[vtkusers] URGENT:Getting world coordinates for any pixel in Render window

[shrinivas kulkarni]

Hi All,

Is there any way to get the world point for any pixel in Render window, even if it is not part of object being drawn. To explain more, attached is the image which describes my problem:
I want to convert points 1,2,3,4 and 5,6,7,8 to world coordinates and check which vertices lie in that region. 

This is what I precisely want to do:

User is allowed to make selection in render window, this can be rectangualr OR Free hand selection. Once this is done, then user can do selective processing of data.

I tried using:

pRenderer->SetDisplayPoint(selectionX,            selectionY, selectionZ);
pRenderer->DisplayToWorld();
worldCoords = pRenderer->GetWorldPoint();

But when I take this transformed point and check for the points in mesh for whether they are "inside region" or not, the test fails even for the points which lie in the region. Therefore, I did some analysis and found that z-depth value is not available for the pixels which are not affected by object rendering. By this I mean to say for the points which are not part of the object.


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