Aerospace and Electronic Systems Magazine June 2017 - 32

Elimination of Resampling Errors in Wide Area Motion Imagery
rithm. The pcolor algorithm displays each pixel as a trapezoid, and
not as a resampled pixel. The new SET model displays the image
with the full resolution of the raw image. This is an important difference at high levels of zoom.
The new SET model requires some additional information that
is not currently supplied to the viewer in the traditional SET model.
This information includes the raw image, camera model, pose for
each frame, and an elevation data base. The raw image can be compressed to the same size as the existing NITF image without loss of
resolution. The camera model is extremely small and required only
once for each data set. The pose data is small and only required
once per frame. The elevation data base may be large, similar in
size to a single raw image, but is only required once per data set.
Thus, we can conclude that the data for the proposed SET model is
the same size as the existing SET model.
The new SET model requires considerably more processing
power when the data is viewed. It is possible that some hybrid
scheme is necessary to ensure the response time of the modified
SET does not impede the work of the analyst. One possibility is to
include a single low resolution NITF for use at low levels of zoom.
At high levels of zoom, the projection can be performed based on
a small subset of the raw image. Projection of a small subset of the
raw image can likely be performed in the modified SET as required
by the analyst without a substantial latency.
The WPAFB data set of 20091021 is representative of many
data sets collected using the hardware platform. The only publicly
released data set is used here. The data set is also representative of
many similar orbiting surveillance platforms. While one data set
might not justify a significant change in the SET it does demonstrate the advantages of the revised SET model. For the WPAFB
data set of 20091021, the loss of resolution is due to resampling.
To eliminate this resampling error a revised SET is proposed that
does not require resampling. This revised SET provides the full
resolution of the original raw image. The end result for this data
set is an improvement in resolution from 1.05 lp/m to 1.23 lp/m, an
improvement of 17 percent.

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