Object Detection Methods for Optical Survey Measurements
Alejandro Pastor
GMV, apastor@gmv.com
Diego Escobar
GMV, descobar@gmv.com
Manuel Sanjurjo-Rivo
Universidad Carlos III de Madrid, manuel.sanjurjo@uc3m.es
Alberto
´
Agueda
GMV, aagueda@gmv.com
ABSTRACT
This work presents a novel sequential filtering algorithm able to identify new objects from optical measurement data by
associating uncorrelated tracks (UCTs) belonging to the same object. It makes use of both Initial Orbit Determination
(IOD) and Orbit Determination (OD) methods to evaluate a figure of merit to help deciding whether certain tracks
belong to the same object or not. Instead of using a brute-force approach by evaluating all possible combinations of
UCTs, several filters and complexity reduction techniques are used to reduce the computational resources required.
Furthermore, the association is performed on the measurements space (track-to-track correlation) rather than in the
orbit space (track-to-orbit or orbit-to-orbit correlation).
A generic object detection methodology based on track association is presented, with a special emphasis on the
correlation of optical tracks, although it has been already applied to correlation of radar tracks. In the former case, the
problem resides in the derivation of enough orbital information from a single track (with less attributables than a
radar track) to allow the application of filters and complexity reduction techniques. Hence, optical track association is
far more complex and resource-consuming than the radar track association, and thus classical approaches are not
enough.
Results have shown that this strategy provides more reliable results than an association made on the orbit space, in
terms of both false positives and number of missed objects. A realistic simulated scenario has been set up to evaluate
the performance of the correlation procedure under a purely build-up scenario. The performance of the methods
is evaluated in terms of clear and well-defined correlation metrics, such as true positives, false positives and false
negatives, providing both ratios and absolute values. They prove that the proposed methodology is able to provide
excellent results for the track association problem, since most of the objects can be detected while providing a very
low number of false detections. This is important during catalog build-up, since the addition of wrong objects is very
undesirable. The computational cost of the algorithm allows real-time processing of new tracks thanks to the selective
generation and pruning that avoid evaluating all possible combinations of tracks.
1. INTRODUCTION
The number of resident space objects (RSO) is increasing year after year and therefore the sensing capabilities are
also growing [1]. Space Surveillance and Tracking (SST) systems are composed by sensors and on-ground processing
infrastructure devoted to the generation of a catalog of RSO: a robust automated database that contains information
of every detected object. During surveillance, large areas of the sky are scanned to obtain data for both catalog
build-up and maintenance activities. The catalog build-up process consists in detecting new objects to include them
in the catalog without any previous information, while the maintenance task entails the update of existing objects
information. Hence, the catalog build-up depends on the capability to detect new objects from measurements, packed
as tracks, provided by a sensor network.
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