PDA

View Full Version : Question: What is the Inverse square fallof start radius?

 CHRiTTeR02-01-2007, 09:33 PMWhen aiming for correct lighting what value should I set the inverse square start radius? Should I set it to the same radius as the lightsource I'm trying to simulate (lightbulb) or ... thanks!
ssk
02-01-2007, 10:36 PM
You right.

CHRiTTeR
02-01-2007, 10:40 PM
ok, that brings up the next question :D

So, if creating a light bulb. Should i set the start radius to the radius of the glass bubble or to the radius of the glowing iron thing (the actual lightsource)?

Rens
02-02-2007, 08:08 AM
So, if creating a light bulb. Should i set the start radius to the radius of the glass bubble or to the radius of the glowing iron thing (the actual lightsource)?
Unless you're doing close ups that shouldn't matter too much. If you want to be precise then I'd set it to the radius of the glass bulb if the glass is coated (white), if the glass is clear I'd set it to the radius of the glowing filament.
The reason for it is that you can set the light's intensity to the intensity of the glass/filament's incandescence, whichever is visible.

CaptainObvious
02-02-2007, 08:56 AM
Typically, the radius and the brightness are interchangeable. The radius is basically just the "nominal distance," as Lightwave puts it. If the radius is 1 meter, and the intensity is 100% (or whatever your application of choice measures in), the light will be at full intensity at 1 meter, at quarter intensity at 2 meters, quadruple intensity at 50 centimeters, and so on.

In the applications I've used, the "Radius" isn't related to the falloff, as such, since the falloff is uniform anyway.

Rens
02-02-2007, 12:26 PM
My guess is he is using max and is talking about the decay start value. This is the value where the decay/falloff will start and where the light intensity is still at 100%, somewhat the same as you decribed. The decay type is then set to linear or inverse square.

CHRiTTeR
02-02-2007, 12:46 PM
My guess is he is using max and is talking about the decay start value.

Bingo!

Unless you're doing close ups that shouldn't matter too much. If you want to be precise then I'd set it to the radius of the glass bulb if the glass is coated (white), if the glass is clear I'd set it to the radius of the glowing filament.
The reason for it is that you can set the light's intensity to the intensity of the glass/filament's incandescence, whichever is visible.

Thanks! :thumbsup:

CGTalk Moderation
02-02-2007, 12:46 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.