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Simulation render issue


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Hi guys, 

I've created a particle simulation which will simulate perfectly fine in houdini view port and will render via mantra node fine up until frame 157. 

on frame 158, the render really grinds down slow. It also tends to suddenly blur the frame quite badly. I've tried disabling the particle color and other nodes which don't seem to make any difference. Since it renders 157 frames as it should, I don't understand why it would suddenly have an issue with frame 158 and beyond. 

Would this be a caching issue while rendering? Or maybe the mantra renderer itself? 

(I am using a PC but I've also tried it on a Mac -same version of houdini with the exact same result). 

Any help would be much appreciated. 






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I've been told that because the particles begin to die on frame 158, the trail node suddenly has to re calculate motion blur for the decreasing amount of particles (makes sense, And I hadn't even thought that at all).


Cheers for your help!

- B

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Yes, by default the Trail SOP tracks each particle by point number. So when you kill off particles, the point numbers change and from the Trail SOPs point of view the particle have  moved, even though it is an entirely different particle. This might lead to really big velocities and then of course insane motion blurring.


Take a look at "Match by Attribute" on the Trail SOP. You'd have to find a way to give a unique ID per particle that doesn't change with the point count, that way it should be fine.


edit: Didn't realize you were using a POPnet, in that case each particle is given an ID by default. So it should already be there for you to use.

Edited by Skybar
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Hi Brayden.

here is your sim, and I managed to get frame 158 rendering just fine now.

No changes have been made in your project.


Could you give it a render at your end and see if it is okay now.










particles_render 158(RENDER_fix_Vel scale 8.62a).hipnc

Edited by mangi
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