Why the horizon is important for airborne sense and avoid applications

  1. Get@NRC: Why the horizon is important for airborne sense and avoid applications (Opens in a new window)
DOIResolve DOI: http://doi.org/10.5194/isprsarchives-XL-1-W4-123-2015
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Journal titleISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
SubjectSAA; ABSAA; UAS; Horizon model; Horizon proximity; Region-of-interest; Feature detector
AbstractThe utility of the horizon for airborne sense-and-avoid (ABSAA) applications is explored in this work. The horizon is a feature boundary across which an airborne scene can be separated into surface and sky and serves as a salient, heading-independent feature that may be mapped into an electro-optical sensor. The virtual horizon as established in this paper represents the horizon that would be seen assuming a featureless earth model and infinite visibility and is distinct from the apparent horizon in an imaging sensor or the pilot’s eye. For level flight, non-maneuvering collision course trajectories, it is expected that targets of interest will appear in close proximity to this virtual horizon. This paper presents a model for establishing the virtual horizon and its projection into a camera reference plane as part of the sensing element in an ABSAA system. Evaluation of the model was performed on a benchmark dataset of airborne collision geometries flown at the National Research Council (NRC) using the Cerberus camera array. The model was compared against ground truth flight test data collected using high accuracy inertial navigation systems aboard aircraft on several ’near-miss’ intercepts. The paper establishes the concept of ’virtual horizon proximity’ (VHP), the minimum distance from a detected target and the virtual horizon, and investigates the utility of using this metric as a means of rejecting false positive detections, and increasing range at first detection through the use of a region of interest (ROI) mask centred on the virtual horizon. The use of this horizon-centred ROI was shown to increase the range at first detection by an average factor of two, and was shown to reduce false positives for six popular feature detector algorithms applied across the suite of flight test imagery.
Publication date
PublisherInternational Society for Photogrammetry and Remote Sensing
Peer reviewedYes
NPARC number23000265
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Record identifier737eb9da-e4a2-4fa1-aa93-3834255ce0ab
Record created2016-06-30
Record modified2016-06-30
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