Graphics Reference
In-Depth Information
normal. The bent normal can then be written to the G-buffer and shaded as part
of the regular deferred lighting pass.
6.2.5 Use with FXAA
This technique works very well together with MSAA, where MSAA takes care
of all the jaggies, just like it is designed to do. But not all games use MSAA
anymore; a whole bunch of filtering-based approaches to antialiasing have been
used recently [Jimenez et al. 11a] and several have gone into shipping games.
Arguably the most popular ones are FXAA [Lottes 09] and MLAA [Reshetov 09,
Jimenez et al. 11b]. We have tested this technique in conjunction with FXAA
and found that FXAA became nearly ineffective on the pixel-wide wires left by
this technique. Consequently, as a workaround, the wire needs to be expanded
somewhat for FXAA to take effect. Fortunately, as little as about 1.3 pixels width
is enough for FXAA to pick up the edges. Somewhat wider wires do result in a
somewhat lower quality overall, but not too bad. Other similar techniques, such
as MLAA, may be better suited for dealing with pixel-thin wires, but the author
has not verified that this is the case.
6.3 Conclusion and Future Work
A technique has been presented that effectively deals with aliasing on a specific
(but frequently occurring) subset of aliasing-prone geometry. This is a welcome
tool to reduce aliasing in games, but it does not solve the entire problem space
of aliasing in real-time rendering. Much research is still needed. An obvious
next step would be to explore ways to extend this technique to other shapes
than cylinders. We believe extending it to rectangular shapes such as bricks
and planks should be relatively straightforward and could work fundamentally
the same, with the exception that we need to take view orientation into account
for estimating size in terms of pixels. From there it may be possible to solve
the staircase. Stairs are a frequent source of aliasing artifacts in games, as the
top and side view of the steps tend to get lit differently, resulting in ugly Moire
patterns when the steps get down to pixel size.
Solving all these special cases may be enough for games, but ideally it would
be desirable to solve the general case, where a model with any amount of fine
detail and thin sub-pixel sized triangles could be rendered in an alias-free manner,
without resorting to super-sampling, and preferably without a preprocessing step.
Bibliography
[Jimenez et al. 11a] Jorge Jimenez et al. “Filtering Approaches for Real-Time
Antialiasing.” SIGGRAPH 2011 Course, Vancouver, Canada, August, 2011.
(Available at http://iryoku.com/aacourse/.)
