diff --git a/TODO b/TODO
index ec86dfd..434c9f2 100644
--- a/TODO
+++ b/TODO
@@ -10,7 +10,7 @@ Technology Preview 2 :
    => Apply model to atmosphere (aerial perspective)
    => Find a proper model for night sky (maybe Shirley)
 - Clouds should keep distance to ground.
-- Implement Bruneton's scattering model.
+- Add fresnel effect to specular lighting.
 - Add clouds to explorer with 3d textures.
 - Start using OpenCL to optimize rendering.
 - Rethink the quality settings and detail smoothing in the distance.
diff --git a/gui_qt/widgetheightmap.cpp b/gui_qt/widgetheightmap.cpp
index 0e11201..50f1e17 100644
--- a/gui_qt/widgetheightmap.cpp
+++ b/gui_qt/widgetheightmap.cpp
@@ -116,7 +116,7 @@ void WidgetHeightMap::mousePressEvent(QMouseEvent* event)
     }
 }
 
-void WidgetHeightMap::mouseReleaseEvent(QMouseEvent* event)
+void WidgetHeightMap::mouseReleaseEvent(QMouseEvent*)
 {
     _last_brush_action = 0;
 }
@@ -365,7 +365,7 @@ void WidgetHeightMap::updateVertexInfo()
 
             vertex->point.x = 80.0 * (double)x / (double)(rx - 1) - 40.0;
             vertex->point.z = 80.0 * (double)z / (double)(rz - 1) - 40.0;
-            
+
             vertex->point.y = _renderer.terrain->getHeight(&_renderer, vertex->point.x, vertex->point.z);
         }
     }
diff --git a/lib_paysages/atmosphere/bruneton.c b/lib_paysages/atmosphere/bruneton.c
index 824730d..885992d 100644
--- a/lib_paysages/atmosphere/bruneton.c
+++ b/lib_paysages/atmosphere/bruneton.c
@@ -613,9 +613,9 @@ static Color _inscatterS(double r, double mu, double muS, double nu, int first,
                 double pm1 = _phaseFunctionM(nu1);
                 Color ray1 = _texture4D(deltaSR, r, w.z, muS, nu1);
                 Color mie1 = _texture4D(deltaSM, r, w.z, muS, nu1);
-                raymie1.r += ray1.r * pr1 + mie1.r + pm1;
-                raymie1.g += ray1.g * pr1 + mie1.g + pm1;
-                raymie1.b += ray1.b * pr1 + mie1.b + pm1;
+                raymie1.r += ray1.r * pr1 + mie1.r * pm1;
+                raymie1.g += ray1.g * pr1 + mie1.g * pm1;
+                raymie1.b += ray1.b * pr1 + mie1.b * pm1;
             }
             else
             {
@@ -949,9 +949,9 @@ static Color _groundColor(Color base, Vector3 x, double t, Vector3 v, Vector3 s,
 
     /* light reflected at x0 (=(R[L0]+R[L*])/T(x,x0)) */
     Color groundColor;
-    groundColor.r = base.r * (max(muS, 0.0) * sunLight.r + groundSkyLight.r) * ISun / M_PI;
-    groundColor.g = base.g * (max(muS, 0.0) * sunLight.g + groundSkyLight.g) * ISun / M_PI;
-    groundColor.b = base.b * (max(muS, 0.0) * sunLight.b + groundSkyLight.b) * ISun / M_PI;
+    groundColor.r = base.r * 0.2 * (max(muS, 0.0) * sunLight.r + groundSkyLight.r) * ISun / M_PI;
+    groundColor.g = base.g * 0.2 * (max(muS, 0.0) * sunLight.g + groundSkyLight.g) * ISun / M_PI;
+    groundColor.b = base.b * 0.2 * (max(muS, 0.0) * sunLight.b + groundSkyLight.b) * ISun / M_PI;
 
     /* water specular color due to sunLight */
     /*if (reflectance.w > 0.0)
diff --git a/lib_paysages/atmosphere/preview.c b/lib_paysages/atmosphere/preview.c
index 89f9502..1b09359 100644
--- a/lib_paysages/atmosphere/preview.c
+++ b/lib_paysages/atmosphere/preview.c
@@ -120,7 +120,7 @@ static inline int _checkHit(Vector3 eye, Vector3 direction, Vector3* hit, Vector
 
 Color atmosphereGetPreview(Renderer* renderer, double x, double y, double heading)
 {
-    Vector3 eye = {0.0, 8.0, 0.0};
+    Vector3 eye = {0.0, 7.0, 0.0};
     Vector3 direction = {x, y, -1.0};
     Vector3 hit, normal;
     Matrix4 rotation;
@@ -167,7 +167,7 @@ Renderer atmosphereCreatePreviewRenderer()
     Renderer result = rendererCreate();
 
     result.camera_location.x = 0.0;
-    result.camera_location.y = 8.0;
+    result.camera_location.y = 7.0;
     result.camera_location.z = 0.0;
 
     result.getLightStatus = _getLightStatus;
diff --git a/lib_paysages/lighting.c b/lib_paysages/lighting.c
index 8cdbea0..590c0dd 100644
--- a/lib_paysages/lighting.c
+++ b/lib_paysages/lighting.c
@@ -162,8 +162,6 @@ static Color _applyDirectLight(LightDefinition* definition, Renderer* renderer,
     normal = v3Normalize(normal);
 
     diffuse = v3Dot(direction_inv, normal);
-    /*diffuse = pow(diffuse * 0.5 + 0.5, 2.0);*/
-    diffuse = diffuse * 0.5 + 0.5;
     if (diffuse > 0.0)
     {
         if (material.shininess > 0.0 && definition->reflection > 0.0)
@@ -174,13 +172,12 @@ static Color _applyDirectLight(LightDefinition* definition, Renderer* renderer,
             specular = v3Dot(reflect, view);
             if (specular > 0.0)
             {
-                specular = pow(specular, material.shininess);
+                specular = pow(specular, material.shininess) * material.reflection;
             }
             else
             {
                 specular = 0.0;
             }
-            specular *= material.reflection;
         }
         else
         {
diff --git a/lib_paysages/terrain/painting.c b/lib_paysages/terrain/painting.c
index 975e401..2edd9e0 100644
--- a/lib_paysages/terrain/painting.c
+++ b/lib_paysages/terrain/painting.c
@@ -6,6 +6,7 @@
 
 #include <stdlib.h>
 #include <string.h>
+#include <math.h>
 
 TerrainHeightMap* terrainHeightMapCreate()
 {
@@ -62,7 +63,7 @@ static void _setFixedCount(TerrainHeightMap* heightmap, int new_count)
 
 void terrainHeightmapCopy(TerrainHeightMap* source, TerrainHeightMap* destination)
 {
-    int i, j;
+    int i;
 
     _setFixedCount(destination, source->fixed_count);
 
@@ -126,6 +127,22 @@ void terrainHeightmapLoad(PackStream* stream, TerrainHeightMap* heightmap)
     heightmap->floating_used = 0;
 }
 
+static void _prepareBrushStroke(TerrainHeightMap* heightmap, TerrainBrush* brush)
+{
+    double cx = brush->relative_x / TERRAIN_HEIGHTMAP_DETAIL;
+    double cz = brush->relative_z / TERRAIN_HEIGHTMAP_DETAIL;
+    double s = brush->smoothed_size + brush->hard_radius;
+    double sx = s / TERRAIN_HEIGHTMAP_DETAIL;
+    double sz = s / TERRAIN_HEIGHTMAP_DETAIL;
+
+    int x1 = (int)floor(cx - sx);
+    int x2 = (int)ceil(cx + sx);
+    int z1 = (int)floor(cz - sz);
+    int z2 = (int)ceil(cz + sz);
+
+    /* TODO Prepare floating data */
+}
+
 void terrainBrushElevation(TerrainHeightMap* heightmap, TerrainBrush* brush, double value)
 {
 }
diff --git a/lib_paysages/terrain/private.h b/lib_paysages/terrain/private.h
index 3c54205..2439925 100644
--- a/lib_paysages/terrain/private.h
+++ b/lib_paysages/terrain/private.h
@@ -22,4 +22,10 @@ struct TerrainHeightMap
     TerrainHeightMapData floating_data;
 };
 
+TerrainHeightMap* terrainHeightMapCreate();
+void terrainHeightmapDelete(TerrainHeightMap* heightmap);
+void terrainHeightmapCopy(TerrainHeightMap* source, TerrainHeightMap* destination);
+void terrainHeightmapSave(PackStream* stream, TerrainHeightMap* heightmap);
+void terrainHeightmapLoad(PackStream* stream, TerrainHeightMap* heightmap);
+
 #endif
diff --git a/lib_paysages/terrain/public.h b/lib_paysages/terrain/public.h
index 63c4332..dd9c9a0 100644
--- a/lib_paysages/terrain/public.h
+++ b/lib_paysages/terrain/public.h
@@ -4,7 +4,6 @@
 #include "../shared/types.h"
 #include "../noise.h"
 #include "../lighting.h"
-#include "private.h"
 
 #ifdef __cplusplus
 extern "C" {