Octane 3 - Volumetric Light ( Sun/Sky )

[joelegecko]

Hi guys,

I was interested in the ability to easily get a scattering medium without the need to set extra geometry. But even if I can get the scattering effect wanted through the "Environment" tab, I can't manage to get any volumetric lighting per-se.

I assumed there might be a "fake shadow ON" optino somewhere but if there isn't any geometry now, where can I find suh an option? Am I missing something here?

[face_off]

As per your PM - set the Medium Radius to something like 100 (ie. a 100m radius around the camera).

Paul

[cyprine]

argl, i keep on failing to understand how the medium works.

in this exemple image (1700 samples)

absorbtion sounds like how much light is absorbed so i set it to dark (not much light is absorbed)
scatter sounds like how much light is bounced back so i set it to white (all light is scattered)
schlik: no idea

now:
Density sounds like how dense the medium is but whats the unit ? - i set it to 0.3
volume step: no idea - randomly set to 100
medium radius: didnt make sens until face_off's post above. - i've set it to 2 (meters)
also Backplate (?) Reflection & refraction are turned on.

the light is coming from some ceiling plates (rgb texture emiter, 100 watts, 10k sampling rate)
the door glass is a specular mat (with some bump & a diffuse mask for the letters)

as a comparaison, here be the same scene without the medium node

[face_off]

Hi - if you run Octane Standalone and mouse over the Texture Environment pins, you get some more information. For example, the Backplate, Reflections and Refractions ON/OFF are ignored for the Environment pin for the Rendertarget (and only used for the Visible Environment pin of the Rendertarget - which is not implemented in the DAZStudio plugin). The Medium Radius is the size of the sphere around the camera (in meters) containing the medium. So set the Medium Radius to a big number, use a Scattering medium, set the Scattering Color to non-black, and control the "fog" power with the Density.

Paul

[face_off]

Here is an example scene.

Paul

[cyprine]

thanks !

i've been playing around the settings and still cant quite get the light to trace nice rays in the fog but i guess its more a matter of photography now.
maybe a stronger light spot behind the door ? denser fog ?

[face_off]

i've been playing around the settings and still cant quite get the light to trace nice rays in the fog but i guess its more a matter of photography now.
maybe a stronger light spot behind the door ? denser fog ?

If you want rays - you need small gaps in geometry for the light to pass through to create the rays. There are a few threads in these forums showing how to do this - so perhaps search for "god rays" or similar.

Paul

[cyprine]

ty for the pointers, i think i'm getting it.

it seems it should work through the glass though as shown here (from blender plugin forum)
download/file.php?id=56029&mode=view

some other comments i read suggested the angle the camera is facing (compared to the direction of the light) plays some role, as well as phase/schlik).

edit, yup !
changed light that was a plain texture emiter to an ies (so i can better control the flod of light)
and turned fake shadows on _ on the window

and a color test (transmission node of the specular as shown in the above tutorial link)

now to make it all look better !

[cyprine]

well, after some testing around, i think i get the gist of it

is there a way to make the image clearer ? (less density ? tweaks in the imager settings ? lighting ?)
is there a way to cut down the render times ?
and since these 2 questions apply to almost anything else i'll just go and read and pratice some more

[face_off]

is there a way to make the image clearer ? (less density ? tweaks in the imager settings ? lighting ?)
is there a way to cut down the render times ?

Pls see the link in my signature. In particular, try reducing GI Clamp to 10 and Path Termination Power (so 0.1 or 0.2).

Paul