when rendering velocity blur it doesnt take the interval_center/shutter_offset into account. mantra does this correctly.
It also seems too take into account the geomtry before and after which i think shouldnt be the case. maybe im worng here though.
I have examples in this scene:
https://drive.google.com/file/d/1S2U…ew?usp=sharing
vray version: 43001, 87bfc3a
houdini 17.5.327 linux
Hello!
Messaging to inform you we’re looking into this. In short, when velocity blur is used, we write the velocity channel itself with the mesh so those options on the ROP have no effect, by design.
We’ll see if we can do something about this and come back to you with more info.
All the best!
Thanks for looking into it! As of now i cant match the velocity without changing the interval_center on the node which in this case i dont want
Regards Alexis
@Gosho.Genchev Was wandering if there is some progress here. We always have had trouble matching fx elements with velocity blur with our deformation/transformation blur and we are using weird values in our motion blur settings to get them to match somehow. I think this is the problem that causes it.
Next nightly will contain some fixes, let me know pls if those will work for you.
here is a bit more visible problem. When having an alembic with frame range like alembic_1000.abc, alembic_1001.abc, alembic_1002.abc and i have duration on 0.5 and interval center it will try to find a geometry that dont exist. In this case we dont want that, we just want vray to pick up the velocity from the @v attribute
https://drive.google.com/drive/folders/1xr2bIWW4qc09AGxV\_crU2gttbbecY7-R?usp=sharing
This is starting to beome a bigger problem now when we mix different kind of geometry in the scene. Is it something that can be looked at?
in this example scene there is 2 alembics that should have the same motion blur. But because 1 has a framenumber in its sequence it picks it up from the wrong frame.
https://drive.google.com/drive/folde…Qa?usp=sharing
Regards Alexis
Changes are currently under review, both cases will be fixed next week.
sounds good, thanks 
Everything works perfect in latest nightly. Thanks alot for the fixes!
We also have wrong behaviour with motionblur when instancing. Here is an example file explaining the issue
moblurInstancing.zip (59.8 KB)
geometry blur dont work in version “43001”, “657d636” no moblur at all. Works in version “43001”, “490e262”.
It was indeed broken but should work in 657d636 - it does for me, and our tests go through successfully there.
@Gosho.Genchev did you guys get time to check the instancing motion blur issue above?
Hey,
yes, it’s not as much an issue as it is simply not implemented - I’ve talked to the devs and will ping you once we have it in the nightlies.
All the best!
Hey, @LeoYfver ,
support for the motion blur settings for geometry over instance points with ‘v’ attribute will be available starting with the next nightly build.
Hope that helps!