Bitmap to density

[Paul Oblomov]

How one can do that ? Like heightfield, without the need to create geo and fill with smoke.

[georgi.zhekov]

You can create an empty grid, set the Smoke opacity to be based on Smoke and shift the leftmost curve point so its value is something more than 0. Then just assign the texture and it should be working without the need of simulation.

[Paul Oblomov]

Hm, you sure ?

[georgi.zhekov]

Yes, check this post here - https://www.facebook.com/groups/VRay...6402350512336/

It works even with Volume Grid on GPU, in the comments there is a video with the full setup.

[Paul Oblomov]

Well, bitmap is not like 3d noise. If you can prove me wrong - would be great!

What I need
map 0-1 from bitmap to Z grid values fitted f.e. to 0-0.05, and resulting volume should be filled with 1

If it can be created via scripted processing - that's fine too. Just show plz some example.

[georgi.zhekov]

As the texture is 2D and the Phoenix Volume is 3d you will need to change the mapping for the bitmap. Set it to Planar from Object XYZ and then pick the right axis.

[Paul Oblomov]

Excuse me, but do you find that projection anyhow useful ?
So, to be straight - there's no way of making what I'm after ?

What I need
map 0-1 from bitmap to Z grid values fitted f.e. to 0-0.05, and resulting volume should be filled with 1

[georgi.zhekov]

Only at render time this is not possible yet. You can try and experiment with a distance texture multiplied by your bitmap, probably that could work for your case?

[Paul Oblomov]

Ok, any ways to script it somehow ? Fill cell by cell f.e. ?

[joconnell]

You could make a mesh, mesh select one side and put a displace on it then use that volume to fill the grid?

[Paul Oblomov]

Without simulation - seems nobody knows Also, it is displacement res + grid res dependent.

Would be great to have one grid slice affected by the texture and then its content multiplied by bitmap intensity.

OR

Maybe convert bitmap to 3d noiselike texture, with only two dimensions active (maybe vector). I remeber we have vector displacement, which reads colored texture and modify grid content. That would be totaly fine, the question is - how to code grayscale bitmap to vector image ?

[joconnell]

Duh, sorry Paul, just read your first post properly. If Georgi can post a few simple examples of how you'd loop through the voxels of a grid setting values with maxscript I'm sure I can come up with something. There was another post on facebook about how to modify clouds to remove the flat bottoms from the chaosgroup tutorial and i'd love to do something like one sim for the main cloud, another sim for the bottom of the cloud and then use maxscript to subtract the voxels of one from another (effectively a boolean operation) between two grids. If I got an example of how to do this it shouldn't be difficult to create what you're mentioning here - it might be quite slow though and perhaps a bit memory intensive?

Alternatively I wonder could you use the surface displacement effect in the rendering section to achieve something similar? It seems like you're doing planetary scale cloudscapes?

[Paul Oblomov]

Yeah. Clouds... a pain. I need rendertime generation/rendering

Maybe idea of filling the grid with data via maxscript is indeed a stupid one But, I want to explore every single option, before going to houdini. Rendertime advection is the only solution to me atm, IMHO. We just have to properly form the bitmap.

[joconnell]

Yep I was thinking the same with render time displacement too but I'm not sure how we could map that to only the upside of a gizmo!

[joconnell]

One of the tough things we'd have too is the curvature - I think krakatoa can do ffd's on voxel grids, I meant to look into that!