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Cinema particles problem with object motion blur

Posted: Tue Jul 01, 2014 10:36 am
by Neb
Hello

I noticed weird problem. I need to simulate falling autumn leafs in my scene. I add simple rectangle particle emitter connect that with a few leafs simple objects and one wind modificator. The simulation is going very well. To prepare maxwell rendering I play animation in 3D Cinema window and falling leafs are going down. I pause simulation when the hole composition is good ( frame 120 for example ) and start render scene via Maxwell Render. Everything looks fine until moment when I try to switch on an object motion blur maxwell system. In this case leafs aren't visible in renderer. It isn't a wrong camera shutter settings. It's a technical problem. Sometimes it works but at the most cases don't. It's a plugin bug or am I do something wrong ?

Regards
Neb

Re: Cinema particles problem with object motion blur

Posted: Tue Jul 01, 2014 5:23 pm
by JDHill
There are quite a few factors that could be in play, so will need to see (please send it to jeremy at nextlimit dotcom or upload to dropbox or similar) the C4D file in order to say what would be the cause.

Re: Cinema particles problem with object motion blur

Posted: Tue Jul 01, 2014 5:27 pm
by Neb
Ok, I'll prepare a scene tomorrow and share it via dropbox to Jeremy.

Re: Cinema particles problem with object motion blur

Posted: Wed Jul 02, 2014 3:33 pm
by JDHill
Thanks, looking at the scene clears things up. The problem is that the emitter can produce different results depending on whether it's run from the beginning, or just at a given frame. For dealing with this, or with any generator that manifests this type of behavior, the plugin provides the Scene Object > Motion Blur & Animation > Pre-roll Timeline option, which instructs the plugin to animate the document through every frame prior to the one being exported.

On a side note, I will also mention that this model is quite a bit more painful to work with than necessary, due mainly to the thousands of leaves being generated outside of the camera's view; I would recommend perhaps changing the emitter's length from 8000 to 4000, moving it so that it is not dropping particles behind the camera, and then cutting the birthrates in half. By changing the emitter further, and modifying the wind, I think you should be able to achieve the final image you're after, but only using a fraction of the number of leaves.

Re: Cinema particles problem with object motion blur

Posted: Wed Jul 02, 2014 4:07 pm
by Neb
Thank you very much. Now it works fine! I should be more smart in this case and test that one small option "Pre-roll Timeline"... :) Yes you have right. The emitter comes from a main scene and it should be optimized a little bit.