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I hope I'll have time soon to experiment after finishing some work rhis week.

Once you have a volumetric cube material, export it - and then just re-import everytime you need it.

After more experimenting - the size and location of the cube is the key. You don't want it too big, otherwise it blocks the sun too much - it just needs to cover the area you want the rays - no bigger.

This is a PMC version - love the dust specs!

Hi Paul,

Great exercise, but I cannot get the rays.. how did you do that.
maybe you can see something in my settings that should be different?

I tried with cube and slab,
but it does not matter if using a slab, cube or otherwise, right?

btw: When having th efog material put against the wall.. it goes wrong.

greetings, Jeroen

but it does not matter if using a slab, cube or otherwise, right?

I haven't tried it with a slab - but one issue would be the slab has 2 materials in the geometry from memory, and you really want just one.

btw: When having th efog material put against the wall.. it goes wrong.

Yes - the rayepsilon is being ignored in this case - which looks like an Octane bug - I will report this to Otoy. So for the moment - do not have the cube touching the walls - which should be fine for your scene. I added the "scene scaling" parameter (in the Configuration) to try to get around this issue - thinking it was a scene scaling issue - but I realised now that it is not.

For working out the workflow for this, I recommend a darker interior, so you can see the effect better.

Set the focus manually - or to get things worked out - set the aperture to 0 - since it's hard to see the rays when out of focus. In your scene the autofocus is hitting the cube.

FOG material needs a scale NON-ZERO. If your scene scale is one - a scattering scale around 0.02 should give you a fog effect. Too high and it will turn the cube into a white block. Set phase to 0.75 (not 1). Roughness 0. Opacity 1.

Good luck!

Paul

Hi Paul,

Unfortunately I cannot get it work to get the fog OK ans for sure not to get the xrays like you did
Maybe you can send/upload the scene to learn from
I am having a nice scene here to experiment... nut I'll try to make a smaller scene and try to copycat your scene to get this work and understand
btw: these images are done with hdri background, but I could not get the fog/xray effect work with daylight either.

greetings, Jeroen

This time I used the fog material from DB and by accident or not I am getting some effect here
where the lightbeams are seen
Now I will study the settings to understand and make fog on purpose in another scene
cheers, Jeroen

Step by step I am getting somewhere.

I started out this trial after seeing the beautiful render by enricocerica,
http://render.otoy.com/forum/viewtopic.php?f=5&t=29462&start=0

This is the latest render trying to make a scene like enricocerica to learn using fog and stained glass.
I added the settings in the prntsreen for you to make comments if you like to improve.
I did not get a good result in AO yet, but in PMC I am getting rays to start with

greetings, Jeroen

Nice work Jeroen.

You can increase caustic_blur to smooth out the light beams.

The fog_specular material should have fake_shadows Enabled I think. Also, scattering_direction = 0.75 seems to increase the effect. You can also increase the "medium" scale to increase the effect. I like the idea of using some turbulence in the "scattering" pin.

Paul

tnx Paul,

This time I used the material from the DB: octanefog (might have been octanefog from Karba... I am not sure now)
and I added some objects to make the scene come more alive.
I got the look and feel I was looking for: so mission accomplished,
but I still have to experiment more with the fog material in combination to different scenes to understand the settings and get to the next level.

I also combined the fogmaterial with lights and just a little bloom and glare effect to see if that work together.
The image is almost a straight render; the only after effect I did was making the people darker while I was not satisfied about the people.
I used 2d silhouettes, because I don't like the 3dpeople form the standard library.

greetz, Jeroen