Volume Shader

[EL_CISNE_POST]

Hi, I tried to find if anyone else posted something relaed to this, but correctly please if I'm wrong (specially about what I'm asking). I saw this video https://www.youtube.com/watch?v=t6R3JwCy02M is related to corona render, and it's volume shader that lets you render you geometry as a cloud or smoke, but I guess that the nice thing is that you can even render an object as bread or as an sponge because I guess it will take in to account all the volume of the object if you are using a procedural noise or something like that. I'm not sure about it because I haven't tried it, but if you can blend it with another shader, something that you cannot done with the vray environment fog, right?
Well, I was just wondering if this could be a new feature for next releases. Thanks!

[Neilg]

I think you might be looking for the 'vrayscattervolume' material

[EL_CISNE_POST]

Hi, thanks for the answer. I think is not the same, it is supossed to be an alternative to SSS but it doesnt let you create volume shaders and holes on it based on procedural map or so. With this (as far as I know) you cannot create a cloud.

[Neilg]

It doesnt look like the corona one can do it either, it appears to be a much more limited version of the same controls you'd get if you used a geometry source for the vray environment fog.

[EL_CISNE_POST]

I don't know, in that demo he doesn't put any procedural at the scattering... I mean, it seems that with that socket you can control the scatter, I wasn't able to find any way to do that. About the environment fog, the problem I find with this is that you cannot bend materials, I mean, if you have the same on a shader you could for example use a vraymtl on the edge and on the interior this shader, for example to create a bread or something like that. I'm not sure I'm wrong, but I cannot reproduce the same effect the guy from corona is doing with any shader, only with the vray enviroment fog

[EL_CISNE_POST]

Another thing I found is that you can deform objects with the vray environment fog but you cannot apply UVW coords so the maps arent going to deform with the mesh :/

[vlado]

The VRayScatterVolume shader is the equivalent of what you see in that video.

Best regards,
Vlado

[Robert Everhardt]

https://www.youtube.com/watch?v=t6R3JwCy02M

looks impressive, seems like a very fast way to model clouds and such.
can we have this for vray?

[EL_CISNE_POST]

Hi Vlado, thanks for your answer, but I'm wondering if it works as an environment fog but for shader or is completly different... is just that I'm kinda lost because I havent tried too the vray scatter volume but also the info about the material is very basic on the vray help, there it only seems that it works as a SSS for brute force but not as a shader that let you render gases or atmospheric effects.

EDIT: it seems it really works as an environment fog, but there is any way to control the scatter radius based on a procedural map?

EDIT: NVM, I found that in slate material you can add maps to radius scatter so, this is exactly what I was looking for. Thanks Vlado and Neilg!

[EL_CISNE_POST]

Hi, I'm sorry still digging about this but I wanted show you something I did. I'm looking forward about this because I have to do a lot of food and stuffs that can make a lot of use of this kind of stuffs but I feel that using a vrayenvironment for this is not the way. I had run some tests using the vrayscatter volume but I found that it wont work as the environment fog, just because it doesnt into account the internal values using a map or something like that from what I have seen. Now, I'm not sure if the scatter volume can do the same the vrayenvironment fog can. I know that sometimes you can achieve that kind of effects with a displacement but is not the same unless you use a vector displacement, but for simple exercise it would be nice to be able to do it with a simple procedural ma. I'm attaching an image and the scene to see if someone can help me and see if I'm doing anything worng. Thanks!

[super gnu]

have a look at the vrayvolumegrid. you can use procedurals to cut and slice that.. and also choose wether it renders as a volumetric cloud or geometry. if geometry you can of course use any material you wish on it. it renders quite slow but is very powerful.

[EL_CISNE_POST]

Hi, thanks for your answer. Didn't know you could do that with volume grid, it is amazing!, and I dont think is slow, actually I feel it render far faster than environment fog (at least as mesh). The nice thing is you can use materials. What I'm still not sure, is that with this you cannot use deformers and also you cannot give material ID to an specific part of the mesh that I was hoping I could do with the volume scatter :/ still hope in a future this can be done with a shader.
But thank you very much for this tip, I found it pretty helpful.
Best

PS: I started talking about this, because of this document http://graphics.pixar.com/library/An...Cook/paper.pdf . Go to page 30-31, they talk about volumetric hypertextures

PS: By the way, I wasn't able to render it as volumetric (I guess like an smoke or something), only set to mesh I can render it, can you tell how you do it please?

[kagemaru]

We talked about something similar here.
As i suggested there, i would look into houdini vdb operations to be used inside vray with volumegrid. I know it can be intimidating but trust me it's gonna be invaluable and not so dramatic.

As a side note I asked a long time ago chaos to at least integrate a feature to "fill" objects with volume in volumegrid, but i don't know if it will come or not. I nowadays do this kind of stuff super easily in houdini.

[EL_CISNE_POST]

Hi Kagemaru thanks for talking you time write. I'd just read all the conversation on the forum and actually yesterday I gave 3 votes to a post on the Autodesk 3dsmax feedback to support the OpenVDB inside max. Strob commented on it also. Here is the link http://3dsmaxfeedback.autodesk.com/f...penvdb-support
I really hope they take this seriously because is very useful.
Yesterday I did some test using the volumegrid and it works fantastic, I wasn't able to render it as volumetric or volumetric geometry, only as mesh (don't know if you can give me any advice about how to do it... I did the mesh rendering without loading any info or .aur file so don't know if that's not the case for volumentric). What I don't like of this is that I need to be attached to the volume grid while, for example, with the VDB you can see it on the viewport and also deform it. I was asking if this kind of volumes could done only using a volume shader but with the VDB comming so popular I guess that no one cares about it.
But what do you mean with fill objects? Like being able to collapse it as geometry?

PS: By the way, I didn't understand why they had to use krakatoa to set a volume with particles, I do that a lot with pflow, the problem is that I don't have a good option for render it because as you can see, the metaballs aren't a great option in term of speed :/
I'm attaching an image using pflow and a noise procedural (I added an operator just to use the grayscale to control the size), but thats far I can get with it without a good option for render it.

[LudvikKoutny]

While heterogenous volumes are great to have, to achieve that result in the tutorial video you posted in your first post, you really do not need volume grid or V-Ray Volume Fog. Yes, you can not map the density of volume, but you can not do that with CoronaVolumeMTL either. So if you follow the tutorial, but use VrayScatterVolume instead of CoronaVolumeMTL, you should get almost the same result.

I am saying almost, because there seems to be issue with VRayScatterVolume, that limits it's maximal albedo to some bright gray value, regardless of how bright scatter color use, or how many diffuse bounces you have set up in you VRayScatterVolume.

Below is the scene with regular diffuse material set to RGB 250 white, and then Volume material with volume color set to same value.

This is how it looks in Corona:


And this is how it looks in V-Ray with 25 bounces set in the ScatterVolume material UI:


So if you are after rendering clouds, which are usually very bright, then this may be a problem. But other than that, everything should work same as in the video.