Need help with vray settings

[Rohan Kulkarni]

I'm attaching a render of a scene I'm working on. I'm rendering at quite high settings, but still getting patches on the wall. Apart from the cove lights (made using vraylightmaterial), there is only one light in the scene - a vray plane just in front of the window. Increasing its subdivs from 8 to 24 helped a lot, but didn't completely remove the patches.

vray.jpg
C5.jpg

So what can I do to improve this render?

[complete-newbie]

You'll get better answers than this one, but just to get the ball rolling:

I would suggest not using Vraylightmat for actually providing light, as it seems that doing this often results in this sort of difficulty to get a clean render, forcing the user to push settings to the point of very slow renders, with no real benefit. Perhaps try to replace the cove lighting with plane light(s) and make sure that there is sufficient light in the scene generally and that, if you are using a Vrayphysicalcamera, you are not using the camera settings to compensate for insufficient light in the scene.

I'm sure better brains than mine may comment on your Hsp subdivs and interpolation etc. but I think a good starting point is make it easier for the renderer with better light quality.

Hope this helps,

good luck.

[george sandoval]

Hi,

I've found that a surface needs a light on it to take away blotches. I've had a white ceiling that looked blotchy
and the minute I shine a plane light on it; no matter how low the brightness - the blotches go away. I would just have a plane light shining on the wall (same size) with a low intensity. If it gets in the way of other geometry just render it separately and splice the non blotchy wall into the overall image. I've found that very often I have to render walls, ceiling and floor separately. And if you do have them separate then you can adjust their values in Photoshop very easily.

[Rohan Kulkarni]

Thanks for the replies. I guess low light is the main problem. Will try replacing cove lights with vray planes. Maybe I can put a vray plane just below the ceiling, to fill up the room with light.

I still need help with GI settings. Where can I read up on them in detail? I don't want to just blindly increase render times if its not going to help the image quality (which is what I've done here I guess).

[complete-newbie]

I think with the lighting improved you'll just be reducing the settings from what you attached previously, hope I'm right. I'd expect you could go back to very low or low on IR presets or an equivalent custom IR setting and reducing your LC sub-divs down almost by half and achieve a similar quality in substantially less time. If you need fine tuning perhaps then just on the image sampler and LC hsp subdiv's / interpolation. Depending on the image size you're producing I would be inclined to switch off any AA filtering too.

Hope this helps

Cheers

[Ramjanur Rahman]

Plane light may be a solution for your problem.
You can try mash light for cove lighting.
Play with noise thrash hold value if u use DMC sampler

[David Sanchez]

VRayLightMtl by default only uses GI, so without a huge number of hemisphere subdivisions in your irradiance map, you will get blotches. In later versions of VRay, you can set the VRayLightMtl to use direct illumination, which makes a huge difference. Other than that, as everyone else suggests, you can use a plane light, which does give-off direct light anyway.

[Corey Beaulieu]

In later versions of VRay, you can set the VRayLightMtl to use direct illumination, which makes a huge difference.

Ticking "Direct Illumination" in a Vray Light Material merely turns the object into a simple Light Mesh, the same as if you selected the object and turned it into a Light Mesh only in this instance you have less control and the method breaks down in a multi-sub scenario.

If you need light, use a light. If you need to fake a frosted glass or ceiling light being on when you are using larger plane lights, then use a light material.