EVALUASI KETELITIAN HASIL ORTHOREKTIFIKASI CITRA SATELIT RESOLUSI TINGGI MENGGUNAKAN DEM STEREO-PAIR PLEIADES

2019 ◽  
Vol 3 ◽  
pp. 11
Author(s):  
Diaz Cahya Kusuma Yuwana ◽  
Maundri Prihanggo ◽  
Agung Syetiawan
Keyword(s):  
Sea Level ◽  
Digital Elevation Model ◽  
Control Point ◽  
Ground Control ◽  
Stereo Pair ◽  
Check Point ◽  
Mean Sea Level ◽  
Rational Polynomial ◽  
Digital Elevation ◽  
Elevation Model

Implementasi proses orthorektifikasi membutuhkan data Digital Elevation Model (DEM) yang akurat. Ketersediaan data DEM yang akurat menjadi permasalahan tersendiri dalam proses orthorektifikasi. DEM hasil proses stereo-pair citra satelit pleiades menjadi sebuah alternatif. Penelitian ini berfokus untuk mengkaji ketelitian geometrik hasil orthorektifikasi dengan masukan DEM hasil stereo-pair (1m) citra satelit plaiades dengan DEM IFSAR (5m). Data yang digunakan meliputi sepasang Citra Satelit Pleiades, data hasil pengukuran GPS sebanyak 23 titik yang nantinya 11 titik dijadikan sebagai Ground Control Point (GCP) dan 12 titik dijadikan sebagai Independent Check Point (ICP), dan data DEM Ifsar 5 meter. Penelitian ini mendasarkan pada perbandingan ketelitian geometrik antara citra hasil othorektifikasi menggunakan masukan DEM IFSAR 5 m dengan masukan DEM dari hasil proses stereo-pair dua pasang citra satelit pleiades. Metode rational polynomial coefficient (RPC) digunakan untuk mendapatkan pembentukan epipolar citra dan citra ortho. DEM hasil stereo-pair citra satelit plaiades memiliki rentang -37 meter sampai dengan 155 meter di atas mean sea level (MSL). DEM hasil stereo-pair jauh lebih detail dari DEM IFSAR, kondisi perumahan dan jalan raya terepresentasikan lebih baik dan lebih jelas. Akurasi pada citra hasil orthorektifikasi menggunkan DEM stereo-pair 1 m adalah 1,04019 lebih baik dari hasil ortho menggunakan DEM IFSAR 5 m yaitu 1,12783. Perbedaan resolusi DEM sebesar 4 meter tidak signifikan mempengaruhi hasil orthorektifikasi citra satelit resolusi tinggi. Secara keseluruhan hasil akhir yang didapat dari kedua citra ortho dengan masukan data DEM tersebut masuk dalam ketelitian peta skala 1:5000 kelas 2 CE90.

PENENTUAN GARIS PANTAI MENGGUNAKAN FOTO UDARA DARI WAHANA TANPA AWAK (Studi Kasus Pantai Ujong Batee Aceh)

2021 ◽  
pp. 707
Author(s):  
Herjuno Gularso ◽  
Andri Daniel Parapat ◽  
Teguh Sulistian ◽  
Alfian Adi Atmaja
Keyword(s):  
Digital Elevation Model ◽  
Point Cloud ◽  
Control Point ◽  
Ground Control ◽  
Check Point ◽  
Ground Sample ◽  
Ground Control Point ◽  
Digital Elevation ◽  
Elevation Model ◽  
Sample Distance

Garis pantai merujuk Undang-undang No 4 tahun 2011 pasal 13 merupakan garis pertemuan antara daratan dengan lautan yang dipengaruhi oleh pasang surut air laut. Pembentukan garis pantai membutuhkan data Digital Elevation Model (DEM) diwilayah pesisir dengan resolusi dan ketelitian tinggi, sementara teknologi foto udara memiliki kemampuan dalam hal ekstraksi point ketinggian (point cloud) dari titik sekutu antar foto udara yang bertampalan dan juga memiliki kelebihan menghemat waktu pekerjaan dan biaya jika dibandingkan dengan pengukuran terestris. Penelitian ini bertujuan untuk menguji hasil pembentukan DEM dari data foto udara yang selanjutnya digunakan untuk pembentukan garis pantai di pantai Ujong Batee Aceh. Proses pengumpulan data menggunaan wahana Multi rotor DJI Mavic Pro. Jumlah titik Ground Control Point (GCP) adalah 10 titik yang tersebar secara merata untuk seluruh area yang dipetakan. Hasil Ground Sample Distance adalah 1,97 cm/pixel dengan cakupan area yaitu 16,8 hektar. Hasil uji akurasi vertikal DEM menggunakan 167 Independent Check Point (ICP) adalah sebesar 0,863 m, dapat disimpulkan bahwa data foto udara kamera non-metrik dalam penelitian ini memenuhi ketelitian vertikal peta RBI pada skala 1:5.000 kelas I (SNI Ketelitian peta dasar 8202:2019). Pembentukan garis pantai menggunakan DEM dari foto udara yang sudah dikoreksi menggunakan model pasut BIG sehingga datum vertikal dari DEM adalah muka air rata- rata. Garis pantai yang terbentuk pada lokasi penelitian hanya garis pantai pasang tertinggi dan muka air laut rata-rata. Pemotretan udara untuk mendapatkan DEM diwilayah pesisir sebaiknya dilakukan pada saat air surut untuk memperoleh garis pantai air muka laut rata-rata dan pasang tertinggi.

PEMUTAKHIRAN DIGITAL ELEVATION MODEL NASIONAL WILAYAH LAUT (Studi Kasus: Wilayah Perairan Aceh)

2021 ◽  
pp. 699
Author(s):  
Teguh Sulistian ◽  
Sandi Aditya ◽  
Fajar Triady Mugiarto ◽  
Fatichatus Istighfarini ◽  
Rifqi Muhammad Harrys ◽  
...  
Keyword(s):  
Sea Level ◽  
Digital Elevation Model ◽  
Mean Sea Level ◽  
Multibeam Echosounder ◽  
Digital Elevation ◽  
Elevation Model

Badan Informasi Geospasial (BIG) telah mempublikasikan Seamless Digital Elevation Model Nasional (DEMNAS) pada tahun 2018. DEMNAS terdiri dari 2 model elevasi yaitu DEMNAS di wilayah darat dengan resolusi spasial 0,27 arc-second dan DEMNAS di wilayah laut atau lebih sering disebut dengan Batimetri Nasional (BATNAS) dengan resolusi spasial 6 arc-second. Tujuan penelitian ini adalah pemutakhiran data DEMNAS wilayah laut dari resolusi spasial 6 arc-second menuju resolusi spasial 2 arc-second dengan menggunakan metode interpolasi spline. Data yang digunakan dalam penelitian ini meliputi data pemeruman singlebeam echosounder (SBES), data pemeruman multibeam echosounder (MBES) dan data satelit altimetri. Data utama yang digunakan merupakan hasil pemeruman dari berbagai instansi yang menjadi kontributor pada program BATNAS. Proses pemutakhiran menggunakan metode asimilasi data batimetri. Proses asimilasi dimulai dari data tersedia yang akan dimutakhirkan yaitu DEMNAS wilayah laut dengan resolusi spasial 6 arc-second diasimilasi menggunakan data pemeruman yang terbaru. Metode interpolasi pembentukan DEM menggunakan metode spline dengan tension 0,27. Tujuan dari peningkatan resolusi spasial dari DEMNAS wilayah laut menjadi 2 arc-second adalah untuk menjaga tingkat kedetailan model pada area-area yang sudah memiliki data pemeruman yang detail. Datum horizontal yang digunakan adalah WGS 1984 dan datum vertikal menggunakan datum mean sea level (MSL). Hasil pengujian menunjukan standar deviasi pada DEMNAS laut yang dimutakhirkan pada resolusi spasial 2 arc-second menunjukan hasil yang paling baik dengan standar deviasi 2,006 m. Sementara untuk DEMNAS Laut yang dimutakhirkan dengan resolusi 6 arc-second menghasilkan standar deviasi lebih rendah yaitu 7,108 m.

Evaluation of Low Cost Digital Cameras for Producing Photogrammetric Output from UAV

2018 ◽  
Vol 7 (2.29) ◽  
pp. 792 ◽  
Author(s):  
Syafiq Sukor ◽  
Anuar Ahmad
Keyword(s):  
Global Positioning System ◽  
Mean Squared Error ◽  
Low Cost ◽  
Control Point ◽  
Ground Control ◽  
Digital Cameras ◽  
Squared Error ◽  
Digital Elevation ◽  
Global Positioning ◽  
Elevation Model

Recently there a lot of improvement in digital photogrammetry and this allow photogrammetry to become faster and cheaper . This study discuss about two type of low cost camera which is the compact camera (Canon Power Shot SX230 ) and action camera (Xiaomi yi) where both of them have different lens distortion. This study is conducted within UTM (Universiti Teknologi Malaysia) Skudai campus at Kolej  Tun Razak. Both of the Canon Power Shot SX230 and Xiaomi yi camera would be attach to the UAV  to take aerial photo with three different altitude which is 60 meter, 80 meter and 100 meter with a similar flight path. Check point (CPs) and Ground control point (GCPs) were also established using rapid static technique of Global Positioning System (GPS) and Total Station. The Canon Power Shot SX230 and Xiaomi yi camera is then calibrated using checkboard calibration this is done by using Agisoft  Lens software. Then all of the pictures that been taken by the Canon Power Shot SX230 and the Xiaomi yi would be processed by using Agisoft Photoscan software to generate Digital Elevation Model (DEM), orthophoto and contour line. The accuracy of DEM was determined based on Root Mean Squared Error (RMSE) value. Both of the result is then analyze visually and statically. Overall both of the camera gives a slight different in accuracy. 

Assessing the accuracy of river channel bathymetry measurements using an RTK rotary-winged Unmanned Aerial Vehicle (UAV) with varying Ground Control Point (GCP) number and placement

2020 ◽  
Author(s):  
Ian Maddock ◽  
Josie Lynch
Keyword(s):  
Control Point ◽  
Base Station ◽  
River Channel ◽  
Ground Control ◽  
Time Saving ◽  
Digital Elevation ◽  
Wadeable Streams ◽  
Rtk Gps ◽  
Elevation Model ◽  
Submerged Area

<p>Previous studies have established the ability to map river channel bathymetry accurately in clear water, shallow wadeable streams using imagery from Unmanned Aerial Vehicles (UAVs), Structure-from-Motion (SfM) photogrammetry and the application of refraction correction. However, because standard rotary-winged UAVs geotag imagery at a relatively low accuracy, there has been a need to use Ground Control Points (GCPs) to georeference the Digital Elevation Model (DEM). This is problematic in that is requires the operators to navigate around the site to place, survey and collect the GCPs which can be very time consuming and/or hazardous. A potential solution lies with the recent introduction of lower cost rotary-winged drones fitted with higher accuracy on-board RTK GPS sensors. These have raised the possibility of conducting UAV surveys with the use of very few or no GCPs across the survey site, saving time and removing the need to access all areas for GCP placement.</p><p>To test this possibility, we flew a 250 metre reach of the River Teme (max depth ~1m) on the English-Welsh border at 40m in July 2019 with two drones, i.e. a DJI Phantom 4 RTK UAV and base station and a DJI Phantom 4 PRO (non-rtk). The Phantom 4 RTK UAV was flown three times, i) using the flight program’s 2D option (nadir only and one flight path) ii) using the 3D option (camera angled at 60° and flown in two directions) and iii) using the RTK off option and then using post-processing (PPK) to correct the image locations. 20 GCPs were placed across the site and their locations surveyed with a Trimble R8 dGPS and an additional 20 Independent Validation Points (IVPs) were surveyed along the floodplain for terrestrial validation points and 100 points within the channel were surveyed submerged area validation points.</p><p>Imagery was processed with Agisoft Metashape (v1.5.5). A total of 28 DEMs were produced using the imagery from the two drones, different flight paths and different combinations of numbers and location of GCPs. These included reducing the number of GCPs from 20, to 10, 5, 3, 1 and 0. When using three GCPs, DEMs were produced by having them i) spread throughout the reach and ii) clustered close to one another. The bed heights of the submerged locations were corrected using the simple refraction correction first used by Westaway et al (2001) and then compared to the measured heights in the field. Accuracy was quantified using linear regression.</p><p>The results of this analysis demonstrated the ability to obtain accurate surveys of bathymetry in depths upto 1m using a DJI Phantom 4 RTK UAV and base station and a significantly reduced number of GCPS, combined with the application of refraction correction. This study confirms that considerable time saving in terms of fieldwork can be gained from the use of an RTK rotary-winged drone and base station. This technology can also be beneficial for obtaining accurate survey data in locations where it may be unsafe or impossible to place GCPs due to the hazardous nature of the terrain.</p>

scholarly journals Digital elevation model generation using UAV-SfM photogrammetry techniques to map sea-level rise scenarios at Cassino Beach, Brazil

2020 ◽  
Vol 2 (12) ◽  
Author(s):  
Deivid Cristian Leal-Alves ◽  
Jair Weschenfelder ◽  
Miguel da Guia Albuquerque ◽  
Jean Marcel de Almeida Espinoza ◽  
Marlize Ferreira-Cravo ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Digital Elevation Model ◽  
Model Generation ◽  
Digital Elevation ◽  
Elevation Model

scholarly journals SAR Interferometric Baseline Refinement Based on Flat-Earth Phase without a Ground Control Point

2020 ◽  
Vol 12 (2) ◽  
pp. 233 ◽  
Author(s):  
Bing Xu ◽  
Zhiwei Li ◽  
Yan Zhu ◽  
Jiancun Shi ◽  
Guangcai Feng
Keyword(s):  
Control Point ◽  
Least Square ◽  
Synthetic Aperture ◽  
Ground Control ◽  
Ground Control Point ◽  
Refinement Method ◽  
Digital Elevation ◽  
Elevation Model ◽  
Interferometric Sar ◽  
Baseline Estimation

Interferometric baseline estimation is a key procedure of interferometric synthetic aperture radar (SAR) data processing. The error of the interferometric baseline affects not only the removal of the flat-earth phase, but also the transformation coefficient between the topographic phase and elevation, which will affect the topographic phase removal for differential interferometric SAR (D-InSAR) and the accuracy of the final generated digital elevation model (DEM) product for interferometric synthetic aperture (InSAR). To obtain a highly accurate interferometric baseline, this paper firstly investigates the geometry of InSAR imaging and establishes a rigorous relationship between the interferometric baseline and the flat-earth phase. Then, a baseline refinement method without a ground control point (GCP) is proposed, where a relevant theoretical model and resolving method are developed. Synthetic and real SAR datasets are used in the experiments, and a comparison with the conventional least-square (LS) baseline refinement method is made. The results demonstrate that the proposed method exhibits an obvious improvement over the conventional LS method, with percentages of up to 51.5% in the cross-track direction. Therefore, the proposed method is effective and advantageous.

scholarly journals Digital elevation model validation with no ground control: application to the topodata dem in Brazil

2014 ◽  
Vol 20 (2) ◽  
pp. 467-479 ◽  
Author(s):  
Laurent Polidori ◽  
Mhamad El Hage ◽  
Márcio De Morisson Valeriano
Keyword(s):  
Digital Elevation Model ◽  
Visual Analysis ◽  
Ground Control ◽  
Ground Control Points ◽  
Geostatistical Approach ◽  
Digital Elevation ◽  
Elevation Model ◽  
Control Application ◽  
Statistical Indicators

Digital Elevation Model (DEM) validation is often carried out by comparing the data with a set of ground control points. However, the quality of a DEM can also be considered in terms of shape realism. Beyond visual analysis, it can be verified that physical and statistical properties of the terrestrial relief are fulfilled. This approach is applied to an extract of Topodata, a DEM obtained by resampling the SRTM DEM over the Brazilian territory with a geostatistical approach. Several statistical indicators are computed, and they show that the quality of Topodata in terms of shape rendering is improved with regards to SRTM.

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