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ch3

Grain simulation collapsing

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I am adding a thick layer of sand on top of an animated robot and let it fall with gravity. What I have so far works, but once I reduce the particle separation to get more grain particles, they all collapse to a thin layer, rather than stucking up a nice little hill.

I've tried to change a few settings (solver.maxNeighbors, solver.neighborQueryScale, contraintIterations) but I haven't had any luck so far. I've also tried to push out the collision geometry by a bit, but it didn't help either.

I am currently using geometry for collisions, but I have a feeling that if I switch to volume based it may go away. But that's not good for me, as I can't get the grain to stick on the collision geometry if it's set to volume.

 

Do you have any ideas of what else to try?

 

thank you

Georgios

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ok got it

 

Dissabling or lowering the Shock Scaling Power solves the problem. I don't understand why... but it now works fine.

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Hi Georgios,


Sounds like you need to move you shock Origin closer to your simulation. I'm guessing your sim is far from the center of the scene. If you don't have a Shock Origin parameter in your POP Grain Update your still using an older version of H14 before the fix. In that case you will have to move your sim closer to the center of the scene.


Quote for the help:


"Shock Origin: The rough center of the sand system. Due to limits of floating point representation, particles too far from this origin will be clamped to min/maximum mass values. A lower scaling power allows for a larger range.


The default values give a range of +/-580 particle separations in the shock axis direction."


Hope thats your problem because then its an easy fix.


Zybrand


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hmmm that's interesting.

We are on v14.0.291 but it's good to know that in later builds this feature has been added.

 

The sim is not that far from the origin, [7,200,20]. But for the time being reducing the Shock Scaling Power seems to solve the issue.

 

thanks for your input

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actually it's the same problem occurs in another shot and it's giving me headaches as what worked on the other case doesn't work in this instance.

hmmmm...

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Did you try moving the sim to origin? And then back to its original place after sim.

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The simulation was almost at the origin anyway.

I recreated the grain setup again from the self button and it worked fine.

My setup that wasn't working was in its own DOP network within a Geometry node, where the shelf button created a new autoDOPNetwork. Even by coping the nodes from one DOP to the other make it break. I ended up using the autoDOPNetwork and finish my shots and unfortunately I didn't have enough time to investigate the problem any further.

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The simulation was almost at the origin anyway.

I recreated the grain setup again from the self button and it worked fine.

My setup that wasn't working was in its own DOP network within a Geometry node, where the shelf button created a new autoDOPNetwork. Even by coping the nodes from one DOP to the other make it break. I ended up using the autoDOPNetwork and finish my shots and unfortunately I didn't have enough time to investigate the problem any further.

 

Hi ch3 :)

 

can you show an mov or a basic file setup having your problem.

i would like to investigate as i am studying pop grains and have faced problems as well.

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