Light directionality bug

V-Ray V-Ray Common Public
1

Hey guys,

So I noticed a bug that appears when using the directionality attribute on VrayLightRect lights.

Enabling the directionality attribute, at certain values, causes strange artifacts to appear that lights cast shadows.

See attached shots comparing a light with no directional value:

https://postimg.org/image/jrbpwg2op/

and then using a directional value of 0.4:

https://postimg.org/image/4u38vfpg9/

The problem appears in both Max and Maya. I can supply my Maya scene file if needed.

- Nathan

2

Yes, a scene would be very helpful. Thanks!

Best regards,
Vlado

3

Sure can! Here you go. I’m using Maya 2016 Extension 2 with Build 3.40.03.

I can replicate the bug in 3dsmax and VRay if needed.

http://www.speedyshare.com/HKAn9/VRayDirectionalityBug.ma

4

Was there ever a workaround or solution for this? It seems to have reared it’s ugly head in a scene I have and I can’t get it cleared up.

5

After further investigation it looks like this was due to the new Adaptive Lights in 3.5, not necessarily the directionality. If I set it to Probabalistic or Full it renders out just fine. Oddly it also seems to mostly go away if I leave it on Adaptive but turn off Sub-Pixel mapping (I had it on before).

With Adaptive on (at 8) and sub pixel mapping off these are the results (it’s only a crop of a larger image):
RGB:

RawLighting:

Sampler:

It’s most evident in the Sampler where the artifacts are showing up but you can see the different shading in the dark vertical bar in the center of the RGB image. If I set it to Probabilistic or Full everything is nice and smooth. The artifacts repeat the same each time as long as I render a full image but it the pattern shifts and seems reduced if I render a smaller area. Rendering it with a higher adaptive amount (e.g., 24) the effect is diminished but still evident.

Any ideas?

RGB.jpg
RGB.jpg860×559 28 KB

Raw Lighting.jpg
Raw Lighting.jpg860×559 66.8 KB

Sampler.jpg
Sampler.jpg860×559 120 KB

6

Do you use light linking? There is a known issue with it that I’m looking at right now.

In any case, having the scene will be very helpful to track and fix the issue.

Best regards,
Vlado

7

I don’t think I have any light linking active. I’ll try and strip down the scene and see if it still occurs and send it along.

8

Here’s the scene.

Just render the camera… It’s stripped down a lot but still has the problem.
Scene.zip (153 KB)

9

Thanks, I can reproduce the issue and I’m looking into it now.

Best regards,
Vlado

10

So I figured out why this happens; now I need to figure out a solution :slight_smile: It should be fine in 3.50.04.

Best regards,
Vlado

11

Great. Glad to help.

12

Hi,

Was there a resolution to this? We’re experience the same issue in Maya 2017 SP3 and V-Ray 3.60.01.

Thanks

Nick

13

Can you attach or send us an example scene with the issue?