luminance mapping...

[Giovanni]

Hi all,
I am trying to use a luminance map (grayscale) to simulate 2x2 fixtures on a large ceiling. Basically, this is a reflected ceiling map, with a bunch of white squares on a white background. I can map it in the self luminance slot of a standard material, and v-ray does pick up the lighting from the mapped squares.

Question is, how do I control the intensity of that lighting? I have the self luminance at 100% and it is still not enough. I played with color mapping for the map, but then the background (the ceiling survace) starts to emit light as well...

What is the "proper" workflow for map lighting using v-ray, in order to have maximum control over the light?

Thank you

regards

gio

[vlado]

Use the VRayLightMtl material.

Best regards,
Vlado

[Giovanni]

hmm, using directly the Vray light material with my luminance map in the texture slot will produce black surface where the map does not cast light.

Is there a way to have the black areas of the map showing the regular diffuse of the object?

I tried to use the vray light material in the luminance slot of a standard material, but I cannot select it, it needs a map, not a material.

Thank you

gio

[peterC]

Did you try and use a blend material?, use the vraylightmaterial in on cannel and the normal white in the other, then use your map to blend between the two.
Hope it helps
Peter

[Giovanni]

Thanks peter, the blend material worked pretty well.

The only thing, it takes very long to render, but I gues it is because I have hundreds of little squares in the mask map, therefore it must be like having lots of light sources...


regards,


gio

[flipside]

I would do this with normal self luminance set to 100. Then instead of cranking up the light parts with whatever method, I would place a large invisible vraylight under your whole ceiling. Then turn off send GI for the ceiling, since that will be taken care of by the vraylight.

Now you have a ceiling with light and normal parts, and it looks as if the ceiling casts light into your scene because the vraylight lights it all up. You have only one light (with vrayshadows---->=nice) instead of hundreds of small lights that cast pure GI and will take long to render with ir map or whatever method.

It's already late, I hope you understood what I'm trying to say

[Giovanni]

Thanks flipside, it is a good idea, however, I think I rather spend some more rendering time than using one vraylight.

The reason is that now I can go back to illustrator and adjust / modify both my diffuse map and the illuminance map, which are mapped in MAX with one UV modifier, and register perfectly onto the model.

Also, the light distribution using the luminance map is much more accurate, and reflects the design of the ceiling system.

Instead, one large vray light would be quite generic, and it would neglect the details of the location of the single fixtures...

Thank you for your replies,

regards,

gio