Global volume MTL affecting sky

[efflam]

Hey guys, here's my problem: you can clearly see the sky is not affected by the volumetrics.
Is there a trick to force the global volume material into affecting the sky?

I hope it's possible O___o

[racoonart]

Yes, it's possible, but you wouldn't find if if you don't know where to look.
1) activate devel/debug mode
2) set environment distance to something bigger (default is 1000cm)
Every ray that's not hitting geometry is assuming the medium is x units thick ( = enviro distance)

[maru]

This is intended, Ondra would explain you the technical details behind it. You can try performance > development/experimental > enviro distance.

[efflam]

Thanks for the reply guys! really appreciate :)

Do you have any idea on how much of a performance hit it would make?

PS : on the same scene I have kind of an issue, the scene parsing is 44s, with 20million polygons, (wich isn't insanely high) and using full 16gigs on my machine.
using 20 million poly for Onyx trees trough Csproxy then Csscatter, + some sparse hand-placed laubwerk plants, it's also a bit crashy, would you guys have some quicktips on memory management in that case? never had this problem with Arnold.

[fobus]

Why this useful feature is hidden? I always wanted to GlobalVolumeMat affect the sky, but didn't even know that is that simple!

[maru]

You can probably break something with it easily. Like make sky completely black. Or you may want to introduce some fog but keep nice clean sky in the background.

[efflam]

For some reason I can't get it to work, increasing distance dims the render, the background models are still always brigther than the sky.
How does one go about doing a plausible Rayleigh scattering atmosphere with the VolumeMTl? what values should I use? I saw no guide on how to do that.

[Dervish]

try this.


    gc() Garbage Collection.
    freescenebitmaps() Cleans up in texture memory.  <--- before renders or if task manager shows a high process.
    clearUndoBuffer() Removes your Undo’s



Taken from 3dtotal.

[maru]

For some reason I can't get it to work, increasing distance dims the render, the background models are still always brigther than the sky.
How does one go about doing a plausible Rayleigh scattering atmosphere with the VolumeMTl? what values should I use? I saw no guide on how to do that.

I think in real life fog is usually layered, which means that it ends at some height so sun rays may travel freely until they hit fog*. In Corona, fog works based on distance. So basically imagine a huge volume filled with scattering media (example: smoke, volcano explosion) - it is bound to make the scene very dark. I would advise you to try some of the following:
-adjust enviro distance and fog material parameters
-change fog directionality to about 0,9 and see what happens (should create nice halo around sun)
-instead of using global fog, use a huge box with fog material, the reason is that it can end at a defined height - just remember not to put your camera inside it


*before someone smart starts talking about atmosphere - this is just a simplification ;)

In attachment is my example of fog, with default enviro distance setting.

[Juraj]

Sort of strange that this isn't how it's working by default, or easily reachable.

Have a look at next Vray's service pack, out-of-box "Atmospheric Haze", now that is how it should be working.