Weird artefacts on tire track in sand? Anyone with an idea on this?

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#1

Hi,

I have an animation with a VW Phoenix truck driving along a sand beach.

It creates the desired tire tracks as can be seen. The subdivision of the surface is reasonably good, as can be seen on the tracks which are good for large parts of the movement. The beach surface is evenly subdivided all over.
Still I get every couple of meter these huge sand spikes which you can see on the screenshot.

Does anyone have an idea how to fix this?

The computer has 72 GB of RAM and 2 Xeon X5650 processors and I am using blender 2.82.
Graphics card is an Nvidia GTX 1060 with 6GB. I’m using Cycles with GPU to render.

Thanks for any suggestions, Pretty

Tiretrack
Tiretrack1920×1080 211 KB

#2

Actually I thought I found the reason. The spikes seem to occur where the underlying path Nurbs changes direction. Need to smooth out that curve :wink: And, just for reference, one can set a maximum displacement value created on the surface, which should solve this issue too.

UPDATE BOTH DOES NOT SOLVE THE ISSUE ;-(

Meanwhile I tried subdividing the surface even more, still it does not help. The dynamic paint modifier is last in the stack.

Still looking for a solution.

#3

Hey, Did you try changing the ‘Sub Steps’ on the modifier ? I would think ‘more’ sub divisions would just compound the issue (just a guess). It does seem to happen at a consistant interval.

#4

Trying that right now.
But when I add substeps the car flys to a completly different location immediately ;-( and then goes crazy.

#5

Yum, maybe it’s only used for the ‘Paint’ part. Are you using an ‘Array’ modifier for the ‘beach’ ? Here is a link to the guys web page that coded ‘DP’ - it’s really old, but then again so is the manual pages on ‘DP’.
https://www.miikahweb.com/en/articles/dynamic-paint-guide

#6

Actually the substep setting is available on displacement and on paint.
Thanks for the link, just found it already 5 minutes ago. Still did not find a solution in there,
Guess the substeps mess up the keyframing of the motion. Not sure…

#7

You have to ‘Re-Bake’ it
BTW; you have a very nice PC set-up :smiley:

#8

I’ll try rebaking in a few minutes.

Thanks, actually its a quite old PC workstation now. They sell the for around 1300€ today…
Dates from 2012, needs replacing in a while…

#9

It creates the desired tire tracks as can be seen. The subdivision of the surface is reasonably good, as can be seen on the tracks which are good for large parts of the movement. The beach surface is evenly subdivided all over.

b

#10

Rebaking did not yield new results the substeps creates chaos.
I deleted the cache manually before.

Tiretrack3
Tiretrack31920×1080 201 KB

#11

Anyone has some more ideas? I’m really puzzled & stuck…

#12

No real help, just a troubleshooting suggestion- I’d try baking some frames to an image texture and use those with a displacement modifier.
I’d also try setting the displacement to only work along the global Z axis to see if that gets rid of the issue.

#13

Actually, can’t believe it, but flipping the normals on the beach did it. Not sure why, but the spikes are gone.
Still I do not understand why it worked in large parts before.

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#14

I was doing so experimenting this mourning and decided to flip some normals on the canvas…that is exactly the results I got, glad to see you figured it out. :+1:

#15

How are you making the tracks at all? I’ve never had to do anything like that before, so I’m curious if you wouldn’t mind giving a brief rundown about the steps you used to accomplish this?