New ovito-python 3.13 (Anari related)

OVITO General questions
1

Hi,
there seems to be something off with the new 3.13 version or I did something wrong. I installed the new version (windows system, Python 3.12.4) via pip (pip install -U ovito). Goal was: “maybe faster Anari/VisRTX/NVidia rendering”.

But the result was doubling rendering time / half performance. I do “tetrahedron rendering” on a system with about 4860 translucent tetrahedra on a RTX 3080.

With new ovito-python 3.13:

image
image491×259 69.1 KB

Back to ovito 3.12 (pip install --force-reinstall -v "ovito==3.12.2"):

image
image474×325 9.23 KB

Rendering options were in both cases:

anari = AnariRenderer(
   ambient_light_radiance = 0.95,
   ambient_occlusion_distance = 24,
   ambient_occlusion_samples = 16,
   denoising_enabled = True,
   direct_light_irradiance = .95,
   direct_light_latitude = np.deg2rad(75.0),
   direct_light_longitude = np.deg2rad(-120.0),
   samples_per_pixel = 24,
)

Rendering results looking very similar (left: 3.13, right: 3.12) with the newer version (left) producing “slightly more reflective” tetrahedron faces:

image
image1920×942 255 KB

Did something change which one has to consider?

–
Addendum: maybe it has to do with this significant change:
image
image880×316 57.4 KB

Thank you for your support!

2

Yes, it is certainly due to the switch to the more complex shading model. VisRTX supports two material models, the so-called “matte” and the “physically based” material. OVITO previously used the “matte” material. However, due to internal changes in recent VisRTX versions, this material has changed its look and is no longer suitable for OVITO, unfortunately.

We have therefore switched to the “physically based” material in OVITO 3.13.0 in order to reproduce the old look (and additionally support a variety of metallic looks). But this new default shading model is significantly more complex and computationally expensive. Hence the loss of performance.

I hope this change is only temporary and we can return to the fast “matte” material as soon as VisRTX adapts its shading models again. We are in talks with the developers about this.

3

Would you mind sending us your script, OVITO state file, and one input frame so we can benchmark and test the rendering ourselves?
If you prefer not to share these files publicly, you can email them to us at [email protected].