Cylindrical vray light, I know this was already asked but really needed now

[priad]

please please please, cylindrical vray light, I know that we can do a cylindrical light with a mesh and vraylight mtl but I don't want to puch the GI to have a correct rendering.
BTW if I scale a sphere light only on one axe does it change the way the light light my scene?
Thanks a lot
cheers

[vlado]

You can create a self-illuminated tube and surround it with 4 rectangle portals lights. Then you will not need the GI to make the material emit light.

Best regards,
Vlado

[^Lele^]

BTW if I scale a sphere light only on one axe does it change the way the light light my scene?

I believe the only spinner that actually works for the spherical area light is the first one, hence it'll always be spherical, regardless of the shape the light helper will take up once scaled with the scale tool.

And Vlado, you DO know that sometimes you p**s me off big-time (in an extremely good way) when you drop these bombshells in the space of a half-hidden reply, yes?

[^Lele^]

So the method works with any geometric shape, but it does have a couple of drawbacks, mainly to do with the need to sample lights a LOT to get clean results, meaning the render phase may be slow with complex geometric lights, and / or textures applied to the vraylight material.
The attached image (heavily compressed) is rendered with 6 light portals with 64 samples each.
Rendertime, without AA, was 7minutes odd on an x2-4200, of course, purely in direct mode (ie. no gi whatsoever).
Quality's governed by the light portals' subdivs, speed is likely to improve as the number of polys making up the light object decrease.

[Aldaryn]

Why did you used six light for that? In this example one would have done the trick too. Actually the complexity of the scene "behind" the portal light has a surprisingly small effect on rendertimes. The main control will simply be how many subdivs you use to sample the Vraylight. But anyway, I could be wrong.

Best regards,
A.

[^Lele^]

Uh, yeah, possibly, I'd need to check how a flat light below the object would handle distribution further away from the projection of the object on the ground.
It's because i am thinking of a script to handle this, so i thought directly of a bounding box

[bardo]

quote for lele.

When yesterday i've read vlado's trick i thought "genius" and i tested it immediately and it works.

Great.

[Aldaryn]

Uh, yeah, possibly, I'd need to check how a flat light below the object would handle distribution further away from the projection of the object on the ground.
It's because i am thinking of a script to handle this, so i thought directly of a bounding box

Ah, got it! You do know that Vlado's working on geometric lights atm?

Another thing, I find it quite amazing how well the skylight portal VRaylight blends with the cached GI solutions. You can hardly see the transition where the irradiance map ends, and a per pixel sampled region of the portal starts.

Best regards,
A.

[^Lele^]

Oh yes, I know that.
It's just that placing 6 planar portals sized to a BB is pretty straightforward...
It's just finding the time to sit and do it which is proving hard atm.
Should have some this afternoon...

[vlado]

Well, for the next update you also get texture-mapped rectangle lights with transparency, so that allows for some nice effects like light-emitting text etc.

Best regards,
Vlado

[MoonDoggie]

surely you kid! Excellent!

[ene.xis]

great news vlado!
can t wait!

[jujubee]

Wow that sounds great.

Vlado did mention the portal trick in a much older thread (previous) forum - it involved a light bulb hanging in a room.

The problem I have with portals is that it raised render times pretty drastically (at least for one scene I was using it on.)

[^Lele^]

I remember light portals in a modified cornell box pretty well, jujubee.
Those, however, were used in conjunction with PPT or LC/QMC situations, not behaving as direct lights portals for a vraylight material.

here: http://www.chaosgroup.com/forums/vbu...ghlight=ppt%2A

[Morbid Angel]

what about object based lights? those are on the way vlado?