Correct workflow if CG object integration onto backplate... ?

[AardmanCGI]

Thanks Tashko,

That scene you sent me appears empty when I open it.

Here's my one:
provident-char-dog_forChaos-light_001.mb.zip


p.s. yes i did mean "self illumination"! sorry for the confusion

[joconnell]

Thanks for the reply joconnell,

Doesnt that require you to rebake everytime you make a lighting change? And how does that work with animation? you must be baking out the whole sequence, so again, if you make a lighting tweak you have to bake the whole sequence out again. It seems like a long winded inefficient work around?

Yeah it kind of does alright - The context that Robert did that in was of a warehouse shot that a cg object was going to be integrated into, so he had reference objects shot on set and calibrated hdr files, so once the lighting was recreated then he was able to do the ground plane bits happily knowing that it wouldn't change again. Not ideal as you say but if you need to do something tomorrow as a once off it's an option.

[jasonhuang1115]

Hey John, I saw your post of another thread and tested the workflow. It worked quite well for a simple situation where I want to integrate CG over a plane. But when I tested the same workflow with this particular scene where the candle geo is part of the mockup geo, I ran into issues of unable to completely suck out the lighting by dividing it out......Have you used this technique often in actual production for complex shots?

A very sneaky trick that I picked up from Robert Harrington in his mya 214 course for fxphd works. If you set your ground plane to pure white, then texture bake it's material to an exr so you get whatever tint and amount of light is falling on it, you can apply your projected background texture to the diffuse channel of your material, but use a divide node using your texture baked material as the second input. It'll remove the amount of light falling on the texture and leave you with the same values as the projected textures, except it'll also allow shadows to fall on it.

[jasonhuang1115]

Hi Jason,

Can you post your scene file here?

The option "Matte for all secondary rays" was introduced in V-Ray for Maya 2.4. Which V-Ray build you are using?

Hi Tashko, I will post the scene later after work. I was testing with Maya 2015 and Vray 3.0 latest RC. I have tested it with Maya 2014 and Vray 2.45 and I couldn't reproduce the test render Vlado made.

[tashko.zashev]

Thanks Tashko,

That scene you sent me appears empty when I open it.

Here's my one:
[ATTACH]21048[/ATTACH]


p.s. yes i did mean "self illumination"! sorry for the confusion

Thank you for the file.

What Maya version do you use? My files are saved for 2014, if you use a prior version I can save it to ASCII.

However, I've made few changes to your scene and you can see how the final render result looks like:


Scene file (without textures):
provident-char-dog_forChaos-light_003_Maya2014.zip

Basically the changes in this setup are:
*) Matte for secondary rays is "Off" - When is "On", the shadow can't be catches due to the self illumination added.
*) I used color gain to adjust the projection map added to the diffuse slot

[AardmanCGI]

Hi Tashko,

I was using Maya 2013.

By increasing the colour gain of the projected plate you are cheating and therefore the reflections look badly balanced and unrealistic. I want to be able to reflect the projected plate exactly as it is without any effect from my CG lighting, and I want the shadows caught within that projected image. That is why I was using the self illumination slot for the projection, I understand why that cant catch the shadows, so what is the proper solution, without gain adjustments...

[joconnell]

Hey John, I saw your post of another thread and tested the workflow. It worked quite well for a simple situation where I want to integrate CG over a plane. But when I tested the same workflow with this particular scene where the candle geo is part of the mockup geo, I ran into issues of unable to completely suck out the lighting by dividing it out......Have you used this technique often in actual production for complex shots?

No, unfortunately just in pretty simple cases as you said with ground planes and simple background walls.

[jasonhuang1115]

Hi Tashko, I've attached both Vray 2.4 (Maya 2014) and Vray 3.0 RC (Maya 2015) scene files here candle.zip.
The shadow is missing in reflections as you can see in test renders of my earlier post. I wonder how Vlado achieved the correct result?

my render

Vlado's render

[Svetlozar Draganov]

Here it is the same setup in Maya:


Some of the original materials are removed since they contained nodes with missing textures.
Scene:3.x.mb.zip

[jasonhuang1115]

Here it is the same setup in Maya:
[ATTACH=CONFIG]21086[/ATTACH]

Some of the original materials are removed since they contained nodes with missing textures.
Scene:[ATTACH]21087[/ATTACH]

Hi Svetlozar,

Thank you for the sample scene. In your sample scene, the main change is to plug the projected plate into the Diffuse Color, instead of Self-Illumination slot. The setup does yield shadows in reflections, but it also messes up the color in reflections (observed in the mirror). If you apply the VrayMtlWrapper to the candle, you will also see in the render that the candle is not 1-to-1 match to the plate anymore.

In Vlado's render, the candle reflection seen in the mirror is correct as of plugging the projected plate into the Self-Illumination slot of the VrayMtl. I am not sure how he got the shadow in reflections and if he has GI turned on?

If you are able to get, in the render:

1. the foreground candle 1-to-1 match to the plate
2. candle in the mirror not darkened/affected by scene lighting
3. with GI turned on

It would be fantastic!

[Svetlozar Draganov]

Edit: The setup that Vlado used didn't involve neither diffuse nor self-illumination slot. It uses a new Matte For Secondary Rays option called Projection Mapping which unfortunately doesn't work in Maya. For now the only option to get similar result in Maya is to use projected-texture inside diffuse slot.
We'll make a note about it into our system and we will inform you when we have some updates on that matter.

[Svetlozar Draganov]

It actually works fine - I have forgotten to plug the background image into Reflection/Refraction slot.



There is no need to plug any maps inside the Base Material of the Wrapper. What is important is to set Matte For Secondary Rays option = With Projection Mapping and to plug the Background texture inside Reflection/Refraction Environment:

Scene:matte-projection-mapping_01.zip

[jasonhuang1115]

It actually works fine - I have forgotten to plug the background image into Reflection/Refraction slot.

[ATTACH=CONFIG]21118[/ATTACH]

There is no need to plug any maps inside the Base Material of the Wrapper. What is important is to set Matte For Secondary Rays option = With Projection Mapping and to plug the Background texture inside Reflection/Refraction Environment:

Scene:[ATTACH]21119[/ATTACH]

Hi Svetlozar,
Thank you for the explanations. I was able to re-produce the desired result with GI "disabled". I would like to confirm couple things:

1. I noticed some artifacts/noise when GI is enabled (BF+BF, image sampler threshold 0.01), which breaks the 1-to-1 match. Is this a bug?
2. Can the same result be achieved in Vray 2.x?

Thanks.

[Svetlozar Draganov]

Hi Svetlozar,
Thank you for the explanations. I was able to re-produce the desired result with GI "disabled". I would like to confirm couple things:

1. I noticed some artifacts/noise when GI is enabled (BF+BF, image sampler threshold 0.01), which breaks the 1-to-1 match. Is this a bug?
2. Can the same result be achieved in Vray 2.x?

Thanks.

1.Can you send us a scene/screen-shot with GI enabled?
2.This workflow works only in version 3.x - in version 2.x you have to use diffuse-texture worflow described above.

[jasonhuang1115]

Hi Svetlozar,
[QUOTE=svetlozar_draganov;632774]1.Can you send us a scene/screen-shot with GI enabled?
Here is the scene file matte-projection-mapping_01_withGI.zipwith GI enabled. I've also applied the VrayMtlWrapper to the candle.

The below are two renders for comparison:
no GI.


with GI enabled (BF+BF).


I have the "No GI on other mattes" enabled in the VrayMtlWrapper, but it doesn't seem to work and yielded bounced light onto the Candle, which is also the matte surface in the scene.

Thanks.