Game Development Reference
The EXtractoR Effect
Several years ago, the famed visual arts stu-
dio, Industrial Light and Magic (ILM) created a
fi le format called OpenEXR. OpenEXR is a still
image fi le format that can store 32 bit HDR data
and is akin to the powerful 3D fi le types men-
tioned at the beginning of this chapter. The big-
gest difference, perhaps, is that OpenEXR can
store many more layers or channels of 3D data.
Many 3D software programs—such as
Cinema 4D, Blender, Lightwave, and others—
support OpenEXR, as well as Photoshop (since
version CS2) and the Mac OS (since 10.4). After
Effects has been able to import OpenEXR fi les
since After Effects 7, but it has never been able
to access all the various layers of data that can
be stored in them. After Effects CS4 includes two
new effects, the EXtractoR effect (did you catch
the capitalized EXR in there?) and the IDentifi er
effect, which can take advantage of layered
OpenEXR fi les.
After applying the EXtractoR effect, click
anywhere in the Channel Info area in the Effect
Controls panel to open a dialog box that will
allow you to choose which channel of data that
you would like to use for each color channel
and the alpha channel.
The OpenEXR format is constantly being
improved and developed. Currently, it can store
up to 49 channels of data. There are so many
in Fig. 2.18 that they don't even fi t on screen
at the same time. Perhaps by the time you
read this, it will be able to contain even more.
For more information on the EXtractoR and
IDentifi er effects, visit the Web site of the devel-
oper, www.fnordware.com. On this site, they
not only have documentation but download-
able sample OpenEXR fi les that contain many
channels that you can practice with.
The Fog 3D Effect
The Fog 3D effect creates fog that traverses
through a scene in 3D space. Again, this effect
uses the Z-depth information stored in a fi le to
determine where to put the fog. This effect works
Figure 2.18 The EXtractoR dialog box can display all
the layers stored in multilayered OpenEXR fi les. You can
choose which layer to use for which color channel.