--- ray/src/cv/bsdfrbf.c	2013/10/21 18:33:15	2.12
+++ ray/src/cv/bsdfrbf.c	2014/03/21 00:42:46	2.23
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: bsdfrbf.c,v 2.12 2013/10/21 18:33:15 greg Exp $";
+static const char RCSid[] = "$Id: bsdfrbf.c,v 2.23 2014/03/21 00:42:46 greg Exp $";
 #endif
 /*
  * Radial basis function representation for BSDF data.
@@ -7,6 +7,20 @@ static const char RCSid[] = "$Id: bsdfrbf.c,v 2.12 201
  *	G. Ward
  */
 
+/****************************************************************
+1) Collect samples into a grid using the Shirley-Chiu
+	angular mapping from a hemisphere to a square.
+
+2) Compute an adaptive quadtree by subdividing the grid so that
+	each leaf node has at least one sample up to as many
+	samples as fit nicely on a plane to within a certain
+	MSE tolerance.
+
+3) Place one Gaussian lobe at each leaf node in the quadtree,
+	sizing it to have a radius equal to the leaf size and
+	a volume equal to the energy in that node.
+*****************************************************************/
+
 #define _USE_MATH_DEFINES
 #include <stdio.h>
 #include <stdlib.h>
@@ -21,13 +35,13 @@ static const char RCSid[] = "$Id: bsdfrbf.c,v 2.12 201
 #define SMOOTH_MSE	5e-5		/* acceptable mean squared error */
 #endif
 #ifndef SMOOTH_MSER
-#define SMOOTH_MSER	0.07		/* acceptable relative MSE */
+#define SMOOTH_MSER	0.03		/* acceptable relative MSE */
 #endif
 #define MAX_RAD		(GRIDRES/8)	/* maximum lobe radius */
 
 #define	RBFALLOCB	10		/* RBF allocation block size */
 
-				/* our loaded grid for this incident angle */
+				/* our loaded grid or comparison DSFs */
 GRIDVAL			dsf_grid[GRIDRES][GRIDRES];
 
 /* Start new DSF input grid */
@@ -58,9 +72,7 @@ add_bsdf_data(double theta_out, double phi_out, double
 	ovec[1] = sin((M_PI/180.)*phi_out) * ovec[2];
 	ovec[2] = sqrt(1. - ovec[2]*ovec[2]);
 
-	if (val <= 0)			/* truncate to zero */
-		val = 0;
-	else if (!isDSF)
+	if (!isDSF)
 		val *= ovec[2];		/* convert from BSDF to DSF */
 
 					/* update BSDF histogram */
@@ -69,16 +81,16 @@ add_bsdf_data(double theta_out, double phi_out, double
 
 	pos_from_vec(pos, ovec);
 
-	dsf_grid[pos[0]][pos[1]].vsum += val;
-	dsf_grid[pos[0]][pos[1]].nval++;
+	dsf_grid[pos[0]][pos[1]].sum.v += val;
+	dsf_grid[pos[0]][pos[1]].sum.n++;
 }
 
 /* Compute minimum BSDF from histogram (does not clear) */
 static void
 comp_bsdf_min()
 {
-	int	cnt;
-	int	i, target;
+	unsigned long	cnt, target;
+	int		i;
 
 	cnt = 0;
 	for (i = HISTLEN; i--; )
@@ -102,7 +114,7 @@ empty_region(int x0, int x1, int y0, int y1)
 
 	for (x = x0; x < x1; x++)
 	    for (y = y0; y < y1; y++)
-		if (dsf_grid[x][y].nval)
+		if (dsf_grid[x][y].sum.n)
 			return(0);
 	return(1);
 }
@@ -120,41 +132,42 @@ smooth_region(int x0, int x1, int y0, int y1)
 	memset(xvec, 0, sizeof(xvec));
 	for (x = x0; x < x1; x++)
 	    for (y = y0; y < y1; y++)
-		if ((n = dsf_grid[x][y].nval) > 0) {
-			double	z = dsf_grid[x][y].vsum;
-			rMtx[0][0] += n*x*x;
-			rMtx[0][1] += n*x*y;
-			rMtx[0][2] += n*x;
-			rMtx[1][1] += n*y*y;
-			rMtx[1][2] += n*y;
-			rMtx[2][2] += n;
+		if ((n = dsf_grid[x][y].sum.n) > 0) {
+			double	z = dsf_grid[x][y].sum.v;
+			rMtx[0][0] += x*x*(double)n;
+			rMtx[0][1] += x*y*(double)n;
+			rMtx[0][2] += x*(double)n;
+			rMtx[1][1] += y*y*(double)n;
+			rMtx[1][2] += y*(double)n;
+			rMtx[2][2] += (double)n;
 			xvec[0] += x*z;
 			xvec[1] += y*z;
 			xvec[2] += z;
 		}
 	rMtx[1][0] = rMtx[0][1];
+	rMtx[2][0] = rMtx[0][2];
 	rMtx[2][1] = rMtx[1][2];
 	nvs = rMtx[2][2];
 	if (SDinvXform(rMtx, rMtx) != SDEnone)
-		return(0);
+		return(1);		/* colinear values */
 	A = DOT(rMtx[0], xvec);
 	B = DOT(rMtx[1], xvec);
 	C = DOT(rMtx[2], xvec);
 	sqerr = 0.0;			/* compute mean squared error */
 	for (x = x0; x < x1; x++)
 	    for (y = y0; y < y1; y++)
-		if ((n = dsf_grid[x][y].nval) > 0) {
-			double	d = A*x + B*y + C - dsf_grid[x][y].vsum/n;
+		if ((n = dsf_grid[x][y].sum.n) > 0) {
+			double	d = A*x + B*y + C - dsf_grid[x][y].sum.v/n;
 			sqerr += n*d*d;
 		}
 	if (sqerr <= nvs*SMOOTH_MSE)	/* below absolute MSE threshold? */
 		return(1);
-					/* below relative MSE threshold? */
+					/* OR below relative MSE threshold? */
 	return(sqerr*nvs <= xvec[2]*xvec[2]*SMOOTH_MSER);
 }
 
 /* Create new lobe based on integrated samples in region */
-static void
+static int
 create_lobe(RBFVAL *rvp, int x0, int x1, int y0, int y1)
 {
 	double	vtot = 0.0;
@@ -164,14 +177,16 @@ create_lobe(RBFVAL *rvp, int x0, int x1, int y0, int y
 					/* compute average for region */
 	for (x = x0; x < x1; x++)
 	    for (y = y0; y < y1; y++) {
-		vtot += dsf_grid[x][y].vsum;
-		nv += dsf_grid[x][y].nval;
+		vtot += dsf_grid[x][y].sum.v;
+		nv += dsf_grid[x][y].sum.n;
 	    }
 	if (!nv) {
 		fprintf(stderr, "%s: internal - missing samples in create_lobe\n",
 				progname);
 		exit(1);
 	}
+	if (vtot <= 0)			/* only create positive lobes */
+		return(0);
 					/* peak value based on integral */
 	vtot *= (x1-x0)*(y1-y0)*(2.*M_PI/GRIDRES/GRIDRES)/(double)nv;
 	rad = (RSCA/(double)GRIDRES)*(x1-x0);
@@ -179,6 +194,7 @@ create_lobe(RBFVAL *rvp, int x0, int x1, int y0, int y
 	rvp->crad = ANG2R(rad);
 	rvp->gx = (x0+x1)>>1;
 	rvp->gy = (y0+y1)>>1;
+	return(1);
 }
 
 /* Recursive function to build radial basis function representation */
@@ -209,7 +225,8 @@ build_rbfrep(RBFVAL **arp, int *np, int x0, int x1, in
 	if (!nleaves)			/* nothing but branches? */
 		return(nadded);
 					/* combine 4 leaves into 1? */
-	if (nleaves == 4 && x1-x0 < MAX_RAD && smooth_region(x0, x1, y0, y1))
+	if ((nleaves == 4) & (x1-x0 <= MAX_RAD) &&
+			smooth_region(x0, x1, y0, y1))
 		return(0);
 					/* need more array space? */
 	if ((*np+nleaves-1)>>RBFALLOCB != (*np-1)>>RBFALLOCB) {
@@ -219,15 +236,18 @@ build_rbfrep(RBFVAL **arp, int *np, int x0, int x1, in
 			return(-1);
 	}
 					/* create lobes for leaves */
-	if (!branched[0])
-		create_lobe(*arp+(*np)++, x0, xmid, y0, ymid);
-	if (!branched[1])
-		create_lobe(*arp+(*np)++, xmid, x1, y0, ymid);
-	if (!branched[2])
-		create_lobe(*arp+(*np)++, x0, xmid, ymid, y1);
-	if (!branched[3])
-		create_lobe(*arp+(*np)++, xmid, x1, ymid, y1);
-	nadded += nleaves;
+	if (!branched[0] && create_lobe(*arp+*np, x0, xmid, y0, ymid)) {
+		++(*np); ++nadded;
+	}
+	if (!branched[1] && create_lobe(*arp+*np, xmid, x1, y0, ymid)) {
+		++(*np); ++nadded;
+	}
+	if (!branched[2] && create_lobe(*arp+*np, x0, xmid, ymid, y1)) {
+		++(*np); ++nadded;
+	}
+	if (!branched[3] && create_lobe(*arp+*np, xmid, x1, ymid, y1)) {
+		++(*np); ++nadded;
+	}
 	return(nadded);
 }
 
@@ -242,8 +262,13 @@ make_rbfrep()
 	comp_bsdf_min();
 				/* create RBF node list */
 	rbfarr = NULL; nn = 0;
-	if (build_rbfrep(&rbfarr, &nn, 0, GRIDRES, 0, GRIDRES) <= 0)
-		goto memerr;
+	if (build_rbfrep(&rbfarr, &nn, 0, GRIDRES, 0, GRIDRES) <= 0) {
+		if (nn)
+			goto memerr;
+		fprintf(stderr, "%s: no usable data in make_rbfrep()\n",
+				progname);
+		exit(1);
+	}
 				/* (re)allocate RBF array */
 	newnode = (RBFNODE *)realloc(rbfarr,
 			sizeof(RBFNODE) + sizeof(RBFVAL)*(nn-1));