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Summing up the different timings of the individual modules, we reach a con-
fident speed of 27 fps for Full HD resolution, but our experimental setup is lim-
ited by 15Hz support in the cameras and Firewire controller hardware. The current
implementation speed allows for further quality optimization by advancing the
algorithm and computational complexity.
6.6.3 Adaptive Nonuniform Plane Distribution
To demonstrate the validity of the adaptive nonuniform plane distribution system in
multiple scenes, we created separate datasets with moving persons. We tested the
method on different scenes and compared image quality and planes required.
The experiment shows that the quality is higher when a low number of planes is
available, compared to the same number of planes using a uniform plane distribution.
To increase the overall quality in both methods, we use foreground-background
segmentation. Figure 6.18 a shows the result for a uniform depth plane distribution.
Artifacts caused by the sparse plane distribution can be clearly seen; the depth map
shows clear outliers. The depth map when using a nonuniform plane distribution,
based on the histogram of the first depth map, can be seen in Fig. 6.18 b. Less noise
and outliers in the depth values can be perceived. Furthermore, the silhouette is
more distinct and the features of the persons are clearer. Using the nonuniform plane
distribution increases the quality of the depth map using a low number of planes,
therefore increasing overall performance.
Figure 6.18 c shows the result for a high number of planes. Here, some noise and
unclear edges can be perceived. These artifacts are effectively filtered out using the
nonuniform plane distribution. The depth planes generating vague edges and noise
are not used and cannot contribute to the depth map, and therefore to the noise and
artifacts.
To demonstrate the effect of the cumulative histograms, Fig. 6.19 shows an input
image of a video sequence (a), the corresponding cumulative histogram of the depth
map of the preceding frame (b) and the corresponding fraction
from Eq. 6.13 (c).
When only one dominant depth can be perceived, such as in Fig. 6.19 (top), one
steep section in the cumulative histogram is visible. This part is transformed to a flat
value of
˄
, thus increasing the density of the planes in the corresponding region in
the sweeping space. Flat sections of the cumulative histogram correspond to steep
values in the graph of
˄
, resulting in a sparse plane distribution.
When multiple dominant depths are available in the scene, the cumulative his-
togram shows multiple steep sections (see Fig. 6.19 , bottom). This results in multiple
dense regions in the plane distribution, as reflected by the values of
˄
˄
.
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