| 1 |
#ifndef lint
|
| 2 |
static const char RCSid[] = "$Id: bsdfrbf.c,v 2.2 2012/11/13 04:23:38 greg Exp $";
|
| 3 |
#endif
|
| 4 |
/*
|
| 5 |
* Radial basis function representation for BSDF data.
|
| 6 |
*
|
| 7 |
* G. Ward
|
| 8 |
*/
|
| 9 |
|
| 10 |
#define _USE_MATH_DEFINES
|
| 11 |
#include <stdio.h>
|
| 12 |
#include <stdlib.h>
|
| 13 |
#include <string.h>
|
| 14 |
#include <math.h>
|
| 15 |
#include "bsdfrep.h"
|
| 16 |
|
| 17 |
#ifndef RSCA
|
| 18 |
#define RSCA 2.7 /* radius scaling factor (empirical) */
|
| 19 |
#endif
|
| 20 |
/* our loaded grid for this incident angle */
|
| 21 |
GRIDVAL dsf_grid[GRIDRES][GRIDRES];
|
| 22 |
|
| 23 |
/* Start new DSF input grid */
|
| 24 |
void
|
| 25 |
new_bsdf_data(double new_theta, double new_phi)
|
| 26 |
{
|
| 27 |
if (!new_input_direction(new_theta, new_phi))
|
| 28 |
exit(1);
|
| 29 |
memset(dsf_grid, 0, sizeof(dsf_grid));
|
| 30 |
}
|
| 31 |
|
| 32 |
/* Add BSDF data point */
|
| 33 |
void
|
| 34 |
add_bsdf_data(double theta_out, double phi_out, double val, int isDSF)
|
| 35 |
{
|
| 36 |
FVECT ovec;
|
| 37 |
int pos[2];
|
| 38 |
|
| 39 |
if (!output_orient) /* check output orientation */
|
| 40 |
output_orient = 1 - 2*(theta_out > 90.);
|
| 41 |
else if (output_orient > 0 ^ theta_out < 90.) {
|
| 42 |
fputs("Cannot handle output angles on both sides of surface\n",
|
| 43 |
stderr);
|
| 44 |
exit(1);
|
| 45 |
}
|
| 46 |
ovec[2] = sin((M_PI/180.)*theta_out);
|
| 47 |
ovec[0] = cos((M_PI/180.)*phi_out) * ovec[2];
|
| 48 |
ovec[1] = sin((M_PI/180.)*phi_out) * ovec[2];
|
| 49 |
ovec[2] = sqrt(1. - ovec[2]*ovec[2]);
|
| 50 |
|
| 51 |
if (!isDSF)
|
| 52 |
val *= ovec[2]; /* convert from BSDF to DSF */
|
| 53 |
|
| 54 |
pos_from_vec(pos, ovec);
|
| 55 |
|
| 56 |
dsf_grid[pos[0]][pos[1]].vsum += val;
|
| 57 |
dsf_grid[pos[0]][pos[1]].nval++;
|
| 58 |
}
|
| 59 |
|
| 60 |
/* Compute radii for non-empty bins */
|
| 61 |
/* (distance to furthest empty bin for which non-empty bin is the closest) */
|
| 62 |
static void
|
| 63 |
compute_radii(void)
|
| 64 |
{
|
| 65 |
unsigned int fill_grid[GRIDRES][GRIDRES];
|
| 66 |
unsigned short fill_cnt[GRIDRES][GRIDRES];
|
| 67 |
FVECT ovec0, ovec1;
|
| 68 |
double ang2, lastang2;
|
| 69 |
int r, i, j, jn, ii, jj, inear, jnear;
|
| 70 |
|
| 71 |
r = GRIDRES/2; /* proceed in zig-zag */
|
| 72 |
for (i = 0; i < GRIDRES; i++)
|
| 73 |
for (jn = 0; jn < GRIDRES; jn++) {
|
| 74 |
j = (i&1) ? jn : GRIDRES-1-jn;
|
| 75 |
if (dsf_grid[i][j].nval) /* find empty grid pos. */
|
| 76 |
continue;
|
| 77 |
ovec_from_pos(ovec0, i, j);
|
| 78 |
inear = jnear = -1; /* find nearest non-empty */
|
| 79 |
lastang2 = M_PI*M_PI;
|
| 80 |
for (ii = i-r; ii <= i+r; ii++) {
|
| 81 |
if (ii < 0) continue;
|
| 82 |
if (ii >= GRIDRES) break;
|
| 83 |
for (jj = j-r; jj <= j+r; jj++) {
|
| 84 |
if (jj < 0) continue;
|
| 85 |
if (jj >= GRIDRES) break;
|
| 86 |
if (!dsf_grid[ii][jj].nval)
|
| 87 |
continue;
|
| 88 |
ovec_from_pos(ovec1, ii, jj);
|
| 89 |
ang2 = 2. - 2.*DOT(ovec0,ovec1);
|
| 90 |
if (ang2 >= lastang2)
|
| 91 |
continue;
|
| 92 |
lastang2 = ang2;
|
| 93 |
inear = ii; jnear = jj;
|
| 94 |
}
|
| 95 |
}
|
| 96 |
if (inear < 0) {
|
| 97 |
fprintf(stderr,
|
| 98 |
"%s: Could not find non-empty neighbor!\n",
|
| 99 |
progname);
|
| 100 |
exit(1);
|
| 101 |
}
|
| 102 |
ang2 = sqrt(lastang2);
|
| 103 |
r = ANG2R(ang2); /* record if > previous */
|
| 104 |
if (r > dsf_grid[inear][jnear].crad)
|
| 105 |
dsf_grid[inear][jnear].crad = r;
|
| 106 |
/* next search radius */
|
| 107 |
r = ang2*(2.*GRIDRES/M_PI) + 3;
|
| 108 |
}
|
| 109 |
/* blur radii over hemisphere */
|
| 110 |
memset(fill_grid, 0, sizeof(fill_grid));
|
| 111 |
memset(fill_cnt, 0, sizeof(fill_cnt));
|
| 112 |
for (i = 0; i < GRIDRES; i++)
|
| 113 |
for (j = 0; j < GRIDRES; j++) {
|
| 114 |
if (!dsf_grid[i][j].crad)
|
| 115 |
continue; /* missing distance */
|
| 116 |
r = R2ANG(dsf_grid[i][j].crad)*(2.*RSCA*GRIDRES/M_PI);
|
| 117 |
for (ii = i-r; ii <= i+r; ii++) {
|
| 118 |
if (ii < 0) continue;
|
| 119 |
if (ii >= GRIDRES) break;
|
| 120 |
for (jj = j-r; jj <= j+r; jj++) {
|
| 121 |
if (jj < 0) continue;
|
| 122 |
if (jj >= GRIDRES) break;
|
| 123 |
if ((ii-i)*(ii-i) + (jj-j)*(jj-j) > r*r)
|
| 124 |
continue;
|
| 125 |
fill_grid[ii][jj] += dsf_grid[i][j].crad;
|
| 126 |
fill_cnt[ii][jj]++;
|
| 127 |
}
|
| 128 |
}
|
| 129 |
}
|
| 130 |
/* copy back blurred radii */
|
| 131 |
for (i = 0; i < GRIDRES; i++)
|
| 132 |
for (j = 0; j < GRIDRES; j++)
|
| 133 |
if (fill_cnt[i][j])
|
| 134 |
dsf_grid[i][j].crad = fill_grid[i][j]/fill_cnt[i][j];
|
| 135 |
}
|
| 136 |
|
| 137 |
/* Cull points for more uniform distribution, leave all nval 0 or 1 */
|
| 138 |
static void
|
| 139 |
cull_values(void)
|
| 140 |
{
|
| 141 |
FVECT ovec0, ovec1;
|
| 142 |
double maxang, maxang2;
|
| 143 |
int i, j, ii, jj, r;
|
| 144 |
/* simple greedy algorithm */
|
| 145 |
for (i = 0; i < GRIDRES; i++)
|
| 146 |
for (j = 0; j < GRIDRES; j++) {
|
| 147 |
if (!dsf_grid[i][j].nval)
|
| 148 |
continue;
|
| 149 |
if (!dsf_grid[i][j].crad)
|
| 150 |
continue; /* shouldn't happen */
|
| 151 |
ovec_from_pos(ovec0, i, j);
|
| 152 |
maxang = 2.*R2ANG(dsf_grid[i][j].crad);
|
| 153 |
if (maxang > ovec0[2]) /* clamp near horizon */
|
| 154 |
maxang = ovec0[2];
|
| 155 |
r = maxang*(2.*GRIDRES/M_PI) + 1;
|
| 156 |
maxang2 = maxang*maxang;
|
| 157 |
for (ii = i-r; ii <= i+r; ii++) {
|
| 158 |
if (ii < 0) continue;
|
| 159 |
if (ii >= GRIDRES) break;
|
| 160 |
for (jj = j-r; jj <= j+r; jj++) {
|
| 161 |
if (jj < 0) continue;
|
| 162 |
if (jj >= GRIDRES) break;
|
| 163 |
if (!dsf_grid[ii][jj].nval)
|
| 164 |
continue;
|
| 165 |
if ((ii == i) & (jj == j))
|
| 166 |
continue; /* don't get self-absorbed */
|
| 167 |
ovec_from_pos(ovec1, ii, jj);
|
| 168 |
if (2. - 2.*DOT(ovec0,ovec1) >= maxang2)
|
| 169 |
continue;
|
| 170 |
/* absorb sum */
|
| 171 |
dsf_grid[i][j].vsum += dsf_grid[ii][jj].vsum;
|
| 172 |
dsf_grid[i][j].nval += dsf_grid[ii][jj].nval;
|
| 173 |
/* keep value, though */
|
| 174 |
dsf_grid[ii][jj].vsum /= (float)dsf_grid[ii][jj].nval;
|
| 175 |
dsf_grid[ii][jj].nval = 0;
|
| 176 |
}
|
| 177 |
}
|
| 178 |
}
|
| 179 |
/* final averaging pass */
|
| 180 |
for (i = 0; i < GRIDRES; i++)
|
| 181 |
for (j = 0; j < GRIDRES; j++)
|
| 182 |
if (dsf_grid[i][j].nval > 1) {
|
| 183 |
dsf_grid[i][j].vsum /= (float)dsf_grid[i][j].nval;
|
| 184 |
dsf_grid[i][j].nval = 1;
|
| 185 |
}
|
| 186 |
}
|
| 187 |
|
| 188 |
/* Count up filled nodes and build RBF representation from current grid */
|
| 189 |
RBFNODE *
|
| 190 |
make_rbfrep(void)
|
| 191 |
{
|
| 192 |
int niter = 16;
|
| 193 |
double lastVar, thisVar = 100.;
|
| 194 |
int nn;
|
| 195 |
RBFNODE *newnode;
|
| 196 |
RBFVAL *itera;
|
| 197 |
int i, j;
|
| 198 |
/* compute RBF radii */
|
| 199 |
compute_radii();
|
| 200 |
/* coagulate lobes */
|
| 201 |
cull_values();
|
| 202 |
nn = 0; /* count selected bins */
|
| 203 |
for (i = 0; i < GRIDRES; i++)
|
| 204 |
for (j = 0; j < GRIDRES; j++)
|
| 205 |
nn += dsf_grid[i][j].nval;
|
| 206 |
/* allocate RBF array */
|
| 207 |
newnode = (RBFNODE *)malloc(sizeof(RBFNODE) + sizeof(RBFVAL)*(nn-1));
|
| 208 |
if (newnode == NULL)
|
| 209 |
goto memerr;
|
| 210 |
newnode->ord = -1;
|
| 211 |
newnode->next = NULL;
|
| 212 |
newnode->ejl = NULL;
|
| 213 |
newnode->invec[2] = sin((M_PI/180.)*theta_in_deg);
|
| 214 |
newnode->invec[0] = cos((M_PI/180.)*phi_in_deg)*newnode->invec[2];
|
| 215 |
newnode->invec[1] = sin((M_PI/180.)*phi_in_deg)*newnode->invec[2];
|
| 216 |
newnode->invec[2] = input_orient*sqrt(1. - newnode->invec[2]*newnode->invec[2]);
|
| 217 |
newnode->vtotal = 0;
|
| 218 |
newnode->nrbf = nn;
|
| 219 |
nn = 0; /* fill RBF array */
|
| 220 |
for (i = 0; i < GRIDRES; i++)
|
| 221 |
for (j = 0; j < GRIDRES; j++)
|
| 222 |
if (dsf_grid[i][j].nval) {
|
| 223 |
newnode->rbfa[nn].peak = dsf_grid[i][j].vsum;
|
| 224 |
newnode->rbfa[nn].crad = RSCA*dsf_grid[i][j].crad + .5;
|
| 225 |
newnode->rbfa[nn].gx = i;
|
| 226 |
newnode->rbfa[nn].gy = j;
|
| 227 |
++nn;
|
| 228 |
}
|
| 229 |
/* iterate to improve interpolation accuracy */
|
| 230 |
itera = (RBFVAL *)malloc(sizeof(RBFVAL)*newnode->nrbf);
|
| 231 |
if (itera == NULL)
|
| 232 |
goto memerr;
|
| 233 |
memcpy(itera, newnode->rbfa, sizeof(RBFVAL)*newnode->nrbf);
|
| 234 |
do {
|
| 235 |
double dsum = 0, dsum2 = 0;
|
| 236 |
nn = 0;
|
| 237 |
for (i = 0; i < GRIDRES; i++)
|
| 238 |
for (j = 0; j < GRIDRES; j++)
|
| 239 |
if (dsf_grid[i][j].nval) {
|
| 240 |
FVECT odir;
|
| 241 |
double corr;
|
| 242 |
ovec_from_pos(odir, i, j);
|
| 243 |
itera[nn++].peak *= corr =
|
| 244 |
dsf_grid[i][j].vsum /
|
| 245 |
eval_rbfrep(newnode, odir);
|
| 246 |
dsum += 1. - corr;
|
| 247 |
dsum2 += (1.-corr)*(1.-corr);
|
| 248 |
}
|
| 249 |
memcpy(newnode->rbfa, itera, sizeof(RBFVAL)*newnode->nrbf);
|
| 250 |
lastVar = thisVar;
|
| 251 |
thisVar = dsum2/(double)nn;
|
| 252 |
#ifdef DEBUG
|
| 253 |
fprintf(stderr, "Avg., RMS error: %.1f%% %.1f%%\n",
|
| 254 |
100.*dsum/(double)nn,
|
| 255 |
100.*sqrt(thisVar));
|
| 256 |
#endif
|
| 257 |
} while (--niter > 0 && lastVar-thisVar > 0.02*lastVar);
|
| 258 |
|
| 259 |
free(itera);
|
| 260 |
nn = 0; /* compute sum for normalization */
|
| 261 |
while (nn < newnode->nrbf)
|
| 262 |
newnode->vtotal += rbf_volume(&newnode->rbfa[nn++]);
|
| 263 |
#ifdef DEBUG
|
| 264 |
fprintf(stderr, "Integrated DSF at (%.1f,%.1f) deg. is %.2f\n",
|
| 265 |
get_theta180(newnode->invec), get_phi360(newnode->invec),
|
| 266 |
newnode->vtotal);
|
| 267 |
#endif
|
| 268 |
insert_dsf(newnode);
|
| 269 |
|
| 270 |
return(newnode);
|
| 271 |
memerr:
|
| 272 |
fprintf(stderr, "%s: Out of memory in make_rbfrep()\n", progname);
|
| 273 |
exit(1);
|
| 274 |
}
|
