【発表者募集】2025年度地理情報システム学会FOSS4G分科会企画セッションについて
武内樹治
それを受けて、FOSS4G分科会では、FOSS4G 2026を盛り上げるべく、複数の話題提供・講演をいただき地図×オープンソースの最前線について事例や知見を共有する。
話題提供・講演から「FOSS4Gの現在地」を把握するとともに、最後にFOSS4G Globalの開催概要・テーマについて報告し、「FOSS4G 2026」への機運を高めたい。
・発表内容：特にテーマを設けず広くFOSS4Gに関する発表を募集します。
FOSS4Gに関するもので、GIS学会に資する内容であればご発表いただけます（商業宣伝的な内容の場合は発表をお断りする可能性がございます）。
・FOSS4G技術を用いたフィールド調査
・FOSS4G技術の開発史と国際的なトレンド
・3次元データ解析や可視化のためのFOSS4G製品開発とその応用
・FOSS4G解析ライブラリを用いた空間分析
・WebGISに関するFOSS4G技術の最前線
発表希望の方はML上で表明（メール返信）いただけますと幸いです。
武内 樹治
Mikiharu Takeuchi
独立行政法人国立文化財機構 奈良文化財研究所
企画調整部文化財情報研究室 アソシエイトフェロー
E-mail: takeuc...@nich.go.jp
mikih...@gmail.com
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Razimul Karim
Dear Takeuchi,
Good Morning. It is my pleasure to attend and present at the 34th Geographic Information Systems Society Meeting that will be held at Toyama University on November 1st and 2nd. I include my name, affiliation, presentation title, and abstract for your reference. I hope it will be accepted for the 2025 Geographic Information Systems Society FOSS4G.
Thank you so much for your consideration.
Title of Presentation: Comparative Accuracy Assessment of LiDAR-derived Digital Terrain Model (DTM), Shuttle Radar Topography Mission (SRTM) and National Digital Elevation Model (DEM) in a Floodplain: A Case Study in Bangladesh
Presenter Name: K H Razimul Karim
Affiliation: Senior Specialist, Center for Environmental and Geographic Information Services (CEGIS), Agargaon Administrative Area, Sher-E-Bangla Nagar, Dhaka-1207, Bangladesh
Abstract
Digital Elevation Models (DEMs) are essential tools in geospatial analysis, widely used for applications in hydrology, geomorphology, agriculture, and disaster management. Among the globally available DEM datasets, the Shuttle Radar Topography Mission (SRTM) provides near-global coverage with a spatial resolution of 30 meters; however, its accuracy is often compromised in flat, vegetated terrains due to vegetation-induced elevation biases and sensor limitations. This study evaluates the vertical accuracy of the SRTM DEM in the low-lying agricultural region of Delduar Upazila, Tangail, Bangladesh, using high-resolution LiDAR data as a reference benchmark. LiDAR dataset was generated through aerial surveys, achieving a vertical accuracy of ±5 cm and point densities of 2 points/m². In contrast, the National DEM has a coarser resolution of 300 meters, compiled from legacy topographic maps and contour data. Elevation differences were analyzed using statistical techniques as mean, minimum, maximum, Standard Deviation and Root Mean Square Error (RMSE), to quantify spatial patterns of error and assess the suitability of SRTM for low-relief terrains. All datasets were projected to a common coordinate system (WGS 1984 UTM Zone 46N) and resampled to a grid 30mX30m to ensure comparability. Elevation values were extracted from 2,528 purposively selected sample points across plain agricultural land, and vertical discrepancies between datasets were quantified using Root Mean Square Error (RMSE) and standard deviation. The analysis reveals that the SRTM DEM overestimates elevation with an RMSE of 1.92 meters and a standard deviation of 1.85 meters, while the National Digital Elevation Model (DEM), as the Reference DEM yields a lower RMSE of 1.40 meters and a standard deviation of 1.12 meters. These results highlight significant spatial variability and elevation biases in widely used global and national DEMs, underscoring the need for high-accuracy datasets like LiDAR. These errors had a significant impact on terrain attributes, which compound elevation values of many grid cells (e.g., slope, aspects, wetness index, etc.). A case study using comparative accuracy assessment of terrain modeling demonstrates that the result of error propagation is most dramatic in a floodplain.
Keywords:
LiDAR, SRTM, DEM, Floodplain, Bangladesh
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このメールは Google グループのグループ「地理情報システム学会FOSS4G分科会」に登録しているユーザーに送られています。
このグループから退会し、グループからのメールの配信を停止するには gisa-foss4g...@googlegroups.com にメールを送信してください。
このディスカッションを表示するには、https://groups.google.com/d/msgid/gisa-foss4g/CAMsTzruY5gSPLNsxpF22JArP_xgEJd6SH5MBMS3FpydMFtogKA%40mail.gmail.com にアクセスしてください。
K.H. Razimul Karim
Senior Specialist (Geographic Information System Division)
F-14/E, Agargaon Administrative Area,
Sher-E-Bangla Nagar, Dhaka-1207,
Bangladesh
E-mail: razim...@gmail.com
Cell: +8801913217793
Website: www.cegisbd.com
Razimul Karim
Dear Takeuchi,
Good Morning. It is my pleasure to attend and present at the 34th Geographic Information Systems Society Meeting that will be held at Toyama University on November 1st and 2nd. I include my name, affiliation, presentation title, and abstract for your reference. I hope it will be accepted for the 2025 Geographic Information Systems Society FOSS4G.
Thank you so much for your consideration.
Title of Presentation: Comparative Accuracy Assessment of LiDAR-derived Digital Terrain Model (DTM), Shuttle Radar Topography Mission (SRTM) and National Digital Elevation Model (DEM) in a Floodplain: A Case Study in Bangladesh
Presenter Name: K H Razimul Karim
Affiliation: Senior Specialist, Center for Environmental and Geographic Information Services (CEGIS), Agargaon Administrative Area, Sher-E-Bangla Nagar, Dhaka-1207, Bangladesh
Abstract
Digital Elevation Models (DEMs) are essential tools in geospatial analysis, widely used for applications in hydrology, geomorphology, agriculture, and disaster management. Among the globally available DEM datasets, the Shuttle Radar Topography Mission (SRTM) provides near-global coverage with a spatial resolution of 30 meters; however, its accuracy is often compromised in flat, vegetated terrains due to vegetation-induced elevation biases and sensor limitations. This study evaluates the vertical accuracy of the SRTM DEM in the low-lying agricultural region of Delduar Upazila, Tangail, Bangladesh, using high-resolution LiDAR data as a reference benchmark. LiDAR dataset was generated through aerial surveys, achieving a vertical accuracy of ±5 cm and point densities of 2 points/m². In contrast, the National DEM has a coarser resolution of 300 meters, compiled from legacy topographic maps and contour data. Elevation differences were analyzed using statistical techniques as mean, minimum, maximum, Standard Deviation and Root Mean Square Error (RMSE), to quantify spatial patterns of error and assess the suitability of SRTM for low-relief terrains. All datasets were projected to a common coordinate system (WGS 1984 UTM Zone 46N) and resampled to a grid 30mX30m to ensure comparability. Elevation values were extracted from 2,528 purposively selected sample points across plain agricultural land, and vertical discrepancies between datasets were quantified using Root Mean Square Error (RMSE) and standard deviation. The analysis reveals that the SRTM DEM overestimates elevation with an RMSE of 1.92 meters and a standard deviation of 1.85 meters, while the National Digital Elevation Model (DEM), as the Reference DEM yields a lower RMSE of 1.40 meters and a standard deviation of 1.12 meters. These results highlight significant spatial variability and elevation biases in widely used global and national DEMs, underscoring the need for high-accuracy datasets like LiDAR. These errors had a significant impact on terrain attributes, which compound elevation values of many grid cells (e.g., slope, aspects, wetness index, etc.). A case study using comparative accuracy assessment of terrain modeling demonstrates that the result of error propagation is most dramatic in a floodplain.
Keywords:
LiDAR, SRTM, DEM, Floodplain, Bangladesh
--
このメールは Google グループのグループ「地理情報システム学会FOSS4G分科会」に登録しているユーザーに送られています。
このグループから退会し、グループからのメールの配信を停止するには gisa-foss4g...@googlegroups.com にメールを送信してください。
このディスカッションを表示するには、https://groups.google.com/d/msgid/gisa-foss4g/CAMsTzruY5gSPLNsxpF22JArP_xgEJd6SH5MBMS3FpydMFtogKA%40mail.gmail.com にアクセスしてください。
武内樹治
Thank you very much for your submission to the FOSS4G Special Interest Group Symposium. We sincerely appreciate your interest in participating.
・All presentations at this meeting are scheduled for on-site participation only at Toyama University. Online presentations will not be available.
・The meeting does not provide travel or financial support for participants.
・We are also unable to provide any support regarding visa arrangements or related documentation.
Mikiharu Takeuchi
Razimul Karim
武内樹治
Thank you again for your interest in the FOSS4G Special Interest Group Symposium.
If on-site participation is difficult for you under these conditions, we kindly ask you to withdraw your submission.
Mikiharu Takeuchi