diff --git a/EgtGraphics.rc b/EgtGraphics.rc
index 4db74ec..2d26983 100644
Binary files a/EgtGraphics.rc and b/EgtGraphics.rc differ
diff --git a/SceneBasic.cpp b/SceneBasic.cpp
index 8afbae0..2d0ea6a 100644
--- a/SceneBasic.cpp
+++ b/SceneBasic.cpp
@@ -982,7 +982,7 @@ Scene::GetPixelZ( const Point3d& ptWin, double& dWinZ)
    float dZ ;
    bool bOk = true ;
    glReadPixels( int( ptWin.x), int( Viewport[3] - ptWin.y), 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &dZ) ;
-   if ( glGetError() == GL_NO_ERROR  &&  dZ > 0.001f  &&  dZ < 0.999f)
+   if ( glGetError() == GL_NO_ERROR  &&  dZ > 0.1f  &&  dZ < 0.9f)
       dWinZ = dZ ;
    else {
       bOk = false ;
diff --git a/SceneCamera.cpp b/SceneCamera.cpp
index 21032ca..d7e4b9d 100644
--- a/SceneCamera.cpp
+++ b/SceneCamera.cpp
@@ -541,7 +541,7 @@ Scene::ZoomOnPoint( const Point3d& ptWin, double dCoeff)
       return false ;
 
   // verifico che il punto sia nelle dimensioni del mondo geometrico
-   if ( ! m_b3ExtWorld.Encloses( ptWorld)) {
+   if ( ! m_b3ExtWorld.IsEmpty()  &&  ! m_b3ExtWorld.Encloses( ptWorld)) {
       ptWorld.x = Clamp( ptWorld.x, m_b3ExtWorld.GetMin().x, m_b3ExtWorld.GetMax().x) ;
       ptWorld.y = Clamp( ptWorld.y, m_b3ExtWorld.GetMin().y, m_b3ExtWorld.GetMax().y) ;
       ptWorld.z = Clamp( ptWorld.z, m_b3ExtWorld.GetMin().z, m_b3ExtWorld.GetMax().z) ;