diff --git a/liboptv/src/multimed.c b/liboptv/src/multimed.c
index 2551cef8..ed0da014 100644
--- a/liboptv/src/multimed.c
+++ b/liboptv/src/multimed.c
@@ -111,32 +111,28 @@ double multimed_r_nlay (Calibration *cal, mm_np *mm, vec3d pos) {
     }
 }
 
-
-/*  trans_Cam_Point() creates the shifted points for each position X,Y,Z 
-    Using Exterior and Interior parameters and the Glass vector of the variable
-    window position and the two vectors that point to the crossing point
+/*  trans_Cam_Point() projects global-coordinate points of the camera and an
+    image points on the glass surface separating those points.
     
-    Arguments: 
-    Exterior structure 'ex'
-    multimedia paramaters mm
-    Glass parameters gl
-    3D space position pos
-    Returns:
-    Pointer to ex_t Exterior parameters after shift
-    vector of doubles for shifted position pos_t
-    vector of 3 doubles of cross_p 
-    vector of 3 doubles of cross_c, both used for back projection
-*/ 
-void trans_Cam_Point(Exterior ex
-                   , mm_np mm
-                   , Glass gl
-                   , vec3d pos
-                   , Exterior *ex_t
-                   , vec3d pos_t
-                   , double cross_p[3]
-                   , double cross_c[3]){
-
-/* Beat Luethi June 07: I change the stuff to a system perpendicular to the interface */
+    Input arguments:
+    Exterior ex - holding global-coordinates camera position.
+    mm_np mm - holding glass thickness.
+    Glass gl - holding the glass position in global-coordinates as a 
+        glass-normal vector.
+    vec3d pos - the global coordinates of the observed point.
+    
+    Output arguments:
+    Exterior ex_t - only the primary point fields are used, and are set 
+        to the glass/Z axis intersection.
+    double cross_p[3] - the observed point projection coordinates in global
+        coordinates.
+    double cross_c[3] - same for the camera position. Since the camera point
+        is projected on the other side of the glass, it'll have a small 
+        difference in Z value from ``cross_p``.
+*/
+void trans_Cam_Point(Exterior ex, mm_np mm, Glass gl, vec3d pos, 
+    Exterior *ex_t, vec3d pos_t, double cross_p[3], double cross_c[3])
+{
     double dist_cam_glas,dist_point_glas,dist_o_glas; //glas inside at water 
     int row, col;
     vec3d glass_dir, primary_pt, renorm_glass, temp;
@@ -345,17 +341,13 @@ double get_mmf_from_mmlut (Calibration *cal, vec3d pos){
     double X,Y,Z;
     vec3d temp;
     
-    vec_copy(temp,pos);
-  
-    rw =  cal->mmlut.rw;
+    rw = cal->mmlut.rw;
   
-    temp[2] -= cal->mmlut.origin[2]; 
+    vec_subt(pos, cal->mmlut.origin, temp);
     sz = temp[2]/rw;
     iz = (int) sz;
     sz -= iz;
     
-    temp[0] -= cal->mmlut.origin[0];
-    temp[1] -= cal->mmlut.origin[1];
     R = norm(temp[0], temp[1], 0);
     
     sr = R/rw;
diff --git a/liboptv/tests/check_multimed.c b/liboptv/tests/check_multimed.c
index 32e98d2f..d0f3dbbe 100644
--- a/liboptv/tests/check_multimed.c
+++ b/liboptv/tests/check_multimed.c
@@ -317,6 +317,7 @@ START_TEST(test_trans_Cam_Point)
 {
     /* input */  
     vec3d pos = {100.0, 100.0, 0.0};     
+    double sep_norm = vec_norm(pos);
         
     Exterior test_Ex = {
         0.0, 0.0, 100.0,
@@ -352,25 +353,25 @@ START_TEST(test_trans_Cam_Point)
 
     trans_Cam_Point(test_Ex, test_mm, test_G, pos, &Ex_t, pos_t, cross_p, cross_c);
     
-    ck_assert_msg( fabs(pos_t[0] - 141.421356) < EPS && 
+    ck_assert_msg( fabs(pos_t[0] - sep_norm) < EPS && 
         fabs(pos_t[1] - 0.0) < EPS && 
-        fabs(pos_t[2] + 50.000000)  < EPS,
-        "Expected 141.421356 0.000000 -50.000000  but found %10.8f %10.8f %10.8f\n", 
-        pos_t[0],pos_t[1],pos_t[2]);
+        fabs(pos_t[2] + test_G.vec_z)  < EPS,
+        "Expected %g 0.000000 %g  but found %10.8f %10.8f %10.8f\n", 
+        sep_norm, -test_G.vec_z, pos_t[0],pos_t[1],pos_t[2]);
          
-    ck_assert_msg( fabs(cross_p[0] - 100.0) < EPS && 
-        fabs(cross_p[1] - 100.0) < EPS && 
-        fabs(cross_p[2] - 50.0)  < EPS,
-        "Expected 100.0 100.0 50.000 but found %10.8f %10.8f %10.8f\n", \
-        cross_p[0],cross_p[1],cross_p[2]);
-    
-    ck_assert_msg(fabs(cross_c[0] + 0.0) < EPS && 
-        fabs(cross_c[1] + 0.0) < EPS && 
-        fabs(cross_c[2] - 55.0)  < EPS,
-        "Expected 0.000000 0.000000 55.000000 but found %10.8f %10.8f %10.8f\n", \
+    ck_assert_msg( fabs(cross_p[0] - pos[0]) < EPS && 
+        fabs(cross_p[1] - pos[1]) < EPS && 
+        fabs(cross_p[2] - test_G.vec_z)  < EPS,
+        "Expected %g %g %g but found %10.8f %10.8f %10.8f\n", \
+        pos[0], pos[1], test_G.vec_z, cross_p[0],cross_p[1],cross_p[2]);
+    
+    ck_assert_msg(fabs(cross_c[0] + test_Ex.x0) < EPS && 
+        fabs(cross_c[1] + test_Ex.y0) < EPS && 
+        fabs(cross_c[2] - (test_G.vec_z + test_mm.d[0]))  < EPS,
+        "Expected %g %g %g but found %10.8f %10.8f %10.8f\n", \
+        -test_Ex.x0, -test_Ex.y0, test_G.vec_z + test_mm.d[0],
         cross_c[0],cross_c[1],cross_c[2]);
     
-    
     ck_assert_msg ( (fabs(correct_Ex_t.x0 - Ex_t.x0) < EPS) && 
                     (fabs(correct_Ex_t.y0 - Ex_t.y0) < EPS) &&
                     (fabs(correct_Ex_t.z0 - Ex_t.z0) < EPS),