[vtkusers] Overhaul of the rendering subsystem in VTK: Volume Rendering update

Aashish Chaudhary aashish.chaudhary at kitware.com
Wed Oct 22 14:27:24 EDT 2014


Some more good news on the rendering side of things. In the last few days,
we have worked on porting two more volume mappers to OpenGL2 (FixedPoint
and Bunyk) and this noon we merged that code into VTK master. This change
should not affect the code that is using the OpenGL (and not OpenGL2)
backend. We will keep an eye on the dashboards and fix any issue that we
may find. Also, we have updated the vtkSmartVolumeMapper to deal with the
OpenGL and OpenGL2 backend.

Please let us know if you have any questions or if you encounter any issues
in the current master related to this change.


On Thu, Oct 16, 2014 at 12:31 PM, Aashish Chaudhary <
aashish.chaudhary at kitware.com> wrote:

> Friends,
> As referred earlier, we are continuously working on improving the volume
> rendering. As part of next set of delivery,  we are going to bring our
> first OpenGL2 volume mapper to the OpenGL2 backend.
> We have a branch that will get merged today and* it should only affect
> the dashboards and code base switched to OpenGL2 backend*. We will
> continue to improve the integration and will use and improve the
> existing OpenGL2 backend code as necessary.
> If you have any questions of concerns or if you find in any ways its
> affecting your regular builds that uses OpenGL(default, and not OpenGL2)
>  backend then let us know as soon as possible.
> Thanks,
> On Fri, Oct 10, 2014 at 9:53 AM, Aashish Chaudhary <
> aashish.chaudhary at kitware.com> wrote:
>> Friends,
>> As reported back in July, we are in the process of a major overhaul of
>> the rendering subsystem in VTK. The July article (
>> http://www.kitware.com/source/home/post/144) focused primarily on our
>> efforts to move to OpenGL 2.1+ to support faster polygonal rendering.  The
>> October Source will contain an article focused on our rewrite of the
>> vtkGPURayCastMapper class to provide a faster, more portable and more
>> easily extensible volume mapper for regular rectilinear grids.
>> VTK has a long history of volume rendering, and unfortunately that
>> history is evident in the large selection of classes available to render
>> volumes. Each of these methods was state-of-the-art at the time, but given
>> VTK’s 20+ year history many of these methods are now quite obsolete. One
>> goal of this effort is to reduce the number of volume mappers to ideally
>> just two - one that supports accelerated rendering on graphics hardware and
>> another that works in parallel on the CPU. In addition, the
>> vtkSmartVolumeMapper would help application developers by automatically
>> choosing between these techniques based on system performance.
>> In this first phase, we have created a replacement for
>> vtkGPURayCastMapper. Currently, this is available for testing from the VTK
>> git repository (in master branch, disabled by default). General
>> instructions on how to build VTK from the source is available at this URL:
>> http://www.vtk.org/Wiki/VTK/Git*. *In order to build the new mapper,
>> enable the Module_vtkRenderingVolumeOpenGLNew module in cmake (via -D
>> *Module_vtkRenderingVolumeOpenGL=ON*), in ccmake or cmake-gui. Once
>> built, it can be used via vtkSmartVolumeMapper or used directly. Once
>> sufficient testing by the community has been performed, this class will
>> replace the old vtkGPURayCastMapper.  In addition, we are adding this new
>> mapper to the OpenGL2 module.  Availability of the new mapper with OpenGL2
>> module will improve the management of textures in the mapper and eventually
>> benefitting both forms of rendering (geometry and volume) by sharing common
>> code between them.
>> Please contact us if you have any questions or encounter any issues.
>> 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
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