A system for live geo-spatial photogrammetry in airborne surveillance videos

Abstract

This paper describes a system to perform real-time Euclidean measurement of scene objects captured from an airborne platform. Novelty resides in the adoption of a video calibration technique which recovers the absolute scene scale from a single ground reference length. The sensor footprint, from which the reference length is derived, is itself acquired by intersecting the sensor field of view with a digital elevation map, rather than the more usual registration of a video frame with an orthographic reference image. The footprint, together with the sensor and platform parameters, are stored in the video metadata for immediate or offline processing. Compliance with Motion Imagery Standards Board standards ensures interoperability and, in particular, that the subsequent camera calibration utilities can be platform independent. Once the camera is calibrated, auxiliary video metrology methods provide 3-D photogrammetric tools for object-level analysis. Two system workflows are presented which allow for live scene mensuration of both autonomously tracked targets or manually chosen ones. Experiments included measuring heights and ground distances from reallife surveillance videos. Comparison with truth and three measurement methods validates our system's performance.