--- ray/src/rt/ambcomp.c	1992/10/02 16:14:38	2.4
+++ ray/src/rt/ambcomp.c	1998/06/24 09:35:00	2.7
@@ -84,8 +84,9 @@ RAY  *r;
 	rayvalue(&ar);
 	ndims--;
 	addcolor(dp->v, ar.rcol);
-	if (ar.rt > FTINY && ar.rt < FHUGE)
-		dp->r += 1.0/ar.rt;
+					/* be conservative and use rot */
+	if (ar.rot > FTINY && ar.rot < FHUGE)
+		dp->r += 1.0/ar.rot;
 					/* (re)initialize error */
 	if (dp->n++) {
 		b2 = bright(dp->v)/dp->n - bright(ar.rcol);
@@ -139,14 +140,15 @@ FVECT  pg, dg;
 			dp->n = 0;
 			if (divsample(dp, &hemi, r) < 0)
 				goto oopsy;
+			arad += dp->r;
 			if (div != NULL)
 				dp++;
-			else {
+			else
 				addcolor(acol, dp->v);
-				arad += dp->r;
-			}
 		}
-	if (ns > 0) {			/* perform super-sampling */
+	if (ns > 0 && arad > FTINY && ndivs/arad < minarad)
+		ns = 0;			/* close enough */
+	else if (ns > 0) {		/* else perform super-sampling */
 		comperrs(div, &hemi);			/* compute errors */
 		qsort(div, ndivs, sizeof(AMBSAMP), ambcmp);	/* sort divs */
 						/* super-sample */
@@ -168,6 +170,7 @@ FVECT  pg, dg;
 	}
 					/* compute returned values */
 	if (div != NULL) {
+		arad = 0.0;
 		for (i = ndivs, dp = div; i-- > 0; dp++) {
 			arad += dp->r;
 			if (dp->n > 1) {