| 1 |
/* Copyright (c) 1986 Regents of the University of California */ |
| 2 |
|
| 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 |
|
| 21 |
extern char *strcpy(), *strcat(), *malloc(); |
| 22 |
extern double stadj(), sdec(), sazi(), salt(); |
| 23 |
|
| 24 |
#define PI 3.141592654 |
| 25 |
|
| 26 |
#define DOT(v1,v2) (v1[0]*v2[0]+v1[1]*v2[1]+v1[2]*v2[2]) |
| 27 |
|
| 28 |
double normsc(); |
| 29 |
/* sun calculation constants */ |
| 30 |
extern double s_latitude; |
| 31 |
extern double s_longitude; |
| 32 |
extern double s_meridian; |
| 33 |
/* required values */ |
| 34 |
int month, day; |
| 35 |
double hour; |
| 36 |
/* default values */ |
| 37 |
int cloudy = 0; |
| 38 |
int dosun = 1; |
| 39 |
double zenithbr = -1.0; |
| 40 |
double turbidity = 2.75; |
| 41 |
double gprefl = 0.2; |
| 42 |
/* computed values */ |
| 43 |
double sundir[3]; |
| 44 |
double groundbr; |
| 45 |
double F2; |
| 46 |
double solarbr; |
| 47 |
|
| 48 |
char *progname; |
| 49 |
char errmsg[128]; |
| 50 |
|
| 51 |
|
| 52 |
main(argc, argv) |
| 53 |
int argc; |
| 54 |
char *argv[]; |
| 55 |
{ |
| 56 |
extern double atof(), fabs(); |
| 57 |
int i; |
| 58 |
|
| 59 |
progname = argv[0]; |
| 60 |
if (argc == 2 && !strcmp(argv[1], "-defaults")) { |
| 61 |
printdefaults(); |
| 62 |
exit(0); |
| 63 |
} |
| 64 |
if (argc < 4) |
| 65 |
userror("arg count"); |
| 66 |
month = atoi(argv[1]); |
| 67 |
day = atoi(argv[2]); |
| 68 |
hour = atof(argv[3]); |
| 69 |
for (i = 4; i < argc; i++) |
| 70 |
if (argv[i][0] == '-' || argv[i][0] == '+') |
| 71 |
switch (argv[i][1]) { |
| 72 |
case 's': |
| 73 |
cloudy = 0; |
| 74 |
dosun = argv[i][0] == '+'; |
| 75 |
break; |
| 76 |
case 'c': |
| 77 |
cloudy = 1; |
| 78 |
dosun = 0; |
| 79 |
break; |
| 80 |
case 't': |
| 81 |
turbidity = atof(argv[++i]); |
| 82 |
break; |
| 83 |
case 'b': |
| 84 |
zenithbr = atof(argv[++i]); |
| 85 |
break; |
| 86 |
case 'g': |
| 87 |
gprefl = atof(argv[++i]); |
| 88 |
break; |
| 89 |
case 'a': |
| 90 |
s_latitude = atof(argv[++i]) * (PI/180); |
| 91 |
break; |
| 92 |
case 'o': |
| 93 |
s_longitude = atof(argv[++i]) * (PI/180); |
| 94 |
break; |
| 95 |
case 'm': |
| 96 |
s_meridian = atof(argv[++i]) * (PI/180); |
| 97 |
break; |
| 98 |
default: |
| 99 |
sprintf(errmsg, "unknown option: %s", argv[i]); |
| 100 |
userror(errmsg); |
| 101 |
} |
| 102 |
else |
| 103 |
userror("bad option"); |
| 104 |
|
| 105 |
if (fabs(s_meridian-s_longitude) > 30*PI/180) |
| 106 |
fprintf(stderr, |
| 107 |
"%s: warning: %.1f hours btwn. standard meridian and longitude\n", |
| 108 |
progname, (s_longitude-s_meridian)*12/PI); |
| 109 |
|
| 110 |
printhead(argc, argv); |
| 111 |
|
| 112 |
computesky(); |
| 113 |
printsky(); |
| 114 |
} |
| 115 |
|
| 116 |
|
| 117 |
computesky() /* compute sky parameters */ |
| 118 |
{ |
| 119 |
int jd; |
| 120 |
double sd, st; |
| 121 |
double altitude, azimuth; |
| 122 |
/* compute solar direction */ |
| 123 |
jd = jdate(month, day); /* Julian date */ |
| 124 |
sd = sdec(jd); /* solar declination */ |
| 125 |
st = hour + stadj(jd); /* solar time */ |
| 126 |
altitude = salt(sd, st); |
| 127 |
azimuth = sazi(sd, st); |
| 128 |
sundir[0] = -sin(azimuth)*cos(altitude); |
| 129 |
sundir[1] = -cos(azimuth)*cos(altitude); |
| 130 |
sundir[2] = sin(altitude); |
| 131 |
|
| 132 |
/* Compute zenith brightness */ |
| 133 |
if (zenithbr <= 0.0) |
| 134 |
if (cloudy) { |
| 135 |
zenithbr = 8.6*sundir[2] + .123; |
| 136 |
zenithbr *= 1000.0*.0064/3.; |
| 137 |
} else { |
| 138 |
zenithbr = (1.376*turbidity-1.81)*tan(altitude)+0.38; |
| 139 |
zenithbr *= 1000.0*.0064/3.; |
| 140 |
} |
| 141 |
if (zenithbr < 0.0) |
| 142 |
zenithbr = 0.0; |
| 143 |
/* Compute horizontal radiance */ |
| 144 |
if (cloudy) { |
| 145 |
groundbr = zenithbr*0.777778; |
| 146 |
printf("# Ground ambient level: %f\n", groundbr); |
| 147 |
} else { |
| 148 |
F2 = 0.274*(0.91 + 10.0*exp(-3.0*(PI/2.0-altitude)) + |
| 149 |
0.45*sundir[2]*sundir[2]); |
| 150 |
groundbr = zenithbr*normsc(PI/2.0-altitude)/F2/PI; |
| 151 |
printf("# Ground ambient level: %f\n", groundbr); |
| 152 |
if (sundir[2] > 0.0) { |
| 153 |
if (sundir[2] > .16) |
| 154 |
solarbr = 2.47e6 - 3.15e5/sundir[2]; |
| 155 |
else |
| 156 |
solarbr = 5e5; |
| 157 |
groundbr += solarbr*6e-5*sundir[2]/PI; |
| 158 |
} else |
| 159 |
dosun = 0; |
| 160 |
} |
| 161 |
groundbr *= gprefl; |
| 162 |
} |
| 163 |
|
| 164 |
|
| 165 |
printsky() /* print out sky */ |
| 166 |
{ |
| 167 |
if (dosun) { |
| 168 |
printf("\nvoid light solar\n"); |
| 169 |
printf("0\n0\n"); |
| 170 |
printf("3 %f %f %f\n", solarbr, solarbr, solarbr); |
| 171 |
printf("\nsolar source sun\n"); |
| 172 |
printf("0\n0\n"); |
| 173 |
printf("4 %f %f %f 0.5\n", sundir[0], sundir[1], sundir[2]); |
| 174 |
} |
| 175 |
|
| 176 |
printf("\nvoid brightfunc skyfunc\n"); |
| 177 |
printf("2 skybright skybright.cal\n"); |
| 178 |
printf("0\n"); |
| 179 |
if (cloudy) |
| 180 |
printf("3 1 %f %f\n", zenithbr, groundbr); |
| 181 |
else |
| 182 |
printf("7 -1 %f %f %f %f %f %f\n", zenithbr, groundbr, F2, |
| 183 |
sundir[0], sundir[1], sundir[2]); |
| 184 |
} |
| 185 |
|
| 186 |
|
| 187 |
printdefaults() /* print default values */ |
| 188 |
{ |
| 189 |
if (cloudy) |
| 190 |
printf("-c\t\t\t\t# Cloudy sky\n"); |
| 191 |
else if (dosun) |
| 192 |
printf("+s\t\t\t\t# Sunny sky with sun\n"); |
| 193 |
else |
| 194 |
printf("-s\t\t\t\t# Sunny sky without sun\n"); |
| 195 |
printf("-g %f\t\t\t# Ground plane reflectance\n", gprefl); |
| 196 |
if (zenithbr > 0.0) |
| 197 |
printf("-b %f\t\t\t# Zenith radiance (watts/ster/m2\n", zenithbr); |
| 198 |
else |
| 199 |
printf("-t %f\t\t\t# Atmospheric turbidity\n", turbidity); |
| 200 |
printf("-a %f\t\t\t# Site latitude (degrees)\n", s_latitude*(180/PI)); |
| 201 |
printf("-o %f\t\t\t# Site longitude (degrees)\n", s_longitude*(180/PI)); |
| 202 |
printf("-m %f\t\t\t# Standard meridian (degrees)\n", s_meridian*(180/PI)); |
| 203 |
} |
| 204 |
|
| 205 |
|
| 206 |
userror(msg) /* print usage error and quit */ |
| 207 |
char *msg; |
| 208 |
{ |
| 209 |
if (msg != NULL) |
| 210 |
fprintf(stderr, "%s: Use error - %s\n", progname, msg); |
| 211 |
fprintf(stderr, "Usage: %s month day hour [options]\n", progname); |
| 212 |
fprintf(stderr, " Or: %s -defaults\n", progname); |
| 213 |
exit(1); |
| 214 |
} |
| 215 |
|
| 216 |
|
| 217 |
double |
| 218 |
normsc(theta) /* compute normalization factor (E0*F2/L0) */ |
| 219 |
double theta; |
| 220 |
{ |
| 221 |
static double nf[5] = {2.766521, 0.547665, |
| 222 |
-0.369832, 0.009237, 0.059229}; |
| 223 |
double x, nsc; |
| 224 |
register int i; |
| 225 |
/* polynomial approximation */ |
| 226 |
x = (theta - PI/4.0)/(PI/4.0); |
| 227 |
nsc = nf[4]; |
| 228 |
for (i = 3; i >= 0; i--) |
| 229 |
nsc = nsc*x + nf[i]; |
| 230 |
|
| 231 |
return(nsc); |
| 232 |
} |
| 233 |
|
| 234 |
|
| 235 |
printhead(ac, av) /* print command header */ |
| 236 |
register int ac; |
| 237 |
register char **av; |
| 238 |
{ |
| 239 |
putchar('#'); |
| 240 |
while (ac--) { |
| 241 |
putchar(' '); |
| 242 |
fputs(*av++, stdout); |
| 243 |
} |
| 244 |
putchar('\n'); |
| 245 |
} |
