takes_forever_to_render_with_global_Illumination

[mhouse777]

Hi,
I've made a simple scene with vray environmental fog for clouds in a box gizmo. My units are in meters. The clouds would render really dark, but would render kind of fast. I then added enabled GI , and now I havent been able to render b/c it was so slow, it will take a few hours to render just one frame. Any help on optimal render settings would be greatly appreciated. Thanks.

3ds Max 2019 64bit, Vray next update 2.1

[hermit.crab]

The slowdown is caused by the excessive amount of GI scatter bounces in the VRayEnvironmentFog settings; the default amount is 1, so start from there.

[DanSHP]

Clouds with vrayfog is tedious and slow...I gave up on it, its just not practical in my experience.

Some of the guys in our office use Enscape with Revit.
Just look at how easy it is to create clouds with instant results.

Settings galore
https://youtu.be/82KRH0V2UmM?t=418

Clouds reacting with light source
https://youtu.be/82KRH0V2UmM?t=483

Is there an easier way to create clouds that doesn't take vast amounts of time to test and render?

I've tried a few VDB clouds and it's similar problem with testing, memory usage and render times.

[Vizioen]

Clouds with vrayfog is tedious and slow...I gave up on it, its just not practical in my experience.

Some of the guys in our office use Enscape with Revit.
Just look at how easy it is to create clouds with instant results.

Settings galore
https://youtu.be/82KRH0V2UmM?t=418

Clouds reacting with light source
https://youtu.be/82KRH0V2UmM?t=483

Is there an easier way to create clouds that doesn't take vast amounts of time to test and render?

I've tried a few VDB clouds and it's similar problem with testing, memory usage and render times.

https://elementacular.com There's this, but it's only maya and it's being discontinued. BUT they are looking to make it open source, so whoever can port this to 3dsmax... would be awesome.

https://www.youtube.com/watch?v=oZJs2OMLPFY

[DanSHP]

https://elementacular.com There's this, but it's only maya and it's being discontinued. BUT they are looking to make it open source, so whoever can port this to 3dsmax... would be awesome.

https://www.youtube.com/watch?v=oZJs2OMLPFY

Looks great!

[mhouse777]

Thanks for the feedback guys. Specifically to Aleksandar Hadzhiev, that made a huge difference, but still very slow. Does scale effect VRayEnvironmentFog rendering? This scene was sent to me by the chaos group and I was trying to apply the settings to a larger scene (meters) instead of centimeters, and it renders very fast..

[DanSHP]

Thanks for the feedback guys. Specifically to Aleksandar Hadzhiev, that made a huge difference, but still very slow. Does scale effect VRayEnvironmentFog rendering? This scene was sent to me by the chaos group and I was trying to apply the settings to a larger scene (meters) instead of centimeters, and it renders very fast..

With your scale set to CM it rendered faster?

[mhouse777]

...the file i posted above was from chaos group , and their scene units were in cm , and rendered way faster than mine which I made in Meters. Btw, does anyone know what causes these black spots in the render? Thx.

[joconnell]

Step size is a big parameter in the environment fog settings - it's pretty much how frequently in depth vray will stop to calculate how much fog has built up. Say you've got a scene that's 100 metres long and you've a step size of 1 metre - that means if vray can see right to the back in some areas it'll keep stopping every 1 metre to record a new fog build up amount a total of 100 times. If you set your step size to 10 metres then vray will stop 10 times through the volume - it'll be less accurate but far faster. I'm not sure if the step size is tied to what unit size you use (so metres to cm could mean a factor of 100 higher) but it'd be worth trying to set this value higher by a factor of 10 and see what it does for your speed.

[mhouse777]

Thanks Joconnell for the explanation and information. I'm spending a lot of time on this scene , learning all the parameters in VRayEnvironmentFog settings, but now I'm dealing with some strange artifacts on the clouds, they look charred or burnt. Any ideas what causes this?

Thanks

[DanSHP]

Thanks Joconnell for the explanation and information. I'm spending a lot of time on this scene , learning all the parameters in VRayEnvironmentFog settings, but now I'm dealing with some strange artifacts on the clouds, they look charred or burnt. Any ideas what causes this?

Thanks

Is that the fog interacting with the bottom of the gizmo box?