Browsing by Author "Din, A.H.M."

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Airborne Gravity Data Reconstruction Strategies for Geoid Optimization in Peninsular Malaysia
(Association for Geoinformation Technology, 2025) Zamri, A.N.M.; Pa’suya, M.F.; Din, A.H.M.; Abbak, R.A.; Ali, T.A.T.; Talib, N.; Othman, N.A.
Geoid height is essential for precise height determination, particularly in surveying and geodetic applications. Airborne gravity data substantially improve geoid models, especially over regions with complex terrain where terrestrial coverage is limited. However, since airborne data are acquired at flight altitude, they require downward continuation to the geoid surface which an inherently unstable process. Despite ongoing advancements, the most effective strategy for combining and gridding gravity data, particularly airborne measurements, remains a topic of research. This study evaluates two downward continuation strategies to assess their influence on geoid accuracy. The first strategy applies downward continuation to airborne data simultaneously with terrestrial and marine data, incorporating a range of buffer distances (0 km, 1 km, 5 km, and 10 km) to examine their effect on model performance. The second strategy involves performing downward continuation on airborne data independently before merging with other datasets. Numerical results indicate the Root Mean Square Error (RMSE) values of 0.044 m for the first strategy and 0.045 m for the second, with a marginal difference of 0.001 m. Although the difference appears minor, even marginal improvements can be pivotal in high-precision geoid modelling particularly in localized regions where complex topography or sparse data coverage may magnify subtle errors. Such refinements are essential to advancing the long-term goal of achieving geoid accuracy at the 1 cm level for Peninsular Malaysia. © Geoinformatics International.
Citation - Scopus: 13
Refinement of Gravimetric Geoid Model by Incorporating Terrestrial, Marine, and Airborne Gravity Using Kth Method
(Springer Science and Business Media Deutschland GmbH, 2021) Pasuya, M.F.; Din, A.H.M.; Yusoff, M.Y.M.; Abbak, R.A.; Hamden, M.H.
We compute a new gravimetric geoid model for Peninsular Malaysia (PMGG2020) based on the Royal Institute of Technology (KTH) method. The PMGG2020 was computed from 8474 terrestrial gravity points, satellite altimetry-derived gravity anomaly (DTU17), 24,855 airborne gravity data, and the TanDEM-X Digital Elevation Model. All the gravity datasets were combined and gridded onto a 1-min resolution using the 3D Least Square Collocation (LSC) method with EIGEN-6C4 as the reference field. GO_CONS_GCF_2_SPW_R4 was used to provide long wavelengths of gravity field up to 130 maximum degrees and order in the geoid computation. Based on an evaluation using 173 Global Navigation Satellite System (GNSS)-levelling points distributed over Peninsular Malaysia, the precision of the PMGG2020 was 0.058 m. It is almost identical to the accuracy of the official Peninsular Malaysia gravimetric geoid, WMG03A. Using airborne gravity, the precision of PMGG2020 showed a significant improvement of ~4 cm over the existing KTH-derived geoid model, PMSGM2014. These results highlight the significant effect of airborne gravity data on the accuracy of the geoid model. © 2021, Saudi Society for Geosciences.