Hair disappears gradually when increasing motion blur

[BorisGoreta]

I have managed to get hair motion blur working but as I increase motion blur amount from 0 - 0.5 the motion blur is visible on the hairs but almost half of the hair disappears ( underlaying object becomes visible instead).

[juanjgon]

Hmm, this sounds like some kind of core limitation while sampling the curves that have long motion blur trails. Can you please share an example scene (as simple as possible) to reproduce the problem here?

Thanks,
-Juanjo

[BorisGoreta]

Here is the scene. I hope you can figure out what am I doing wrong.

hair MB.rar

(415.51 KiB) Downloaded 162 times

[juanjgon]

I think that the problem is that the hair is too thin, breaking the motion blur sampling. As soon as it is thicker, the rendering seems better.

Thanks,
-Juanjo

[juanjgon]

Anyway, let me look into this issue because I think that the hair motion blur is weird. Perhaps there is a core bug or something like that.

Thanks,
-Juanjo

[juanjgon]

Yep, something is broken. Check what happens when you raise the shutter time. I'll report it to the core devs.

Thanks,
-Juanjo

[juanjgon]

Quick update: There is indeed a problem with the hair motion blur rendering. The core team will try to resolve it as soon as possible.

Thanks for your patience,
-Juanjo