7 minutes, the area light solution took just under 1 minute. Following is
another solution.
In this solution, a single point light was used in place of the area
light. The problems are that the lighting is yet again less accurate than a
true radiosity solution, and a bright spot is visible on the floor near
where the point light is located. I attempted to hide this by placing it
within the square of light from the exterior source, but an equally valid
solution would be to make the floor a separate object and exclude the
light from the floor object. Even so, the solution doesn’t look quite as
good as the previous versions. But there are times you may need a very
cheap solution to provide some apparent bounce in your environment.
This render took 11.7 seconds. A radiosity solution takes 35 times lon
ger. So you get to decide between physically correct renders with
immense render times, or not-bad looking lighting with great render
times or just about anything in between.
Every light in the toolbox can be used as a fake radiosity bounce
source. You need only to know the qualities and properties of that
bounce, where it originates, what color it should be, how intense it
should be, and what direction it is going. Just treat the bounce as though
it were a lighting instrument and proceed accordingly.
Baking Radiosity
One of the best new lighting tools in LightWave v9 is the Surface Baking
What this great gadget does is take all the layers of painstakingly painted
textures you have created and mash them flat into one layer that you can
then apply back to the surface. This new surface takes less time to ren
der because, well, it is only one texture instead of many.
Part II: LightWave’s Lighting Tools ······························
Figure 12.10
The Surface
Baking Camera
We used to use a surface shader plug-in called “Surface Baker,”
which was slow, single threaded, and could not be used on a render farm.
The beauty of the Surface Baking camera is that it will render every
thing that you make visible in your scene, just like any other camera
does, it can render multi-threaded, and it can be rendered on a net
worked render farm, just like any other shot, which is especially useful if
you are baking out an image sequence.
“So why does this make my lighting better?” you ask. Simple: You
can also bake lighting information into the texture. This means that you
can create a detailed radiosity or HDRI lighting solution, render a single
frame to bake the textures, then apply the new texture, lighting informa
tion included, back onto your surface. You set your surface luminosity to
100% and your surface diffuse to 0% and voilà. The clever artist will
bake only the illumination data into the map and apply that on the illumi
nation channel of the texture to avoid losing the advantage of having
separate channels of control in the Surface Editor. See the manual for
more detailed information on how to use the Surface Baking camera.
Note: Don’t forget to then turn off radiosity and switch to the
normal render camera before continuing with your render after
your baking is done.
The drawback to this is that any surface-baked surfaces must not move
during the animation; otherwise the shadows will not move with the
object — the lighting and shadows are baked into the texture, right?
Also, because the luminosity is up and the diffuse is down, you will not
be able to cast shadows onto the baked surface. There are ways around
this, of course, such as rendering separate elements and then
compositing them, but it is good to be aware. You can also have the dif
fuse value higher than 0% to receive shadows, but then the texture will
be brighter than it originally was. This is fine, provided you plan for it
when creating your textures.
If you have a scene in which you can use this technique, it will save
many hours of render time and afford you the beauty of radiosity at a
fraction of the cost. For example, if you have a character walking down a
street with buildings on both sides of the street, the character’s shadows
never touch the buildings, and the buildings never move, then you can
bake a beautiful radiosity solution into the buildings’ surfaces. You leave
the ground alone so it can receive shadows from the walking character.
Turn Radiosity off and render the sequence. You will get radiosity light
ing on your building walls and still have shadows from the character
···································Chapter 12: Radiosity

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