GPU raycasting with iso-surface refinement (problems at silhouettes)

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Mobeen
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Joined: 09/23/2010

Hi all,

   I have been doing GPU based volume raycasting for quite some time now.  When using raycasting with iso-surface, I notice flickering near the silhouette. I am using bisection based refinement with 5 steps to refine the search but still the flickering is there. See the attached images.

Iso-surface raycasting without bisection based refinement

isosurface refinement with bisection based refinement

 

 

 

 

 

 

 

 

 

 

 

 

 

On the left is the non-refined result while on the right is the refined result. Note that at the sihouettes, the iso-surface is not correctly identified . I am doing 5 steps already for the bisection. If i increase it, i dont see any difference visually but then the frame rate drops. In the famouse iso-surface paper by Markus et al. http://medvis.vrvis.at/fileadmin/publications/realtime-isosurfaces.pdf, they mention using the Lipchitz continuity condition to find the step gradient to be used but I am unable to understand how to put it into the GPU raycasting framework. Does anyone have any idea how to do it.

Regards,

 Mobeen

 [edit: I dont know why but the post does not display images in the thread but it is shown fine in the preview???]

aschuh
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Joined: 11/06/2009
I have temporarily fixed the problem.

I have temporarily fixed the problem but will need to look into what caused it. Everyone should now be able to see the images as posted.