Hemispherical Imaging for Situational Awareness

The US Fleet Forces are often present in congested waterways throughout the world for a variety of humanitarian and military purposes. To maintain situational awareness (SA) and to support target detection, tracking, and identification, electro-optical (EO) and infrared (IR) sensors could be employed for their superior resolution and image-forming mode of operation, in contrast to radar. Surface ships require self-protection against a diversity of threats, surface and air borne. As such it is important to monitor the entire hemispherical dome (360 degrees azimuth X 90 degree vertical) for potential threats. The operational range and resolution requirements make it impractical to deploy a conventional imaging sensor since that would lead to single frames with hundreds of megapixels of data. In most operational scenarios a large fraction of these pixels (>90%) will not contain meaningful or relevant information and hence such an approach is deemed to be extremely inefficient. It should also be noted that as the vertical angle changes from near the horizon to directly overhead, the nature of the background and expected threat signatures will also change in a dramatic manner. Therefore it would not be appropriate to employ an imaging sensor with operational characteristics that remain invariant over the range of vertical angles. Researcher initiatives in Computational Imaging and Application Specific Imaging have suggested alternate measurements that produce far lower volume of data without losing underlying task-relevant information. They accomplish this by tailoring the measurements appropriately by incorporating prior information about the background and target statistics. Employing multi-modal sensing (spectral, polarization and temporal signatures) is another approach to reducing the data volume generated by conventional imaging sensors. The ONR Code 312 EO-IR Technologies Focus Area seeks information on unconventional approaches to full hemispherical imaging for situational awareness. Designs concepts of interest will yield systems that are simpler, less expensive, and reduce the data load by at least two orders of magnitude, while maintaining performance as indicated by probability of detection for selected target sets, and low false alarm rates for given background conditions. High-performance designs and architectures may be of interest even if required underlying technologies are not available currently.