diff --git a/src/engine/InterestManagement/Terrain.java b/src/engine/InterestManagement/Terrain.java
index 7ffbcf6b..3e36c68b 100644
--- a/src/engine/InterestManagement/Terrain.java
+++ b/src/engine/InterestManagement/Terrain.java
@@ -39,18 +39,24 @@ public class Terrain {
 
         this.heightmap = this.zone.terrain_image;
 
-        // Configure PLANAR
+        // Configure PLANAR zones to use the same
+        // 16x16 pixel image that all other flat
+        // terrains share.
 
         if (this.zone.terrain_type.equals("PLANAR"))
             this.heightmap = 1006300;
 
-        this.terrain_size.x = this.zone.major_radius * 2;
-        this.terrain_size.y = this.zone.minor_radius * 2;
+        // Load pixel data for this terrain from cache
 
         this.terrain_pixel_data = Terrain._heightmap_pixel_cache.get(heightmap);
 
         if (terrain_pixel_data == null)
-            Logger.error("Pixel map empty for zone: " + zone.getObjectUUID() + ":" + zone.zoneName);
+            Logger.error("Pixel map empty for zone: " + this.zone.getObjectUUID() + ":" + this.zone.zoneName);
+
+        // Configure terrain based on zone properties
+
+        this.terrain_size.x = this.zone.major_radius * 2;
+        this.terrain_size.y = this.zone.minor_radius * 2;
 
         this.cell_count.x = this.terrain_pixel_data.length - 1;
         this.cell_count.y = this.terrain_pixel_data[0].length - 1;
@@ -67,6 +73,10 @@ public class Terrain {
 
     public static Zone getNextZoneWithTerrain(Zone zone) {
 
+        // Not all zones have a terrain.  Some are for display only
+        // and heights returned are from the parent heightmap.  This
+        // is controlled in the JSON via the has_terrain_gen field.
+
         Zone terrain_zone = zone;
 
         if (zone == null)
@@ -88,9 +98,7 @@ public class Terrain {
 
         Zone terrainZone;
 
-        // Retrieve the next zone with a heightmap attached.
-        // Zones without a heightmap use the next zone up the
-        // tree to calculate heights from.
+        // Retrieve the next zone with a terrain defined.
 
         terrainZone = getNextZoneWithTerrain(currentZone);
 
@@ -136,11 +144,10 @@ public class Terrain {
 
             Vector2f terrain_cell = getTerrainCell(terrainLoc);
 
-            int gridX = (int) Math.floor(terrain_cell.x);
-            int gridY = (int) Math.floor(terrain_cell.y);
+            int pixel_x = (int) Math.floor(terrain_cell.x);
+            int pixel_t = (int) Math.floor(terrain_cell.y);
 
-            float offsetX = terrain_cell.x % 1;
-            float offsetY = terrain_cell.y % 1;
+            Vector2f pixel_offset = new Vector2f(terrain_cell.x % 1, terrain_cell.y % 1);
 
             //get 4 surrounding vertices from the pixel array.
 
@@ -149,17 +156,17 @@ public class Terrain {
             float bottomLeftHeight;
             float bottomRightHeight;
 
-            topLeftHeight = terrain_pixel_data[gridX][gridY];
-            topRightHeight = terrain_pixel_data[gridX + 1][gridY];
-            bottomLeftHeight = terrain_pixel_data[gridX][gridY + 1];
-            bottomRightHeight = terrain_pixel_data[gridX + 1][gridY + 1];
+            topLeftHeight = terrain_pixel_data[pixel_x][pixel_t];
+            topRightHeight = terrain_pixel_data[pixel_x + 1][pixel_t];
+            bottomLeftHeight = terrain_pixel_data[pixel_x][pixel_t + 1];
+            bottomRightHeight = terrain_pixel_data[pixel_x + 1][pixel_t + 1];
 
             // Interpolate between the 4 vertices
 
-            interpolatedHeight = topLeftHeight * (1 - offsetX) * (1 - offsetY);
-            interpolatedHeight += topRightHeight * (1 - offsetY) * (offsetX);
-            interpolatedHeight += (bottomLeftHeight * (1 - offsetX) * offsetY);
-            interpolatedHeight += (bottomRightHeight * offsetY * offsetX);
+            interpolatedHeight = topLeftHeight * (1 - pixel_offset.x) * (1 - pixel_offset.y);
+            interpolatedHeight += topRightHeight * (1 - pixel_offset.y) * (pixel_offset.x);
+            interpolatedHeight += (bottomLeftHeight * (1 - pixel_offset.x) * pixel_offset.y);
+            interpolatedHeight += (bottomRightHeight * pixel_offset.y * pixel_offset.x);
 
             interpolatedHeight *= this.terrain_scale; // Scale height