--- ray/src/common/bsdf_m.c	2011/04/19 21:31:22	3.10
+++ ray/src/common/bsdf_m.c	2011/04/20 14:44:05	3.11
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: bsdf_m.c,v 3.10 2011/04/19 21:31:22 greg Exp $";
+static const char RCSid[] = "$Id: bsdf_m.c,v 3.11 2011/04/20 14:44:05 greg Exp $";
 #endif
 /*
  *  bsdf_m.c
@@ -664,6 +664,10 @@ SDqueryMtxProjSA(double *psa, const FVECT v1, const RR
 					/* get projected solid angles */
 	out_psa = mBSDF_outohm(dp, mBSDF_outndx(dp, v1));
 	inc_psa = mBSDF_incohm(dp, mBSDF_incndx(dp, v2));
+	if ((out_psa <= 0) & (inc_psa <= 0)) {
+		inc_psa = mBSDF_outohm(dp, mBSDF_outndx(dp, v2));
+		out_psa = mBSDF_incohm(dp, mBSDF_incndx(dp, v1));
+	}
 
 	switch (qflags) {		/* record based on flag settings */
 	case SDqueryVal: