A practical guide to the use of consumer-level digital still cameras for precise stereogrammetric in situ assessments in aquatic environments

摘要: Scientists planning to use underwater stereoscopic image technologies are often faced with numerous problems during the methodological implementations: commercial equipment is too expensive; setup or calibration complex; imaging processing (i.e. measuring objects in stereo-images) complicated be performed without a time-consuming phase of training and evaluation. The present paper addresses some these describes workflow for measurements marine biologists. It also provides instructions on how assemble an stereo-photographic system two digital consumer cameras gives step-by-step guidelines setting up hardware. second part details software procedure correct stereo-image pairs lens distortions, which especially important when using non-calibrated optical units. final presents guide process lengths (or distances) pairs. To reveal applicability restrictions described systems test effects different types camera (a compact SLR type), experiments were determine precision accuracy generic stereo-imaging units: diver-operated based Olympus Mju 1030SW cable-connected observatory Canon 1100D cameras. In simplest any correction distortion, low-budget achieved mean errors (percentage deviation measurement from object’s real size) between 10.2 –7.6% (overall value: –0.6%), depending size, orientation distance measured object camera. With single reflex (SLR) system, very similar values 10.1% –3.4% –1.2%) observed. Correction distortion significantly improved either system. Even more, (spread accuracy) both systems. Neither wide-angle converter nor multiple reassembly had significant negative effect results. study shows that stereophotography, independent has high potential robust non-destructive situ sampling can used prior specialist training.