[vtkusers] scan simulation with vtkPointPicker

[Moti Freiman]

Hello!
I'm trying to simulate laser scan of an object.
i put the object at window, and try to pick from all pixels of window, 
i've got the coords of the object, but all its (0 0 0).
follow my scanning code, do someone know what the problem? or if there 
another way to do it?

my code:
    fstream file;
    file.open("F:\\Neurobot\\LaserSimulation\\intersectedPoints.txt", 
ios::out);
    double intersectionCoords [3];
    vtkPointPicker * ray = vtkPointPicker::New();
    vtkProp3DCollection * prop3DCollection = vtkProp3DCollection::New();
    int x,y;

//viewer - handle mapper, actor etc for viewing polydata
    viewer.getScreenSize (x,y);
    int intersectionOccured = 0;
    for (int index1=0;index1<x;index1++){
        for (int index2=0;index2<y;index2++){
            intersectionOccured = 
ray->Pick(index1,index2,0,viewer.renderer);
            if (intersectionOccured) {
                
ray->GetProp3Ds()->GetLastProp3D()->GetPosition(intersectionCoords);
                file<<intersectionCoords[0]<<" 
"<<intersectionCoords[1]<<" "<<intersectionCoords[2]<<endl;
            }

        }
    }

    file.close();

-- 
Moti Freiman.
Medical Image Processing and Computer-Assisted Surgery Laboratory.
School of Computer Science and Engineering.
The Hebrew University of Jerusalem Givat Ram, Jerusalem 91904, Israel 
Phone: +(972)-2-658-5371 (laboratory) 
E-mail: freiman at cs.huji.ac.il 
WWW site: http://www.cs.huji.ac.il/~freiman