Author Topic: Fade-out Radius for Volumes  (Read 615 times)

2018-07-07, 01:14:14

Eddoron

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This would be very handy, especially until VDB support is available.

Clouds, for example, the volume creates artifacts at the edges that are hard to remove when the mesh is not primitive shaped. (pic)

A Fade-Out radius where one can choose mm, cm, m, and a numeric value+ the type of the Fade-out (Linear, Cubic, Square...)

2018-07-09, 10:37:46
Reply #1

houska

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Hey there, I'm sorry but what kind of artifacts do you mean? Can you show it in the picture? Otherwise, a change like this is not very probable, I'm afraid. I'll check it out...

2018-07-09, 10:55:24
Reply #2

cecofuli

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You can use CoronaDistance+Geometry for Fade-out .
But yes, a "Fade-out map inside CoronaVolumeMtl will be great!

2018-07-09, 11:22:20
Reply #3

maru

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If using OpenVDB would help in this case, then I do not think it makes sense to even consider adding such new feature - OpenVDB support should be added soon(ish) since we already have in 3ds Max.

2018-07-14, 03:50:22
Reply #4

Eddoron

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If OpenVDB/volume materials are coming soon, then there less need for that feature.
Artifact wasn't the best choice to describe the problem, but I didn't come up with a better one.

In the cloud, on the top side, there are visible displaced polys/small bumps where especially the sides of the bumps are often (fully) colored by the volume and the fade out only visible on the top of the bump. This leaves "spikes" in the image, depending on the viewing angle.

The other, lower areas are completely opaque, whereas a real cloud would have at least some fade to 0 for every area.
The latter is the bigger problem when using displacement.


It takes some time to tweak the settings to minimize it to the small spikes problem etc.
The picture shows the tweaked values. I could increase the distance, but then it'd lose its definition or give out something that looks cut off.


However, it would still be useful for things, such as an atmosphere for planets.
The absorption distance controls the density and the fade out could be used to fade it out.
Instead of a unit value, it should use a relative one.

btw, how would you convert a Vray material that has Fade-out radius enabled?

edit: bad example, look at the second exaggerated picture.
« Last Edit: 2018-07-17, 15:04:51 by Eddoron »