On the Accurate Determination of the Orthometric Correction to Levelled Height Differences - A Case Study in Hong Kong

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F49777513%3A23520%2F25%3A43976758" target="_blank" >RIV/49777513:23520/25:43976758 - isvavai.cz</a>

Result on the web

<a href="https://www.mdpi.com/2673-7418/5/4/71" target="_blank" >https://www.mdpi.com/2673-7418/5/4/71</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.3390/geomatics5040071" target="_blank" >10.3390/geomatics5040071</a>

Result language

angličtina

Original language name

On the Accurate Determination of the Orthometric Correction to Levelled Height Differences - A Case Study in Hong Kong

Original language description

Orthometric heights are practically determined from levelling and gravity measurements by applying orthometric corrections to levelled height differences. Currently, Helmert’s definition of orthometric heights is mostly used, with the mean gravity computed only approximately from observed surface gravity by applying the Poincaré-Prey gravity reduction. In this study, we compute orthometric corrections by applying the state-of-the-art method that utilizes advanced numerical procedures to account for the topographic relief and 3D mass density variations, while adopting the Earth’s spherical approximation. The non-topographic contribution of masses inside the geoid is evaluated by solving geodetic boundary-values problems. We apply this numerical procedure for the first time to practically determine orthometric heights of levelling benchmarks from levelling and gravity measurements and digital terrain and rock density models. Results obtained after readjustment of newly determined orthometric heights at the levelling network covering the Hong Kong territories are compared with Helmert’s orthometric heights. Comparison reveals that errors in Helmert’s orthometric heights vary between -3.13 and 0.95 cm. Such errors are very significant when compared to accurate values of the cumulative orthometric correction between -1.88 and 0.84 cm. Moreover, large errors (up to 1 cm) occur already at levelling benchmarks at very low elevations (&lt; 100 m). These findings demonstrate that an accurate determination of orthometric heights is crucial even for regions with moderately elevated topography.

Czech name

—

Czech description

—

Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10508 - Physical geography

Project

<a href="/en/project/GA23-07031S" target="_blank" >GA23-07031S: Ellipsoidal modelling of planetary gravitational fields</a><br>

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2025

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Geomatics

ISSN

2673-7418

e-ISSN

2673-7418

Volume of the periodical

5

Issue of the periodical within the volume

4

Country of publishing house

CH - SWITZERLAND

Number of pages

34

Pages from-to

1-34

UT code for WoS article

001648287100001

EID of the result in the Scopus database

2-s2.0-105026386455