Abstract
The popularity of automatic photogrammetric techniques has promoted many experiments in underwater scenarios leading to quite impressive visual results, even by non-experts. Despite these achievements, a deep understanding of camera and lens behaviors as well as optical phenomena involved in underwater operations is fundamental to better plan field campaigns and anticipate the achievable results. The paper presents a geometric investigation of a consumer grade underwater camera housing, manufactured by NiMAR and equipped with a 7′′ dome port. After a review of flat and dome ports, the work analyzes, using simulations and real experiments, the main optical phenomena involved when operating a camera underwater. Specific aspects which deal with photogrammetric acquisitions are considered with some tests in laboratory and in a swimming pool. Results and considerations are shown and commented.
Highlights
Despite being a hostile environment both for humans and optical equipment, underwater measurement using photogrammetry can be feasible in several cases
In this contribution a geometric investigation of a consumer grade underwater camera housing equipped with a 711 dome port is presented
The paper presented the optic and geometric characterization of a consumer grade pressure camera housing that was successfully used in the underwater survey of the Costa Concordia gash [6]
Summary
Despite being a hostile environment both for humans and optical equipment, underwater measurement using photogrammetry can be feasible in several cases. The knowledge about photographic equipment and its behavior in different conditions is the first step to be investigated Whether they are in shallow or deep water, most underwater photogrammetric applications have to deal with a challenging optical environment due to water ripple reflections, light absorption and turbidity. As for all close-range photogrammetric surveys carried out in air, the key parameters for network planning and acquisition—such as ground sample distance (GSD), baseline, image overlap, expected accuracy, nominal focal length, sensor resolution, aperture value, depth of field, etc.—must be known to plan the survey In this contribution a geometric investigation of a consumer grade underwater camera housing equipped with a 711 dome port is presented. Underwater acquisitions were performed in a 2 meter deep swimming pool
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