Problems with motion blur and render passes.

[artem_shcherbakov]

I have a very heavy scene: animated alembics, scatter, a million objects and polygons.
https://disk.yandex.com/i/LklybWtPvqtj0g



But when I turn on Motion Blur, my alembic hair and some instance-objects are missing. I don't know why.
https://disk.yandex.com/d/V_hq2TVfQBWEIQ




V-Ray for Houdini number:19573 hash:eece632 from 21 Dec 2021 04:57 (build number:19573)
V-Ray Core 5.20.02 [d249e0b5] from 18 Dec 2021


Also I have some troubles with objectID render-channel.
I gave to objects different objIDs. But everything is dark in the rendering.
1. https://disk.yandex.com/i/knmX_SKH0MnIMA
2. https://disk.yandex.com/i/s3GBZhZLT1jnaQ
3. https://disk.yandex.com/i/W0hpYMGLbfgWUA
4. https://disk.yandex.com/i/yIp7M8agrAJIog

If I assign objID 1 to an alembic, I see the result: https://disk.yandex.com/d/DzKQLS7LWq5RbQ
But other objects (grass with objID 2 and ground with objID 3) are ignored.

[chakarov]

Hello artem_shcherbakov , without the scene will be really hard to reproduce and isolate the problems.
My best guess about moblur and missing abc hair is that your hair animation is saved in alembic files per frame and the moblur settings are evaluated to a float frame number /e.g. 2.3333/ instead of integer frame number /2 or 3/. Could be same for missing scatered geos if they are animated too.
Can you try to export animations in a single alembic files and check if meshes/hairs are still missing in the render. If the problem is still there I'll need at least a simple scene where the problem exist.
Also I can't reproduce missing meshes/alembics in objectID element. Again even a simple scene with the problem will help a lot.