vray dome light

[CCS]

Anyone using the dome light regularly? I played with it back when it came out, but haven't done much since.

If you use it, care to post some samples?

[priad]

I haven't any answer to this but I would like also to know the interest of it!
what are the differences between the dome light and just an environement setting for light. they make very soft lighting perhaps more shadows with dome light?

[flipside]

Priad, the dome light creates raytraced area shadows, while the skylight is GI light and shadows depend on GI settings.

So dome light casts very fine shadows on every detail, but it needs high enough subdivs to be noise free, resulting in high rendertimes.

I never used it in a real project, only for testing when it was new

[priad]

humm.. ok I were on the way no?

[CCS]

Ah. I was under the impression people were using it in some cases as a substitute for GI.

[cpnichols]

Actually it is a substitute for a skylight. It is basically what Ambient Occlusion would be. GI would mean that the light is bouncing around, which neither the dome light nor Ambient Occlusion do.

[instinct]

It´s a completely different approach tho....as ambient occlusion is only geometry based and not light- or gi-based.

Greetings,
Thorsten

[CCS]

Ok, let's try to gather all these opinions into one thought, cuz I'm already getting confused.

Here's how I see it - tell me if I'm wrong:

The vray dome light is a light that simulates the old traditional dome light method in that light comes from all directions inward to simulate GI.

It is different from other lights in that it does not obey the vray global light/GI settings. It traces rays from all directions inward until it "hits a wall". At that point it casts an area shadow and ceases bouncing.

It differs from the old light dome method in that it is directional, allowing it to simulate a directional sun and GI simultaneously.

It gives a similar look to ambient occlusion, but because it is still based on the environmental "light", it is not truly AO.


Is this close?

[cpnichols]

I don't blame you for being confused. While the method of doing ambient occlusion is different, the result is identical. You can achieve Ambient Occlusion a number of ways: using an irradiance map on the primary bounce and none on the second, using a light dome, etc... Not sure what you mean by Geometry based. Basically AO just implies that you are looking where the geometry is occluding the Ambient light (or skylight). Maybe that is what you mean by geometry. But trust me, they are the same, since a shadow is an occlusion of light. The old dome lights with 64 light sources shadow mapping is the same deal. You could technically call that an Ambient Occlusion. That is what they used on Gollum in two towers. I think it was first used in Pearl Harbor. But I may be wrong. Either way, they called it Ambient Occlusion way back then.

http://www.andrew-whitehurst.net/amb_occlude.html

One thing to keep clear CCS is that AO and the Skylight have nothing to do with GI, no matter what people tell you. They give you the "look" of GI, but without light bouncing around, you get no GI.

[natty]

This image was produce purley from the dome light ... i think its a fantastic edition to vray but has its limitations.

[CCS]

Ok....

Followup then.

Is it faster than GI? (Would seem it would be)

Is it redundant to run a dome light + GI ? (Would seem so, although I see people are doing this)

[RErender]

Not that it can't be used without GI but

Sorry I missed that you had used GI, but isnt the point of the dome light to fake radiosity so that you dont need to calculate the GI?

Nope, the dome light is not a replacement for GI, but you can use it with GI quite successfully. In this case, you have very good details for the sky shadows plus the color bleeding from the GI. The dome light was actually created for a specific case, where I needed good sky shadows but I wanted to use the lightmap for fast/smooth GI (it was an animation).

Best regards,
Vlado

We have found it works well as a skylight replacement, when used with "store with arradiance map" and pretty high sub divisions it can clean up some GI artifacts without adding much to the render times. Haven't tried it with just lightcache but it sounds like thats what Vlado was eluding to.

[CCS]

Yeah I remember that post too.
Which takes me back to being completely baffled.

I guess I understand that he made it for a specific case. But being that it is called a "dome light", that makes me think of the old dome arrays we used to make, and their whole purpose was fake GI.....

So, if not a replacement for GI, and it's not faster, then I suppose that would explain why I haven't heard much about it.

[RErender]

It's better than skylight

When we are able to map a hdri to it it will be even better

[RErender]

Here's two images, one rendered with skylight and imap/qmc at "very low"
preset. The second imap/qmc at "very low" and a dome light (saved
with imap 64 subs)