You can find this software, along with tutorials and a discussion
forum, by doing a simple web search for “HDRShop.” At the time of
publication, the web address for HDRShop was www.hdrshop.com.
Faking Radiosity
Let’s leave the dream world of Monte Carlo radiosity and HDRI illumi
-
nation. Most of us don’t have the render power to tackle this sort of
lighting setup, so let’s wake up and smell the coffee. Come on; snap out
of it!
We always want that beautiful diffuse reflected light if we can get it.
It makes our renders look great. Why? Because the world is full of dif
-
fuse reflected light. It may not be as obvious as direct lighting, but it’s
everywhere. The absence of this lighting is one of the things that really
makes CG work stand out as fake. So let’s find a way to add reflected
light without having to use radiosity and HDRI.
There are tons of ways to fake diffuse reflected light. The first step
is to understand the source of the diffuse reflection and grasp what the
reflection should look like. For example, if a person is standing on some
light gray concrete outside and it’s a sunny day, we know that there will
be a fairly bright reflection of light on the portions of the face that are
normally in shadow. Light will reflect into areas such as the underside of
the nose, the chin, and the eye socket. We also know that this is a diffuse
reflection because the concrete is a very uneven surface and that means
the shadows will be very soft. We also know that the light source is fairly
large — as large as the area of concrete that is reflecting the sunlight.
If the shadows are very soft, we can’t use ray-traced shadows from
spotlights, distant lights, or point lights for that light because they result
in very hard-edged shadows. If the light were reflected from a mirror, a
glass office building, or even a pool of water, the shadows would be more
hard-edged and we could use ray tracing then, but not in this case.
So now that we know what sort of lighting properties we are looking
at, let’s try out a few methods of tackling this particular problem.
Part III: Creating Lighting ··································
444
Adding Lights for Reflections
Let’s load up a head into Layout and use the default light, a distant light
at 100% with ray-traced shadows, as our key light source. Nothing spe
-
cial to start with.
Using a Point Light
Now all we have to do in order to simulate a
radiosity reflection from the concrete in
front of the person is insert a light below the
face and turn it on; then we’ll take a look at
adjusting settings. Let’s start with a simple
point light. We can’t use ray-traced shadows
as we mentioned before, so after you add
the point light, open the Light Properties
panel for that light, click the Shadows tab,
and make sure Shadow Type is set to Off.
This works as though it were a “directional
ambient” light source.
Place the point light in front of and
below the head. Leave it at its default inten
-
sity of 50% and its default color for now.
······························Chapter 25: Tips, Tricks, ’n’ Tutes
445
Figure 25.97
Figure 25.98
Make sure Ray Trace Shadows is turned on in your Render Globals
panel. Open up the Global Illum tab from your Render Globals panel and
check to make sure the Ambient Intensity setting is 0%. This is not one
of those occasions when we like ambient intensity. Now hit the F9 key
and take a look at the results so far.
Part III: Creating Lighting ··································
446
Figure 25.99
Figure 25.100

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