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root/radiance/ray/src/cv/bsdfrbf.c
Revision: 2.5
Committed: Fri Jun 28 23:18:51 2013 UTC (10 years, 10 months ago) by greg
Content type: text/plain
Branch: MAIN
Changes since 2.4: +25 -1 lines
Log Message:
Fixed calculation of bsdf_min

File Contents

# User Rev Content
1 greg 2.1 #ifndef lint
2 greg 2.5 static const char RCSid[] = "$Id: bsdfrbf.c,v 2.4 2013/03/20 01:00:22 greg Exp $";
3 greg 2.1 #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 greg 2.4 /* update BSDF histogram */
55     if (val < BSDF2BIG*ovec[2] && val > BSDF2SML*ovec[2])
56     ++bsdf_hist[histndx(val/ovec[2])];
57    
58 greg 2.1 pos_from_vec(pos, ovec);
59    
60     dsf_grid[pos[0]][pos[1]].vsum += val;
61     dsf_grid[pos[0]][pos[1]].nval++;
62     }
63    
64     /* Compute radii for non-empty bins */
65     /* (distance to furthest empty bin for which non-empty bin is the closest) */
66     static void
67     compute_radii(void)
68     {
69     unsigned int fill_grid[GRIDRES][GRIDRES];
70     unsigned short fill_cnt[GRIDRES][GRIDRES];
71     FVECT ovec0, ovec1;
72     double ang2, lastang2;
73     int r, i, j, jn, ii, jj, inear, jnear;
74    
75     r = GRIDRES/2; /* proceed in zig-zag */
76     for (i = 0; i < GRIDRES; i++)
77     for (jn = 0; jn < GRIDRES; jn++) {
78     j = (i&1) ? jn : GRIDRES-1-jn;
79     if (dsf_grid[i][j].nval) /* find empty grid pos. */
80     continue;
81     ovec_from_pos(ovec0, i, j);
82     inear = jnear = -1; /* find nearest non-empty */
83     lastang2 = M_PI*M_PI;
84     for (ii = i-r; ii <= i+r; ii++) {
85     if (ii < 0) continue;
86     if (ii >= GRIDRES) break;
87     for (jj = j-r; jj <= j+r; jj++) {
88     if (jj < 0) continue;
89     if (jj >= GRIDRES) break;
90     if (!dsf_grid[ii][jj].nval)
91     continue;
92     ovec_from_pos(ovec1, ii, jj);
93     ang2 = 2. - 2.*DOT(ovec0,ovec1);
94     if (ang2 >= lastang2)
95     continue;
96     lastang2 = ang2;
97     inear = ii; jnear = jj;
98     }
99     }
100     if (inear < 0) {
101     fprintf(stderr,
102     "%s: Could not find non-empty neighbor!\n",
103     progname);
104     exit(1);
105     }
106     ang2 = sqrt(lastang2);
107     r = ANG2R(ang2); /* record if > previous */
108     if (r > dsf_grid[inear][jnear].crad)
109     dsf_grid[inear][jnear].crad = r;
110     /* next search radius */
111     r = ang2*(2.*GRIDRES/M_PI) + 3;
112     }
113     /* blur radii over hemisphere */
114     memset(fill_grid, 0, sizeof(fill_grid));
115     memset(fill_cnt, 0, sizeof(fill_cnt));
116     for (i = 0; i < GRIDRES; i++)
117     for (j = 0; j < GRIDRES; j++) {
118     if (!dsf_grid[i][j].crad)
119     continue; /* missing distance */
120     r = R2ANG(dsf_grid[i][j].crad)*(2.*RSCA*GRIDRES/M_PI);
121     for (ii = i-r; ii <= i+r; ii++) {
122     if (ii < 0) continue;
123     if (ii >= GRIDRES) break;
124     for (jj = j-r; jj <= j+r; jj++) {
125     if (jj < 0) continue;
126     if (jj >= GRIDRES) break;
127     if ((ii-i)*(ii-i) + (jj-j)*(jj-j) > r*r)
128     continue;
129     fill_grid[ii][jj] += dsf_grid[i][j].crad;
130     fill_cnt[ii][jj]++;
131     }
132     }
133     }
134     /* copy back blurred radii */
135     for (i = 0; i < GRIDRES; i++)
136     for (j = 0; j < GRIDRES; j++)
137     if (fill_cnt[i][j])
138     dsf_grid[i][j].crad = fill_grid[i][j]/fill_cnt[i][j];
139     }
140    
141     /* Cull points for more uniform distribution, leave all nval 0 or 1 */
142     static void
143     cull_values(void)
144     {
145     FVECT ovec0, ovec1;
146     double maxang, maxang2;
147     int i, j, ii, jj, r;
148     /* simple greedy algorithm */
149     for (i = 0; i < GRIDRES; i++)
150     for (j = 0; j < GRIDRES; j++) {
151     if (!dsf_grid[i][j].nval)
152     continue;
153     if (!dsf_grid[i][j].crad)
154     continue; /* shouldn't happen */
155     ovec_from_pos(ovec0, i, j);
156     maxang = 2.*R2ANG(dsf_grid[i][j].crad);
157     if (maxang > ovec0[2]) /* clamp near horizon */
158     maxang = ovec0[2];
159     r = maxang*(2.*GRIDRES/M_PI) + 1;
160     maxang2 = maxang*maxang;
161     for (ii = i-r; ii <= i+r; ii++) {
162     if (ii < 0) continue;
163     if (ii >= GRIDRES) break;
164     for (jj = j-r; jj <= j+r; jj++) {
165     if (jj < 0) continue;
166     if (jj >= GRIDRES) break;
167     if (!dsf_grid[ii][jj].nval)
168     continue;
169     if ((ii == i) & (jj == j))
170     continue; /* don't get self-absorbed */
171     ovec_from_pos(ovec1, ii, jj);
172     if (2. - 2.*DOT(ovec0,ovec1) >= maxang2)
173     continue;
174     /* absorb sum */
175     dsf_grid[i][j].vsum += dsf_grid[ii][jj].vsum;
176     dsf_grid[i][j].nval += dsf_grid[ii][jj].nval;
177     /* keep value, though */
178     dsf_grid[ii][jj].vsum /= (float)dsf_grid[ii][jj].nval;
179     dsf_grid[ii][jj].nval = 0;
180     }
181     }
182     }
183     /* final averaging pass */
184     for (i = 0; i < GRIDRES; i++)
185     for (j = 0; j < GRIDRES; j++)
186     if (dsf_grid[i][j].nval > 1) {
187     dsf_grid[i][j].vsum /= (float)dsf_grid[i][j].nval;
188     dsf_grid[i][j].nval = 1;
189     }
190     }
191    
192 greg 2.5 /* Compute minimum BSDF from histogram and clear it */
193     static void
194     comp_bsdf_min()
195     {
196     int cnt;
197     int i, target;
198    
199     cnt = 0;
200     for (i = HISTLEN; i--; )
201     cnt += bsdf_hist[i];
202     if (!cnt) { /* shouldn't happen */
203     bsdf_min = 0;
204     return;
205     }
206     target = cnt/100; /* ignore bottom 1% */
207     cnt = 0;
208     for (i = 0; cnt <= target; i++)
209     cnt += bsdf_hist[i];
210     bsdf_min = histval(i-1);
211     memset(bsdf_hist, 0, sizeof(bsdf_hist));
212     }
213    
214 greg 2.1 /* Count up filled nodes and build RBF representation from current grid */
215     RBFNODE *
216     make_rbfrep(void)
217     {
218     int niter = 16;
219     double lastVar, thisVar = 100.;
220     int nn;
221     RBFNODE *newnode;
222 greg 2.2 RBFVAL *itera;
223 greg 2.1 int i, j;
224     /* compute RBF radii */
225     compute_radii();
226     /* coagulate lobes */
227     cull_values();
228     nn = 0; /* count selected bins */
229     for (i = 0; i < GRIDRES; i++)
230     for (j = 0; j < GRIDRES; j++)
231     nn += dsf_grid[i][j].nval;
232 greg 2.5 /* compute minimum BSDF */
233     comp_bsdf_min();
234 greg 2.1 /* allocate RBF array */
235     newnode = (RBFNODE *)malloc(sizeof(RBFNODE) + sizeof(RBFVAL)*(nn-1));
236 greg 2.2 if (newnode == NULL)
237     goto memerr;
238 greg 2.1 newnode->ord = -1;
239     newnode->next = NULL;
240     newnode->ejl = NULL;
241     newnode->invec[2] = sin((M_PI/180.)*theta_in_deg);
242     newnode->invec[0] = cos((M_PI/180.)*phi_in_deg)*newnode->invec[2];
243     newnode->invec[1] = sin((M_PI/180.)*phi_in_deg)*newnode->invec[2];
244     newnode->invec[2] = input_orient*sqrt(1. - newnode->invec[2]*newnode->invec[2]);
245     newnode->vtotal = 0;
246     newnode->nrbf = nn;
247     nn = 0; /* fill RBF array */
248     for (i = 0; i < GRIDRES; i++)
249     for (j = 0; j < GRIDRES; j++)
250     if (dsf_grid[i][j].nval) {
251     newnode->rbfa[nn].peak = dsf_grid[i][j].vsum;
252     newnode->rbfa[nn].crad = RSCA*dsf_grid[i][j].crad + .5;
253     newnode->rbfa[nn].gx = i;
254     newnode->rbfa[nn].gy = j;
255     ++nn;
256     }
257     /* iterate to improve interpolation accuracy */
258 greg 2.2 itera = (RBFVAL *)malloc(sizeof(RBFVAL)*newnode->nrbf);
259     if (itera == NULL)
260     goto memerr;
261     memcpy(itera, newnode->rbfa, sizeof(RBFVAL)*newnode->nrbf);
262 greg 2.1 do {
263     double dsum = 0, dsum2 = 0;
264     nn = 0;
265     for (i = 0; i < GRIDRES; i++)
266     for (j = 0; j < GRIDRES; j++)
267     if (dsf_grid[i][j].nval) {
268     FVECT odir;
269     double corr;
270     ovec_from_pos(odir, i, j);
271 greg 2.2 itera[nn++].peak *= corr =
272 greg 2.1 dsf_grid[i][j].vsum /
273     eval_rbfrep(newnode, odir);
274 greg 2.2 dsum += 1. - corr;
275     dsum2 += (1.-corr)*(1.-corr);
276 greg 2.1 }
277 greg 2.2 memcpy(newnode->rbfa, itera, sizeof(RBFVAL)*newnode->nrbf);
278 greg 2.1 lastVar = thisVar;
279     thisVar = dsum2/(double)nn;
280     #ifdef DEBUG
281     fprintf(stderr, "Avg., RMS error: %.1f%% %.1f%%\n",
282     100.*dsum/(double)nn,
283     100.*sqrt(thisVar));
284     #endif
285     } while (--niter > 0 && lastVar-thisVar > 0.02*lastVar);
286    
287 greg 2.2 free(itera);
288 greg 2.1 nn = 0; /* compute sum for normalization */
289     while (nn < newnode->nrbf)
290     newnode->vtotal += rbf_volume(&newnode->rbfa[nn++]);
291 greg 2.3 #ifdef DEBUG
292     fprintf(stderr, "Integrated DSF at (%.1f,%.1f) deg. is %.2f\n",
293     get_theta180(newnode->invec), get_phi360(newnode->invec),
294     newnode->vtotal);
295     #endif
296 greg 2.1 insert_dsf(newnode);
297    
298     return(newnode);
299 greg 2.2 memerr:
300     fprintf(stderr, "%s: Out of memory in make_rbfrep()\n", progname);
301     exit(1);
302 greg 2.1 }