look through light renders wrong

[andrewjohn81]

one of the little "tricks" i do for casting complicated shadows through windows is as follows, but dosn't work in vray:

create the light you want to cast shadows (directional works best, but spot will do in most cases).
Look through the light and render out a black and white image. In vray I would use a material override and hide what you want behind the windows.

Edit in photoshop, and you have yourself a fairly decent gobo. It won't match perfectly, I wish it would, but for many situations it works fantastically.

The only problem is Vray isn't rendering nice with the lights. When you render a light view it is cropped wrong, thus the image you create from it may not be correct.

I just thought I would bring that some attention in case anyone cared.

[dlparisi]

I've had this same problem trying to render out a shadow cast for RPCs. If I remember correct it's actually a problem rendering out orthographic cameras, not just through lights. For the RPC shadows I just render out a pass through the scanline render, but I'm not sure if this would work in your case.

[Da_elf]

ummm. thats more or less (in loose concept) the principle behind shadow maps.

[andrewjohn81]

yeah, pretty much the idea behind shadow maps, only I don't want Any shadows. All I want to do is create light on the floor and avoid shadows all together.

Basically I don't want to have to include the entire scene to just cast a little splash of light on the floor.

the problem is I have blinds and things like that to worry about. Creating it this way gives the illusion that it is accurate and no one ever knows.


I suppose I probably could create a shadow map once then tweak it in photshop and save it? is that what you are saying?


edit: hmmmm, only I don't know how to save the shadow map.