Red Splotch Problem VRay_Adv_1_47_03 - Scene File Included.

[bdahlinger]

Hello,

The red splotch problem still gets us from time to time, this time I trapped the little buggers.

http://www.rezn8.com/images/Rezn8_Re...ctLight_01.max

Seems to be a problem with a direct light casting a shadow map. Change the shadow plugin to vray shadow map, and the splotches go away.

Only happens on these frames: 168, 276, and 404

Max7.5
VRay_Adv_1_47_03

Thanks,
Bill Dahlinger

[natty]

Its very hard to see what you mean .. you havent got anything set up?

i would say it is your shader .. you are using a standard Metal shader ..

[bdahlinger]

On 3 different machines, it is reproducable..

go to camera view, render frame 404...red splotches on metal tube.
change shadow type for the direct light to vray shadow map, render, no splotches.

one thing i meant to do was change the sampling to adaptive..that will help show the problem better.

Thanks!
Bill


tested also on vray_1.46.15..also red splotches.


Standard shadow map in Direct Light

VRay shadow map in Direct Light

Its very hard to see what you mean .. you havent got anything set up?

i would say it is your shader .. you are using a standard Metal shader ..

[jacksc02]

Change your metal shader to a vray material and the splotches will go away

[bdahlinger]

Thanks for the tip!

I've found a work-around by changing the shadow type. This post is meant to expose another method to the common red-splotch problem so that the vray developers can fix it. It comes up often at my office and it would be best if vray worked with say, metal shaders, rather than finding the work-arounds by converting standard materials to vray materials. Maybe the core of the problem lies in the direct light, because I've seen this happen in another scene.

Thanks!
Bill Dahlinger

Change your metal shader to a vray material and the splotches will go away

[vlado]

Bill, thanks for the file - I can reproduce the problem here and I'll be looking into it.

Best regards,
Vlado

[natty]

Why dont you just change your non suppoted shader ? .. works here .

[vlado]

It's not a matter of shading, as this happens even with VRay materials. I think it is the combination of shadow maps and the fact that the light falls exactly parallel to some surface; the fact that it happens only with shadow maps, and not with any other shadow type leads me to believe that this is a problem of the 3dsmax shadow map. This is supported by the fact that changing some of the shadow map parameters leads to changes in the red dots as well. I will have to do some more tests though.

Best regards,
Vlado

[dimo]

And again it's time for a vray shadow map. And it could render Vrayproxies as well...

Here' s my wishlist:

-Being able to save and load the shadow map for static scenes
-Better blurring (zBased?)
-Rendering of all Vray supported geometry (proxies, etc)


I started to write this myself but I got stuck with it. I couln't get any helpful sourcecode of the actual shadow map generator. And I could't figure out how to do this (The appwizard isn't very helpful with this).

Of course Shadow Maps are old technology but we have some lighters here that can do wonderful things with simple shadow maps.

Best Regards,
Dieter