diff --git a/SceneCamera.cpp b/SceneCamera.cpp
index a94662a..87c784e 100644
--- a/SceneCamera.cpp
+++ b/SceneCamera.cpp
@@ -319,12 +319,15 @@ bool
 Scene::PanCamera( const Point3d& ptWinOld, const Point3d& ptWinNew)
 {
   // porto i due punti in coordinate mondo
-   double dZCenter = GetProjectedCenter().z ;
-   Point3d ptViewOld( ptWinOld.x, ptWinOld.y, dZCenter) ;
+   double dOldZCenter ;
+   GetPixelZ( ptWinOld, dOldZCenter) ;
+   Point3d ptViewOld( ptWinOld.x, ptWinOld.y, dOldZCenter) ;
    Point3d ptWorldOld ;
    if ( ! UnProject( ptViewOld, ptWorldOld))
       return false ;
-   Point3d ptViewNew( ptWinNew.x, ptWinNew.y, dZCenter) ;
+   double dNewZCenter ;
+   GetPixelZ( ptWinNew, dNewZCenter) ;
+   Point3d ptViewNew( ptWinNew.x, ptWinNew.y, dNewZCenter) ;
    Point3d ptWorldNew ;
    if ( ! UnProject( ptViewNew, ptWorldNew))
       return false ;