundbr;
double  F2;
double  solarbr = 0.0;
int     u_solar = 0;                            /* -1=irradiance, 1=radiance */

char  *progname;
char  errmsg[128];


main(argc, argv)
int  argc;
char  *argv[];
{
        int  i;

        progname = argv[0];
        if (argc == 2 && !strcmp(argv[1], "-defaults")) {
                printdefaults();
                exit(0);
        }
        if (argc < 4)
                userror("arg count");
        if (!strcmp(argv[1], "-ang")) {
                altitude = atof(argv[2]) * (PI/180);
                azimuth = atof(argv[3]) * (PI/180);
                month = 0;
        } else {
                month = atoi(argv[1]);
                if (month < 1 || month > 12)
                        userror("bad month");
                day = atoi(argv[2]);
                if (day < 1 || day > 31)
                        userror("bad day");
                hour = atof(argv[3]);
                if (hour < 0 || hour >= 24)
                        userror("bad hour");
                tsolar = argv[3][0] == '+';
        }
        for (i = 4; i < argc; i++)
                if (argv[i][0] == '-' || argv[i][0] == '+')
                        switch (argv[i][1]) {
                        case 's':
                                skytype = S_CLEAR;
                                dosun = argv[i][0] == '+';
                                break;
                        case 'r':
                        case 'R':
                                u_solar = argv[i][1]=='R' ? -1 : 1;
                                solarbr = atof(argv[++i]);
                                break;
                        case 'c':
                                skytype = S_OVER;
                                break;
                        case 'u':
                                skytype = S_UNIF;
                                break;
                        case 'i':
                                skytype = S_INTER;
                                dosun = argv[i][0] == '+';
                                break;
                        case 't':
                                turbidity = atof(argv[++i]);
                                break;
                        case 'b':
                        case 'B':
                                u_zenith = argv[i][1]=='B' ? -1 : 1;
                                zenithbr = atof(argv[++i]);
                                break;
                        case 'g':
                                gprefl = atof(argv[++i]);
                                break;
                        case 'a':
                                s_latitude = atof(argv[++i]) * (PI/180);
                                break;
                        case 'o':
                                s_longitude = atof(argv[++i]) * (PI/180);
                                break;
                        case 'm':
                                s_meridian = atof(argv[++i]) * (PI/180);
                                break;
                        default:
                                sprintf(errmsg, "unknown option: %s", argv[i]);
                                userror(errmsg);
                        }
                else
                        userror("bad option");

        if (fabs(s_meridian-s_longitude) > 30*PI/180)
                fprintf(stderr,
        "%s: warning: %.1f hours btwn. standard meridian and longitude\n",
                        progname, (s_longitude-s_meridian)*12/PI);

        printhead(argc, argv);

        computesky();
        printsky();
}


computesky()                    /* compute sky parameters */
{
        double  normfactor;
                                        /* compute solar direction */
        if (month) {                    /* from date and time */
                int  jd;
                double  sd, st;

                jd = jdate(month, day);         /* Julian date */
                sd = sdec(jd);                  /* solar declination */
                if (tsolar)                     /* solar time */
                        st = hour;
                else
                        st = hour + stadj(jd);
                altitude = salt(sd, st);
                azimuth = sazi(sd, st);
                printf("# Solar altitude and azimuth: %.1f %.1f\n",
                                180./PI*altitude, 180./PI*azimuth);
        }
        if (!overcast && altitude > 87.*PI/180.) {
                fprintf(stderr,
"%s: warning - sun too close to zenith, reducing altitude to 87 degrees\n",
                                progname);
                printf(
"# warning - sun too close to zenith, reducing altitude to 87 degrees\n");
                altitude = 87.*PI/180.;
        }
        sundir[0] = -sin(azimuth)*cos(altitude);
        sundir[1] = -cos(azimuth)*cos(altitude);
        sundir[2] = sin(altitude);

                                        /* Compute normalization factor */
        switch (skytype) {
        case S_UNIF:
                normfactor = 1.0;
                break;
        case S_OVER:
                normfactor = 0.777778;
                break;
        case S_CLEAR:
                F2 = 0.274*(0.91 + 10.0*exp(-3.0*(PI/2.0-altitude)) +
                                0.45*sundir[2]*sundir[2]);
                normfactor = normsc()/F2/PI;
                break;
        case S_INTER:
                F2 = (2.739 + .9891*sin(.3119+2.6*altitude)) *
                        exp(-(PI/2.0-altitude)*(.4441+1.48*altitude));
                normfactor = normsc()/F2/PI;
                break;
        }
                                        /* Compute zenith brightness */
        if (u_zenith == -1)
                zenithbr /= normfactor*PI;
        else if (u_zenith == 0) {
                if (overcast)
                        zenithbr = 8.6*sundir[2] + .123;
                else
                        zenithbr = (1.376*turbidity-1.81)*tan(altitude)+0.38;
                if (skytype == S_INTER)
                        zenithbr = (zenithbr + 8.6*sundir[2] + .123)/2.0;
                if (zenithbr < 0.0)
                        zenithbr = 0.0;
                else
                        zenithbr *= 1000.0/SKYEFFICACY;
        }
                                        /* Compute horizontal radiance */
        groundbr = zenithbr*normfactor;
        printf("# Ground ambient level: %.1f\n", groundbr);
        if (!overcast && sundir[2] > 0.0 && (!u_solar || solarbr > 0.0)) {
                if (u_solar == -1)
                        solarbr /= 6e-5*sundir[2];
                else if (u_solar == 0) {
                        solarbr = 1.5e9/SUNEFFICACY *
                        (1.147 - .147/(sundir[2]>.16?sundir[2]:.16));
                        if (skytype == S_INTER)
                                solarbr *= 0.15;        /* fudge factor! */
                }
                groundbr += 6e-5/PI*solarbr*sundir[2];
        } else
                dosun = 0;
        groundbr *= gprefl;
}


printsky()                      /* print out sky */
{
        if (dosun) {
                printf("\nvoid light solar\n");
                printf("0\n0\n");
                printf("3 %.2e %.2e %.2e\n", solarbr, solarbr, solarbr);
                printf("\nsolar source sun\n");
                printf("0\n0\n");
                printf("4 %f %f %f 0.5\n", sundir[0], sundir[1], sundir[2]);
        }
        
        printf("\nvoid brightfunc skyfunc\n");
        printf("2 skybr skybright.cal\n");
        printf("0\n");
        if (overcast)
                printf("3 %d %.2e %.2e\n", skytype, zenithbr, groundbr);
        else
                printf("7 %d %.2e %.2e %.2e %f %f %f\n",
                                skytype, zenithbr, groundbr, F2,
                                sundir[0], sundir[1], sundir[2]);
}


printdefaults()                 /* print default values */
{
        switch (skytype) {
        case S_OVER:
                printf("-c\t\t\t\t# Cloudy sky\n");
                break;
        case S_UNIF:
                printf("-u\t\t\t\t# Uniform cloudy sky\n");
                break;
        case S_INTER:
                if (dosun)
                        printf("+i\t\t\t\t# Intermediate sky with sun\n");
                else
                        printf("-i\t\t\t\t# Intermediate sky without sun\n");
                break;
        case S_CLEAR:
                if (dosun)
                        printf("+s\t\t\t\t# Sunny sky with sun\n");
                else
                        printf("-s\t\t\t\t# Sunny sky without sun\n");
                break;
        }
        printf("-g %f\t\t\t# Ground plane reflectance\n", gprefl);
        if (zenithbr > 0.0)
                printf("-b %f\t\t\t# Zenith radiance (watts/ster/m2\n", zenithbr);
        else
                printf("-t %f\t\t\t# Atmospheric turbidity\n", turbidity);
        printf("-a %f\t\t\t# Site latitude (degrees)\n", s_latitude*(180/PI));
        printf("-o %f\t\t\t# Site longitude (degrees)\n", s_longitude*(180/PI));
        printf("-m %f\t\t\t# Standard meridian (degrees)\n", s_meridian*(180/PI));
}


userror(msg)                    /* print usage error and quit */
char  *msg;
{
        if (msg != NULL)
                fprintf(stderr, "%s: Use error - %s\n", progname, msg);
        fprintf(stderr, "Usage: %s month day hour [options]\n", progname);
        fprintf(stderr, "   Or: %s -ang altitude azimuth [options]\n", progname);
        fprintf(stderr, "   Or: %s -defaults\n", progname);
        exit(1);
}


double
normsc()                        /* compute normalization factor (E0*F2/L0) */
{
        static double  nfc[2][5] = {
                                /* clear sky approx. */
                {2.766521, 0.547665, -0.369832, 0.009237, 0.059229},
                                /* intermediate sky approx. */
                {3.5556, -2.7152, -1.3081, 1.0660, 0.60227},
        };
        register double  *nf;
        double  x, nsc;
        register int  i;
                                        /* polynomial approximation */
        nf = nfc[skytype==S_INTER];
        x = (altitude - PI/4.0)/(PI/4.0);
        nsc = nf[i=4];
        while (i--)
                nsc = nsc*x + nf[i];

        return(nsc);
}


printhead(ac, av)               /* print command header */
register int  ac;
register char  **av;
{
        putchar('#');
        while (ac--) {
                putchar(' ');
                fputs(*av++, stdout);
        }
        putchar('\n');
}
Revision:	2.14
Committed:	Mon Jan 31 12:53:49 1994 UTC (30 years, 2 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.13:	+1 -3 lines
Log Message:	fixed bug in calculation of ground brightness for uniform and overcast skies
#	User	Rev	Content
1	greg	2.9	/* Copyright (c) 1992 Regents of the University of California */
2	greg	1.1
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ LBL";
5			#endif
6
7			/*
8			* gensky.c - program to generate sky functions.
9			* Our zenith is along the Z-axis, the X-axis
10			* points east, and the Y-axis points north.
11			* Radiance is in watts/steradian/sq. meter.
12			*
13			* 3/26/86
14			*/
15
16			#include <stdio.h>
17
18			#include <math.h>
19
20	greg	1.6	#include "color.h"
21	greg	1.1
22			extern char strcpy(), strcat(), *malloc();
23			extern double stadj(), sdec(), sazi(), salt();
24
25			#define PI 3.141592654
26
27			#define DOT(v1,v2) (v1[0]v2[0]+v1[1]v2[1]+v1[2]*v2[2])
28
29	greg	2.13	#define S_CLEAR 1
30			#define S_OVER 2
31			#define S_UNIF 3
32			#define S_INTER 4
33
34			#define overcast (skytype==S_OVER\|skytype==S_UNIF)
35
36	greg	1.1	double normsc();
37			/* sun calculation constants */
38			extern double s_latitude;
39			extern double s_longitude;
40			extern double s_meridian;
41			/* required values */
42	greg	2.3	int month, day; /* date */
43	greg	2.5	double hour; /* time */
44			int tsolar; /* 0=standard, 1=solar */
45	greg	2.3	double altitude, azimuth; /* or solar angles */
46	greg	1.1	/* default values */
47	greg	2.13	int skytype = S_CLEAR; /* sky type */
48	greg	1.1	int dosun = 1;
49	greg	2.12	double zenithbr = 0.0;
50			int u_zenith = 0; /* -1=irradiance, 1=radiance */
51	greg	1.1	double turbidity = 2.75;
52			double gprefl = 0.2;
53			/* computed values */
54			double sundir[3];
55			double groundbr;
56			double F2;
57	greg	2.12	double solarbr = 0.0;
58			int u_solar = 0; /* -1=irradiance, 1=radiance */
59	greg	1.1
60			char *progname;
61			char errmsg[128];
62
63
64			main(argc, argv)
65			int argc;
66			char *argv[];
67			{
68			int i;
69
70			progname = argv[0];
71			if (argc == 2 && !strcmp(argv[1], "-defaults")) {
72			printdefaults();
73			exit(0);
74			}
75			if (argc < 4)
76			userror("arg count");
77	greg	2.3	if (!strcmp(argv[1], "-ang")) {
78			altitude = atof(argv[2]) * (PI/180);
79			azimuth = atof(argv[3]) * (PI/180);
80			month = 0;
81			} else {
82			month = atoi(argv[1]);
83	greg	2.6	if (month < 1 \|\| month > 12)
84			userror("bad month");
85	greg	2.3	day = atoi(argv[2]);
86	greg	2.6	if (day < 1 \|\| day > 31)
87			userror("bad day");
88	greg	2.3	hour = atof(argv[3]);
89	greg	2.6	if (hour < 0 \|\| hour >= 24)
90			userror("bad hour");
91	greg	2.5	tsolar = argv[3][0] == '+';
92	greg	2.3	}
93	greg	1.1	for (i = 4; i < argc; i++)
94			if (argv[i][0] == '-' \|\| argv[i][0] == '+')
95			switch (argv[i][1]) {
96			case 's':
97	greg	2.13	skytype = S_CLEAR;
98	greg	1.1	dosun = argv[i][0] == '+';
99			break;
100	greg	2.8	case 'r':
101	greg	2.12	case 'R':
102			u_solar = argv[i][1]=='R' ? -1 : 1;
103	greg	2.8	solarbr = atof(argv[++i]);
104			break;
105	greg	1.1	case 'c':
106	greg	2.13	skytype = S_OVER;
107	greg	1.1	break;
108	greg	2.13	case 'u':
109			skytype = S_UNIF;
110			break;
111			case 'i':
112			skytype = S_INTER;
113			dosun = argv[i][0] == '+';
114			break;
115	greg	1.1	case 't':
116			turbidity = atof(argv[++i]);
117			break;
118			case 'b':
119	greg	2.12	case 'B':
120			u_zenith = argv[i][1]=='B' ? -1 : 1;
121	greg	1.1	zenithbr = atof(argv[++i]);
122			break;
123			case 'g':
124			gprefl = atof(argv[++i]);
125			break;
126			case 'a':
127			s_latitude = atof(argv[++i]) * (PI/180);
128			break;
129			case 'o':
130			s_longitude = atof(argv[++i]) * (PI/180);
131			break;
132			case 'm':
133			s_meridian = atof(argv[++i]) * (PI/180);
134			break;
135			default:
136			sprintf(errmsg, "unknown option: %s", argv[i]);
137			userror(errmsg);
138			}
139			else
140			userror("bad option");
141	greg	1.5
142			if (fabs(s_meridian-s_longitude) > 30*PI/180)
143			fprintf(stderr,
144			"%s: warning: %.1f hours btwn. standard meridian and longitude\n",
145			progname, (s_longitude-s_meridian)*12/PI);
146	greg	1.1
147			printhead(argc, argv);
148
149			computesky();
150			printsky();
151			}
152
153
154			computesky() /* compute sky parameters */
155			{
156	greg	2.12	double normfactor;
157	greg	1.1	/* compute solar direction */
158	greg	2.3	if (month) { /* from date and time */
159			int jd;
160			double sd, st;
161
162			jd = jdate(month, day); /* Julian date */
163			sd = sdec(jd); /* solar declination */
164	greg	2.5	if (tsolar) /* solar time */
165			st = hour;
166			else
167			st = hour + stadj(jd);
168	greg	2.3	altitude = salt(sd, st);
169			azimuth = sazi(sd, st);
170	greg	2.13	printf("# Solar altitude and azimuth: %.1f %.1f\n",
171	greg	2.11	180./PIaltitude, 180./PIazimuth);
172	greg	2.9	}
173	greg	2.13	if (!overcast && altitude > 87.*PI/180.) {
174	greg	2.9	fprintf(stderr,
175			"%s: warning - sun too close to zenith, reducing altitude to 87 degrees\n",
176			progname);
177			printf(
178			"# warning - sun too close to zenith, reducing altitude to 87 degrees\n");
179			altitude = 87.*PI/180.;
180	greg	2.3	}
181	greg	1.1	sundir[0] = -sin(azimuth)*cos(altitude);
182			sundir[1] = -cos(azimuth)*cos(altitude);
183			sundir[2] = sin(altitude);
184
185	greg	2.12	/* Compute normalization factor */
186	greg	2.13	switch (skytype) {
187			case S_UNIF:
188	greg	2.12	normfactor = 1.0;
189	greg	2.13	break;
190			case S_OVER:
191	greg	2.12	normfactor = 0.777778;
192	greg	2.13	break;
193			case S_CLEAR:
194	greg	2.12	F2 = 0.274(0.91 + 10.0exp(-3.0*(PI/2.0-altitude)) +
195			0.45sundir[2]sundir[2]);
196	greg	2.13	normfactor = normsc()/F2/PI;
197			break;
198			case S_INTER:
199			F2 = (2.739 + .9891sin(.3119+2.6altitude)) *
200			exp(-(PI/2.0-altitude)(.4441+1.48altitude));
201			normfactor = normsc()/F2/PI;
202			break;
203	greg	2.12	}
204	greg	1.1	/* Compute zenith brightness */
205	greg	2.12	if (u_zenith == -1)
206			zenithbr /= normfactor*PI;
207			else if (u_zenith == 0) {
208	greg	2.13	if (overcast)
209	greg	1.1	zenithbr = 8.6*sundir[2] + .123;
210	greg	2.12	else
211	greg	1.1	zenithbr = (1.376turbidity-1.81)tan(altitude)+0.38;
212	greg	2.13	if (skytype == S_INTER)
213			zenithbr = (zenithbr + 8.6*sundir[2] + .123)/2.0;
214	greg	2.12	if (zenithbr < 0.0)
215			zenithbr = 0.0;
216			else
217	greg	1.6	zenithbr *= 1000.0/SKYEFFICACY;
218	greg	2.12	}
219	greg	1.1	/* Compute horizontal radiance */
220	greg	2.12	groundbr = zenithbr*normfactor;
221	greg	2.13	printf("# Ground ambient level: %.1f\n", groundbr);
222	greg	2.14	if (!overcast && sundir[2] > 0.0 && (!u_solar \|\| solarbr > 0.0)) {
223	greg	2.12	if (u_solar == -1)
224			solarbr /= 6e-5*sundir[2];
225	greg	2.13	else if (u_solar == 0) {
226	greg	2.12	solarbr = 1.5e9/SUNEFFICACY *
227			(1.147 - .147/(sundir[2]>.16?sundir[2]:.16));
228	greg	2.13	if (skytype == S_INTER)
229			solarbr = 0.15; / fudge factor! */
230			}
231	greg	2.12	groundbr += 6e-5/PIsolarbrsundir[2];
232			} else
233			dosun = 0;
234	greg	1.1	groundbr *= gprefl;
235			}
236
237
238			printsky() /* print out sky */
239			{
240			if (dosun) {
241			printf("\nvoid light solar\n");
242			printf("0\n0\n");
243	greg	1.6	printf("3 %.2e %.2e %.2e\n", solarbr, solarbr, solarbr);
244	greg	1.1	printf("\nsolar source sun\n");
245			printf("0\n0\n");
246			printf("4 %f %f %f 0.5\n", sundir[0], sundir[1], sundir[2]);
247			}
248
249			printf("\nvoid brightfunc skyfunc\n");
250	greg	2.13	printf("2 skybr skybright.cal\n");
251	greg	1.1	printf("0\n");
252	greg	2.13	if (overcast)
253			printf("3 %d %.2e %.2e\n", skytype, zenithbr, groundbr);
254	greg	1.1	else
255	greg	2.13	printf("7 %d %.2e %.2e %.2e %f %f %f\n",
256			skytype, zenithbr, groundbr, F2,
257			sundir[0], sundir[1], sundir[2]);
258	greg	1.1	}
259
260
261			printdefaults() /* print default values */
262			{
263	greg	2.13	switch (skytype) {
264			case S_OVER:
265	greg	1.1	printf("-c\t\t\t\t# Cloudy sky\n");
266	greg	2.13	break;
267			case S_UNIF:
268			printf("-u\t\t\t\t# Uniform cloudy sky\n");
269			break;
270			case S_INTER:
271			if (dosun)
272			printf("+i\t\t\t\t# Intermediate sky with sun\n");
273			else
274			printf("-i\t\t\t\t# Intermediate sky without sun\n");
275			break;
276			case S_CLEAR:
277			if (dosun)
278			printf("+s\t\t\t\t# Sunny sky with sun\n");
279			else
280			printf("-s\t\t\t\t# Sunny sky without sun\n");
281			break;
282			}
283	greg	1.1	printf("-g %f\t\t\t# Ground plane reflectance\n", gprefl);
284			if (zenithbr > 0.0)
285			printf("-b %f\t\t\t# Zenith radiance (watts/ster/m2\n", zenithbr);
286			else
287			printf("-t %f\t\t\t# Atmospheric turbidity\n", turbidity);
288			printf("-a %f\t\t\t# Site latitude (degrees)\n", s_latitude*(180/PI));
289			printf("-o %f\t\t\t# Site longitude (degrees)\n", s_longitude*(180/PI));
290			printf("-m %f\t\t\t# Standard meridian (degrees)\n", s_meridian*(180/PI));
291			}
292
293
294			userror(msg) /* print usage error and quit */
295			char *msg;
296			{
297			if (msg != NULL)
298			fprintf(stderr, "%s: Use error - %s\n", progname, msg);
299			fprintf(stderr, "Usage: %s month day hour [options]\n", progname);
300	greg	2.3	fprintf(stderr, " Or: %s -ang altitude azimuth [options]\n", progname);
301	greg	1.1	fprintf(stderr, " Or: %s -defaults\n", progname);
302			exit(1);
303			}
304
305
306			double
307	greg	2.13	normsc() /* compute normalization factor (E0F2/L0) /
308	greg	1.1	{
309	greg	2.13	static double nfc[2][5] = {
310			/* clear sky approx. */
311			{2.766521, 0.547665, -0.369832, 0.009237, 0.059229},
312			/* intermediate sky approx. */
313			{3.5556, -2.7152, -1.3081, 1.0660, 0.60227},
314			};
315			register double *nf;
316	greg	1.1	double x, nsc;
317			register int i;
318			/* polynomial approximation */
319	greg	2.13	nf = nfc[skytype==S_INTER];
320			x = (altitude - PI/4.0)/(PI/4.0);
321			nsc = nf[i=4];
322			while (i--)
323	greg	1.1	nsc = nsc*x + nf[i];
324
325			return(nsc);
326			}
327
328
329			printhead(ac, av) /* print command header */
330			register int ac;
331			register char **av;
332			{
333			putchar('#');
334			while (ac--) {
335			putchar(' ');
336			fputs(*av++, stdout);
337			}
338			putchar('\n');
339			}