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modi
07-25-2003, 08:03 AM
Hey all, i have an animation of my character watching TV and i want to use the light from the tv as my main source light.
How would i go about setting up a light so as to make it look like the whole room is lit just by the tv
and also to get the subtle fluctuations every time the channel changes or a cut. Any help would be appreciated. Cheers.

(Mods, sorry for posting this in the wrong thread earlier)

fxjeane
07-25-2003, 02:21 PM
There are many ways you can do this.. I believe the easiest is to create a spotlight and place it somewhere behind the TV so that the lighting "cone" goes through the screen and as close as possible to the corners of the screen.
I dont know what package you are using but most spotlight light sources allow you to change the light from a circular spot to a rectangular spot (sometimes using barn doors). Do this to get a "rectangular" light cone.

Finally, map your image sequence or movie to the light color. Once again most packages support this, but some time is like a "GEL" or a "projection" map . This way the light will take the color info from your image sequence. All the cuts and tone variations should be apparent in the illumination.

Remember that you will still need to add several other lights to simmulate light bouncing in the scene.

I hope this helps


FxJeane

modi
07-25-2003, 07:37 PM
hey thanx, btw i'm using Maya.

kfc
08-04-2003, 10:40 AM
well.... there's alot of ways to achieve it tho. For me I would place lights manually with low intensity (shadowmaps) spot lights and area light to create low and subtile lighting to the whole environment. but if it's an animation and the TV screen constantly changing over time.
I would use MR to do the trick. Make the screen a animated texture and assign it to incadecent of material. the turn on Final gather. with the correct setting (i guess some ppl might find it to be difficult), It can be rendered nicely. If you are looking for a much more realistic approach, U might can turn on GI too in the MR global.
anyway, there's still a bunch of turn arounds on this matter tho. it just depends on the time given and the requirements of the director. :beer:

fig
08-06-2003, 04:06 PM
there's a tutorial on stephen mack's site (http://www.gnomist.com/oldsite/pages/art/tvs/index.html) that deals with lighting a tv that you might find helpful.

chris

CourtJester
08-12-2003, 07:43 PM
Like this?

http://www.altyna.com/portfolio/images/colortv.jpg

If you want accuracy of lighting and reflection from the TV screen, don't want the render hit of GI or radiosity, work in LightWave, and have the patience of a saint, consider this hack:

Textured Area Light Hack (http://www.altyna.com/lw/specrefl.htm)

It's a $%^& to set up, especially because of the numerous, serious bugs in Image Editor, but once it's working, it's accurate and very fast. (those reflections you see on the floor and the big smartie are in the *specular* channel.)

While built in Lightwave, this hack can be adapted to any 3D app that permits reading pixel RGB values from an image or sequence, feeding the results to the RGB inputs of a light, and use naive timeslice motion blur. OR you can just build a non-moving grid of lights.

Edited to add: I just saw that you are working in Maya. Well, I haven't done it, but Maya ought to be a lot easier to set this thing up in.

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