View Full Version : how to choose between depthmap shadow and raytrace?

09 September 2012, 11:14 AM
Is there any common or specific reasons, when you choose between depthmap shadows and ray trace?

09 September 2012, 12:09 PM
Generally speaking, depthmap is faster. While raytrace is more accurate. Some raytrace renderers do not support depthmap (such as vray) so in that case raytrace shadow will be your only choice.

09 September 2012, 07:32 AM
Historically speaking, when CG was in it's infancy - raytracing was slow and memory intensive, so depth maps were used as a practical workaround. Although things have changed in the last few years - aside from a few exceptions (hair/fur being the main one) - most shadows are calculated using raytracing, even when using PRMan or 3Delight.

The main benefit of depth-map shadows is that you could store and re-use the shadow calculation. This could save you time when lighting or re-rendering - as long as the animation or the light position didn't change you didn't need to redo the shadows. For static lights you could also calculate the shadows on one frame and re-use it through an animation. You could also things such as blur the shadow map to create soft-shadow effects.

The downside of this is that you had to manage an additional set of data in order to get the most use out of depth-map shadows.

09 September 2012, 07:11 PM
thanks alot:)

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09 September 2012, 07:11 PM
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