[jfrancis]

A typical Maxwell emitter - light goes everywhere.



An eggcrate gridded emitter - light is restricted to more parallel rays. Shadows are sharper. Sides of room are darker.

If an emitter had a 'roughness' or 'randomness' slider then the rays could be made more and more parallel. This is commonly done in studios to prevent too much light from spreading all over the place and ruining the drama of the shot. When you grid a light, you lose a lot of rays. If you redirect those rays with a parabola or a fresnel lens then you still get parallel rays, but you retain more brightness.



http://www.digitalartform.com/archives/ ... th_eg.html

[Richard]

Mate I'm not so smart to understand your principles here though do like the results your proving!

Is your grid in front of the emitter plane? And could a second BSDF layer with roughness be utilised to create this effect - I could be misunderstanding but keen to maintain an eye on this!

Edit: No I read again and get it!! The grid restricts the outward dispersion of the light! Ah - slow on the uptake! Though I'm then not sure how roughness would create more omni directional lighting? And would not providing blanking panels around the light create or maintain the same effect?

[jfrancis]

Roughness was probably a bad choice of words, since I'm using it to talk about uniform vs randomized (in this case) light dispersion.

So the default emitter right now is fully 'rough' in that it acts like a 'softbox' with white cloth in front.





A grid keeps the light from getting thrown too far to the sides. It also somewhat hardens the shadows.

[Hervé]

hello jfrancis, you can already do so... I have just tried to map a light cloth on a poly, then I modeled a grid (like the one you posted.. made it black (33gray - 100 roughness), and then put it in front of the emitter.. works as expected.. non-spilled light...

btw, I have some hdri's from HDRI-Studio, I have just copy in PS a soft cloth, and mapped it to a polygon (hdr emitter)..
(I give the link, but I don't work for them.. ) http://www.hdri-studio.com/index.html
voila..

(you can even scale it, also making the flag white works as a half spiller... hehe)

[jfrancis]

Yes, those are Maya/Maxwell grids in front of a Maxwell emitter in my first post. I probably should have mentioned that.

The problem is the deeper the grids the more light is lost, and the more noise seems to be introduced, and the longer it takes to clear.

[Fernando Tella]

And would be nicer if it could be done without modeling anything.