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View Full Version : Render farm problems with Dynamics and general dynamic sorcery issues. Any ideas?



xandercom
08-17-2013, 08:47 AM
Hi all,

I'm having some trouble with a scene I have created and now with the farm.
It's an incredibly complex scene with hundreds of asteroids using dynamics to create interactions with around half a dozen "master" asteroids which transfer their motion to the rest of the asteroid field as they collide, so we end up with things flying about and bouncing off eachother. All looks good so far.
Then I have some larger objects with Fracture which smash into a few hundred other pieces, all bouncing around with the the other objects already moving.
The scene looks great when I render out at home. However if I completely save and re-open the file, I then find objects have visually moved from their starting positions, in some cases moved completely out of the field of view, even though their coordinates are correct. Turn on and off dynamics and nothing changes.

I noticed that if I select any object in the scene at frame zero and move it a minimal amount (say 0.01mm) then suddenly the dynamics will kick in and start calculating the scene again and everything goes to where it should be. Items that were meters out of place return to their starting points and rendering can begin without any further problems.

This is rather odd, as technically there shouldn't really be any major dynamics interactions in the earlier frames anyway, and certainly not enough to make objects move vast distances in one frame. But anyway, for me it's not an issue as I only need to do this recalculation once before I start rendering.


So this is where the problem with the farm comes in. For my scene to render out correctly, each node on the farm has to do this stupid recalculation before it can throw out a frame. Then the next frame it is assigned to render has to once again work out all these dynamics from scratch. This problem turns a 35 render service cost into 250.

Basically it seems that LightWave (11.5 by the way) isn't actually exporting a valid dynamics cache when packaging the scene even though it's clearly there in it's folder. Each time the scene is opened on either my machine or on the farm it has to start calculating from scratch before any kind of rendering can take place.


Has anyone else had similar problems? Is there a fix? Could I somehow mass export individual motion paths for all of these hundreds of little objects and do away with dynamics altogether after it's calculated?

The farm said they have run into this before with others, and also with particles sometimes too. I can't believe there would be such a massive bug in LW farm rendering!



Any help or suggestions would be much appreciated while I still have hair left to pull out..

Thanks :)

nickdigital
08-17-2013, 11:39 AM
Bake your simulation to mdd files. Your particle simulations should be baked to pfx files.

sukardi
08-17-2013, 07:59 PM
Nick basically said it

Always 'bake everything' if you are sending to a render farm. It is just not worth the hassle and cost trying to trouble shoot individual problems...

xandercom
08-20-2013, 12:35 PM
I had guessed that perhaps there was a way to bake or export the motion, but couldn't find anywhere with this option.
Would one you you kind people mind pointing me to where I can mass-bake into a .mdd file please?

Secondarily I'm experiencing a new problem.. one of my objects in the scene is having an odd effect on collisions... when made active in dynamics it's colliding with things it shouldn't, in some cases they are meters away from the object. I've turned the collision accuracy right down to 0.01mm but still it's causing things to bounce away from it even though it's nowhere near them. The item that's selected in dynamics to be the collision surface is basically a cube shape. I've even changed from "surface" to "cube" in dynamics to see if that will pull the collisions in toward the object.

Any further help would be greatly appreciated.

Many thanks indeed.

nickdigital
08-20-2013, 12:46 PM
I had guessed that perhaps there was a way to bake or export the motion, but couldn't find anywhere with this option.
Would one you you kind people mind pointing me to where I can mass-bake into a .mdd file please?


If you have LW11.
https://www.lightwave3d.com/learn/article/lightwave-115-mdd-multi-loader/

xandercom
08-20-2013, 12:49 PM
If you have LW11.
https://www.lightwave3d.com/learn/article/lightwave-115-mdd-multi-loader/

What a legend. You sir have saved me from my own ignorance.