Graphics Programs Reference
In-Depth Information
Figure 14-2: Using layers as mask layers. Here the monkey object is placed on layer 2, with everything else on layer 1. On the
left, both layers are checked under Layer, and everything renders as expected. On the right, layer 2 is used as a mask layer
instead, so you see a transparent hole where the monkey head obscures the other objects.
animation. The Resolution settings let you choose
the size of your final render, while the Frame Range
settings are used to specify the number of frames in
your animation. Aspect Ratio sets the aspect ratio
for the pixels in the image (some video formats use
nonsquare pixels, but for stills, always use square 1:1
ratio pixels).
You can use the Border and Crop settings to
render a small patch of your image rather than the
whole thing. To do so, switch to the camera view in
the 3D Viewport ( numpad 0). Then press shift -B
and drag out a rectangle over the area you wish to
restrict the render to. This will automatically enable
the Border setting. Use the Crop setting to reduce
an image's dimensions to the size of your border
region; otherwise, the remaining area will be filled
with black.
Figure 14-3: Anti-aliasing reduces the appearance of jagged
edges in renders. Left: No anti-aliasing. Right: Anti-aliasing
turned on with the number of subsamples set to 8.
Use the numbers on the left of the Anti-Aliasing
panel to determine how many samples will be taken
(more samples will result in smoother renders but
longer render times). The drop-down menu on the
right sets the type of filter used to blend the sam-
ples: The default of Mitchell-Netravali gives good
results without taking too much sharpness out of
the render, but when working with higher-resolution
images, try Gaussian. Use the Full Sample option
to make Blender maintain each sample separately,
even during compositing, which can help with alias-
ing issues at the compositing stage.
Sampled motion blur is similar to anti-aliasing
in that multiple samples are taken per pixel but at
different times rather than different locations. This
results in motion blur for fast-moving objects once
Anti-Aliasing and Motion Blur
Aliasing is an artifact in a pixel-based image where
sharp boundaries may look jagged due to the finite
resolution of the image (see Figure 14-3). Aliasing
is often most obvious on the outlines of objects or
shadows, but it can also crop up in textures or spec-
ular highlights. Anti-aliasing addresses this problem
by taking multiple subsamples of each pixel with
slightly different offsets and blending them, result-
ing in a smoother-looking boundary, as you can see
in the figure.
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