diff --git a/TODO b/TODO
index 5497c48..a7fe1b8 100644
--- a/TODO
+++ b/TODO
@@ -1,7 +1,6 @@
 Technology Preview 2 :
 - Fully move layer management from BaseForm to BaseFormLayer.
 - Replace math.h methods by optimized ones (fastfloor, fastsin...).
-- Reimplement perlin noise and custom noise.
 - Replace terrain canvas editor by full sculpting editor.
    => Add a generation dialog, with fixed resolution.
    => Store local terrain modifications in fully dynamic canvas.
diff --git a/gui_qt/dialognoise.cpp b/gui_qt/dialognoise.cpp
index ccef198..6b47782 100644
--- a/gui_qt/dialognoise.cpp
+++ b/gui_qt/dialognoise.cpp
@@ -9,6 +9,7 @@
 #include <QScrollArea>
 #include <QPushButton>
 #include <math.h>
+#include <qt4/QtGui/qwidget.h>
 
 /**************** Previews ****************/
 class PreviewLevel:public BasePreview
@@ -124,13 +125,14 @@ DialogNoise::DialogNoise(QWidget *parent, NoiseGenerator* value):
     
     function->layout()->addWidget(new QLabel(tr("Noise function")));
     function_algo = new QComboBox(function);
-    function_algo->addItems(QStringList(tr("Simplex")) << tr("Perlin") << tr("Naive"));
+    function_algo->addItems(QStringList(tr("Simplex (best)")) << tr("Perlin (fast)") << tr("Naive (slow)"));
     function->layout()->addWidget(function_algo);
     function->layout()->addWidget(new QLabel(tr("Ridge factor")));
     function_ridge = new QSlider(Qt::Horizontal, function);
     function_ridge->setRange(-10, 10);
     function_ridge->setTickInterval(10);
     function_ridge->setTickPosition(QSlider::TicksBelow);
+    function_ridge->setMinimumWidth(150);
     function->layout()->addWidget(function_ridge);
     QObject::connect(function_algo, SIGNAL(currentIndexChanged(int)), this, SLOT(functionChanged()));
     QObject::connect(function_ridge, SIGNAL(valueChanged(int)), this, SLOT(functionChanged()));
diff --git a/lib_paysages/noise.c b/lib_paysages/noise.c
index ad9cc87..9ab950a 100644
--- a/lib_paysages/noise.c
+++ b/lib_paysages/noise.c
@@ -361,6 +361,18 @@ void noiseNormalizeHeight(NoiseGenerator* generator, double min_height, double m
 static inline double _applyRidge(double value, double ridge)
 {
     if (ridge > 0.0)
+    {
+        return fabs(value + 0.5 - ridge) / (1.0 - ridge) - 0.5;
+    }
+    else if (ridge < 0.0)
+    {
+        return -fabs(value - 0.5 - ridge) / (1.0 + ridge) + 0.5;
+    }
+    else
+    {
+        return value;
+    }
+    /*if (ridge > 0.0)
     {
         return fabs(value + 0.5 - ridge) - 0.5 + ridge;
     }
@@ -371,7 +383,7 @@ static inline double _applyRidge(double value, double ridge)
     else
     {
         return value;
-    }
+    }*/
 }
 
 
@@ -379,7 +391,7 @@ static inline double _applyRidge(double value, double ridge)
 
 static inline double _get1DLevelValue(NoiseGenerator* generator, NoiseLevel* level, double x)
 {
-    return _applyRidge(generator->_func_noise_1d(x / level->scaling + level->xoffset) * level->height, generator->function.ridge_factor);
+    return _applyRidge(generator->_func_noise_1d(x / level->scaling + level->xoffset), generator->function.ridge_factor) * level->height;
 }
 
 double noiseGet1DLevel(NoiseGenerator* generator, int level, double x)
@@ -436,7 +448,7 @@ double noiseGet1DDetail(NoiseGenerator* generator, double x, double detail)
 
 static inline double _get2DLevelValue(NoiseGenerator* generator, NoiseLevel* level, double x, double y)
 {
-    return _applyRidge(generator->_func_noise_2d(x / level->scaling + level->xoffset, y / level->scaling + level->yoffset) * level->height, generator->function.ridge_factor);
+    return _applyRidge(generator->_func_noise_2d(x / level->scaling + level->xoffset, y / level->scaling + level->yoffset), generator->function.ridge_factor) * level->height;
 }
 
 double noiseGet2DLevel(NoiseGenerator* generator, int level, double x, double y)
@@ -493,7 +505,7 @@ double noiseGet2DDetail(NoiseGenerator* generator, double x, double y, double de
 
 static inline double _get3DLevelValue(NoiseGenerator* generator, NoiseLevel* level, double x, double y, double z)
 {
-    return _applyRidge(generator->_func_noise_3d(x / level->scaling + level->xoffset, y / level->scaling + level->yoffset, z / level->scaling + level->zoffset) * level->height, generator->function.ridge_factor);
+    return _applyRidge(generator->_func_noise_3d(x / level->scaling + level->xoffset, y / level->scaling + level->yoffset, z / level->scaling + level->zoffset), generator->function.ridge_factor) * level->height;
 }
 
 double noiseGet3DLevel(NoiseGenerator* generator, int level, double x, double y, double z)