"Store with irradiance map"-like feature for direct lighting only

[henning]

For the many occasions when not using indirect illumination it would still be helpful to be able to bake certain lights into a separate lighting-map.
This could help to speed up for example rendering of big area-lights that are set to only affect diffuse anyway.
There could be a global light-map and also every light could have the option to bake out its own light-map to a separate file (or sequence for animated/moving lights).

As I understand the underlying technology is already there and implemented in the irradiance and shape-maps. So is this proposal somewhat doable?

regards,
Henning

[super gnu]

what you are asking for can be done -to an extent - this is what "shadow map" does.. although i do understand its somewhat limited (low shadow quality, no vraylights etc. ) maybe an extension to that system...?

[vlado]

To some extent you can do that by limiting the GI distance for the irradiance map to be very small (or zero), so that only direct illumination is stored in the map. The GI distance is not exposed in the UI though, you'll have to set it from MaxScript like this (works for V-Ray 2.0 only):

renderers.current.gi_rayDistanceOn=true
renderers.current.gi_rayDistance=0.0

Also make sure that the V-Ray GI environment is black. With these settings, V-Ray will not trace any GI rays - it will just store the direct light.

Best regards,
Vlado

[henning]

This is interesting. Thank you!
If you can find the time, I'd be happy if you can comment on the feature I suggested.

regards,
Henning

[vlado]

It is not impossible, although it can get quite messy, to add per-light irradiance map.

Best regards,
Vlado

[super gnu]

i guess that would tie in with the "multilight" feature people keep asking for..

[vlado]

i guess that would tie in with the "multilight" feature people keep asking for..

No, not really... they are quite different things.

Best regards,
Vlado

[super gnu]

ok! well i guess thats why you write the software and i just use it

[vlado]

Hehe They are both about storing light information, but the multilight is splitting the image into separate images for the contribution of each light or group of lights; whereas Henning's suggestion is for speeding up rendering.

Best regards,
Vlado

[super gnu]

hehe yes i understood the original suggestion was regarding speeding up rendering, but when you said it would be possible to do a separate irradiance map for each light, i assumed it would be a relatively small step on from this to output each to a separate render element, therefore giving a multilight type capability (even if not very elegant, and depending on number of lights required, damn slow!)