diff --git a/VirtualRobot/MathTools.cpp b/VirtualRobot/MathTools.cpp
index d6d376abc506efd8b4fb3d3c79c9c6e18e596368..37e672dcc397d74e016532f07bc26faf4b5a8ef4 100644
--- a/VirtualRobot/MathTools.cpp
+++ b/VirtualRobot/MathTools.cpp
@@ -313,7 +313,7 @@ MathTools::ConvexHull2DPtr MathTools::createConvexHull2D( std::vector< Eigen::Ve
 	int n = (int)P.size();
 	THROW_VR_EXCEPTION_IF(n<3,"Could not generate convex hull with " << n << " points...");
 	std::vector< Eigen::Vector2f > H;
-	H.resize(n);
+	H.resize(n*2);
 
 	// the output array H[] will be used as the stack
 	int    bot=0, top=(-1);  // indices for bottom and top of the stack
diff --git a/VirtualRobot/Visualization/CoinVisualization/CoinVisualizationFactory.cpp b/VirtualRobot/Visualization/CoinVisualization/CoinVisualizationFactory.cpp
index 5fdd96e3798d2752048db9dd1046fbb0e72f35af..c84fd39f94016790a5baca1e2171d261bed63e32 100644
--- a/VirtualRobot/Visualization/CoinVisualization/CoinVisualizationFactory.cpp
+++ b/VirtualRobot/Visualization/CoinVisualization/CoinVisualizationFactory.cpp
@@ -746,13 +746,14 @@ namespace VirtualRobot {
         u->units = SoUnits::MILLIMETERS;
         visu->addChild(u);
 
-
-        SoMaterial *m = new SoMaterial;
-        m->diffuseColor.setValue(colorInner.r, colorInner.g, colorInner.b);
-        m->ambientColor.setValue(colorInner.r, colorInner.g, colorInner.b);
-        m->transparency.setValue(colorInner.transparency);
-        visu->addChild(m);
-
+		if (!colorInner.isNone())
+		{
+			SoMaterial *m = new SoMaterial;
+			m->diffuseColor.setValue(colorInner.r, colorInner.g, colorInner.b);
+			m->ambientColor.setValue(colorInner.r, colorInner.g, colorInner.b);
+			m->transparency.setValue(colorInner.transparency);
+			visu->addChild(m);
+		}
 
         SoCoordinate3* coordinate3 = new SoCoordinate3;
         SoCoordinate3* coordinate3b = new SoCoordinate3;