Moving Target Detection for a Multi-Band Pushbroom Sensor

摘要

A pushbroom MSI sensor collects image data from the ground, parallel to the flight path, at a specific point angle. Images taken at two instances of time while the scanner moves with the platform usually have a spatial offset, and need to be registered before they can be compared for any changes between the two images. Moving target detection is a special case of change detection that requires the time between frames be small enough that a moving vehicle remains in close proximity on the two frames. We propose an algorithm for the detection of moving targets in a multi-band line scanning pushbroom sensor. Ideally, change detection works best when images have the same spectral bandwidth and are perfectly registered to one another, since differencing the two images automatically removes most of the common background signal. However, this is not always the case. For example, the sensor considered here has different bandwidths for its component bands, and since it is a line-scanner it is much more challenging regarding image registration than a framed-based scanner. In this study, we will use simulated data of the same bandwidth to demonstrate the fundamental algorithm of detection and velocity calculation. The velocity calculation is that of distance divided by time; but, depending on the focal plane layout and other operating considerations and conversion between image space to physical units, this calculation is not as simple as it seems. We will also discuss our effort in applying our algorithm to real line-scan imagery, of different bandwidths in the two channels. We will show the extra image processing efforts needed to make it work, and show some of the test results.