Disney Releases Production Assets for R&D and Education

[Njen]

Disney released two amazing data sets yesterday from Moana, a detailed volumetric cloud, and practically a whole island with various plant and other natural assets. All up about 6gb in total:
https://www.fxguide.com/quicktakes/disney-releases-production-assets-for-rd-and-education/

[Frood]

Holy teapot, 2.8GB of (compressed) data for that cloud :) Of couse I have to try it though. Would you be allowed to use the island assets for your movie? I think it's not explicit if it is a non profit production even when there is a lot R&D involved.


Good Luck

[cecofuli]

It's unbelievable... 2.8 Gb for only a cloud! And 42 GB for the Island!  I'm trying to render in Corona. Ok, my Pc is not very powerful... (I7 970). But, with Step size 1cm ( I tried 2 or 5cm, but I lose a lot of detail) I have 500.000 Rays/s 

[Frood]

Are you able to create any render close to the hyperion reference with Corona? I'm miles away from it :-/

BTW rays/s (i7-3820):

1 meter step size: 350,000
1 cm step size: 8,000 :)

I used a meter scene, maybe there is some unit mismatch somewhere.

Good Luck

[cecofuli]

Yes, it's not very complicated =)
Unfortunately, the CVolumeGrid has not so much parameter.
It looks like the Hyperion reference has some shader similar to CoronaSkin. It's more "soft".
In CVolumeGrid I had to add a little bit of Emission to simulate SSS, and disable "Single bounce only".
Don't forget to  use "Max ray depth = 100". It's very important
I use scene in cm and Step size=1cm => 700.000 Rays/s
With 2cm I already see some degradation. 10cm (or 10meter depending of your settings) is too much!

--- CORONA ---


--- HYPERION ---

[pokoy]

You need to use forward scattering for clouds (or refractive droplets in general), values from 0.4 to 0.7 will work nicely. The scientific value for ideal clouds is somewhere between 0.65 to 0.88 with an ideal value of 0.74. Starting from ~0.6 you'll see the darkening on the caps, which is what clouds do due to refraction, however we don't have a refraction parameter, something like that would be needed to produce the same detailed look with forward scattering.

I'm running some tests right now, too, but the Hyperion render still looks better. I have bounces set to 50, judging by how dark the cloud is in Disney's render they probably a lower value. But we can't say, they probably have a custom cloud shader. 100 bounces were producing too much illumination at the bottom, but it would be more realistic, of course.

[arqrenderz]

Lovely comparisons :)! Hyperion is a beast, i guess its full of settings and knobs, the tool for the job. Corona is perfect for archviz and we are very happy with it :)

[cecofuli]

I forgot to say that, in my test, Directionality=0.3 .
0.5 was too much in my opinion.
The problem is that, without Emission (Channel = Density, Mode = Channel mapping with some curve adjustment, Scale = 0.5) the cloud looks very dark, too dark, and not "soft".
And yes, I think they have some "special" Cloud shader. Like Skinshader or CarPaint (and not soooo sloooow I hope)
Clouds are a very important objects in every movie, right now.

[pokoy]

Where's you density at? I found 1.0 to be too much, this will also make the surface appear too solid. Ideally, you shouldn't have to use emission, it's not being used in the Mitsuba xml either.

Also, are you sure you're seeing a difference between step size of 1cm vs. 2cm? I've set it to 1m and don't think it's too little... will try to use lower values, who knows.

[cecofuli]

Shading rollout -> Emission Channel ON -> Channel: Density

My scene is set in cm =) (Customize -> Unite Setup...  ) And yes, there is a little difference between 1cm and 2cm (or 1mt and 2mt if your scene is set in meter)

About Emission, I don't know. I do it my "eyes" =)
Without emission, the clouds looks "dark", I don't know how to explain, not "Real".
But I use a little bit of emission, like Scale = 0.5. and I changed the Curve inside Channel color mapping... Mine is very "vertical"

[pokoy]

Aah, if your scene is in cm that makes sense, I just tried with a step size of 5cm and it looks like it's going to render for a few decades.

[pokoy]

Attached my attempt. Rendering with a slightly lower step size and a bit more density now. I have to say it's fun and I'm so happy we can do this now in Corona.

[cecofuli]

2.700.000 Rays/s...  (^__^)

Not bad. But, if you look the Pixar version, the cloud has more "contrast". Like there is "water" inside.
Your version is very cool, but it look like "perfect puffy cloud"
In the part in shadow (on the right side of the cloud) your version is "flat". The Pixar version has a lot of detail.
I know, it's very difficult to obtain such effect with Corona and, in the same time, to maintain the "softness" of the cloud.

[Njen]

That extra detail in shadow area of the Disney render feels to me to be some sort of fresnel/reflection effect. I mean clouds are water vapour, and water is reflective. As mentioned before, this is probably built into Disney's awesome volume shader.

[cecofuli]

As Ondra said, "clouds are super difficult to render".
So, we will need some sort of optimized CoronaCloudMtl =)
It would be amazing to export Clouds layer in VDB format from Terragen and render it in Corona (^__^)