[Paraview-developers] OSPRay, server-side, parallel

[David E DeMarle]

On Thu, Feb 2, 2017 at 7:58 AM, Favre Jean <jfavre at cscs.ch> wrote:

> Hello folks
>
> I have been trying to do some server-side OSPRay renderings. Am not sure
> of the state of the implementation. I am using the lastest git pull of
> ParaView and OSPRay. Have compiled OSPRay with Intel's icc compiler
> (17.0.1) with TBB. Have compiled ParaView with GNU. The system is
> haswell-based.
>
> Trying different levels of concurrency in batch mode (1 pvserver per node,
> but several MPI-based pvservers), I am getting different images (different
> shadows). The zones were shadows are dimmer (or stronger) seem to follow
> diagonal lines. It's pretty curious.
>

Unfortunately secondary rays will not be correct in the distributed memory
parallel, high spatial resolution type context that ParaView is built for.
Without some mix of either sending rays to data or data to rays, shadows,
reflections, refractions, ambient occlusion sampling, and pixel
supersampling based antialiasing will all show artifacts. Intel and TACC
are working toward that but it is a ways out from being exposed in ParaView
to the best of my knowledge.

If data is relatively small you can run ospray itself in MPI parallel to
speed things up, but that won't let you render any more geometry than can
fit in everyone's local memory.


> another thing I have noticed is while in interactive mode with a GUI,
> moving the mouse results in the model being displaced widely across the
> screen, with empty regions popping up. On mouse release (still render), the
> model is shown in the right place. Interestingly, if I create a camera
> animation track (orbit), it all plays smoothly.
>
>
This is a known issue, but one that is not yet on the bug tracker. Please
report it there to help me remember to fix it.


> I'd be happy to share images, models, and scripts with developers. Let me
> know of your experience.
>
> TIA
>
> Jean/CSCS
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