fractal noise sliding on animated geometry in Bifrost volume

[amitesh3d]

Hello Guys,

I have an animated char which I need to convert into cloud.

The problem is my fractal noise is sliding as the char is moving in the world. Is there a way to finalise the noise pattern on char UV/ static mesh and bind it to the animated mesh?

Please let me know if it makes sense or I will try to upload some pics for the same.

TIA,

AA

[morten.bojsen-hansen]

You can definitely do what you are describing, but perhaps it would be easier to simply translate the noise pattern in the opposite direction to where your character is moving to avoid the sliding?

[amitesh3d]

I could stop the sliding by adding the transform after the volume conversion but the problem is deforming mesh of the character.

In Houdini, we could use a rest position for volume conversion and then point deform to transfer the deformation of the mesh. In Maya terms more like a wrap deformation but on volume and points.

Could someone guide which nodes to use in Bifrost to mimic similar workflow?

Cheers!

[amitesh3d]

I am attaching a file to explain the issue here. The animated torus, when converted to volume is giving random noise on each frame (I imagine the noise is a 3D volume noise which is affecting the voxels on world position).

How to keep the noise pattern the same for the shape, irrespective of world position?

[Grahame_Fuller]

You can sample the noise values once on the first frame of your animation, and then use those values for all the subsequent frames. There are a few ways to do this.

One way is to use a feedback port to cache the sampled noise values in memory. Inside a compound, use an if node to test the current frame and either sample the field on the first frame or pass the previously sampled values along on the subsequent frames. To reset the cache, you'd need to return to the first frame. The inside of your compound would look something like this:

Another way is to use a file cache -- write the values out to a file once and then read them back for the animation. You can use any condition you want to control when to update the cache. For example, you can test the frame number as above, or use a separate scene whose only job is to write the file, etc.

I hope that helps,

gray

[amitesh3d]

Hey Gray,

Finally some light!

I could follow you till the caching of the samples noise data. I wrote it for frame 1, but don't know how to use it or connect it to my animated volume?

Another question is - this noise data while reading is having geometry as well. Am I doing something wrong? or it is supposed to be extracted. Totally in the blank here as I have just started using Bifrost.

It would be great if you could setup a dummy file to explain this. Many thanks!!