[vtkusers] vtkRenderWindow::GetZbufferData too slow. Alternatives?

[Ignacio Avellino]

Hey all!
Though I've crawled the vtk forums for a long time, this is my first post.

I need to compare the z buffers of two images in order to check for a
certain distance value between the projection of two models.
For this I render them on a vtkRenderWindow and then I get their z buffer by
calling GetZbufferData

This is extremely slow, it's taking about 500ms for a 320 x 240 image.

Anyone knows how to access the z-buffer from an image in a faster way?

If we look at the implementation of GetZbufferData, there is a call to
glReadpixels which is the culprit for the big time consumed.

Any ideas anyone?

Many many thanks in advance :)

Ignacio



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