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Image props and area lights


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I?m having an issue using image props in front of area lights. I typically convert a NURBS curve to an area light to serve as a lit cyclorama for my scenic model renderings. Recently I?ve begun to have issues with image props placed in front of that area light. When I use a prop with a mask (an image of a human for example) I attach a black mask on the grayscale-transparent and my figure looks terrific in Open GL standing in front of the cyc (area light) but as soon as I kick it up to any renderworks style the mask stops working and I get a black box around my figure anywhere it overlaps the cyc. If I place the figure in front of an opaque object it looks great as it does if I turn off the area light attached to the cyc object. The mask even works for the lower half of my figures where the stage floor is behind them. Is there a way to fix this? Interestingly when I sent the file to Cinema 4D the exact same thing happened?but not with all of them! Some figures looked great, some had the mask showing yet all were created in exactly the same way.

Any answers anybody? Thanks

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Nothing like posting a question to help you find the answer. Way down at the bottom of the Obj Info setting for the area light there is a check box labeled ?Render Geometry? un-checking this box and cranking up the dimmer to around 1000 seemed to fix the problem. But I got to thinking about the Glow option on the reflectivity channel and I created a texture with a pale blue color and set the Glow to 100% (higher started to wash out the color) and applied that texture to the cyc object. I turned out all the front lights and sure enough a lovely background glow silhouetting my image props perfectly in Renderworks. I suspect this will render faster than the huge area light and it would also be easy to drop an image instead of the color for other cyc effects as well.

--Sean O'Skea

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Sean; I find that I use IES files for cyc lighting (much better than the spotlight fixtures), as they provide a greater degree of verisimilitude and I can simulate my actual hang with a reasonable degree of accuracy...

I have attached three files showing in order a render from 2008 showing design intent, next file a shot from the show, and the last a render with a hastily built image prop, the IES cyc groundrow system and a sloppily focussed gobo on the image prop, so I could check to see if the IES-based light source created the same issues you found with the area light.

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