Ngozumpa Glacier Gokyo ice cliffs photographic surface model

<p>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.</p> <p>Details of how the data were produced:</p> <ul> <li>1160 full resolution JPEG images were used to make the difgital surface model (DSM)</li> <li>Photos were taken using Nikon D5000 with 100mm Tamron macro lens on 4th April 2016</li> <li>7 ground control points (GCPs) within the captured scene were used to scale and georeference the DSM</li> <li>GCPs were measured using a Trimble XH6000 with Tornado antenna as rover and a Trimble Geo7X with Zephyr antenna as a local base station</li> <li>Agisoft Photoscan (v1.26) was used to make the DSM using a SfM-MVS workflow</li> <li>Point pairs appearing in only one  image pair and havoing a reprojection error grreater than 0.5 pixels were removed</li> <li>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.</li> <li>The dense point cloud was generated using the ‘High’ quality setting with ‘Aggressive’ point filtering.</li> <li>The dense point cloud was then used directly to generate the DSM and orthomosaic at resolutions of 0.046 and 0.023 m respectively.</li> </ul> <p>Description of files:</p> <ul> <li><strong>GokyoIceCliffs_POINTCLOUD.txt:</strong> dense point cloud including the whole scene covered by the photographs. Format: x,y,z, text file, WGS 84 / UTM zone 45N.</li> <li><strong>GokyoIceCliffs_DSM_0.04.tif:</strong> 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.</li> <li><strong>GokyoIceCliffs_ORTHO_0.04.tif: </strong>0.023 m resolution orthophoto covering the area of interest including the 3 sampled ice cliffs. Format: TIFF WGS 84 / UTM zone 45N.</li> </ul> <p> </p>