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Well using z-depth is indeed a good solution in postpro but I wanted something working at render time. A massive cube with a scattering material and volumetric would probably give the more reatistic result (I already used it with other render engines) but it whould take ages to render.

So as some as guess this tricky solution is based on several planes in front of the camera with a distance of about 4m between each of them, playing with the opacity you could control the fog fx. As the planes are not parralel to the camera you can see one of them in the left part as icelaglace mentioned it.

Well this is indeed very tricky but really fast, this image was rendered in about 15 min with DL in 1600px.

More to come ...

enricocerica wrote:Well using z-depth is indeed a good solution in postpro but I wanted something working at render time. A massive cube with a scattering material and volumetric would probably give the more reatistic result (I already used it with other render engines) but it whould take ages to render.

So as some as guess this tricky solution is based on several planes in front of the camera with a distance of about 4m between each of them, playing with the opacity you could control the fog fx. As the planes are not parralel to the camera you can see one of them in the left part as icelaglace mentioned it.

Well this is indeed very tricky but really fast, this image was rendered in about 15 min with DL in 1600px.

More to come ...

really good and fast way to simulate fog directly at render time, but probably (considering the time for setting-up the position of the different palnes and then adjust their opacity for reaching the "best result".....could be even fast (maybe faster), as Roubal suggest, with the Z-depth, isn't it?

In the past, I used the trick of multiple planes in Blender for a long street perspective. I placed the different planes between the buildings, so no visible joint were visible. The planes were not numerous, and the render was fast. Faster than Blender built-in mist if I remember well.

I also tried many close planes with a 3D cloud texture before volumetric materials have been added in Blender, for an animated view from an airplane chasing an other one through a cloudy sky : Huge render time, and the planes had to track the camera, or be parented to the camera and using global coordinates. Some weird shift effects of the texture were sometimes noticeable.

Yes, you need a volume, but when you have a plane in front of the camera the volume is infinite! =)

TBFX wrote:

manalokos wrote:for fog you don't need a massive cube but only a tiny plane in front of the camera with a specular material and scattering node.

NICE! I'd always thought you needed a volume as the scattering medium didn't work without one, but that works a treat!

T.

Yes, you need a volume, but when you have a plane in front of the camera the volume is infinite! =)

It is the reason why when using a specular transparent material for glass it is important to create thick glass. Mainly for cars with curved windows, otherwise the whole car looks like filled with glass and looks like a giant magnifier !

Simple glossy material doesn't show this problem and simple planes are often sufficient for ordinary windows.

manalokos wrote:for fog you don't need a massive cube but only a tiny plane in front of the camera with a specular material and scattering node.

i am not sure if that works. normally the fog gets denser with increasing distance from the Camera.
I normally use the ZDepth Channel to create that effect.
Never tried an actual volume...

enricocerica wrote:As the planes are not parralel to the camera you can see one of them in the left part as icelaglace mentioned it.

Even if the planes would be parallel to the camera you would see them cutting through ond some objects.
For me Z-Depth would be the way to go but these tests are really worth to go and I appreciate your time sharing you experiemention.

gueoct wrote:i am not sure if that works. normally the fog gets denser with increasing distance from the Camera.

Yeah it works, and gives a true light scattering volume that can also obscure with depth but it is really slow to converge and I wouldn't use it for outdoor scenes, I'd use z-depth just like every one else. But for expansive indoor and/or self lit scenes it will give a far superior atmosphere to z-depth if you can stand the render time. I did a large spacecraft hanger scene for a short film late last year in the first version of Octane that had SSS and it worked great but was really slow. Unfortunately until that film is finished I cannot post the scene here, but here is a test scene I did recently to test a volume I'd set up before I knew a plane in front of camera extending outside your view would act as an infinite volume. You can't do that with z-depth.

T.

Yep,

Z-depth is for sure the best solution if we consider it at postpro, it would than be great if this process could be integrated during the render time ...

I think it would be great if we could set a material on the camera, like some sort of "medium material", a material where the camera would be in. Underwater scenes would be as simple as plugging a water material to this slot, the same with fog