A natural situation

[CTZn]

if you have the version of the cloud material that has got a haze option, you should use haze. Either what I'm afraid the shader specifies a value of zero below the clouds bottom, no matter what; it should be edited somewhat for your purpose.

Sorry about the drawback :/

PS: you can set the value named cloudless (iirc) that is defined as zero to a working scattering value (cf fog material). In case the variable cloudless is a boolean condition, then it is used to define a scattering variable I forgot the name of within the non-cloudy space.

(Espero no molestar !)

[Onizuka]

Well I don't think I have one of this versions.. I have if i am correct a version Ono made when he was making some of the first clouds shader

I was out for the day so I letted run a rendering for about 7hours with the clouds box going at -50meters under the bottom; the clouds start at 300m, the box is 7700x7700m and ends at 800m hight. I dont have an "amazing" processor ( i5 661 at 3.33 GHz ) but I don't see any god rays; or the render must run much more longer, or this cloud material does not create god rays..? I looked at real photos of god rays and I believe that the sun position is correct.

This has no haze options, it's the one with options for top, bottom, softclouds, gaps, caracteristic scale, offset, layers, complexity, noisescaleratio, noise strenght, stretching, absorption.

I also made a try wit the clouds in that "variation" scene of yonosoy :

Hi. A variation with one cloud layer.
5500 Samples/p in 15h. Filtered and resized from 1920 to 1440.
Mie_cumulus phase function is extremely peak and extremely fascinating...

I saved the material and imported it on the same box I made of 7700x7700 but there was just no clouds appearing after a fiew minutes. I don't know why.

I'm gonna search those materials in the thread, or if someone knows what page they are :p

edit: I'm sorry the download link of yonosy's scene hasn't be quoted

[yonosoy]

Hi Onizuka.
The thing is that indigo´s air medium has not SSS defined (you can´t expect see godrays using the captured simulation). Try using an atmospheric simulation with an extra atmospheric sun.
Or go with two boxes, one for clouds and the other (below the clouds) for a material with an amount of SSS.
In the page 18 of CTZn´s thread you can find a pigs called " Canyons 2 with clouds C.pigs". This cloud definition comes with haze. You can use a single box (from ground to the top of clouds) and expand the haze to the bottom of the clouds or even give a value different of zero to the parameter "Cloudless" in the SSS definition of the code to have a basic atmosphere.

You need a volume with an amount of SSS below the clouds...
Hope this helps. If not, I can post an example in atmosphere (I always tend to render the clouds with atmosphere).

P.D. The position and thickness for the clouds in the picture two are no corrects.

[Onizuka]

Thanks Yonosoy for your answer,

By using an atmospheric simulation do you mean to create and atmosphere sphere the same as when we make a planet ? Because extra atmospheric enabled in indigo renders zero atmosphere and so the sky is black.

About creating a box under the clouds with an SSS value, well that's exactly what I meen when I ask if I need to create a fog box under the clouds; I usually do it because I like to catch the density of the atmosphere on some renders, but I must admit I never catched god rays by doing so.. I guess I did not place the sun and parameter the clouds correctly to get the effect.

Yes it effectively helps, so I will try this solution clouds box with a fog SSS box under, thank you.

Thanks also for the link

[yonosoy]

Yesterday I launched an example but don´t know why it stop at 8 hours. In the future I post a less exhaustive example. The first sign of godrays appears for me when I elevate the cloud system over 10000 meters and occlused perfectly the scene with the clouds!
Still don´t know exactly, this is the second test; I share in the case that helps.

200x200x2 km.

Godrays_2.pigs

for v4.0

(5.03 KiB) Downloaded 404 times

[yonosoy]

With uniform phase function.
15h, 6200 spp (circular aperture shape is substantially slower than a generated one, I don´t test the quality of the samples).
Clouds at 8000 m of altitude.
I was searching godrays almost a year without results...

[Oscar J]

Awesome!

[Onizuka]

I never noticed that uniform phase function absorbs all the colors of the land, on my renders using uniform phase function for the clouds I get only the clouds being grey scaled, even in uniform sometimes they become colored from ground reflections.. on your render it looks like a black and white image or something from a horror movie

Since last messages I made some tests in situation but I don't think I've seen god rays yet, or maybe very little one, I keep testing and I will show you, but for now I'm sorry I can't upload anything for some reasons.. it will come
Thank you for your examples

[yonosoy]

Thanks Oscar!
Hi Onizuka.
Looking forward your situation! God luck.
The uniform phase is right, I decided to post the image in BW with a stong contrast. I like this way, maybe an horror way but this is at the moment

[Onizuka]

Haha ok I understand, yes I like it too, but I first thought it was due to the uniform phase function.
Reguarding this cloud material, when we modify one parameter it is turned into uniform, but how can I set it back to RGB values even if I change some parameters ?
example, I changed the max extinc coeff from 0.05 to 0.01 because it renders a lot more fast but it turns it to uniform. Or I change the shape or details and it does the same

[yonosoy]

Yes, this is an issue mentioned some times before but I never posted a bug report about it.
Maybe is time to do it...

[Onizuka]

I've seen it mentioned before but never asked more.. I might do it yes

[yonosoy]

9 h. and 5600 spp.
With a generated aperture runs very much faster than with circular one. The samples are of quality with an aperture radius of 0.4 (preset).
Absorption of clouds at 0.001 (more light).
With a little post process in lightroom (contrast, noise and light).

[burnin]

Nice! Congrats on great work.
To make these conditions as visually pleasing as are to human vision, it's even hard for a 'cheap' camera photography...

triple exposure FujiHS35EXR + picturenaut

[yonosoy]

Thank you very much burnin.
A lake attempt. An hour of process.