

Le 20230124 à 16:17, 88Keys a écrit :
> Hello.
>
> I'm trying to work with Area Lights, but I can't seem to orient them correctly.
> I've been trying a <50 , 0 , 50 > , <50 , 0 , 50 > and that doesn't seem to
> illuminate my scene, so I tried a <50 , 0 , 0 > , < 0 , 50 , 0 > in an attempt
> to make the angles at 90 degrees to each other, but that doesn't seem to have
> worked either.
>
> Any tips on how to generate a proper Area Light? The documentation is a little
> slim. What I have developed seems pretty dull, too.
>
> Thanks very much.
>
Always start with with your light set as a regular light.
Once the light is properly placed, add the area_light options.
It's better to have the sides at 90° from one another, but, that's not a
requirement. It'll only make your area_light into a parallelogram.
If you want an area_light that act like a bright ball or light bulb, you
are better using the circular and orient options.
The circular option make the light into a circle, or ellipse if the
sides are of different length.
With orient active, the orientation of the array is no longer important.
It demand that the light starts as a square with the same sampling
density in both direction. If not, a warning is displayed and the
offending part altered to meet the requirement.
Remember that the vectors used to define the area_light are ALWAYS
relative to the location of the area_light, NEVER the origin of the scene.
Sample :
light_source{
<100, 1000, 75>// the location
rgb 1 // colour and intensity, can be more than 1
//add the following only after the light is properly placed
area_light 20*x 20*y// It's dimension or extant
33 33// maximum number of samples to use
adaptive 0// turn on adaptive sampling starting
// with the corners, or a 2x2 array
//increase the value if you get artefacts
circular // make it into a circle
orient // always oriented toward the location currently evaluated
}
The starting sampling arrays associated with various adaptive values :
Adaptive MINIMUM suggested minimum array
Value sampling size to use to see
to use the benefit
0 2 x 2 9 x 9
1 3 x 3 33 x 33
2 5 x 5 65 x 65
3 9 x 9 129 x 129
4 17 x 17 257 x 257
5 33 x 33 513 x 513
Any sampling array size between those values will be silently increased
to the following size of the list. A 4 x 4 adaptive is really 5 x 5, 6 x
6 is promoted to 9 x 9 and 10 x 10 become 17 x 17.
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