diff --git a/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs b/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs
index f67f422019..b0996f5cf6 100644
--- a/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs
+++ b/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs
@@ -4556,22 +4556,52 @@ namespace OpenSim.Region.ScriptEngine.Shared.Api
         public LSL_Types.Vector3 llGroundSlope(LSL_Types.Vector3 offset)
         {
             m_host.AddScriptLPS(1);
-            NotImplemented("llGroundSlope");
-            return new LSL_Types.Vector3();
+
+            Vector3 pos = m_host.AbsolutePosition + new Vector3((float)offset.x,
+                                                                (float)offset.y,
+                                                                (float)offset.z);
+
+            Vector3 p0 = new Vector3(pos.X, pos.Y,
+                                     (float)llGround(
+                                                 new LSL_Types.Vector3(pos.X, pos.Y, pos.Z)
+                                                 ));
+            Vector3 p1 = new Vector3(pos.X + 1, pos.Y,
+                                     (float)llGround(
+                                                 new LSL_Types.Vector3(pos.X + 1, pos.Y, pos.Z)
+                                                 ));
+            Vector3 p2 = new Vector3(pos.X, pos.Y + 1,
+                                     (float)llGround(
+                                                 new LSL_Types.Vector3(pos.X, pos.Y + 1, pos.Z)
+                                                 ));
+
+            Vector3 v0 = new Vector3(
+                p1.X - p0.X, p1.Y - p0.Y, p1.Z - p0.Z);
+            Vector3 v1 = new Vector3(
+                p2.X - p1.X, p2.Y - p1.Y, p2.Z - p1.Z);
+
+            v0.Normalize();
+            v1.Normalize();
+
+            Vector3 tv = new Vector3();
+            tv.X = (v0.Y * v1.Z) - (v0.Z * v1.Y);
+            tv.Y = (v0.Z * v1.X) - (v0.X * v1.Z);
+            tv.Z = (v0.X * v1.Y) - (v0.Y * v1.X);
+
+            return new LSL_Types.Vector3(tv.X, tv.Y, tv.Z);
         }
 
         public LSL_Types.Vector3 llGroundNormal(LSL_Types.Vector3 offset)
         {
             m_host.AddScriptLPS(1);
-            NotImplemented("llGroundNormal");
-            return new LSL_Types.Vector3();
+            LSL_Types.Vector3 x = llGroundSlope(offset);
+            return new LSL_Types.Vector3(x.x, x.y, 1.0);
         }
 
         public LSL_Types.Vector3 llGroundContour(LSL_Types.Vector3 offset)
         {
             m_host.AddScriptLPS(1);
-            NotImplemented("llGroundContour");
-            return new LSL_Types.Vector3();
+            LSL_Types.Vector3 x = llGroundSlope(offset);
+            return new LSL_Types.Vector3(-x.y, x.x, 0.0);
         }
 
         public LSL_Types.LSLInteger llGetAttached()