diff --git a/gui_qt/dialogheightmap.cpp b/gui_qt/dialogheightmap.cpp
index 88f40ff..e69ee7a 100644
--- a/gui_qt/dialogheightmap.cpp
+++ b/gui_qt/dialogheightmap.cpp
@@ -88,6 +88,15 @@ DialogHeightMap::DialogHeightMap(QWidget* parent, HeightMap* heightmap) : Dialog
     slider->setRange(0, 1000);
     connect(slider, SIGNAL(valueChanged(int)), this, SLOT(brushSmoothingChanged(int)));
     panel->layout()->addWidget(slider);
+    slider->setValue(600);
+    
+    label = new QLabel(tr("Brush strength"), panel);
+    panel->layout()->addWidget(label);
+    
+    slider = new QSlider(Qt::Horizontal, panel);
+    slider->setRange(0, 1000);
+    connect(slider, SIGNAL(valueChanged(int)), this, SLOT(brushStrengthChanged(int)));
+    panel->layout()->addWidget(slider);
     slider->setValue(200);
     
     // Buttons layout
@@ -120,11 +129,14 @@ bool DialogHeightMap::editHeightMap(QWidget* parent, HeightMap* heightmap)
 
 void DialogHeightMap::accept()
 {
+    heightmapCopy(&_value_modified, _value_original);
     QDialog::accept();
 }
 
 void DialogHeightMap::revert()
 {
+    heightmapCopy(_value_original, &_value_modified);
+    _3dview->revert();
 }
 
 void DialogHeightMap::angleHChanged(int value)
@@ -151,3 +163,8 @@ void DialogHeightMap::brushSmoothingChanged(int value)
 {
     _3dview->setBrushSmoothing((double)value / 1000.0);
 }
+
+void DialogHeightMap::brushStrengthChanged(int value)
+{
+    _3dview->setBrushStrength((double)value / 2000.0);
+}
diff --git a/gui_qt/dialogheightmap.h b/gui_qt/dialogheightmap.h
index 099d5f5..b87ac34 100644
--- a/gui_qt/dialogheightmap.h
+++ b/gui_qt/dialogheightmap.h
@@ -22,6 +22,7 @@ private slots:
     void brushModeChanged(int value);
     void brushSizeChanged(int value);
     void brushSmoothingChanged(int value);
+    void brushStrengthChanged(int value);
 
 private:
     HeightMap* _value_original;
diff --git a/gui_qt/widgetheightmap.cpp b/gui_qt/widgetheightmap.cpp
index 1aa9cbb..0737b98 100644
--- a/gui_qt/widgetheightmap.cpp
+++ b/gui_qt/widgetheightmap.cpp
@@ -14,6 +14,8 @@ WidgetHeightMap::WidgetHeightMap(QWidget *parent, HeightMap* heightmap):
     setMinimumSize(500, 500);
     setFocusPolicy(Qt::StrongFocus);
     setMouseTracking(true);
+    setCursor(Qt::CrossCursor);
+    startTimer(100);
 
     _heightmap = heightmap;
     _vertexes = new _VertexInfo[heightmap->resolution_x * heightmap->resolution_z];
@@ -22,6 +24,7 @@ WidgetHeightMap::WidgetHeightMap(QWidget *parent, HeightMap* heightmap):
     
     _average_frame_time = 0.0;
     
+    _last_brush_action = 0;
     _last_mouse_x = 0;
     _last_mouse_y = 0;
     
@@ -33,6 +36,7 @@ WidgetHeightMap::WidgetHeightMap(QWidget *parent, HeightMap* heightmap):
     _brush_mode = HEIGHTMAP_BRUSH_RAISE;
     _brush_size = 10.0;
     _brush_smoothing = 0.5;
+    _brush_strength = 1.0;
 }
 
 WidgetHeightMap::~WidgetHeightMap()
@@ -55,6 +59,9 @@ void WidgetHeightMap::setVerticalViewAngle(double angle_v)
 void WidgetHeightMap::setBrushMode(HeightMapBrushMode mode)
 {
     _brush_mode = mode;
+    _brush_x = 0.0;
+    _brush_z = 0.0;
+    updateGL();
 }
 
 void WidgetHeightMap::setBrushSize(double size)
@@ -73,6 +80,20 @@ void WidgetHeightMap::setBrushSmoothing(double smoothing)
     updateGL();
 }
 
+void WidgetHeightMap::setBrushStrength(double strength)
+{
+    _brush_strength = strength;
+    _brush_x = 0.0;
+    _brush_z = 0.0;
+    updateGL();
+}
+
+void WidgetHeightMap::revert()
+{
+    _dirty = true;
+    updateGL();
+}
+
 void WidgetHeightMap::resetToTerrain()
 {
     TerrainDefinition terrain;
@@ -92,83 +113,69 @@ void WidgetHeightMap::resetToTerrain()
     }
 
     terrainDeleteDefinition(&terrain);
-    _dirty = true;
-    updateGL();
-}
-
-void WidgetHeightMap::keyPressEvent(QKeyEvent* event)
-{
+    revert();
 }
 
 void WidgetHeightMap::mousePressEvent(QMouseEvent* event)
 {
-    mouseMoveEvent(event);
+    _last_mouse_x = event->x();
+    _last_mouse_y = event->y();
+    if (event->buttons() & Qt::LeftButton)
+    {
+        _last_brush_action = 1;
+    }
+    else if (event->buttons() & Qt::RightButton)
+    {
+        _last_brush_action = -1;
+    }
+}
+
+void WidgetHeightMap::mouseReleaseEvent(QMouseEvent* event)
+{
+    _last_brush_action = 0;
 }
 
 void WidgetHeightMap::mouseMoveEvent(QMouseEvent* event)
 {
-    int move_x = event->x() - _last_mouse_x;
-    int move_y = event->y() - _last_mouse_y;
+    if (event->buttons() & Qt::MiddleButton)
+    {
+        // Rotate around the turntable
+        int move_x = event->x() - _last_mouse_x;
+        int move_y = event->y() - _last_mouse_y;
+        
+        _angle_h -= (double)move_x * 0.008;
+        _angle_v += (double)move_y * 0.003;
+    }
     
-    if ((event->buttons() & Qt::LeftButton) || (event->buttons() & Qt::RightButton))
+    _last_mouse_x = event->x();
+    _last_mouse_y = event->y();
+
+    updateGL();
+}
+
+void WidgetHeightMap::timerEvent(QTimerEvent* event)
+{
+    if (_last_brush_action)
     {
         HeightMapBrush brush;
 
         brush.relative_x = (_brush_x + 40.0) / 80.0;
         brush.relative_z = (_brush_z + 40.0) / 80.0;
-        brush.hard_radius = _brush_size / 80.0 - _brush_smoothing;
-        brush.smoothed_size = (_brush_size / 80.0) * _brush_smoothing;
+        brush.hard_radius = _brush_size * (1.0 - _brush_smoothing) / 80.0;
+        brush.smoothed_size = _brush_size * _brush_smoothing / 80.0;
         
         switch (_brush_mode)
         {
             case HEIGHTMAP_BRUSH_RAISE:
-                heightmapBrushElevation(_heightmap, &brush, (event->buttons() & Qt::RightButton) ? -0.01 : 0.01);
-                _dirty = true;
-                updateGL();
+                heightmapBrushElevation(_heightmap, &brush, _brush_strength * _last_brush_action);
                 break;
             default:
-                ;
+                return;
         }
-    }
-    else if (event->buttons() & Qt::MiddleButton)
-    {
-        // Rotate around the turntable
-        _angle_h -= (double)move_x * 0.008;
-        _angle_v += (double)move_y * 0.003;
         
+        _dirty = true;
         updateGL();
     }
-    else
-    {
-        // OpenGL picking using z-buffer
-        GLint viewport[4];
-        GLdouble modelview[16];
-        GLdouble projection[16];
-        GLfloat winX, winY, winZ;
-        Vector3 point;
-
-        glGetDoublev(GL_MODELVIEW_MATRIX, modelview);
-        glGetDoublev(GL_PROJECTION_MATRIX, projection);
-        glGetIntegerv(GL_VIEWPORT, viewport);
-
-        winX = (float)event->x();
-        winY = (float)height() - (float)event->y();
-        glReadPixels(event->x(), (int)winY, 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &winZ);
-
-        gluUnProject(winX, winY, winZ, modelview, projection, viewport, &point.x, &point.y, &point.z);
-
-        _brush_x = point.x;
-        _brush_z = point.z;
-
-        updateGL();
-    }
-    
-    _last_mouse_x = event->x();
-    _last_mouse_y = event->y();
-}
-
-void WidgetHeightMap::wheelEvent(QWheelEvent* event)
-{
 }
 
 void WidgetHeightMap::initializeGL()
@@ -230,6 +237,26 @@ void WidgetHeightMap::paintGL()
         _dirty = false;
     }
     
+    // Picking mouse position using z-buffer (for brush)
+    GLint viewport[4];
+    GLdouble modelview[16];
+    GLdouble projection[16];
+    GLfloat winX, winY, winZ;
+    Vector3 point;
+
+    glGetDoublev(GL_MODELVIEW_MATRIX, modelview);
+    glGetDoublev(GL_PROJECTION_MATRIX, projection);
+    glGetIntegerv(GL_VIEWPORT, viewport);
+
+    winX = (float)_last_mouse_x;
+    winY = (float)height() - (float)_last_mouse_y;
+    glReadPixels(_last_mouse_x, (int)winY, 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &winZ);
+
+    gluUnProject(winX, winY, winZ, modelview, projection, viewport, &point.x, &point.y, &point.z);
+
+    _brush_x = point.x;
+    _brush_z = point.z;
+    
     // Place camera
     glMatrixMode(GL_MODELVIEW);
     glLoadIdentity();
diff --git a/gui_qt/widgetheightmap.h b/gui_qt/widgetheightmap.h
index e3d0f8e..3bddf33 100644
--- a/gui_qt/widgetheightmap.h
+++ b/gui_qt/widgetheightmap.h
@@ -29,15 +29,18 @@ public:
     void setBrushMode(HeightMapBrushMode mode);
     void setBrushSize(double size);
     void setBrushSmoothing(double smoothing);
+    void setBrushStrength(double smoothing);
     
 public slots:
+    void revert();
     void resetToTerrain();
 
 protected:
-    void keyPressEvent(QKeyEvent* event);
     void mousePressEvent(QMouseEvent* event);
+    void mouseReleaseEvent(QMouseEvent* event);
     void mouseMoveEvent(QMouseEvent* event);
-    void wheelEvent(QWheelEvent* event);
+    
+    void timerEvent(QTimerEvent* event);
 
     void initializeGL();
     void resizeGL(int w, int h);
@@ -54,6 +57,7 @@ private:
     
     double _average_frame_time;
     
+    int _last_brush_action;
     int _last_mouse_x;
     int _last_mouse_y;
     
@@ -65,6 +69,7 @@ private:
     HeightMapBrushMode _brush_mode;
     double _brush_size;
     double _brush_smoothing;
+    double _brush_strength;
 };
 
 #endif
diff --git a/lib_paysages/heightmap.c b/lib_paysages/heightmap.c
index 7371da6..24bd555 100644
--- a/lib_paysages/heightmap.c
+++ b/lib_paysages/heightmap.c
@@ -50,6 +50,7 @@ void heightmapLoad(PackStream* stream, HeightMap* heightmap)
     
     packReadInt(stream, &heightmap->resolution_x);
     packReadInt(stream, &heightmap->resolution_z);
+    heightmap->data = realloc(heightmap->data, sizeof(double) * heightmap->resolution_x * heightmap->resolution_z);
     for (i = 0; i < heightmap->resolution_x * heightmap->resolution_z; i++)
     {
         packReadDouble(stream, &heightmap->data[i]);
@@ -70,6 +71,12 @@ void heightmapChangeResolution(HeightMap* heightmap, int resolution_x, int resol
     }
 }
 
+double heightmapGetValue(HeightMap* heightmap, double x, double z)
+{
+    // TODO Bicubic interpolation
+    return heightmap->data[lround(z * (heightmap->resolution_z - 1)) * heightmap->resolution_x + lround(x * (heightmap->resolution_x - 1))];
+}
+
 void heightmapBrushElevation(HeightMap* heightmap, HeightMapBrush* brush, double value)
 {
     int x, z;
@@ -89,7 +96,7 @@ void heightmapBrushElevation(HeightMap* heightmap, HeightMapBrush* brush, double
             {
                 if (distance <= brush->hard_radius + brush->smoothed_size)
                 {
-                    heightmap->data[z * heightmap->resolution_x +x] += value * (distance - brush->hard_radius) / brush->smoothed_size;
+                    heightmap->data[z * heightmap->resolution_x +x] += value * (1.0 - (distance - brush->hard_radius) / brush->smoothed_size);
                 }
             }
             else
diff --git a/lib_paysages/heightmap.h b/lib_paysages/heightmap.h
index 0ef3d77..e2cb222 100644
--- a/lib_paysages/heightmap.h
+++ b/lib_paysages/heightmap.h
@@ -33,6 +33,7 @@ void heightmapSave(PackStream* stream, HeightMap* heightmap);
 void heightmapLoad(PackStream* stream, HeightMap* heightmap);
 
 void heightmapChangeResolution(HeightMap* heightmap, int resolution_x, int resolution_z);
+double heightmapGetValue(HeightMap* heightmap, double x, double z);
 
 void heightmapBrushElevation(HeightMap* heightmap, HeightMapBrush* brush, double value);
     
diff --git a/lib_paysages/terrain.c b/lib_paysages/terrain.c
index db169c4..5485a83 100644
--- a/lib_paysages/terrain.c
+++ b/lib_paysages/terrain.c
@@ -19,7 +19,7 @@ void terrainSave(PackStream* stream, TerrainDefinition* definition)
     noiseSaveGenerator(stream, definition->height_noise);
     packWriteDouble(stream, &definition->height_factor);
     packWriteDouble(stream, &definition->scaling);
-    layersSave(stream, &definition->canvases);
+    layersSave(stream, definition->canvases);
     packWriteDouble(stream, &definition->shadow_smoothing);
 }
 
@@ -28,7 +28,7 @@ void terrainLoad(PackStream* stream, TerrainDefinition* definition)
     noiseLoadGenerator(stream, definition->height_noise);
     packReadDouble(stream, &definition->height_factor);
     packReadDouble(stream, &definition->scaling);
-    layersLoad(stream, &definition->canvases);
+    layersLoad(stream, definition->canvases);
     packReadDouble(stream, &definition->shadow_smoothing);
 
     terrainValidateDefinition(definition);
@@ -81,28 +81,44 @@ void terrainValidateDefinition(TerrainDefinition* definition)
 
 static inline double _getHeight(TerrainDefinition* definition, double x, double z)
 {
+    TerrainCanvas* canvas;
     Vector3 location;
-    int i;
+    int i, n;
 
     location.x = x;
     location.y = noiseGet2DTotal(definition->height_noise, x / definition->scaling, z / definition->scaling) * definition->height_factor;
     location.z = z;
+    
+    n = layersCount(definition->canvases);
+    for (i = 0; i < n; i++)
+    {
+        canvas = layersGetLayer(definition->canvases, i);
+        location = terrainCanvasApply(canvas, location);
+    }
 
-    /* TODO Apply canvases and modifiers */
+    /* TODO Apply modifiers */
 
     return location.y;
 }
 
 static inline double _getHeightDetail(TerrainDefinition* definition, double x, double z, double detail)
 {
+    TerrainCanvas* canvas;
     Vector3 location;
-    int i;
+    int i, n;
 
     location.x = x;
     location.y = noiseGet2DDetail(definition->height_noise, x / definition->scaling, z / definition->scaling, detail / definition->height_factor) * definition->height_factor;
     location.z = z;
 
-    /* TODO Apply canvases and modifiers */
+    n = layersCount(definition->canvases);
+    for (i = 0; i < n; i++)
+    {
+        canvas = layersGetLayer(definition->canvases, i);
+        location = terrainCanvasApply(canvas, location);
+    }
+
+    /* TODO Apply modifiers */
 
     return location.y;
 }
diff --git a/lib_paysages/terraincanvas.c b/lib_paysages/terraincanvas.c
index 708894e..47f5528 100644
--- a/lib_paysages/terraincanvas.c
+++ b/lib_paysages/terraincanvas.c
@@ -8,10 +8,10 @@ TerrainCanvas* terrainCanvasCreate()
     TerrainCanvas* result = malloc(sizeof(TerrainCanvas));
     
     result->area.bounded = 1;
-    result->area.location_x = 0.0;
-    result->area.location_z = 0.0;
-    result->area.size_x = 1.0;
-    result->area.size_z = 1.0;
+    result->area.location_x = -40.0;
+    result->area.location_z = -40.0;
+    result->area.size_x = 80.0;
+    result->area.size_z = 80.0;
     result->offset_z = 0.0;
     result->height_map = heightmapCreate();
     heightmapChangeResolution(&result->height_map, 256, 256);
@@ -107,6 +107,14 @@ void terrainCanvasRevertToTerrain(TerrainCanvas* canvas, TerrainDefinition* terr
 {
 }
 
-Vector3 terrainCanvasApply(TerrainCanvas* canvas, Vector3 position)
+Vector3 terrainCanvasApply(TerrainCanvas* canvas, Vector3 location)
 {
+    if (location.x >= canvas->area.location_x &&
+        location.z >= canvas->area.location_z &&
+        location.x <= canvas->area.location_x + canvas->area.size_x &&
+        location.z <= canvas->area.location_z + canvas->area.size_z)
+    {
+        location.y = heightmapGetValue(&canvas->height_map, (location.x - canvas->area.location_x) / canvas->area.size_x, (location.z - canvas->area.location_z) / canvas->area.size_z);
+    }
+    return location;
 }
diff --git a/lib_paysages/terraincanvas.h b/lib_paysages/terraincanvas.h
index 273b70a..8435827 100644
--- a/lib_paysages/terraincanvas.h
+++ b/lib_paysages/terraincanvas.h
@@ -48,7 +48,7 @@ void terrainCanvasSave(PackStream* stream, TerrainCanvas* canvas);
 void terrainCanvasLoad(PackStream* stream, TerrainCanvas* canvas);
 
 void terrainCanvasRevertToTerrain(TerrainCanvas* canvas, TerrainDefinition* terrain, int only_masked);
-Vector3 terrainCanvasApply(TerrainCanvas* canvas, Vector3 position);
+Vector3 terrainCanvasApply(TerrainCanvas* canvas, Vector3 location);
     
 #ifdef __cplusplus
 }