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Area Raytraced Shadows
The Area light source can only cast raytraced shadows. It shares with other lamp types common shadows options described here.
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| The Shadow and Spot panel of the Area lamp when ray shadows are enabled. | |
Raytraced Shadows
The raytraced shadows settings of this lamp are mostly shared with other ones, as described here. However, there are some specificities with this lamp, which are detailed bellow:
- Shadow Sample Generator Type
- Constant Jittered
- The Area lamp has a third sample generator method, Constant Jittered (I think it’s its original one), which is more like simulating an array of lights. It has the same options as the old one: Umbra, Dither and Noise.
- Samples
- This have the same role as with other lamps, but when using a Rect Area lamp, you have two samples settings: SamplesX and SamplesY, for the two axes of the area plane!
- Note also that when using Constant Jittered sample generator method, this is more or less equivalent to the number of virtual lamps in the area. With QMC sample generator methods, it behave similarly as with Lamp or Spot lamps.
The Soft Size parameter has disappeared.
The following three parameters are only available when using Constant Jittered sample generator method, and are intended to artificially boost the “soft” shadow effect, with possible loss in quality:
- Umbra
- Emphasizes the intensity of shadows in the area fully within the shadow rays. The light transition between fully shadowed areas and fully lit areas changes more quickly (i.e. a sharp shadow gradient). You need Samples values equal to or greater than 2 to see any influence of this button.
- Dither
- Applies a sampling over the borders of the shadows, in a similar same way anti-aliasing is applied by the OSA button on the borders of an object. It artificially softens the borders of shadows; when Samples is set very low, you can expect poor results, so Dither is better used with medium Samples values. It is not useful at all with high Samples values, as the borders will appear already soft.
- Noise
- Adds noise to break up the edges of solid shadow samples, offsetting them from each other in a pseudo-random way. Once again, this option is not very useful when you use high Samples values where the drawback is that Noise generates quite visible graininess.
See Also
