Dataset Open Access

Ngozumpa Glacier Gokyo ice cliffs photographic surface model

Nicholson, Lindsey; Mertes, Jordan

Data files of a photographic surface model of three ice cliffs exposed on the surface of the Ngozumpa Glacier ( 27°57′N, 85°42′E), Nepal, near the village of Gokyo.

Details of how the data were produced:

  • 1160 full resolution JPEG images were used to make the difgital surface model (DSM)
  • Photos were taken using Nikon D5000 with 100mm Tamron macro lens on 4th April 2016
  • 7 ground control points (GCPs) within the captured scene were used to scale and georeference the DSM
  • GCPs were measured using a Trimble XH6000 with Tornado antenna as rover and a Trimble Geo7X with Zephyr antenna as a local base station
  • Agisoft Photoscan (v1.26) was used to make the DSM using a SfM-MVS workflow
  • Point pairs appearing in only one  image pair and havoing a reprojection error grreater than 0.5 pixels were removed
  • Model optimization was done using default parameters of f, b1, b2, cx, cy, k1-4, p1 and p2 and, as the lens distortion plot showed no extreme skewing or distortion, these optimization settings were accepted.
  • The dense point cloud was generated using the ‘High’ quality setting with ‘Aggressive’ point filtering.
  • The dense point cloud was then used directly to generate the DSM and orthomosaic at resolutions of 0.046 and 0.023 m respectively.

Description of files:

  • GokyoIceCliffs_POINTCLOUD.txt: dense point cloud including the whole scene covered by the photographs. Format: x,y,z, text file, WGS 84 / UTM zone 45N.
  • GokyoIceCliffs_DSM_0.04.tif: 0.046 m resolution digital terrain model derived from the dense point cloud covering the area of interest including the 3 sampled ice cliffs. Format: TIFF WGS 84 / UTM zone 45N.
  • GokyoIceCliffs_ORTHO_0.04.tif: 0.023 m resolution orthophoto covering the area of interest including the 3 sampled ice cliffs. Format: TIFF WGS 84 / UTM zone 45N.

 

Files (8.1 GB)
Name Size
GokyoIceCliffs_DSM_0.04m.tif md5:dc33e13a880f8dff311a7edef9413834 306.4 MB Download
GokyoIceCliffs_ORTHO_0.02m.tif md5:20febc0db0d93c2034e14211f0b44489 1.5 GB Download
GokyoIceCliffs_POINTCLOUD.txt md5:1a67632e0e41d387d5a4491f1ef69854 6.3 GB Download

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