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View Full Version : Shadow rendering times - how do you approach?

zook10
02-18-2008, 04:48 PM
I'm interested in the different times it takes various types of shadow to render. The C4D manual suggests that hard raytraced shads take longer to render than soft ones, but in a scene I am creating the soft shads seem to take longer to render (there are around 20 lights in the animation - a flythrough of a retail outlet).

GI aside (due to the length of time they take to render), how does anyone here optimise their shads for faster renders?
abdelouahabb
02-18-2008, 05:08 PM
i think you should use shadow maps because it give more options, for exemple if you go to render setting you can find that you can save the shadow cache data to reuse it. just a suggestion.
DaveD
02-18-2008, 05:32 PM
My understanding was the opposite. Hard shadows render the fastest, soft the next fastest, and area shadows take the most time.

For your situation, depending on exactly what the lights are, I'd create one or two main light sources with shadows. Then I'd turn off all shadows for smaller lights. Even if it's not always 100% accurate I find I can get more impactful results this way. Too many shadows can cause strange and distracting patterns.
LucentDreams
02-18-2008, 06:28 PM
well soft shadows sometimes are faster sometimes are slower. It depends on the scene and your memory. Shadow maps take up memory and when memory is running short they take up virtual memory which means writing to hard drive which means waiting which means slower overall.
Andy1010
02-18-2008, 07:12 PM
What is the size of your shadow maps? Do you have any filtering turned on?
zook10
02-19-2008, 11:08 AM
The shadow maps are all 250x250, with no filters applied. I have been rendering using hard shads but this seems to take a while to render.
AdamT
02-19-2008, 02:08 PM
If you're doing a straight camera animation (fly-through) you can turn on shadow map caching and they will be very much faster than hard shadows after the first frame, i.e., no additional render overhead.
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