hard shadow method

[rago]

Hi there,
I've been having some problems trying to get some hard shadows with directional lights coming in a room thru a window; actually the effect I'd love to get is a white over lit window, such as when you overexpose an interior to brighten up an ambient, and at the same time get some hard shadows. I tried putting a directional light behind a visible rectangular light but the latter keeps the directional light from giving nice hard shadows, for some reason it's occluding it.



I'm working from school so I don't know if they have the latest Vray version, is this a bug and is there some workarounds?

Thanx,

Rago.

[dalomar_cg]

Re: hard shadow method

I think you might want to ditch the rectangular light. Adding that light is only going to get in the way of the sharp shadows of the dir light. Maybe you could disable the shadows on the rec light, but personally I don't like doing that as it will lead to things looking very fake and flat. If you want an over exposed window, then I'd suggest using the physical camera and adjusting the exposure that way. Also, make sure that you have Affect Shadows checked on your refractive glass material to let the shadows through.

[rago]

Re: hard shadow method

Thanx Dalomar,
I also found out that to get a white background you have to crank up the multiplier on acolor to big numbers such as thousands or so:
before that everything is black, or at least on the release the school has installed.

As soon as I'm done with testing I'll post something!

[dalomar_cg]

Re: hard shadow method

No need to test anything, as this is expected behavior. The physical camera changes the exposure level for the image. Therefore, light emitting elements (gi, background, lights, emissive materials) will all have their appearance changed by this exposure. Increasing their intensity simply matches their appearance to the exposure of the scene. Depending on what you have the physical camera set to, it may only be an 100 or it may be to the tens of thousands.

[Micha_cg]

Re: hard shadow method

If I remember me right, set the rect light at "portal" mode and the directional light can shine through. Than, the rect light use the colors/intensity from the GI environment.
But why not try to render without a rect light, with a physical sky only? OK, high IM subdivs are needed, but it should work here, the window is quite big.

Window glass - look at the material tutorial for the architectural glass with a reflection layer only. Could be, that it work better here, the calculation could be faster, because it's the simpliest "glass".

The typical light distributation should make, that the area around the window is overexposured, if your general exposure is right. For a more realistic glow effect some postwork is needed.