[vtkusers] vtkVolumeTextureMapper3D behaves differently between v5.1 and v6.2

[Weiguang guan]

Thank you very much for confirming the problem and related information.

Best,
Weiguang

On 14/09/2015 10:48 AM, Simon ESNEAULT wrote:
> Hello,
>
> Yes we were suffering the same issue.
> I believe the change occurred with this commit
> https://github.com/Kitware/VTK/commit/0164fa1e25d9c584e7ec60acb7e221f7ea9e5d7c
> The 128x256x256 thing is no longer hard coded, it now relies on 
> the vtkgl::MAX_3D_TEXTURE_SIZE variable to compute a correct reduction 
> ratio, which will lead to this significant slow down.
>
> Some more explanations :
> http://marc.info/?l=vtkusers&m=128869084800678
>
> The Volume Texture Mapper 3D has just been marked as deprecated so I 
> don't think there will be any sort of fix, but you should be able to 
> restore the old behavior if you look to the commit, and revert the 
> changes made in the method
> int vtkOpenGLVolumeTextureMapper3D::IsTextureSizeSupported(int 
> size[3], int components){...}
>
> Best Regards
> Simon
>
>
>
> 2015-09-14 15:55 GMT+02:00 Weiguang guan <guanw at rhpcs.mcmaster.ca 
> <mailto:guanw at rhpcs.mcmaster.ca>>:
>
>     Hi David,
>
>     I'll try vtkImageResize. Thanks.
>
>     Best,
>     Weiguang
>
>
>     On 11/09/2015 1:48 PM, David Gobbi wrote:
>>     Hi Weiguang,
>>
>>     You can do the image resizing as a preliminary step with
>>     vtkImageResize, which does efficient band-limited sinc
>>     interpolation and can do a good job of shrinking the image
>>     without introducing aliasing artifacts.
>>
>>     Hopefully someone else will answer your question about
>>     vtkVolumeTextureMapper3D (I haven't used it in a while).
>>
>>      - David
>>
>>     On Fri, Sep 11, 2015 at 11:22 AM, Weiguang guan
>>     <guanw at rhpcs.mcmaster.ca <mailto:guanw at rhpcs.mcmaster.ca>> wrote:
>>
>>         Hello VTK users,
>>
>>         We develop a viz system using vtkVolumeTextureMapper3D for
>>         volume rendering. Recently, we've moved up from v5.1 to v6.2.
>>         After that, we notice our viz system has a significant
>>         slow-down in rendering speed (compared on the same computer)
>>         when volume size is large, say LxWxH ~= 512^^3 . It can
>>         always render small volumes at interactive rate.
>>
>>         I know that vtkVolumeTextureMapper3D needs to resample large
>>         volume to fit in 128*256*256 (BTW, our data is regular volume
>>         data with a single component). But this down-sampling process
>>         is not new in 6.2. Are there other changes that cause the
>>         performance issue? Does anyone experience the same issue?
>>         Thanks.
>>
>>         Best,
>>         Weiguang
>>
>>
>
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> -- 
> ------------------------------------------------------------------
> Simon Esneault
> Rennes, France
> ------------------------------------------------------------------

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