diff --git a/gui_qt/formterraincanvas.cpp b/gui_qt/formterraincanvas.cpp
index 757a6d2..b90e620 100644
--- a/gui_qt/formterraincanvas.cpp
+++ b/gui_qt/formterraincanvas.cpp
@@ -11,8 +11,8 @@ public:
         
         //addOsd(QString("geolocation"));
         
-        configScaling(0.5, 200.0, 3.0, 50.0);
-        configScrolling(-1000.0, 1000.0, 0.0, -1000.0, 1000.0, 0.0);
+        configScaling(1.0, 1.0, 1.0, 1.0);
+        //configScrolling(-1000.0, 1000.0, 0.0, -1000.0, 1000.0, 0.0);
     }
     
     ~PreviewTerrainCanvasHeight()
@@ -22,18 +22,37 @@ public:
 protected:
     QColor getColor(double x, double y)
     {
+        Color col, mask;
         double height;
 
-        height = 0.0; // TODO
-        return QColor((int)(255.0 * height), (int)(255.0 * height), (int)(255.0 * height));
+        if (_max - _min < 0.000001)
+        {
+            return Qt::black;
+        }
+        else
+        {
+            height = heightmapGetValue(&_preview_canvas->height_map, x + 0.5, y + 0.5);
+            col.r = col.g = col.b = (height - _min) / (_max - _min);
+            col.a = 1.0;
+            
+            mask.r = 0.3;
+            mask.g = 0.0;
+            mask.b = 0.0;
+            mask.a = 1.0 - terrainCanvasGetMaskValue(_preview_canvas, x + 0.5, y + 0.5);
+            colorMask(&col, &mask);
+            
+            return colorToQColor(col);
+        }
     }
     void updateData()
     {
         terrainCanvasCopy(_base_canvas, _preview_canvas);
+        heightmapGetLimits(&_preview_canvas->height_map, &_min, &_max);
     }
 private:
     TerrainCanvas* _base_canvas;
     TerrainCanvas* _preview_canvas;
+    double _max, _min;
 };
 
 /**************** Form ****************/
diff --git a/lib_paysages/terraincanvas.c b/lib_paysages/terraincanvas.c
index 3bb0aaa..2bf4595 100644
--- a/lib_paysages/terraincanvas.c
+++ b/lib_paysages/terraincanvas.c
@@ -126,8 +126,7 @@ Vector3 terrainCanvasApply(TerrainCanvas* canvas, Vector3 location)
         double height, distance;
         
         /* Get height map displacement */
-        inside_x = (location.x - canvas->area.location_x) / canvas->area.size_x;
-        inside_z = (location.z - canvas->area.location_z) / canvas->area.size_z;
+        geoareaToLocal(&canvas->area, location.x, location.z, &inside_x, &inside_z);
         height = heightmapGetValue(&canvas->height_map, inside_x, inside_z);
         
         /* Apply factor */
@@ -137,28 +136,41 @@ Vector3 terrainCanvasApply(TerrainCanvas* canvas, Vector3 location)
         height += noiseGet2DTotal(canvas->detail_noise, location.x / canvas->detail_scaling, location.z / canvas->detail_scaling) * canvas->detail_height_factor;
         
         /* Apply integration mask */
-        inside_x = (inside_x - 0.5) * 2.0;
-        inside_z = (inside_z - 0.5) * 2.0;
-        if (canvas->mask.mode == INTEGRATIONMASK_MODE_SQUARE)
-        {
-            inside_x = fabs(inside_x);
-            inside_z = fabs(inside_z);
-            distance = inside_x > inside_z ? inside_x : inside_z;
-        }
-        else
-        {
-            distance = sqrt(inside_x * inside_x + inside_z * inside_z);
-        }
-        if (distance <= 1.0 - canvas->mask.smoothing)
-        {
-            location.y = height;
-        }
-        else if (distance <= 1.0)
-        {
-            double influence = (1.0 - distance) / canvas->mask.smoothing;
-            location.y = influence * height + (1.0 - influence) * location.y;
-        }
+        double influence = terrainCanvasGetMaskValue(canvas, inside_x, inside_z);
+        location.y = influence * height + (1.0 - influence) * location.y;
         
     }
     return location;
 }
+
+double terrainCanvasGetMaskValue(TerrainCanvas* canvas, double local_x, double local_z)
+{
+    double distance;
+    
+    local_x = (local_x - 0.5) * 2.0;
+    local_z = (local_z - 0.5) * 2.0;
+    
+    if (canvas->mask.mode == INTEGRATIONMASK_MODE_SQUARE)
+    {
+        local_x = fabs(local_x);
+        local_z = fabs(local_z);
+        distance = local_x > local_z ? local_x : local_z;
+    }
+    else
+    {
+        distance = sqrt(local_x * local_x + local_z * local_z);
+    }
+    
+    if (distance <= 1.0 - canvas->mask.smoothing)
+    {
+        return 1.0;
+    }
+    else if (distance <= 1.0)
+    {
+        return (1.0 - distance) / canvas->mask.smoothing;
+    }
+    else
+    {
+        return 0.0;
+    }
+}
diff --git a/lib_paysages/terraincanvas.h b/lib_paysages/terraincanvas.h
index e61c8d2..45488ac 100644
--- a/lib_paysages/terraincanvas.h
+++ b/lib_paysages/terraincanvas.h
@@ -47,6 +47,7 @@ void terrainCanvasLoad(PackStream* stream, TerrainCanvas* canvas);
 void terrainCanvasGetLimits(TerrainCanvas* canvas, double* ymin, double* ymax);
 void terrainCanvasRevertToTerrain(TerrainCanvas* canvas);
 Vector3 terrainCanvasApply(TerrainCanvas* canvas, Vector3 location);
+double terrainCanvasGetMaskValue(TerrainCanvas* canvas, double local_x, double local_z);
     
 #ifdef __cplusplus
 }