Curl Noise problem with imported geometry

[mattyjrogers]

Hi guys,

I have imported a very simple obj from 3ds max and I am trying to apply a curl noise effect to the surface of it... I have played around with the amplitude etc but nothing seems to create very long lines and it looks pretty awful.... (I have attached an image...)

When really I want to be getting an effect like the image below my image.... does anyone know why this may be? I am wondering if it is a scale issue perhaps?

I want it to stick quite close to the geometry which has long trails but does flick off the geometry every now and then like my reference image....

Any help would be great!

Thanks

Matty

 

 

 

 

[toadstorm]

hard to tell what's going on from a screenshot, but here's a HIP showing the effect you're looking for.

pig_sdf_advection.hip

[mattyjrogers]

Thanks a lot! This is precisely what I am looking for

I think the issue is with the size of the geometry. All the standard test geometries work fine, but when i try it with my own geometries they don't seem to work but I think that is because I am importing them at 1:1 building size. Whereas all the test geometries are very small!

I will have a play!

Thanks again

[toadstorm]

Scale up your curl velocities to match your scene scale. If the curl noise amplitude is low compared to your scene size, you won't get nice long trails. Same goes for the Surface Effect Radius on your Curl Noise VOP.

Edited February 6, 2018 by toadstorm

[mattyjrogers]

I tried to increase the amplitude massively, even when I increased it to a million there wasn't much of a difference between 4,000 which is what I have it at in the screenshot and 1,000,000. Is this what you mean?

As an additional question, does houdini cope well with complex geometries? E.g. turbosmooths from 3ds.

Thanks!

[toadstorm]

Sounds like something else might be messed up. Can you post your HIP with the model?

Houdini shouldn't have any trouble handling most kinds of geometry, as long as it's a compatible type (OBJ, ABC, FBX, STL, etc)

edit: one other thing, if your trails are too short, you can just use a volume wrangle to scale your vel field up:
 

@vel *= 10;

 

Edited February 6, 2018 by toadstorm

[mattyjrogers]

For sure, here is both of the models!

Really appreciate this!

Square Tower.obj

Tower Test.hipnc

[toadstorm]

Just tweaked a few parameters and scaled the vel field up in a wrangle. I think the wrangle was the big missing part; forgot that scaling up the curl noise vop amplitude doesn't necessarily get you scaled-up magnitudes.

Tower Test_2.hipnc

[mattyjrogers]

Ah yes! That is perfect, thank you! I was close....

 

Top man