diff --git a/zenovis/xinxinoptix/LightBounds.cpp b/zenovis/xinxinoptix/LightBounds.cpp
index 018c99c74..5c90944ad 100644
--- a/zenovis/xinxinoptix/LightBounds.cpp
+++ b/zenovis/xinxinoptix/LightBounds.cpp
@@ -44,7 +44,10 @@ float LightBounds::importance(Vector3f p, Vector3f n) const {
         return 0;
 
     // Return final importance at reference point
-    float importance = phi * cosThetap / d2;
+    //float importance = phi * cosThetap / d2;
+    float r2 = 1.0f; float d = sqrtf(d2);
+    float importance = phi * cosThetap * 2.0f / ( d  * sqrtf(d2 + r2) + d2 + r2 );
+
     DCHECK(importance >= -1e-3);
     // Account for $\cos\theta_\roman{i}$ in importance at surfaces
     if (n[0]!=0 && n[1]!=0 && n[2]!=0) {
diff --git a/zenovis/xinxinoptix/LightTree.h b/zenovis/xinxinoptix/LightTree.h
index e2f1dd7d9..c2ce16ca7 100644
--- a/zenovis/xinxinoptix/LightTree.h
+++ b/zenovis/xinxinoptix/LightTree.h
@@ -154,7 +154,10 @@ struct CompactLightBounds {
             return 0;
 
         // Return final importance at reference point
-        float importance = phi * cosThetap / d2;
+        //float importance = phi * cosThetap / d2;
+        float r2 = 1.0f; float d = sqrtf(d2);
+        float importance = phi * cosThetap * 2.0f / ( d  * sqrtf(d2 + r2) + d2 + r2 );
+
         DCHECK(importance >= -1e-3f);
 
         if (n[0]!=0 && n[1]!=0 && n[2]!=0) {