Exclude include material id for lights

[MANUEL_MOUSIOL]

I often have one object with a multi sub material and wasn to use certain lights only for certain areas of the object that have a different material assigned to it.
would it be possible to add a function to the vray light exclude include list to support material IDs?

[MANUEL_MOUSIOL]

Is this technically not possible?

[vlado]

It's quite complicated... Can you tell me in what situations you need to do this?

Best regards,
Vlado

[MANUEL_MOUSIOL]

I often have product shots with different materials, that are often mapped (no separate geometry for these materials, e.g. a logo). Instead of having to render out a different lighting setup i could do it with existinge including towards a material id and have everything in one shot.
like for example a logo on a surface, which needs to stand out in the middle of a highlight. In photography you would have different takes and then comp on the different lighting setups. With 3d it would be possible to circumvent that step .

[andy51]

I am confused now. Have you tired the V-Ray Switch material. If you have a product, which will be rendered with a variety of materials, the switch material would be a good choice, but I am confused when you say different lighting setups and having everything in one shot. Are you asking for different lighting setups, that use material different material ID's, so you would render out that particular ID's element and have lighting for that part of the scene only and therefore you could render out a scene, using several elements, which would result in you rendering out several lighting setups in one render.

[MANUEL_MOUSIOL]

More or less The later l, even though I didn't think of render elements. Just to be able to exclude/include material ids for each light.

Look at this product shot I downloaded from Google . The logo needs to stand out. it has a different material than the body it sits on. Probably i would need different lighting to make it look so shiny and a different lighting for the body which needs broader lights, then for the upper part different lighting again.
usually Id need to render out two versions and comp in the logo. If I could tell the lights to ignore one material and only be visible in another, then it could be done with one render, saving a lot of time .

[andy51]

To be honest, I think yuo are making this way more complicated than it needs to be. For instance, the product shot you posted could have been done one of three ways. It could be a product photo, edited in photoshop. It could be a totally photoshop created image (my guess since it looks fake to me, not ) or it could be a 3d object, rendered and then edited in photoshop.

The reason I say that product shot is al Photoshop, is that the printing doesn't seem to wrap around the shape of the container , it looks very flat. and there's the fake shadow and reflection on the surface the product is standing on.

If you are required to model something like this, I would imagine the lighting would look far more accurate (hand created HDRI most likely) the whole thing would look more realistic as far as the printing wrapping the object correctly, along with correct shadow casting and reflection. BUT this things about hiding certain parts of the scene, from certain lights, via material ID's, therefore creating a single image, that has totally fake lighting, that would never be possible in reality, just seems like a lot of work, to add a feature, just to create totally fake product shots. Rather than creating materials that react to the lighting correctly in the first place

The label material for example, would have diffuse pink and black for the text. a refelction map to create the dul sheen for the main pink part and slightly less blurry shine on the logo and of course you'd need to use proper UV Mapping....

Anyway, I am pretty sure fol has been producing procust shots similar to this , using Max and V-ray and never thought about a feature as you have requested.. Sounds to me that you need to practice more on your material creation and studio lighting setup, rather than try have V-Ray lights, bascially fake it for you... In my opinion, Vlado is right and the whole thing would be far to compicated to implement, when in my opinion, it is not really necessary.. But hey, that's only my opinion

[MANUEL_MOUSIOL]

Sure, you're right . Maybe my clients are right too though, and I'm speaking here only from 8 years of experience in retouching and cgi for cosmetics, vitamins, cameras and tobacco.
hey,I would love to do everything realistically and in one shot, but a lot of times that's simply not possible. It's not even a matter of my posted image being good or not or real or not. It was just an example of what I mean, quickly searched on Google. It's a matter of what is being asked for me on a daily basis.

and if a client asks to see the logo in a certain way and wants to bring out the metalic texture of another part but wants the even other part to look as soft as the material of the product feels, there is no way to do it in one shot. Product shots are not supposed to be realistic, they are supposed to show you how it looks and feels when you have it in your hands or even better, how the producer WANTS you to see it. how would you go about doing something like this if not having multiple setups and photoshoping them together (and thats what we do daily)? Just asking interested about your approach.

Anyway, bottom point, for me this feature would be super useful and I'm thinking I'm not alone, looking at the 20 year history of the company I am working for and what they produced and are producing.

[^Lele^]

If the parts have to be so different to require radically different a lighting setup, my suggestion would be to mimic the Photography part: shoot twice, comp.
For even if you could have such a setup as the one you wish, the setting up, maintenance and general control of it would be utter hell (imagine matIDs are needed to change for some other, shading, reason...).

[MANUEL_MOUSIOL]

That's what we are doing right now.
it doesn't need to be radically different lighting though . Just one light added and one excluded could do the trick to make something stand out .
I mean, that's what exclude include is for, right? There's a reason why it was invented. Why would it be a bad idea to have it for materials too?
I'm my case I never switch material IDs . If I would want to change something I just add a new.
maybe there's another way than material IDs...

I want to remind you: the comping of different setups is a standard procedure in advertisement graphics. But why go the hard route if it could be done in one shot? Sure, the coding seems to be complicated ... but that didn't stop us from doing amazing things in the past, right?

[^Lele^]

Oh no, i do see your case.
What worries me is general (mis) use, not its usefulness in the specific scenario, or your ability to have it do what you want it to.

For example, i'd contend you could make this work right now, using MMs (with matIDs) and light groups with LightSelect REs. One setup, render, a bit of post.

[MANUEL_MOUSIOL]

Sorry, could you elaborate on that? I didn't get it

[^Lele^]

a combination of masks by material ID (MultiMattes in MTlID mode) and full lightSelect render elements would allow you right now to have both lighting setups affecting both material IDs, and then to freely, and very quickly, split and recompose as you wish in post.
See the attached max file, i'm sure the comping part will be obvious.
multilighting_by_MtlID.zip

I'll attach an example comp, and the results as contact sheet.

edit: thanks for this Manuel. In fact, with Adaptive lights, you could throw at a single scene as many "light rigs" as you pleased, to render in one go (properly split in their REs, up to, i think 64), and then be mixed later through one-click, perfect masks. Your issue, revisited in light of the new techs, has opened me a pandora's box of possibilities.

[MANUEL_MOUSIOL]

Right! Great idea! Never thought about that . Thanks .
I'm still hoping my request will someday come true