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increase coverageBoost . If an obvious transition line is visible between the blurred
near-field region and the sharp mid-field, then decrease the coverageBoost .Which
of these cases an application is in largely depends on whether the field of view
makes the ground plane visible within this transition region. For example, a
first-person camera typically cannot see the ground plane in this region but a
third-person camera often can. The third-person camera benefits from a smaller
coverageBoost setting.
Because the effect assumes a single depth at each pixel in the input, we process
particle systems separately by MIP-biasing their textures during a forward ren-
dering pass rather than relying on the post-processing. For non-particle, translu-
cent and reflective objects such as glass, we simply choose to use the depth of the
translucent object or the background depending on the amount of translucency.
We knew that depth of field was an essential effect for the art direction of Sky-
landers SWAP Force , where the visuals resemble a CG animated film more than
a traditional video game. By addressing the perception of the phenomenon of
blurring instead of the underlying physics, we were able to achieve both high
quality and high performance on a range of target platforms.
The primary limitations of previous real-time depth-of-field approaches are
poor near-field blur and poor transitions between blurred and sharp regions.
Figure 1.2 s hows that even under a narrow depth of field, our effect overcomes
both of those limitations. The interaction of depth of field with translucent
surfaces remains problematic in the general case; however, we've described the
forward-rendering techniques that we applied successfully to such surfaces in this
specific game.
It is important for game graphics to serve game design for engagement as
well as to please the eye. In this game, we've found depth of field to be a
powerful tool for both gameplay and cinematic expression. Designers employ it
for controlling attention and indicating gameplay elements as well as the artists
using it to enhance visuals and mitigate certain artifacts. We hold this effect
as an example of a technological advance serving to enhance all aspects of the
player's experience.
[Cook et al. 84] Robert L. Cook, Thomas Porter, and Loren Carpenter. “Dis-
tributed Ray Tracing.” In SIGGRAPH '84: Proceedings of the 11th Annual
Conference on Computer Graphics and Interactive Techniques , pp. 137-145.
New York: ACM, 1984.
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