Abstract
Abstract. Systematic errors may result from the adoption of an incomplete functional model that is not able to properly incorporate all the effects involved in the image formation process. These errors very likely appear as systematic residual patterns in image observations and produce deformations of the photogrammetric model in object space. The Brown/Beyer model of self-calibration is often adopted in underwater photogrammetry, although it does not take into account the refraction introduced by the passage of the optical ray through different media, i.e. air and water. This reduces the potential accuracy of photogrammetry underwater. In this work, we investigate through simulations the depth-dependent systematic errors introduced by unmodelled refraction effects when both flat and dome ports are used. The importance of camera geometry to reduce the deformation in the object space is analyzed and mitigation measures to reduce the systematic patterns in image observations are investigated. It is shown how, for flat ports, the use of a stochastic approach, consisting in radial weighting of image observations, improves the accuracy in object space up to 50%. Iterative look-up table corrections are instead adopted to reduce the evident systematic residual patterns in the case of dome ports.
Highlights
INTRODUCTIONImage residuals from bundle adjustment result from errors in the observations (random errors and gross errors), and from errors in the functional or stochastical model (systematic errors) (Vlcek, 1969)
Image residuals from bundle adjustment result from errors in the observations, and from errors in the functional or stochastical model (Vlcek, 1969)
The residual systematic errors are due to the incomplete functional model adopted, which alone is not sufficient to model the different refractive effects originating at the interface between water and the glass from a number of different sources such as, for example, a non-centered dome port, the use of a Ivanoff-Rebikoff corrector, a wet lens converter, or a flat port
Summary
Image residuals from bundle adjustment result from errors in the observations (random errors and gross errors), and from errors in the functional or stochastical model (systematic errors) (Vlcek, 1969). In Nocerino et al (2019) the authors showed that in the context of monitoring coral reefs through underwater photogrammetry performed by SCUBA divers, digital cameras mounted in dome ports display residual systematic patterns after bundle adjustment, which could not be compensated by standard selfcalibration functions. Errors in object space are analyzed and mitigation strategies are proposed These comprise different camera network image acquisitions and two photogrammetric processing strategies implemented by the authors in DBAT software (Börlin & Grussenmeyer, 2013) based respectively on radial weighting (Menna et al, 2018) and the use of an implicit method (d’Autume, 1972) integrated in an iterative selfcalibration approach for the correction of systematic image residuals. Experiments are reported in the case of self-calibration using standard underwater photogrammetry collinearity model with additional parameters
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
