vray matte surface reflection AND gi not showing

[bumba]

Hallo,
there is allready a thread: vray matte surface reflection not showing. I did not want to hijack the thread.

But I need to expand this topic. It is not only the Reflection, that is missing in the RGB Channel, the GI information is missing as well. I tested wit the nightly vray_adv_41203_maya2019_x64_29461.

Gi is harder to spot, but I supply the scene test.ma (test.zip)



rendered "beauty"

rendered with wrapper (no reflections and gi in the RGB channel)

alpha of wrapper




Thx in advance

[bumba]

I just tested against an older version of vray : vray_adv_40404_maya2019_x64_29418

The reflections used to work, but allready then the gi was not captured ...
Thx again

[hermit.crab]

Thanks for the report. We're aware of the missing reflections on the matte surface issue, it is already reported to our developers and it is on their to-do lists. However, there doesn't seem to be an issue with the GI shadows, you would need to change the environment color so that they are visible (or change color of the shadow itself).

[bumba]

Hi Aleksandar,
I disagree. I do not now what GI shadow is. But there is red bounce light from the sphere on the grey plane in the "beauty", which comes from the gi. If you look at the raw_gi renderelment the red bounce from the sphere it is getting mor obvious. This red conamination is also accounted for in the alpha. But nothing is in the rgb Channel. The gi as well as the reflection is NOT present. Probably both problems are related and the developers could fix both in one stroke



THX in advance
Christian

[hermit.crab]

The lack of GI in this scenario is expected. Though it happens with a matte surface (with a black background), it is not tightly linked to it - any material with a pure black diffuse won't generate GI.

[bumba]

Hi Aleksandar,
"any material with a pure black diffuse won't generate GI"
The material of the plane, as the beauty in the first post shows is GREY, not black.

What would then be the workflow to capture gi in the rgb channel of the vrayMtlWrapper?

And what ar these for (From the online help) :
... "base material is still used for things like GI, caustics, reflections, etc"
"GI amount – Determines the amount of GI shadows." ...

Ther is a scene file in the test.zip of the first post.

Thx in advance
Christian

[hermit.crab]

I understand your confusion, however, the GI shadows are dependent on the background color.

Regarding the main topic, the missing matte reflections - there is a fix for the issue that will be implemented in tomorrows nighty build.

[bumba]

Hi Aleksandar,

the following current Version does still not work for reflections:
[2019/Sep/10|18:23:52] V-Ray: V-Ray Next for Maya, update 1.2 version 4.12.03.29488, revision 29488 from Sep 10 2019, 03:43:49
[2019/Sep/10|18:23:52] V-Ray: V-Ray core version is 4.12.03

the following Version did work (for reflections, not for gi)
[2019/Sep/10|22:26:23] V-Ray: V-Ray Next for Maya, hotfix 3 version 4.04.04.29418, revision 29418 from Aug 15 2019, 18:03:06
[2019/Sep/10|22:26:23] V-Ray: V-Ray core version is 4.04.04

From my memory earlier Vray Versions worked for gi also, but I cannot test it anymore, because I will not install older maya versions.

The VRayMtlWrapper is from my understanding a kind of a helper shader, which can be used in compositing.
It should enable us, to comp an image in a compositing application
with or without reflections,
with or without shadows,
with or without gi,
with or without refractions,

... WITHOUT the background (that is important or I would not use this shader in the first place)

with the help of an alpha over a backplate.

Currently I cannot do this.
I can cach the gi, reflections and the shadows with a couple of renderlayers and some overrides, but this requires more renderings and is tedious to setup.
And VRay is super userfriendly and interactive in so many ways and I feel we are regressing.

If VRayMtlWrapper ist not cast for this job, I guess we should put this thread into the whishlist and invent a new shader that does it.
And yes, by now I am confused.

If there is an elegant way to catch the above mentioned without to many overrides, help is apreciated.
THX in advance

Christian

[bumba]

- 0002339: [bug] "Generate GI" and "Receive GI" options in the wrapper material and object properties have no effect;

perhaps related ... from the changelog.txt

[hermit.crab]

Thanks for the feedback. We'll consider your suggestion. Regarding requests for nightly build access, please write to support@chaosgroup.com mentioning this thread.

[bumba]

REFLECTIONS WORK AGAIN !!!

Hi Aleksandar,

I am using nightlies all the time and also reffering to them

Todays build works with REFLECTION, yeah, (still not with GI though ...)

[2019/Sep/11|16:55:26] V-Ray: V-Ray Next for Maya, update 1.2 version 4.12.03.29492, revision 29492 from Sep 11 2019, 02:36:16
[2019/Sep/11|16:55:26] V-Ray: V-Ray core version is 4.12.03

THX
Christian