[vtkusers] vtkOpenGLHAVSVolumeMapper a problem or not ?

Alfredo Gourbish the.answer3 at libertysurf.fr
Wed Jul 18 15:05:02 EDT 2007

Okay, thanks you Ken for these explanations.  It's true that I have a 
structured data too. But now, I have another question : how can read Dicom 
images in order to write an unstructured grid ? For the moment, I read these 
images with ITK and write a VTK volume which is a "structuredpoints" data.


----- Original Message ----- 
From: "Moreland, Kenneth" <kmorel at sandia.gov>
To: <the.answer3 at libertysurf.fr>; "vtkusers" <vtkusers at vtk.org>
Sent: Wednesday, July 18, 2007 8:41 PM
Subject: RE: [vtkusers] vtkOpenGLHAVSVolumeMapper a problem or not ?

The HAVS volume mapper was really designed for unstructured grids.  I 
believe the test, for convenience, converts a structured grid to an 
unstructured grid.  But this conversion causes the number of cells to grow 
significantly and virtually guarantees that the rendering rate per cell will 
be slower.  Neither of things matter for a regression test, but they make a 
big deal in practice.

In practice, you would really only use the HAVS volume mapper in situations 
where you start with an unstructured grid.  In this case, the volume ray 
cast mapper is not really an option.


> -----Original Message-----
> From: vtkusers-bounces+kmorel=sandia.gov at vtk.org [mailto:vtkusers-
> bounces+kmorel=sandia.gov at vtk.org] On Behalf Of the.answer3 at libertysurf.fr
> Sent: Wednesday, July 18, 2007 6:46 AM
> To: vtkusers
> Subject: [vtkusers] vtkOpenGLHAVSVolumeMapper a problem or not ?
> Hi all,
> I tried to use the vtkOpenGLHAVSVolumeMapper to render a big vtk volume
> (14 081 Ko). I watched the test TestHAVSVolumeMapper.cxx to see how this
> mapper works. So I used the same filters, etc... in my program than in the
> test.
> Finally, I have bad results with this mapper since the result is very
> slower and less detailled than when I use vtkVolumeRayCastMapper. I can
> understand that the RayCast is more detailled but not faster than the
> Here is the config of my working PC :
> Intel Core 2 6600 - 2Go RAM - NVIDIA GeForce 8800 GTS
> That's why I wanted to use the GPU in order to accelerate the render...
> Does somebody have an idea on why I have so bad results ?
> Gourbish
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