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Open AccessArticle

Past and Present Practices of Topographic Base Map Database Update in Nepal

by Nimisha Wagle 1 and Tri Dev Acharya 2,3,4,*
1
Survey Department, Government of Nepal, Minbhawan, Kathmandu 44600, Nepal
2
Institute of Industrial Technology, Kangwon National University, Chuncheon 24341, Korea
3
School of Geomatics and Urban Spatial Information, Beijing University of Civil Engineering and Architecture, Beijing 102616, China
4
Institute of Transportation Studies, University of California Davis, Davis, CA 95616, USA
*
Author to whom correspondence should be addressed.
ISPRS Int. J. Geo-Inf. 2020, 9(6), 397; https://doi.org/10.3390/ijgi9060397
Received: 6 May 2020 / Revised: 5 June 2020 / Accepted: 14 June 2020 / Published: 16 June 2020
Topographic Base Maps (TBMs) are those maps that portray ground relief as the form of contour lines and show planimetric details. Various other maps like geomorphological maps, contour maps, and land use planning maps are derived from topographical maps. In this constantly changing world, the update of TBMs is indispensable. In Nepal, their update and maintenance are done by the Survey Department (SD) as a national mapping agency. This paper presents the history of topographical mapping and the reasons for the lack of updates. Currently, the SD is updating the TBM database using panchromatic and multispectral images from the Zi Yuan-3 (ZY-3) satellite with a resolution of 2.1 and 5.8 m, respectively. The updated methodology includes the orthorectification of images, the pansharpening of images, field data collection, digitization, change detection, and updating, the overlay of vector data and field verification, data quality control, and printing map production. A TBM in the Dang district of Nepal is presented as casework to show the changes in the area and issues faced during the update. Though the present digitizing procedure is time-consuming and labor-intensive, the use of high-resolution imagery has made mapping accurate and has produced high-quality maps. However, audit and automation can be introduced from the experiences of other countries for accurate and frequent updates of the TBM database in Nepal. View Full-Text
Keywords: topographic base map; national mapping agency; updates; history; ZY-3; Nepal topographic base map; national mapping agency; updates; history; ZY-3; Nepal
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Wagle, N.; Acharya, T.D. Past and Present Practices of Topographic Base Map Database Update in Nepal. ISPRS Int. J. Geo-Inf. 2020, 9, 397.

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