Achieving that geometry/shading of a bubble bath

[super gnu]

well that does look very nice.. even without the bubbles. why not render the bubbles seperately with a simple glass material, ior=1 and comp them over your base foam..


you could also consider this:

http://forums.chaosgroup.com/showthr...ight=thin+film

to add some nice colour detail.

[Art48]

Thanks - yeah I am actually considering rendering seperate and comping. First I wanna try by layering a normal surface on top of the foam with a heavy cellular bump map and glass material and see what happens
Thin Film is also a good idea! Will post updates.

[Art48]

Here with a glass "plate" on top and the ThinFilm reflection.
I'm not quite satisfied with it, since it gives a too harsh edge. Maybe really comp but I would love to get the effect in-camera.

Rendertime: 17 minutes

[Art48]

Interesting thing: If I reduce the visibility (under object properties) of the glass-plate on top to 0.3 the rendertime severely shoots up (guess is around 5-10 times). This shouldn't hapen I think.

[super gnu]

i think it would help if the bubbles didnt entirely cover the foam underneath. just a few patches of larger bubbles. the foam looks great.. the skin of bubbles is too uniform.

[Art48]

That's actually a good idea - but I still need SOME amount of reflection on the foam and with the ScatterVolumeMtl I can't get that properly.
I will propably render a seperate image with the glassplate on top and paint it in later.
Will now do some bigger bubbles, especially inbetween the ridges.

Here's a small part of the image with 0.3 visibility on the glass plate. Rendertime 21 minutes (with 1 machine, so 10 minutes as reference with two machines, like the others) for that little area you can see there. No way this is intended. I will now try to make it via transparency of the material instead of visibility.

[super gnu]

hm i think you would be fine to have some bits of the foam without any bubbles/ reflectivity.. when you look at foam with micro bubbles ( the effect of your base geometry) its really not very reflective.. which is why your base foam with bubbles actually looks nice alone. or maybe just some tiny sparkles would be sufficient, which you could do any number of ways.

[Mokiki]

I'm currently having a go at this myself. Just one question do you have the newest service pack installed? As far as I know they improved the calculation for the scatter material and in my tests using the scatter material for the main foam body + covering it with 200k small bubbles on top doesn't really render that slow. I have a few "black lines" in my render but those are just because my foam geometry is overlapping. Just used a simple noise modifier and really screwed my geometry ;P

*edit* for full resolution on that picture "right click -> open new tab"

[Art48]

Now the glass has a VRayColor Opacity of RGB 64 64 64 (g2.2) and it gives some more definition to the foam which I think is good. Although the rendertime went up to 50 minutes I think it's aceptable, although you only see the difference in A/B split.

Now I need to get it into the main scene and do a test render with the right camera angle and sun angle and see what I see of the foam and if I really need bigger bubbles. But I guess so...time will tell

[Art48]

I'm currently having a go at this myself. Just one question do you have the newest service pack installed? As far as I know they improved the calculation for the scatter material and in my tests using the scatter material for the main foam body + covering it with 200k small bubbles on top doesn't really render that slow. I have a few "black lines" in my render but those are just because my foam geometry is overlapping. Just used a simple noise modifier and really screwed my geometry ;P

*edit* for full resolution on that picture "right click -> open new tab"

Thats actually really nice. I roll with 3.10.02 at the moment. So you go with 3.20?
What does the geometry of one bubble look like? shelled sphere? only sphere? material with an IOR of >1.0? Looks good to me

It's funny - foam gets DARKER when I scatter the bubbles on top despite 255 refraction...

[Mokiki]

Yeah I'm using 3.20 at the moment. My sphere is a really low poly sphere (8 segments, no shell).
Bubble Material =
Diffuse almost white (218 value)
Reflection: Full white 1.33 fresnel (max depth 30 (could probably be reduced I just cranked it up because I had some black spots which were caused by the scatter mtl))
Refraction: Full white IOR 1,05 (affect shadows on)

(Since I didn't model to scale the following values might be different for you)
Foam:
Color Mode: Sub surface color + scatter radius
Sub surface color : 196
scatter color : 193
scatter radius: 80
phase function 0.2
bounces: 20
subdivs: 8

The render time was: 15 minutes on an intel xeon x2 @3ghz (24 threads)

I could also upload the scene. (only thing that wouldn't work would be the camera because I'm using the new one in max2016, assuming you are using max2014 like mentioned in your signature)

*edit* You mentioned the foam getting darker. I had the same problem with my bubbles they got really dark until I raised my scatter radius for the foam.

[Art48]

Hm....thanks for the info.
The scatterMtl shouldnt really be affected by the bubbles - so what would the scatter radius have to do with that?...strange...

[super gnu]

do you have "affect shadows" turned on for the bubble material? you could also try excluding them from recieving/visible to gi, maybe even from shadowcasting..

[Art48]

Yeah of course, affect shadows is ticked. It got much better now since I increased the refraction and reflection depth, also doubled my scatter radius.
Its still not where I want it though... I need to experiment some more, maybe size of bubbles, number of bubbles, etc.