--- ray/src/rt/pmapkdt.c	2018/01/24 19:39:05	1.3
+++ ray/src/rt/pmapkdt.c	2018/05/31 12:34:16	1.4
@@ -8,7 +8,7 @@
        supported by the Swiss National Science Foundation (SNSF, #147053)
    ======================================================================
    
-   $Id: pmapkdt.c,v 1.3 2018/01/24 19:39:05 rschregle Exp $
+   $Id: pmapkdt.c,v 1.4 2018/05/31 12:34:16 rschregle Exp $
 */
 
 
@@ -424,8 +424,9 @@ void kdT_FindPhotons (struct PhotonMap *pmap, const FV
    
    /* Photon pos & normal stored at lower precision */
    VCOPY(p, pos);
-   VCOPY(n, norm);
-   kdT_FindNearest(pmap, p, n, 1);
+   if (norm)
+      VCOPY(n, norm);
+   kdT_FindNearest(pmap, p, norm ? n : NULL, 1);
 }
 
 
@@ -464,7 +465,7 @@ static void kdT_Find1Nearest (PhotonMap *pmap, const f
    d2 = DOT(dv, dv);
    
    if (d2 < pmap -> maxDist2 && 
-       DOT(norm, p -> norm) > PMAP_NORM_TOL * 127 * frandom()) {
+       (!norm || DOT(norm, p -> norm) > PMAP_NORM_TOL * 127 * frandom())) {
       /* Closest photon so far with similar normal. We allow for tolerance
        * to account for perturbation in the latter; note the photon normal
        * is coded in the range [-127,127], hence we factor this in  */
@@ -483,8 +484,9 @@ void kdT_Find1Photon (struct PhotonMap *pmap, const FV
    
    /* Photon pos & normal stored at lower precision */
    VCOPY(p, pos);
-   VCOPY(n, norm);
-   kdT_Find1Nearest(pmap, p, n, &pnn, 1);
+   if (norm)
+      VCOPY(n, norm);   
+   kdT_Find1Nearest(pmap, p, norm ? n : NULL, &pnn, 1);
    memcpy(photon, pnn, sizeof(Photon));
 }