Heri Andreas
Kelompok Keahlian Geodesi, Institut Teknologi Bandung

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Penentuan Tinggi Orthometrik Gunung Semeru Berdasarkan Data Survei GPS dan Model Geoid EGM 1996 Hasanuddin Z. Abidin; Heri Andreas; Dinar Maulana; M. Hendrasto; M. Gamal; Oni K. Suganda
Journal of Mathematical and Fundamental Sciences Vol. 36 No. 2 (2004)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2004.36.2.4

Abstract

Semeru is the highest mountain in Java island with an altitude of about +3676 m above the sea level. This altitude was measured during the Dutch colonial times using the Triangulation method, which is based on angles measurements using a theodolite on the measurement points. At the present times, with the advancement in positioning technology and better knowledge on the Earth's gravity field, an orthometric altitude of a mountain can also be determined by utilizing GPS satellites observation data and a global geopotential model. In this paper, the methodology, mechanism and results of the altitude determination of Semeru mountain using the August 2003 and August 2004 GPS survey data and EGM 1996 geoid model will be described and discussed.The obtained results show that the altitude of Semeru at the present times is about +3677 m above the mean sea level.The paper will be sum up with some closing remarks.
Pemodelan TEC Regional dari Data GPS Stasiun Tetap di Indonesia dan Sekitarnya Buldan Muslim; Hasanuddin Z. Abidin; The Houw Liong; Wedyanto Kuntjoro; Cecep Subarya; Heri Andreas; M. Gamal
Journal of Mathematical and Fundamental Sciences Vol. 38 No. 2 (2006)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2006.38.2.6

Abstract

 Ionosphere affect propagation of electromagnetic waves through it by adding a transmission delay time. In GPS positioning and navigation, ionospheric delay is largest source of error after error from Selective Availability (SA) was turned off. For GPS positioning precisely ionospheric effect must be estimated so ionospheric correction can be determinated to eliminate ionospheric effect on GPS observation. In positioning by using GPS single frequency, ionospheric correction can be obtained from GPS dual frequency receiver at reference station or model. This paper describes method of determination and modeling of regional total electron content (TEC) from continuous GPS station in Indonesia and it's around. Spatial model of TEC at certain time is estimated by using polynomial function. Diurnal variation of polynomial model coefficient at certain hour from 00.00 "“ 23.00 UT is estimated with Fourier expansion.
EFEK AKURASI DAN GEOMETRIK SISTEM TINGGI DIGITAL ELEVATION MODEL (DEM) TERHADAP PEMODELAN BAHAYA BANJIR ROB DI JAKARTA Juliandri, Firman; Andreas, Heri; Pradipta, Dhota
Bulletin of Geology Vol 6 No 2 (2022): Bulletin of Geology Special Issue: International Seminar on Earth Sciences and Te
Publisher : Fakultas Ilmu dan Teknologi Kebumian (FITB), Institut Teknologi Bandung (ITB)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/bull.geol.2022.6.2.2

Abstract

Penelitian ini bertujuan untuk mengetahui efek akurasi DEM terhadap hasil pemodelan bahaya banjir rob di Jakarta dengan membandingkan hasil pemodelan menggunakan beberapa data DEM yang memiliki variasi akurasi. Model berbasis DEM LiDAR yang memiliki akurasi tinggi dijadikan baseline untuk pengukuran akurasi model lainnya. Pemodelan dengan DEMNAS menghasilkan luas area tergenang yang mendekati model DEM LiDAR dengan rasio perbandingan sebesar 97%. Pemodelan DEM global (open access), terdiri dari DEM SRTM (30 m), DEM TanDEM-X (60 m), dan DEM AW3D (30 m), menghasilkan luas area tergenang yang memiliki variasi antara 5% - 48% dari model DEM LiDAR. Pemodelan menunjukkan korelasi positif antara akurasi vertikal dan resolusi spasial DEM dengan akurasi produk model bahaya banjir rob di Jakarta. Perbandingan antar model secara lebih lanjut dilakukan untuk mendapatkan efek akurasi model terhadap hasil penilaian risiko bencana banjir rob. Penggunaan model DEM global yang berakurasi rendah menghasilkan nilai risiko jumlah penduduk terpapar sebesar 2,2 - 54,0 kali lebih rendah, serta nilai risiko kerugian ekonomi sebesar 1,9 - 37,6 lebih rendah dibandingkan penilaian risiko menggunakan model berbasis DEM LiDAR. Kata kunci: DEM, Jakarta, pemodelan banjir rob, penilaian risiko
ORTHOMETRIC HEIGHT DETERMINATION IN JAKARTA AND SUNDA STRAIT AREA USING THE GEOPOTENTIAL NUMBER APPROACH Sarsito, Dina Anggreni; Bramanto, Brian; Andreas, Heri; Pradipta, Dhota; Triwibowo, Sidiq
Bulletin of Geology Vol 8 No 1 (2024): Bulletin of Geology Vol. 8 no. 1
Publisher : Fakultas Ilmu dan Teknologi Kebumian (FITB), Institut Teknologi Bandung (ITB)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/bull.geol.2024.8.1.2

Abstract

Orthometric height is a physical height type used by Indonesia in local/national reference systems for determining positions used in various scientific and engineering activities. The main constraint in determining orthometric height is that it is theoretically difficult to realize that gravity measurements must be carried out along the plumb lines that connect the topographic equipotential surface with the geoid surface. Another constraint is that it requires precise physical height difference measurementsfrom tie points, which are usually located in coastal areas, to locations on land that are far from the coast. This research examines the possibility of determining orthometric physical height at several GNSS stations in the Jakarta and Sunda Strait areasusing the geopotential number approach as an alternative solution to the difficulties caused by the aforementioned constraints. The first type of orthometric height obtained from GNSS geodetic height observations with geoid undulation obtained from the EGM2008 global gravity model is then used as a comparison for the second type of orthometric height obtained from the geopotential number approach. The pattern of geopotential numbers on the islands of Java and Sumatra has the same pattern, namely that the value increases as the topographic elevation increases. This phenomenon is in line with the terrestrial survey approach carried outso far, that the meansea level can be assumed to be an estimate of the geoid surface, which is used as a reference for the gravity potential surface. The average difference in height between the two types of orthometric height is 0.39 meters, with a difference interval between -1.80 meters and 2.73 meters. The results obtained show that the geopotential number approach can be used as an alternative for determining orthometric height if direct gravity measurements and/or precise physical height difference measurements cannot be carried out in the monitoring area. Key words: Orthometric, Geopotential Number, Geoid, Jakarta, Sunda Strait.