Hi all,

I have a fairly simply model feeding a dops sim, small vex textures and spot lit.

When i render a frame without motion blur it completes in around 6 minutes. However, with deformation blur on, it just sits there with no progress after 40 mins.

How can i speed up the render?

Cheers

What engine is this in? micropolygon? sounds funny to me as motion blur is normally pretty quick in mantra. be sure to not render raytraced motion blur, and you can use the parameter “motion factor” on the mantra ROP (properties->sampling) to speed up shading of motion blurred micropolys. the higher you set this value, the less shading will be done in the blurred pixels, so the quicker it will render.

Sounds like somethings going wrong, yeah. Perhaps you have crazy motion-blurred geometry accidentally sitting on top of the camera point?

Otherwise, see “Motion Factor” on the ROP - it will decrease fidelity of the shading in highly motion-blurred objects, resulting in a speed up.

Hi, thanks for the help.

Is motion factor a Houdini 9 feature as I'm still on 8!

Cheers

There is a way to do this in H8 as well.

If I remember correctly, the command passed to the IFD is called ray_motionfactor. To pass this to the IFD properly, it has to be a pre-include on the cameras render tab (eg.: ray_motionfactor 1).

On the other hand..now that you've mentioned you're on H8. We had serious problems with rendering heavy (that means 3-4 x 600k polygons) deformation blurred geometry together with raytracing (occlusion) in mantra8. In that situation there wasn't extreme blur as the camera was following the objects, but it was still showing this problem. It went away in mantra9.