Graphics Programs Reference
In-Depth Information
Figure 11.84
The images
compiled into
an HDR file and
cropped to the ball
extensive range of the HDR, because the great majority of computer displays are limited
to a display of 8-bit color. But you'll see that the image is cropped to the chrome ball's
edges, because the ball's reflection of the office is what you're really after, not the desk.
The HDR will be mapped onto an IBL sphere. This
is a large sphere that surrounds the environment in
your Maya scene. Although you could use the simple
DeskHDR.hdr
and map it to the IBL sphere, it wouldn't
be very accurate, because the corners of the square
image show through to the desktop and background.
The image first needs to be converted to a rectangu-
lar image file in which the sphere is unwrapped, as
shown in Figure 11.85. This layout is called
LatLong
(Latitude/Longitude) and is just as if a geographic map
on a school room globe was unwrapped into a rectan-
gular sheet of paper. You can do this with a tool like
HDRShop, available online. This LatLong image will
now map more accurately onto the IBL sphere; only
the reflection of the office in the ball will be used in
the scene's lighting.
We won't get into the details of creating the HDRI,
because it's an advanced topic using Photoshop CS3 or CS4; however, it's good to know
the origins of HDR images and how they come to be used in IBL.
Figure 11.85
The chrome ball
image is unwrapped
and turned into a
latlong rectangular
image.
