Utilizing Airborne LiDAR and UAV Photogrammetry Techniques in Local Geoid Model Determination and Validation

Serdar Erol,Bihter Erol,Emrah Özögel,Ramazan Alper Kuçak

doi:10.3390/ijgi9090528

Serdar Erol, Bihter Erol + Show 2 more

Open Access

https://doi.org/10.3390/ijgi9090528

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Abstract

This investigation evaluates the performance of digital terrain models (DTMs) generated in different vertical datums by aerial LiDAR and unmanned aerial vehicle (UAV) photogrammetry techniques, for the determination and validation of local geoid models. Many engineering projects require the point heights referring to a physical surface, i.e., geoid, rather than an ellipsoid. When a high-accuracy local geoid model is available in the study area, the physical heights are practically obtained with the transformation of global navigation satellite system (GNSS) ellipsoidal heights of the points. Besides the commonly used geodetic methods, this study introduces a novel approach for the determination and validation of the local geoid surface models using photogrammetry. The numeric tests were carried out in the Bergama region, in the west of Turkey. Using direct georeferenced airborne LiDAR and indirect georeferenced UAV photogrammetry-derived point clouds, DTMs were generated in ellipsoidal and geoidal vertical datums, respectively. After this, the local geoid models were calculated as differences between the generated DTMs. Generated local geoid models in the grid and pointwise formats were tested and compared with the regional gravimetric geoid model (TG03) and a high-resolution global geoid model (EIGEN6C4), respectively. In conclusion, the applied approach provided sufficient performance for modeling and validating the geoid heights with centimeter-level accuracy.

Highlights

Digital elevation models (DEM) provide information on the topographic surface elevation with respect to a reference datum
The two digital terrain models (DTMs) by unmanned aerial vehicle (UAV) photogrammetric imagery were for providing the orthometric heights of the same points in TIUSPDRKS AInt9.9J.dGaeot-uInmf..20A20c,c9o,rxdFiOngRlPy,EtEwRoREloVcIEaWl geoid surface models were generated using the DTM-cou17polef s26 (N = hDTMI − HDTMII ) by Envi LiDAR and Global Mapper outputs, respectively. algoFrigthumrea1p1pslhieodwusstihnegcGallcoublalteMdalopcpaelrgGeoISidssouftrwfaacrees [u4s0i]n.gInDrTeMsusltgse, ntheerattwedo bDyTEMnsvibLyiDaeAriRal(aL)iDanAdR Gdloatbaawl Meraepipnehra(nbd), froerspoebcttaiivneilnyg
Integration of global navigation satellite system (GNSS)/INS sensors mounted on the aerial vehicles in photogrammetric applications brought the direct georeferencing opportunity, which made a positive impact on the implementation of these techniques

Summary

Introduction

Digital elevation models (DEM) provide information on the topographic surface elevation with respect to a reference datum. DTM means the elevation of the bare surface of the topography without man-made structures, vegetation and other surface features, whereas DSM includes the elevations of all these ground cover objects [2,3]. Depending on this definition, the application areas of DSM and DTM may be different. Various factors including data acquisition technique, terrain character, topographical slope, landscape cover, computation strategy affect the accuracy of generated DEM. The uncertainties naturally occur in DEM generation because of the mentioned observational and computational error factors These uncertainties eventually affect the outcome quality and analysis precision in DEM applications [5]. Various methods can be applied for quality assessments of the DEM data in a study area prior to the application

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