Abstract
It is necessary to periodically obtain topographic maps of the geographical and environmental characteristics of tidal flats to systemically manage and monitor them. Accurate digital elevation models (DEMs) of the tidal flats are produced while using ground control points (GCPs); however, it is both complicated and difficult to conduct GPS surveys and readings of image coordinates that correspond to these because tidal flat areas are not easy to access. The position and distribution of GCPs affect DEMs, because the entire working area cannot be covered during a survey. In this study, a least-squares height-difference (LHD) DEM matching method with a polynomial model is proposed to increase the number of DEM grids while using a presecured precise DEM to rectify the distortion and bowl effect produced by unmanned aerial vehicle (UAV) images. The most appropriate result was obtained when the translation parameters were quadratic curve polynomials with an increasing number of grids and the rotation parameters were constant. The experimental results indicated that the proposed method reduced the distortion and eliminated the error caused by the bowl effect while only using a reference DEM.
Highlights
Coastal areas are vulnerable regions that are affected by natural and artificial environmental changes
This study proposes an least-squares height-difference (LHD) digital elevation models (DEMs) matching technique with a polynomial model to correct the distortion in the DEM produced by the unmanned aerial vehicle (UAV), while using the existing reference DEM such as light detection and ranging (LiDAR) or pre-compensated dense DEM instead of the ground control points (GCPs)
We proposed a polynomial LHD DEM matching method by which the position and rotation distortion and bowl effect error were removed, without the requirement of GCPs, in a tidal flat DEM produced from UAV images using a photogrammetry software
Summary
Coastal areas are vulnerable regions that are affected by natural and artificial environmental changes. The intertidal flat is submerged in water during high tide and its surface is fully exposed during low tide. It possesses significant features in terms of habitat for shellfish, water purification, maintenance of diverse species, flood control, and recreational and scenic resources [3]. The Korean intertidal flat is one of the largest tidal flats in the world. It is an internationally protected shelter for endangered migratory birds and is considered to be one of the prosperous ecosystems inhabited by various species living in clusters [4]
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