Why unstructured volume performance in OpenVKL is better than in OSPRay ?

[anskwagh]

I used same unstructured data with OpenVKL examples.exe and with OSPRay examples.exe. I saw that OpenVKL volume performs much better than ospray (w.r.t FPS). Does anyone know why is that and how to fix it ?

[johguenther]

I would expect that the volume sample performance itself is the same (after all, OSPRay uses VKL for that). But OSPRay's renderer support much more features and flexibility (geometry, clipping, multiple volumes, AOVs, ...), which comes with some toll compared to VKL examples (which only handles a single volume).
Then, let's make sure to compare apples to apples, i.e.

• VKL density_pathtracer_ispc with OSPRay pathtracer renderer
• VKL ray_march_iterator_ispc with OSPRay scivis renderer
• same transfer function
• using similar settings (VKL has per default no scattering, while OSPRay computes up to 20 bounces per default and 1 lightsample, ...)

Still, in the end it will come down to the additional overhead in OSPRay due to it's features.

[anskwagh]

Ohhk. Thanks for the reply @johguenther