Orthometric Height Improvement in Tainan City using RTK GPS and Local Geoid Corrector Surface Models

Lin, Lao-Sheng

doi:10.1061/(asce)su.1943-5428.0000114

Cited by 7 publications

(2 citation statements)

References 18 publications

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“…On the other hand, if height di erences are not used i.e., absolute height value of the points are sought at a certain epoch, one has to be concerned with the geoid model used for those particular orthometric height determinations because di erent geoid models (https://www.ngs.noaa.gov/GEOID/) produce different orthometric heights, which is beyond the scope of this paper. However, interested readers are referred to Wang and Soler (2014) and Lin (2013). NGS has been producing geoid models to convert ellipsoidal height obtained from GPS to orthometric height of a speci c vertical datum.…”

Section: Methodsmentioning

confidence: 99%

Subsidence determination in the Central Valley, California

Romero

Berber

2018

Reports on Geodesy and Geoinformatics

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Twenty four hour GNSS (Global Navigation Satellite System) data acquired monthly for 5 years from 8 CORS (Continuously Operating Reference Station) stations in Central Valley, California are processed and vertical velocities of the points are determined. To process GNSS data, online GNSS data processing service APPS (Automatic Precise Positioning Service) is used. GNSS data downloaded from NGS (National Geodetic Survey) CORS are analyzed and subsidence at these points is portrayed with graphics. It is revealed that elevation changes range from 5 mm uplift in the north to 163 mm subsidence in the southern part of the valley.

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Section: Methodsmentioning

confidence: 99%

Subsidence determination in the Central Valley, California

Romero

Berber

2018

Reports on Geodesy and Geoinformatics

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“…In conclusion, for the GNSS-RTK technology to meet geodetic standards, it is of high importance to apply correction surfaces (local geoid model) to RTK ellipsoidal heights in order to remove systematic errors and increase their reliability [40].…”

Section: Motivation For Creating and Using The Local Quasigeoidmentioning

confidence: 99%

Proposed Methodology for Accuracy Improvement of LOD1 3D Building Models Created Based on Stereo Pléiades Satellite Imagery

Breaban

Oniga²,

Chirila³

et al. 2022

Remote Sensing

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Three-dimensional city models play an important role for a large number of applications in urban environments, and thus it is of high interest to create them automatically, accurately and in a cost-effective manner. This paper presents a new methodology for point cloud accuracy improvement to generate terrain topographic models and 3D building modeling with the Open Geospatial Consortium (OGC) CityGML standard, level of detail 1 (LOD1), using very high-resolution (VHR) satellite images. In that context, a number of steps are given attention (which are often (in the literature) not considered in detail), including the local geoid and the role of the digital terrain model (DTM) in the dense image matching process. The quality of the resulting models is analyzed thoroughly. For this objective, two stereo Pléiades 1 satellite images over Iasi city were acquired in September 2016, and 142 points were measured in situ by global navigation satellite system real-time kinematic positioning (GNSS-RTK) technology. First, the quasigeoid surface resulting from EGG2008 regional gravimetric model was corrected based on data from GNSS and leveling measurements using a four-parameter transformation, and the ellipsoidal heights of the 142 GNSS-RTK points were corrected based on the local quasigeoid surface. The DTM of the study area was created based on low-resolution airborne laser scanner (LR ALS) point clouds that have been filtered using the robust filter algorithm and a mask for buildings, and the ellipsoidal heights were also corrected with the local quasigeoid surface, resulting in a standard deviation of 37.3 cm for 50 levelling points and 28.1 cm for the 142 GNSS-RTK points. For the point cloud generation, two scenarios were considered: (1) no DTM and ground control points (GCPs) with uncorrected ellipsoidal heights resulting in an RMS difference (Z) for the 64 GCPs and 78 ChPs of 69.8 cm and (2) with LR ALS-DTM and GCPs with corrected ellipsoidal height values resulting in an RMS difference (Z) of 60.9 cm. The LOD1 models of 1550 buildings from the Iasi city center were created based on Pléiades-DSM point clouds (corrected and not corrected) and existing building sub-footprints, with four methods for the derivation of the building roof elevations, resulting in a standard deviation of 1.6 m against high-resolution (HR) ALS point cloud in the case of the best scenario. The proposed method for height extraction and reconstruction of the city structure performed the best compared with other studies on multiple satellite stereo imagery.

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