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#ifndef lint |
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static const char RCSid[] = "$Id: gensky.c,v 2.28 2020/07/25 19:18:01 greg Exp $"; |
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#endif |
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/* |
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* gensky.c - program to generate sky functions. |
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* Our zenith is along the Z-axis, the X-axis |
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* points east, and the Y-axis points north. |
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* Radiance is in watts/steradian/sq. meter. |
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* |
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* 3/26/86 |
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*/ |
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|
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#include "rtio.h" |
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#include <stdlib.h> |
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#include <math.h> |
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#include <ctype.h> |
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#include "sun.h" |
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#include "color.h" |
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|
| 20 |
#ifndef PI |
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#define PI 3.14159265358979323846 |
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#endif |
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|
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#define DOT(v1,v2) (v1[0]*v2[0]+v1[1]*v2[1]+v1[2]*v2[2]) |
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|
| 26 |
#define S_CLEAR 1 |
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#define S_OVER 2 |
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#define S_UNIF 3 |
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#define S_INTER 4 |
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|
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#define overcast ((skytype==S_OVER)|(skytype==S_UNIF)) |
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|
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double normsc(); |
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|
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#undef toupper |
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#define toupper(c) ((c) & ~0x20) /* ASCII trick to convert case */ |
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|
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/* European and North American zones */ |
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struct { |
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char zname[8]; /* time zone name (all caps) */ |
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float zmer; /* standard meridian */ |
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} tzone[] = { |
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{"YST", 135}, {"YDT", 120}, |
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{"PST", 120}, {"PDT", 105}, |
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{"MST", 105}, {"MDT", 90}, |
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{"CST", 90}, {"CDT", 75}, |
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{"EST", 75}, {"EDT", 60}, |
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{"AST", 60}, {"ADT", 45}, |
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{"NST", 52.5}, {"NDT", 37.5}, |
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{"GMT", 0}, {"BST", -15}, |
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{"CET", -15}, {"CEST", -30}, |
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{"EET", -30}, {"EEST", -45}, |
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{"AST", -45}, {"ADT", -60}, |
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{"GST", -60}, {"GDT", -75}, |
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{"IST", -82.5}, {"IDT", -97.5}, |
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{"JST", -135}, {"NDT", -150}, |
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{"NZST", -180}, {"NZDT", -195}, |
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{"", 0} |
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}; |
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/* required values */ |
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int year = 0; /* year (optional) */ |
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int month, day; /* date */ |
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double hour; /* time */ |
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int tsolar; /* 0=standard, 1=solar */ |
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double altitude, azimuth; /* or solar angles */ |
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/* default values */ |
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int skytype = S_CLEAR; /* sky type */ |
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int dosun = 1; |
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double zenithbr = 0.0; |
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int u_zenith = 0; /* -1=irradiance, 1=radiance */ |
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double turbidity = 2.45; |
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double gprefl = 0.2; |
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/* computed values */ |
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double sundir[3]; |
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double groundbr; |
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double F2; |
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double solarbr = 0.0; |
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int u_solar = 0; /* -1=irradiance, 1=radiance */ |
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|
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char *progname; |
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char errmsg[128]; |
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|
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void computesky(void); |
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void printsky(void); |
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void printdefaults(void); |
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void userror(char *msg); |
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double normsc(void); |
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int cvthour(char *hs); |
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|
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|
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int |
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main( |
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int argc, |
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char *argv[] |
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) |
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{ |
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int got_meridian = 0; |
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int i; |
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|
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progname = argv[0]; |
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if (argc == 2 && !strcmp(argv[1], "-defaults")) { |
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printdefaults(); |
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exit(0); |
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} |
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if (argc < 4) |
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userror("arg count"); |
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if (!strcmp(argv[1], "-ang")) { |
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altitude = atof(argv[2]) * (PI/180); |
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azimuth = atof(argv[3]) * (PI/180); |
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month = 0; |
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} else { |
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month = atoi(argv[1]); |
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if (month < 1 || month > 12) |
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userror("bad month"); |
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day = atoi(argv[2]); |
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if (day < 1 || day > 31) |
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userror("bad day"); |
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got_meridian = cvthour(argv[3]); |
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} |
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for (i = 4; i < argc; i++) |
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if (argv[i][0] == '-' || argv[i][0] == '+') |
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switch (argv[i][1]) { |
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case 's': |
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skytype = S_CLEAR; |
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dosun = argv[i][0] == '+'; |
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break; |
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case 'y': |
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year = atoi(argv[++i]); |
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break; |
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case 'r': |
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case 'R': |
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u_solar = argv[i][1]=='R' ? -1 : 1; |
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solarbr = atof(argv[++i]); |
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break; |
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case 'c': |
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skytype = S_OVER; |
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break; |
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case 'u': |
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skytype = S_UNIF; |
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break; |
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case 'i': |
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skytype = S_INTER; |
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dosun = argv[i][0] == '+'; |
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break; |
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case 't': |
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turbidity = atof(argv[++i]); |
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break; |
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case 'b': |
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case 'B': |
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u_zenith = argv[i][1]=='B' ? -1 : 1; |
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zenithbr = atof(argv[++i]); |
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break; |
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case 'g': |
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gprefl = atof(argv[++i]); |
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break; |
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case 'a': |
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s_latitude = atof(argv[++i]) * (PI/180); |
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break; |
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case 'o': |
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s_longitude = atof(argv[++i]) * (PI/180); |
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break; |
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case 'm': |
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if (got_meridian) { |
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++i; |
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break; /* time overrides */ |
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} |
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s_meridian = atof(argv[++i]) * (PI/180); |
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break; |
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default: |
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sprintf(errmsg, "unknown option: %s", argv[i]); |
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userror(errmsg); |
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} |
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else |
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userror("bad option"); |
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|
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if (year && (year < 1950) | (year > 2050)) |
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fprintf(stderr, |
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"%s: warning - year should be in range 1950-2050\n", |
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progname); |
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if (month && !tsolar && fabs(s_meridian-s_longitude) > 45*PI/180) |
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fprintf(stderr, |
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"%s: warning - %.1f hours btwn. standard meridian and longitude\n", |
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progname, (s_longitude-s_meridian)*12/PI); |
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|
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fputs("# ", stdout); |
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printargs(argc, argv, stdout); |
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|
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computesky(); |
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printsky(); |
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|
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exit(0); |
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} |
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|
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|
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void |
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computesky(void) /* compute sky parameters */ |
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{ |
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double normfactor; |
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/* compute solar direction */ |
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if (month) { /* from date and time */ |
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double sd, st = hour; |
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|
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if (year) { /* Michalsky algorithm? */ |
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double mjd = mjdate(year, month, day, hour); |
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if (tsolar) |
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sd = msdec(mjd, NULL); |
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else |
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sd = msdec(mjd, &st); |
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} else { |
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int jd = jdate(month, day); /* Julian date */ |
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sd = sdec(jd); /* solar declination */ |
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if (!tsolar) /* get solar time? */ |
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st = hour + stadj(jd); |
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} |
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altitude = salt(sd, st); |
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azimuth = sazi(sd, st); |
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printf("# Local solar time: %.2f\n", st); |
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printf("# Solar altitude and azimuth: %.1f %.1f\n", |
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180./PI*altitude, 180./PI*azimuth); |
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} |
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if (!overcast && altitude > 87.*PI/180.) { |
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fprintf(stderr, |
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"%s: warning - sun too close to zenith, reducing altitude to 87 degrees\n", |
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progname); |
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printf( |
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"# warning - sun too close to zenith, reducing altitude to 87 degrees\n"); |
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altitude = 87.*PI/180.; |
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} |
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sundir[0] = -sin(azimuth)*cos(altitude); |
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sundir[1] = -cos(azimuth)*cos(altitude); |
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sundir[2] = sin(altitude); |
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|
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/* Compute normalization factor */ |
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switch (skytype) { |
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case S_UNIF: |
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normfactor = 1.0; |
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break; |
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case S_OVER: |
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normfactor = 0.777778; |
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break; |
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case S_CLEAR: |
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F2 = 0.274*(0.91 + 10.0*exp(-3.0*(PI/2.0-altitude)) + |
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0.45*sundir[2]*sundir[2]); |
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normfactor = normsc()/F2/PI; |
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break; |
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case S_INTER: |
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F2 = (2.739 + .9891*sin(.3119+2.6*altitude)) * |
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exp(-(PI/2.0-altitude)*(.4441+1.48*altitude)); |
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normfactor = normsc()/F2/PI; |
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break; |
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} |
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/* Compute zenith brightness */ |
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if (u_zenith == -1) |
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zenithbr /= normfactor*PI; |
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else if (u_zenith == 0) { |
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if (overcast) |
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zenithbr = 8.6*sundir[2] + .123; |
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else |
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zenithbr = (1.376*turbidity-1.81)*tan(altitude)+0.38; |
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if (skytype == S_INTER) |
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zenithbr = (zenithbr + 8.6*sundir[2] + .123)/2.0; |
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if (zenithbr < 0.0) |
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zenithbr = 0.0; |
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else |
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zenithbr *= 1000.0/SKYEFFICACY; |
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} |
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/* Compute horizontal radiance */ |
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groundbr = zenithbr*normfactor; |
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printf("# Ground ambient level: %.1f\n", groundbr); |
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if (!overcast && sundir[2] > 0.0 && (!u_solar || solarbr > 0.0)) { |
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if (u_solar == -1) |
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solarbr /= 6e-5*sundir[2]; |
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else if (u_solar == 0) { |
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solarbr = 1.5e9/SUNEFFICACY * |
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(1.147 - .147/(sundir[2]>.16?sundir[2]:.16)); |
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if (skytype == S_INTER) |
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solarbr *= 0.15; /* fudge factor! */ |
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} |
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groundbr += 6e-5/PI*solarbr*sundir[2]; |
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} else |
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dosun = 0; |
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groundbr *= gprefl; |
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} |
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|
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|
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void |
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printsky(void) /* print out sky */ |
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{ |
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if (dosun) { |
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printf("\nvoid light solar\n"); |
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printf("0\n0\n"); |
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printf("3 %.3e %.3e %.3e\n", solarbr, solarbr, solarbr); |
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printf("\nsolar source sun\n"); |
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printf("0\n0\n"); |
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printf("4 %f %f %f 0.5\n", sundir[0], sundir[1], sundir[2]); |
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} |
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|
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printf("\nvoid brightfunc skyfunc\n"); |
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printf("2 skybr skybright.cal\n"); |
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printf("0\n"); |
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if (overcast) |
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printf("3 %d %.3e %.3e\n", skytype, zenithbr, groundbr); |
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else |
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printf("7 %d %.3e %.3e %.3e %f %f %f\n", |
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skytype, zenithbr, groundbr, F2, |
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sundir[0], sundir[1], sundir[2]); |
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} |
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|
| 309 |
|
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void |
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printdefaults(void) /* print default values */ |
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{ |
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switch (skytype) { |
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case S_OVER: |
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printf("-c\t\t\t\t# Cloudy sky\n"); |
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break; |
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case S_UNIF: |
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printf("-u\t\t\t\t# Uniform cloudy sky\n"); |
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break; |
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case S_INTER: |
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if (dosun) |
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printf("+i\t\t\t\t# Intermediate sky with sun\n"); |
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else |
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printf("-i\t\t\t\t# Intermediate sky without sun\n"); |
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break; |
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case S_CLEAR: |
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if (dosun) |
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printf("+s\t\t\t\t# Sunny sky with sun\n"); |
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else |
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printf("-s\t\t\t\t# Sunny sky without sun\n"); |
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break; |
| 332 |
} |
| 333 |
printf("-g %f\t\t\t# Ground plane reflectance\n", gprefl); |
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if (zenithbr > 0.0) |
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printf("-b %f\t\t\t# Zenith radiance (watts/ster/m2\n", zenithbr); |
| 336 |
else |
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printf("-t %f\t\t\t# Atmospheric turbidity\n", turbidity); |
| 338 |
printf("-a %f\t\t\t# Site latitude (degrees)\n", s_latitude*(180/PI)); |
| 339 |
printf("-o %f\t\t\t# Site longitude (degrees)\n", s_longitude*(180/PI)); |
| 340 |
printf("-m %f\t\t\t# Standard meridian (degrees)\n", s_meridian*(180/PI)); |
| 341 |
} |
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|
| 343 |
|
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void |
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userror( /* print usage error and quit */ |
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char *msg |
| 347 |
) |
| 348 |
{ |
| 349 |
if (msg != NULL) |
| 350 |
fprintf(stderr, "%s: Use error - %s\n", progname, msg); |
| 351 |
fprintf(stderr, "Usage: %s month day hour [options]\n", progname); |
| 352 |
fprintf(stderr, " Or: %s -ang altitude azimuth [options]\n", progname); |
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fprintf(stderr, " Or: %s -defaults\n", progname); |
| 354 |
exit(1); |
| 355 |
} |
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|
| 357 |
|
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double |
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normsc(void) /* compute normalization factor (E0*F2/L0) */ |
| 360 |
{ |
| 361 |
static double nfc[2][5] = { |
| 362 |
/* clear sky approx. */ |
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{2.766521, 0.547665, -0.369832, 0.009237, 0.059229}, |
| 364 |
/* intermediate sky approx. */ |
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{3.5556, -2.7152, -1.3081, 1.0660, 0.60227}, |
| 366 |
}; |
| 367 |
double *nf; |
| 368 |
double x, nsc; |
| 369 |
int i; |
| 370 |
/* polynomial approximation */ |
| 371 |
nf = nfc[skytype==S_INTER]; |
| 372 |
x = (altitude - PI/4.0)/(PI/4.0); |
| 373 |
nsc = nf[i=4]; |
| 374 |
while (i--) |
| 375 |
nsc = nsc*x + nf[i]; |
| 376 |
|
| 377 |
return(nsc); |
| 378 |
} |
| 379 |
|
| 380 |
|
| 381 |
int |
| 382 |
cvthour( /* convert hour string */ |
| 383 |
char *hs |
| 384 |
) |
| 385 |
{ |
| 386 |
char *cp = hs; |
| 387 |
int i, j; |
| 388 |
|
| 389 |
if ( (tsolar = *cp == '+') ) cp++; /* solar time? */ |
| 390 |
while (isdigit(*cp)) cp++; |
| 391 |
if (*cp == ':') |
| 392 |
hour = atoi(hs) + atoi(++cp)/60.0; |
| 393 |
else { |
| 394 |
hour = atof(hs); |
| 395 |
if (*cp == '.') cp++; |
| 396 |
} |
| 397 |
while (isdigit(*cp)) cp++; |
| 398 |
if (!*cp) |
| 399 |
return(0); |
| 400 |
if (tsolar || !isalpha(*cp)) { |
| 401 |
fprintf(stderr, "%s: bad time format: %s\n", progname, hs); |
| 402 |
exit(1); |
| 403 |
} |
| 404 |
i = 0; |
| 405 |
do { |
| 406 |
for (j = 0; cp[j]; j++) |
| 407 |
if (toupper(cp[j]) != tzone[i].zname[j]) |
| 408 |
break; |
| 409 |
if (!cp[j] && !tzone[i].zname[j]) { |
| 410 |
s_meridian = tzone[i].zmer * (PI/180); |
| 411 |
return(1); |
| 412 |
} |
| 413 |
} while (tzone[i++].zname[0]); |
| 414 |
|
| 415 |
fprintf(stderr, "%s: unknown time zone: %s\n", progname, cp); |
| 416 |
fprintf(stderr, "Known time zones:\n\t%s", tzone[0].zname); |
| 417 |
for (i = 1; tzone[i].zname[0]; i++) |
| 418 |
fprintf(stderr, " %s", tzone[i].zname); |
| 419 |
putc('\n', stderr); |
| 420 |
exit(1); |
| 421 |
} |
