V-Ray GI HDRi Splotches/Blotches/Spots

[johnclayton]

Hi all! I've been having a rather annoying problem with V-Ray and I wondered whether you guys could lend a hand.

 

I am trying to render a simple scene consisting of a plane, a cube and a teapot. All of these objects use a standard VRayMtl with just the diffuse colour set differently for each.

 

The problem is, when using a HDR image for the GI Environment (skylight) override, the render always comes out with large splotches over the floor plane and objects.

Also, if there is any animation in the scene, a large amount of flickering and 'glitching' happens around the objects in question.

 

In the GI tab, all settings are left at default with the primary render engine on "Irradiance Map" and the secondary on "Brute Force".

I have rendered out the exact same scene twice, using just a Vray Light for the first and removing the Vray Light and using a HDR image for the GI Environment (skylight) override for number two. All other settings are default. As you can see, the HDRi is causing really nasty splotches everywhere.

 

 

 

I believe this problem is caused by the Irradiance Map, as using a lower preset causes larger spots, however, since I wish to light my animations with a HDRi, I'd rather keep the render times as short as possible, and using high Irradiance Map settings drastically increases render times.

 

The method I am using with the HDRi is putting the "VRayHDRI" material in the GI Environment (skylight) override slot, instancing that to an empty slot in the material editor and in the VRayHDRI options, selecting the HDRi I am using (http://www.openfootage.net/?p=255). I also set the overall multiplier to 12 in the processing.

 

So, my question is, how can I remove these horrible splotches but still keep my render times realistic? Also, could this be what is causing the horrible flickering and glitching with animations?

 

I have attached the scene file for anyone who might want to take a deeper look. The HDR file I'm using is this: http://www.openfootage.net/?p=255

 

I'm using V-Ray Adv 2.30.01, 3DS Max 2012 on a Windows 7 machine.

Specs (just in case):

 

i7 2600K (3.4GHz)

16 GB RAM

nVidia GeForce GTX 590

 

Thanks very much in advance!

VrayHDR Problem.zip

[Ismael]

In the Irradiance roll-out, Increase the HSph.subdivs to 90 and the Interp samples to 60...

 

Look at the bottom of this page: http://www.spot3d.com/vray/help/150SP1/troubleshooting.htm#splotches

titled "I get splotches in my rendering when using the irradiance map"

[johnclayton]

Thanks ever so much for that! I can't believe I actually spent weeks trying all different complex settings when simply increasing the samples fixed it Cheers again!

[ludnid]

Or you can do the reverse. Hemispheric Subdivision - 20, 30 and interpolation sampling - 100

[Scott Schroeder]

Don't use it in your environment slot, use the HDRI in the texure map of the dome. Increase your sampling and texture resolution on your dome, usually around 64-128 samples (always stay in power of 2 numbers) and around 1024-2048 for your texture resolution in your dome settings. This way, you don't have to mess with your presets.

 

The multiplier should not be that high. I'm usually around 3-4 and the gamma on the hdri map is set to .5-.8 to get a little sharper shadow and light definitions. Using the HDRI in the dome light gives you far more control.

[Ricardo Eloy]

When it comes to IBL, the VRay Dome Light is the ONLY way to go. Do as Scott says and you'll be fine. My only consideration is that I normally set the dome multiplier to 1 (no matter which map I'm using, an HDRI or a VRaySky) and control everything inside the map itself (including the overall multiplier).