[nemac4]

I was playing with LW lights and had an idea for an alternative to area lights. It may have limited use but seems to work well.

Create a Spotlight with a shadow map at the desired fuzziness, intensity (set it to about half of what you need), and falloff.

Add another Spotlight and parent it to the first light. Set this one to Raytraced Shadows (You can set it to Shadow Mapped if you wish but you should then set fuzz to 0). Now set the intensity to *1.5 over the intensity of the first light. Set the falloff to x/3.2. X being the falloff of the first light.

Turn on Shading Noise Reduction for cleaner shadows or increase the shadow map size. Be sure to turn on Raytrace Shadows.

Here is a render time comparison from my PC.


Scene1: 2 spot lights. 1 Raytraced, 1 Shadow Mapped at 1024 map size and 15 fuzz. 1 point light for fill (no shadows or spec for the fill light). With and without SNR

RT+SM Trick = 6.6 sec | 20.3 sec

Scene2: 1 area light, Quality lvl 4 (I reduced the area light size to match the shadow of the spotlights) and 1 point light for fill (no shadows or spec for the fill light). With and without SNR

Area Light = 25.0 sec | 38.9

Download Scene Files
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RT+SM no SNR

[nemac4]

RT+SM w/ SNR

[nemac4]

area light w/ no SNR

[nemac4]

area light w/ SNR

[Mark]

That's a pretty good trick there David. How does the trick look when you have reflective objects in the scene (assuming the light is at a reasonable distance from the object) - are the hotspots realistic enough to get away with using the trick?

[nemac4]

Originally posted by Mark That's a pretty good trick there David. How does the trick look when you have reflective objects in the scene (assuming the light is at a reasonable distance from the object) - are the hotspots realistic enough to get away with using the trick?

Thanks Mark.

Here is a render with a reflective object:

render time 111.8 seconds

[nemac4]

This one has 2 sets of lights for a mini array.
Render Time 163.5 seconds

[nemac4]

This is a render with the area light version.
Render time 353.2 seconds

[nemac4]

As you can see,.. the further the object is from the light the less accurate it is. If specular highlights become a problem you could disable spec for the lights and add another light with affect specular checked and with diffuse disabled.