diff --git a/EgtGraphics.rc b/EgtGraphics.rc
index 967d0cd..94ee3f2 100644
Binary files a/EgtGraphics.rc and b/EgtGraphics.rc differ
diff --git a/SceneGeom.cpp b/SceneGeom.cpp
index 39d503e..06f7ba5 100644
--- a/SceneGeom.cpp
+++ b/SceneGeom.cpp
@@ -383,9 +383,9 @@ Scene::DrawGeoObj( const IGdbIterator& iIter, int nPass, const MdStMkCol& siObj)
 bool
 Scene::DrawAlphaSurfVector( void)
 {
-  // ordino vettore in senso crescente secondo Zmin
+  // ordino vettore in senso crescente secondo Zmax (asse Z punta verso osservatore)
    sort( m_vAlphaSurf.begin(), m_vAlphaSurf.end(), 
-         []( const AlphaSurf& a, const AlphaSurf&b) { return a.dZmin < b.dZmin ; }) ;
+         []( const AlphaSurf& a, const AlphaSurf&b) { return a.dZmax < b.dZmax ; }) ;
 
   // eseguo visualizzazione
    for ( int i = 0 ; i < int( m_vAlphaSurf.size()) ; ++i) {
diff --git a/SceneGrid.cpp b/SceneGrid.cpp
index 946a3f2..4d89e34 100644
--- a/SceneGrid.cpp
+++ b/SceneGrid.cpp
@@ -66,7 +66,7 @@ Scene::DrawGrid( void)
   // semi-estensione della griglia
    float dExt = float( m_nExtSstep * m_dSnapStep) ;
   // abbassamento in Z per evitare sovrapposizioni con geometria
-   const float Z_DOWN = float( - 0.0005) ;
+   const float Z_DOWN = float( - 0.01) ;
 
   // se richiesto, disegno la griglia
    if ( m_bShowGrid) {