diff --git a/components/sceneutil/mwshadowtechnique.cpp b/components/sceneutil/mwshadowtechnique.cpp
index 5ed5e5a99a..ea52ec24a8 100644
--- a/components/sceneutil/mwshadowtechnique.cpp
+++ b/components/sceneutil/mwshadowtechnique.cpp
@@ -1315,6 +1315,29 @@ void MWShadowTechnique::cull(osgUtil::CullVisitor& cv)
 
             if (!orthographicViewFrustum && settings->getShadowMapProjectionHint()==ShadowSettings::PERSPECTIVE_SHADOW_MAP)
             {
+                {
+                    osg::Matrix validRegionMatrix = cv.getCurrentCamera()->getInverseViewMatrix() *  camera->getViewMatrix() * camera->getProjectionMatrix();
+
+                    std::string validRegionUniformName = "validRegionMatrix" + std::to_string(sm_i);
+                    osg::ref_ptr<osg::Uniform> validRegionUniform;
+
+                    OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_accessUniformsAndProgramMutex);
+
+                    for (auto uniform : _uniforms)
+                    {
+                        if (uniform->getName() == validRegionUniformName)
+                            validRegionUniform = uniform;
+                    }
+
+                    if (!validRegionUniform)
+                    {
+                        validRegionUniform = new osg::Uniform(osg::Uniform::FLOAT_MAT4, validRegionUniformName);
+                        _uniforms.push_back(validRegionUniform);
+                    }
+
+                    validRegionUniform->set(validRegionMatrix);
+                }
+
                 if (settings->getMultipleShadowMapHint() == ShadowSettings::CASCADED)
                     adjustPerspectiveShadowMapCameraSettings(vdsmCallback->getRenderStage(), frustum, pl, camera.get(), cascaseNear, cascadeFar);
                 else
diff --git a/components/sceneutil/shadow.cpp b/components/sceneutil/shadow.cpp
index a6559e9b9e..d3655dfb5c 100644
--- a/components/sceneutil/shadow.cpp
+++ b/components/sceneutil/shadow.cpp
@@ -119,6 +119,12 @@ namespace SceneUtil
         else
             definesWithShadows["useShadowDebugOverlay"] = "0";
 
+        // switch this to reading settings if it's ever exposed to the user
+        if (mShadowSettings->getShadowMapProjectionHint() == ShadowSettings::PERSPECTIVE_SHADOW_MAP)
+            definesWithShadows["perspectiveShadowMaps"] = "1";
+        else
+            definesWithShadows["perspectiveShadowMaps"] = "0";
+
         return definesWithShadows;
     }
 
@@ -132,6 +138,8 @@ namespace SceneUtil
 
         definesWithShadows["useShadowDebugOverlay"] = "0";
 
+        definesWithShadows["perspectiveShadowMaps"] = "0";
+
         return definesWithShadows;
     }
     void ShadowManager::enableIndoorMode()
diff --git a/files/shaders/shadows_fragment.glsl b/files/shaders/shadows_fragment.glsl
index 220e00efaa..713473458b 100644
--- a/files/shaders/shadows_fragment.glsl
+++ b/files/shaders/shadows_fragment.glsl
@@ -4,6 +4,10 @@
     @foreach shadow_texture_unit_index @shadow_texture_unit_list
         uniform sampler2DShadow shadowTexture@shadow_texture_unit_index;
         varying vec4 shadowSpaceCoords@shadow_texture_unit_index;
+
+#if @perspectiveShadowMaps
+        varying vec4 shadowRegionCoords@shadow_texture_unit_index;
+#endif
     @endforeach
 #endif // SHADOWS
 
@@ -17,13 +21,18 @@ float unshadowedLightRatio()
             if (!doneShadows)
             {
                 vec3 shadowXYZ = shadowSpaceCoords@shadow_texture_unit_index.xyz / shadowSpaceCoords@shadow_texture_unit_index.w;
-                vec2 shadowXY = shadowXYZ.xy;
-                if (all(lessThan(shadowXY, vec2(1.0, 1.0))) && all(greaterThan(shadowXY, vec2(0.0, 0.0))))
+#if @perspectiveShadowMaps
+                vec3 shadowRegionXYZ = shadowRegionCoords@shadow_texture_unit_index.xyz / shadowRegionCoords@shadow_texture_unit_index.w;
+#endif
+                if (all(lessThan(shadowXYZ.xy, vec2(1.0, 1.0))) && all(greaterThan(shadowXYZ.xy, vec2(0.0, 0.0))))
                 {
                     shadowing = min(shadow2DProj(shadowTexture@shadow_texture_unit_index, shadowSpaceCoords@shadow_texture_unit_index).r, shadowing);
 
-                    if (all(lessThan(shadowXYZ, vec3(0.95, 0.95, 1.0))) && all(greaterThan(shadowXYZ, vec3(0.05, 0.05, 0.0))))
-                        doneShadows = true;
+                    
+                    doneShadows = all(lessThan(shadowXYZ, vec3(0.95, 0.95, 1.0))) && all(greaterThan(shadowXYZ.xy, vec2(0.05, 0.05)));
+#if @perspectiveShadowMaps
+                    doneShadows = doneShadows && all(lessThan(shadowRegionXYZ, vec3(1.0, 1.0, 1.0))) && all(greaterThan(shadowRegionXYZ.xy, vec2(-1.0, -1.0)));
+#endif
                 }
             }
         @endforeach
@@ -44,8 +53,11 @@ void applyShadowDebugOverlay()
     @foreach shadow_texture_unit_index @shadow_texture_unit_list
         if (!doneOverlay)
         {
-            vec2 shadowXY = shadowSpaceCoords@shadow_texture_unit_index.xy / shadowSpaceCoords@shadow_texture_unit_index.w;
-            if (all(lessThan(shadowXY, vec2(1.0, 1.0))) && all(greaterThan(shadowXY, vec2(0.0, 0.0))))
+            vec3 shadowXYZ = shadowSpaceCoords@shadow_texture_unit_index.xyz / shadowSpaceCoords@shadow_texture_unit_index.w;
+#if @perspectiveShadowMaps
+            vec3 shadowRegionXYZ = shadowRegionCoords@shadow_texture_unit_index.xyz / shadowRegionCoords@shadow_texture_unit_index.w;
+#endif
+            if (all(lessThan(shadowXYZ.xy, vec2(1.0, 1.0))) && all(greaterThan(shadowXYZ.xy, vec2(0.0, 0.0))))
             {
                 colourIndex = mod(@shadow_texture_unit_index.0, 3.0);
 		        if (colourIndex < 1.0)
@@ -55,8 +67,10 @@ void applyShadowDebugOverlay()
 		        else
 			        gl_FragData[0].z += 0.1;
 
-                if (all(lessThan(shadowXY, vec2(0.95, 0.95))) && all(greaterThan(shadowXY, vec2(0.05, 0.05))))
-                    doneOverlay = true;
+                doneOverlay = all(lessThan(shadowXYZ, vec3(0.95, 0.95, 1.0))) && all(greaterThan(shadowXYZ.xy, vec2(0.05, 0.05)));
+#if @perspectiveShadowMaps
+                doneOverlay = doneOverlay && all(lessThan(shadowRegionXYZ.xyz, vec3(1.0, 1.0, 1.0))) && all(greaterThan(shadowRegionXYZ.xy, vec2(-1.0, -1.0)));
+#endif
             }
         }
     @endforeach
diff --git a/files/shaders/shadows_vertex.glsl b/files/shaders/shadows_vertex.glsl
index bbc1a40368..4baa249c11 100644
--- a/files/shaders/shadows_vertex.glsl
+++ b/files/shaders/shadows_vertex.glsl
@@ -4,6 +4,11 @@
     @foreach shadow_texture_unit_index @shadow_texture_unit_list
         uniform int shadowTextureUnit@shadow_texture_unit_index;
         varying vec4 shadowSpaceCoords@shadow_texture_unit_index;
+
+#if @perspectiveShadowMaps
+        uniform mat4 validRegionMatrix@shadow_texture_unit_index;
+        varying vec4 shadowRegionCoords@shadow_texture_unit_index;
+#endif
     @endforeach
 #endif // SHADOWS
 
@@ -15,6 +20,10 @@ void setupShadowCoords(vec4 viewPos)
     @foreach shadow_texture_unit_index @shadow_texture_unit_list
         eyePlaneMat = mat4(gl_EyePlaneS[shadowTextureUnit@shadow_texture_unit_index], gl_EyePlaneT[shadowTextureUnit@shadow_texture_unit_index], gl_EyePlaneR[shadowTextureUnit@shadow_texture_unit_index], gl_EyePlaneQ[shadowTextureUnit@shadow_texture_unit_index]);
         shadowSpaceCoords@shadow_texture_unit_index = viewPos * eyePlaneMat;
+
+#if @perspectiveShadowMaps
+        shadowRegionCoords@shadow_texture_unit_index = validRegionMatrix@shadow_texture_unit_index * viewPos;
+#endif
     @endforeach
 #endif // SHADOWS
 }
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