--- ray/src/rt/ambient.c	2014/04/23 06:04:18	2.76
+++ ray/src/rt/ambient.c	2014/04/24 19:16:52	2.78
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char	RCSid[] = "$Id: ambient.c,v 2.76 2014/04/23 06:04:18 greg Exp $";
+static const char	RCSid[] = "$Id: ambient.c,v 2.78 2014/04/24 19:16:52 greg Exp $";
 #endif
 /*
  *  ambient.c - routines dealing with ambient (inter-reflected) component.
@@ -152,7 +152,7 @@ setambient(void)				/* initialize calculation */
 	ambdone();
 						/* init ambient limits */
 	setambres(ambres);
-	setambacc(ambacc);
+	qambacc = sqrt(sqrt(ambacc *= (ambacc > FTINY)));
 	if (ambfile == NULL || !ambfile[0])
 		return;
 	if (ambacc <= FTINY) {
@@ -406,7 +406,7 @@ sumambient(		/* get interpolated ambient value */
 		d = 0.0;
 		for (j = 0; j < 3; j++)
 			d += (r->rop[j] - av->pos[j])*(uvw[2][j] + r->ron[j]);
-		if (d*0.5 < -minarad*ambacc-.001)
+		if (d*0.5 < -minarad*qambacc-.001)
 			continue;
 		/*
 		 *  Extrapolate value and compute final weight (hat function)