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ALGORITMA PENENTUAN DAN REKONTRUKSI ARAH KIBLAT TELITI MENGGUNAKAN DATA GNSS Gumilar, Irwan; Trihantoro, Nur Fajar; Bramanto, Brian; Andreas, Heri; Abidin, Hasanuddin Zainal; Gamal, Mohamad
GEOMATIKA Vol 25, No 2 (2019)
Publisher : Badan Informasi Geospasial in Partnership with MAPIN

Kiblat merupakan arah yang dituju umat Muslim ketika melakukan ibadah shalat. Terdapat beberapa dalil baik Al-Quran ataupun As-Sunnah yang mewajibkan ibadah shalat untuk menghadap kiblat. Perkembangan teknologi penentuan posisi dan algoritma pengukuran arah sangat memungkinkan untuk menentukan arah kiblat secara teliti, sekalipun untuk daerah yang tidak memungkinkan untuk melihat Kakbah. Tujuan penelitian ini yaitu menentukan mekanisme perhitungan arah kiblat dan rekonstruksinya menggunakan teknologi GNSS. Metodologi yang dilakukan yaitu dengan menerapkan beberapa metode penentuan posisi menggunakan GNSS untuk menentukan arah kiblat dan perhitungan arah kiblat di atas bidang elipsoid menggunakan metode Vincenty. Rekontruksi arah kiblat dilakukan dengan menerapkan irisan koreksi normal geodesik, koreksi skew normal, dan koreksi defleksi vertikal. Hasil penelitian menunjukkan bahwa metode statik, RTK, dan RTPPP GNSS dapat digunakan untuk menentukan arah kiblat. Penerapan metode Vincenty di atas bidang elipsoid untuk penentuan azimut memperlihatkan arah yang tepat ke arah Kakbah. Untuk keperluan rekonstruksi arah kiblat, pemberian koreksi normal geodesik, koreksi skew normal, dan koreksi defleksi vertikal dapat meningkatkan ketelitian sekitar 2 menit. Khusus untuk pengukuran titik backsight dengan RTK, azimut yang didapatkan berbeda sekitar 2 menit dibandingkan dengan metode statik. Perbedaan 2 menit ini menyebabkan arah Kakbah bergeser sekitar 3,6 km, walaupun masih tetap berada di kota Mekah. Dengan demikian dapat disimpulkan bahwa untuk mendapatkan ketelitian yang tinggi untuk pengukuran tepat ke arah kiblat maka harus digunakan metode penentuan posisi statik, menggunakan metode Vincenty di atas elipsoid untuk pengukuran azimutnya, serta menerapkan koreksi irisan normal geodesik, koreksi skew normal, dan koreksi defleksi vertikal untuk rekonstruksinya.

Analisis Hasil Pengukuran Terrestrial Laser Scanner untuk Deteksi Rekahan dalam kaitannya dengan Analisis Struktur Geologi (Studi Kasus: Tebing Citatah 125, Jawa Barat) Gusti Ayu Jessy Kartini; Irwan Gumilar; Budi Brahmantyo; Brian Bramanto; Nia Haerani
Jurnal Lingkungan dan Bencana Geologi Vol 9, No 3 (2018)
Publisher : Badan Geologi

Scanline adalah salah satu metode yang umum digunakan untuk mengobservasi dan mengukur rekahan pada suatu bidang permukaan, namun metode ini memiliki beberapa keterbatasan. Salah satunya adalah sulitnya melakukan sampling pada area ekstrim sehingga dapat membahayakan operator. Mengacu pada keterbatasan tersebut, terrestrial laser scanner menjadi salah satu metode yang potensial untuk menutupi keterbatasan tersebut. TLS dapat merekam jutaan point cloud yang dapat merepresentasikan permukaan tanpa harus mengukurnya secara langsung, yang kemudian dapat menjadi metode pendukung dalam akuisisi data rekahan. Penelitian ini bertujuan untuk mengidentifikasi rekahan menggunakan TLS yang kemudian dibandingkan dan divalidasi dengan metode scanline (studi kasus: Tebing Citatah 125, Kabupaten Bandung Barat, Provinsi Jawa Barat). Penelitian ini dimulai dengan akuisisi data rekahan dengan menggunakan metode scanline dan TLS yang hasilnya kemudian dianalisis dengan diagram rose. Penelitian ini menghasilkan kesimpulan bahwa TLS memiliki potensi sebagai metode pendukung untuk akuisisi data rekahan. Hal tersebut dibuktikan dengan kemiripan hasil orientasi rekahan pada Tebing Citatah 125 menggunakan TLS terhadap hasil metode scanline pada orientasi rekahan arah timur laut-barat daya dengan kemiringan relatif tegak 30o-90o.

DIGITAL ELEVATION MODEL ALTERNATIVES ASSESSMENT FOR DEFORMATION ANALYSIS PURPOSES USING GNSS AND INSAR Dina Anggreni Sarsito; Brian Bramanto
Jurnal Meteorologi dan Geofisika Vol 23, No 1 (2022)
Publisher : Pusat Penelitian dan Pengembangan BMKG

Digital Elevation Model (DEM) is the starting point in the analysis performed to explain the deformation pattern changes from the Earth's surface. The estimated value of deformation based on point-wise GPS and InSAR data with a better spatial resolution must be defined in a reference frame system that reflects the phenomenon of deformation of the real physical world, e.g., orthometric height for the vertical component. Therefore, this study aims to provide alternative DEM models based on a suitable combination between the Global Geopotential Model of Earth Geopotential Model 2008 (EGM2008) and global terrain models, providing position changes with respect to the orthometric height. The alternative DEM models are (i) the global elevation model of ETOPO1 (DEM1), (ii) the modified global elevation model of SRTM30_PLUS (DEM2), and (iii) the regional elevation model of DEMNAS (DEM3). These alternative models comply with each other for the land areas with mean difference values lower than 1 meter. While for the ocean areas, we found that DEM1 and DEM2 have apparent differences due to the different types of data used. However, a similar assessment could not be performed for DEM3 as it only covers the land areas. Additionally, we compared the orthometric height from these terrain models with leveling observations for the coinciding locations. DEM3 achieves the highest accuracy with the estimated standard deviation of 11.2745 meters and is followed by DEM2 and DEM1 with the respective standard deviation of 29.4498 and 37.6872 meters. We found that these models can be used as a starting position determination for horizontal and vertical deformation analysis.

The Combined Use of Terrestrial Laser Scanner and Handheld 3D Scanner for 3D Modeling of Piping Instrumentation at Oil and Gas Company Irwan Gumilar; Farhan Farohi; Made Munarda; Brian Bramanto; Gusti Ayu Jessy Kartini
Journal of Engineering and Technological Sciences Vol. 54 No. 6 (2022)
Publisher : Directorate for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2022.54.6.3

Three-dimensional (3D) models are indispensable in managing, operating, maintaining, and repairing piping instrumentation activities in oil and gas companies. 3D models are expected to provide more interactive and representative information according to actual objects. Several technologies that can be used to generate piping instrumentation 3D maps are Terrestrial Laser Scanner (TLS) and Handheld 3D Scanner (HS). This study aims to create a 3D model of piping instrumentation using a combination of TLS and HS and analyze the results of data validation used for modeling. The results showed that a 3D modeling of piping instrumentation could be generated accurately using a combination of TLS and HS technologies. Merging between the two data is carried out through a cloud-to-cloud registration process based on the geometry of the object by considering the selection of reference data, the similarity of the scale factor, the unit of measure, and the overlap of the two data. The registration error generated in combining these two methods is less than 0.003 m. The resulting model still has drawbacks, which is the absence of coding for the pipe caused by the unavailability of the Piping and Instrumentation Diagram (P&ID) during modeling. The geometric validation of the model size value using reference data and the field size has the largest absolute difference of 0.0034 m with an average absolute deviation of 0.0016 m.

DIGITAL ELEVATION MODEL ALTERNATIVES ASSESSMENT FOR DEFORMATION ANALYSIS PURPOSES USING GNSS AND INSAR Dina Anggreni Sarsito; Brian Bramanto
Jurnal Meteorologi dan Geofisika Vol. 23 No. 1 (2022)
Publisher : Pusat Penelitian dan Pengembangan BMKG

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31172/jmg.v23i1.845

Digital Elevation Model (DEM) is the starting point in the analysis performed to explain the deformation pattern changes from the Earth's surface. The estimated value of deformation based on point-wise GPS and InSAR data with a better spatial resolution must be defined in a reference frame system that reflects the phenomenon of deformation of the real physical world, e.g., orthometric height for the vertical component. Therefore, this study aims to provide alternative DEM models based on a suitable combination between the Global Geopotential Model of Earth Geopotential Model 2008 (EGM2008) and global terrain models, providing position changes with respect to the orthometric height. The alternative DEM models are (i) the global elevation model of ETOPO1 (DEM1), (ii) the modified global elevation model of SRTM30_PLUS (DEM2), and (iii) the regional elevation model of DEMNAS (DEM3). These alternative models comply with each other for the land areas with mean difference values lower than 1 meter. While for the ocean areas, we found that DEM1 and DEM2 have apparent differences due to the different types of data used. However, a similar assessment could not be performed for DEM3 as it only covers the land areas. Additionally, we compared the orthometric height from these terrain models with leveling observations for the coinciding locations. DEM3 achieves the highest accuracy with the estimated standard deviation of 11.2745 meters and is followed by DEM2 and DEM1 with the respective standard deviation of 29.4498 and 37.6872 meters. We found that these models can be used as a starting position determination for horizontal and vertical deformation analysis.

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

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.

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