[vtkusers] Volume Rendering Update

[Aashish Chaudhary]

Hi Mike,

On Mon, Jun 1, 2015 at 5:48 PM, Mike Guttman <mguttman at jhu.edu> wrote:

> Disappointing to hear that the current plan is to discontinue
> vtkOpenGLVolumeTextureMapper3D.  It was always a reliable tool and produced
> good looking renderings with little tweaking.
>

Sorry to hear this. You can get same or better quality with
GPUVolumeMapper. Most of the modern renderers use Ray Casting algorithm and
for most part it is the most recent algorithm that gives most features,
image quality, and performance. Have you tried using it? I would love to
hear more on what you find out.


>  Perhaps this can be ported to work with the OpenGL2 backend?
>

There has to be a strong reason why we need to support it. We have
FixedPoint (CPU) and RayCast (GPU). GPU Mapper now supports more features
than CPU or any other mapper, flexibility (via custom shaders), and
performance. In our testing, the new mapper out performs old mapper (w/o
shading) and with my new branch it will out perform old mapper w/ shading.
If you can identify reasons for vtkOpenGLVolumeTextureMapper3D, then we can
see what we can on on our end.

- aashish


>
> On Jun 1, 2015, at 4:26 PM, Aashish Chaudhary <
> aashish.chaudhary at kitware.com> wrote:
>
> On Mon, Jun 1, 2015 at 10:47 AM, Mike Guttman <mguttman at yahoo.com> wrote:
>
>> Guess I wasn't tracking the permutations carefully.  When backend is set
>> to OpenGL2, there's an error when I turn on
>> Module_vtkRenderingVolumeOpenGL.  It seems okay with
>> Module_vtkRenderingExternal.
>>
>
> yes, you cannot use  Module_vtkRenderingVolumeOpenGL with OpenGL2 as it
> was written for previous implementation.
>
>>
>> I use vtkOpenGLVolumeTextureMapper3D in my application.  Perhaps this is
>> not available with OpenGL2 backend?
>>
>
> Yes, it is not. Since most of the platforms now support all of the
> features needed for Ray Casting (for OpenGL 2 version), we don't need this
> mapper anymore.
>
>
>> I believe this is not included with Module_vtkRenderingVolumeOpenGLNew.
>>
>
> Right. In current master, we remvoed that module as it was there to serve
> until we had a reasonable OpenGL2 mapper which we do now.
>
> Thanks,
>
>
>
>
>>
>> After your comment, I tried it again after pulling from the repo just now.
>>
>> Thanks,
>> Mike
>>
>>
>>
>>
>>
>>   On Monday, June 1, 2015 10:05 AM, Aashish Chaudhary <
>> aashish.chaudhary at kitware.com> wrote:
>>
>>
>> On Sat, May 30, 2015 at 4:59 PM, Mike Guttman <mguttman at yahoo.com> wrote:
>>
>> Hello Aashish,
>>
>> It seems you cannot enable ExternalVTKWidget with OpenGL2.  Any idea when
>> this combination will be supported?
>>
>>
>> What SHA of git you are using?
>>
>>
>> Thanks,
>> Mike
>>
>> *From: *Aashish Chaudhary <aashish.chaudhary at kitware.com>
>> *To: *vtkusers <vtkusers at vtk.org>, VTK Developers <vtk-developers at vtk.org
>> >
>> *Date: *May 29, 2015 at 5:31:34 PM EDT
>> *Subject: **[vtkusers] Volume Rendering Update*
>>
>>
>> Folks,
>>
>> We made some recent improvements to VTK volume rendering including fixes
>> to related components. Here is a list of those changes:
>>
>> 1) Now new GPU Volume Mapper respect Interpolation Type (Linear or
>> Nearest). Default is Nearest as in the last GPU mapper.
>>
>> 2) Shading is now twice as fast as before. There will be another branch
>> to make it even faster.
>>
>> 3) Fixed lighting bug (number of lights kept on increasing with change in
>> volume property)
>>
>> 4) Saving and Restoring GL state properly for textures
>>
>> 5) Bias and Scale are now performed in Shader.
>>
>> 6) We changed some GL texture format information to support OpenGL 3
>> context
>>
>> 7) Fixed extensions were not reported correctly on GL2 context
>>
>> 8) Fixed few failing tests specifically on Mesa
>>
>> 9) Removed VolumeOpenGLNew module as it was not as usable with OpenGL2
>> getting ready for primetime
>>
>> 10)  Added convenience API to SmartVolume Mapper
>>
>> 11) Cleaned up logic for dealing with context changes in Volume Mapper
>>
>>
>> Please let us know if you have any questions.
>>
>> Thanks,
>>
>>
>> --
>>
>>
>>
>> *| Aashish Chaudhary | Technical Leader         | Kitware Inc.
>>   *
>> *| http://www.kitware.com/company/team/chaudhary.html
>> <http://www.kitware.com/company/team/chaudhary.html>*
>>
>>
>>
>>
>> --
>>
>>
>>
>> *| Aashish Chaudhary | Technical Leader         | Kitware Inc.
>> *
>> *| http://www.kitware.com/company/team/chaudhary.html
>> <http://www.kitware.com/company/team/chaudhary.html>*
>>
>>
>>
>
>
> --
>
>
>
> *| Aashish Chaudhary | Technical Leader         | Kitware Inc.            *
> *| http://www.kitware.com/company/team/chaudhary.html
> <http://www.kitware.com/company/team/chaudhary.html>*
>
>
>


-- 



*| Aashish Chaudhary | Technical Leader         | Kitware Inc.            *
*| http://www.kitware.com/company/team/chaudhary.html
<http://www.kitware.com/company/team/chaudhary.html>*
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