LuxRender official feature request thread

[Lord Crc]

Ok, here's one: Multiple camera's per scene.
The camera's would be rendered simultaneously sharing light paths and memory. Useful for walkthrough animations, archviz with multiple pov's, 3d stereo, etc.

While this sounds good on paper, I suspect the speed-up is minimal and the added complexity would be great (not to mention memory usage for larger resolutions). The problem is that generating the light path is a relatively small part of the whole pie. The majority of intersection tests (which in total stands for 60-80% of the cpu time) comes from connecting the eye and the light paths, and since the eye paths will be different there's little to share here.

For animation and such I suspect photon mapping or something similar would be a better approach.

[SATtva]

Or even like that?

No, actually I was aiming for the effect of molten marbles cooling off on a production line. They start off orange hot, but eventually gradiate through red and then to black, and the red is somewhat clear, yet emissive. Sorry to go a little off topic.

I'm sure this is also possible, but too tired now to make the material. I'll take a look tomorrow if I have time.

[thomas]

@patro & Lord crc. Yeah, I already guessed that the Multicam™ feature wouldn't work. After all, why else would no renderer have implemented it. I think I figured you could reuse also the eye paths after the first vertex or something. Thanks for your explenation lord crc.

[patro]

added feature request for Multilayer texture with blend mode!

I opened a task in mantis:
http://www.luxrender.net/mantis/view.php?id=834
it's linked with this thread.

[juusop]

Off-topic continues, sorry.

Hi SATva, and thanks for those tips on lights. They seem really useful if you want to create for instance more interesting soft boxes. But I've been wondering whether it's possible to use a half transparent light material using an opacity map. If I understand correctly one should avoid using mesh lights with high polygon count. Therefore modeling a good old umbrella light for reflections may not be the most efficent way to create studio-like reflections. Of course if the background is completely black using the methods you mentioned will work but if there's some kind of environment there will be a strange looking black border around the light which destroys the illusion.

[SATtva]

whether it's possible to use a half transparent light material using an opacity map

Well, you can use the opacity map to also control the emission color (as you observed with my examples above) and make it black (non-emissive) in parts which should remain transparent.

If I understand correctly one should avoid using mesh lights with high polygon count. Therefore modeling a good old umbrella light for reflections may not be the most efficent way to create studio-like reflections.

Umbrellas are used as light reflectors. So it's much easier to make a simple rectangular meshlight and place it in front of an umbrella (with highly reflective material) so the light will reflect off of it in the direction of your objects.

[juusop]

Umbrellas are used as light reflectors. So it's much easier to make a simple rectangular meshlight and place it in front of an umbrella (with highly reflective material) so the light will reflect off of it in the direction of your objects.

I feel like an idiot now. I'm too used to biased rendering (VRay, mental ray) where you usually try to avoid indirect illumination by using all kind of dirty tricks. But yeah, your solution sounds like the right way to do it.

One thing about those opacity mapped emitters though. I tried using a black and white image to control emission color which produces a strange looking black border around the light as I mentioned earlier. Actually it's grey but yeah, it's still looks pretty weird when it's in front of an environment map. But accidentally, really, I assigned a null material to my mesh light and noticed that it has emission options and when the opacity map is used here the border is gone. It's good to know that this possibility exists. Here's a quick test.

[SATtva]

Yep, precisely, with unbiased you can just think as a photographer without resorting to all kinds of black magic. If you need a screen, place a mattetranslucent mesh between the lightsource and scene objects. When you need an umbrella, make a reflective umbrella.

[Lord Crc]

Yep, precisely, with unbiased you can just think as a photographer without resorting to all kinds of black magic.

I think what you meant to say is "with unbiased you can just think as a photographer resorting different kinds of black magic"

[SATtva]

Um, well, this depends on your point of view.