3.50.01 DomeLight reflects in matte objects

[LudvikKoutny]

Hi,

I've encountered a serious show stopper with latest V-Ray beta.

I have a tracked TV shot plate with stand in objects and a 3D scan of hero car object which is tracked on top of the real car on the plate. I will be needing to add some elements into the scene, that reflect in the car. Obvious choice would be making tracked car geometry a matte object that has reflections enabled, but it's that pesky DomeLight again

It seems that DomeLight gets reflected in scene's matte objects that have some reflectivity on them. That of course does not makes sense in context of CG integration, because objects shot at the location already contain reflections of their surroundings, so DomeLight getting reflected again in the CG recreation of your scene basically adds second set of reflections on top of already existing ones, making scene look wrong.

If I do not use DomeLight, just environment map and GI, this problem does not occur and environment reflections are correctly ignored. Two other renderers that I regularly use do this correctly too, regardless of if importance sampled IBL is on or off, so that should not be a limitation.

Would it be possible to squeeze fix of this to beta 2 perhaps?

[Art48]

Dunno if I get correctly what you do but what about:

Possibility 1) Uncheck "affect reflections" in the domelight (Dunno if that works for your scene since you may need reflections of it somewhere else?)
Possibility 2) Check out trace sets and exclude only your desired geometry from reflections.
Possibility 3) Dial down the reflections spinner to 0 on the matte object properties of your matte object.

I guess 3 is the way to go for your scene if I understand you correctly.

[vlado]

Can you get me a specific scene example where I can see the issue?

Best regards,
Vlado

[LudvikKoutny]

Can you get me a specific scene example where I can see the issue?

Best regards,
Vlado

Yep, here you go: DomeLight_MatteReflection.zip

Here's example with DomeLight enabled:


And here's how it looks with Dome disabled:

Dunno if I get correctly what you do but what about:

Possibility 1) Uncheck "affect reflections" in the domelight (Dunno if that works for your scene since you may need reflections of it somewhere else?)
Possibility 2) Check out trace sets and exclude only your desired geometry from reflections.
Possibility 3) Dial down the reflections spinner to 0 on the matte object properties of your matte object.

I guess 3 is the way to go for your scene if I understand you correctly.

Nope, none of them is a solution, because:

Possibility 1 - My CG objects that are added into shot scene would then have no reflections from domelight
Possibility 2 - DomeLight is not a geometry, so it can not be picked in trace sets
Possibility 3 - My CG objects would then not reflect into stand ins of objects shot on the plate, as desired

[vlado]

Select the sphere, open the MaxScript editor and type this:

t=vrayAddTraceSets $
append t.reflect_exclude $VRayLight001

This will exclude the dome light from reflecting in the sphere.

Other than that, I will take some time to do changes to the code and test whether everything still works correctly.

Best regards,
Vlado

[vlado]

An alternative solution is to select the material of the sphere, enable the "Dim distance" option in the Reflection section, and put some large-ish reflection distance like 10000 or something.

Best regards,
Vlado

[LudvikKoutny]

Thank you very much! Will try those out ASAP.

It seems like 33% of issues I run into with V-Ray are related to DomeLight being considered actual physical object in the scene rather than scene environment background.

I am not a programmer, but I reckon it could be better to change DomeLight to be sort of an environment background modifier rather than actual physical light source in the scene. I mean... right now it looks like it requires more and more exceptions added into the code I may be wrong though

[vlado]

Well, like with everything there are pros and cons...

Best regards,
Vlado

[LudvikKoutny]

Well, like with everything there are pros and cons...

Best regards,
Vlado

Yep, I understand

And just tried dim distance trick, and it worked. So I guess I am safe until the fix is out. Thanks again!

[Alan Iglesias]

Well, like with everything there are pros and cons...

Best regards,
Vlado

Yes, but options serve both uses.

How about a Dome Light option for Object/Environment orientation?

-Alan

[vlado]

How about a Dome Light option for Object/Environment orientation?

Can you explain this a little bit?

Best regards,
Vlado

[Alan Iglesias]

Can you explain this a little bit?

Best regards,
Vlado

Sure.

If I understood correctly, Recon422 was saying that he has seen a number of issues using the the Vray Dome Light for Environmental purposes that were not working so well due to the Dome Light's object-orientation as a light source. Then he suggests a change of the Dome Light's primary purpose to more of an Environmental tool than an object-based lighting tool:

("It seems like 33% of issues I run into with V-Ray are related to DomeLight being considered actual physical object in the scene rather than scene environment background." ...I reckon it could be better to change DomeLight to be sort of an environment background modifier rather than actual physical light source in the scene. I mean..")

Then you replied that there would be "pros and cons to that", which means to me that you are probably concerned that if you changed the Dome Light too radically, many users would be unhappy, which of course makes perfect sense.

I am just saying that perhaps an option to turn any Dome Light into something more Environmentally-Oriented (I'm sure Recon422 can give you the details of what that would be exactly) would satisfy both customers - those who want it to stay the same and those who are looking for more environment-friendly usage (perhaps even a new special-class Dome Lght?)

Well, that was my meaning. If I somehow mis-understood the conversation please disregard.

-Alan

[vlado]

No, I wasn't really concerned about users being unhappy as the things that I plan to do will be mostly transparent to them. One is to implement the skylight portal option for dome lights, which we discussed in another thread and it is almost done. The other is an option in the environment dialog to internally create such a light automatically. I can't see anyone being unhappy with either.

Best regards,
Vlado

[Alan Iglesias]

Understood!

-Alan

[LudvikKoutny]

Hi,

I just checked this, and it is still present in Beta 2.

It would be good to have finally all of the matte cg integration toolset working correctly in 3.5.