A 3-D model of The Bear Trap: A unique stone structure on the northwest tip of the Nuussuaq Peninsula, Greenland

• Main Authors: Carlson, Daniel F., Walsh, Matthew J., Tejsner, Pelle, Thomsen, Steffen
• Format: Dataset
• Language: English
• Published: 2020
• Subjects: Greenland; Norse; Archaeology; Structure from Motion Photogrammetry; 3D model; Ruin; Nuussuaq; Vaigat; greenlandic; kalaallisut
• Online Access: https://zenodo.org/record/3980541; https://doi.org/10.5281/zenodo.3980541

This dataset consists of three files that can be used to view a high-resolution 3D model of ‘The Bear Trap’, a unique Norse ruin at the western end of the Nuussuaq Peninsula in NW Greenland (also called ‘Bjørnefælden’ in Danish, and ‘Putdlagssuaq’ or ‘The Great Trap’ Greenlandic Kalaallisut). The 3D model was created from thousands of photographs that were processed using Structure from Motion Multiview Stereo photogrammetry software (in this case Agisoft PhotoScan Pro v1.4; Linux Ubuntu). A 24.3 megapixel Sony a5100 APS-C mirrorless camera fitted with a 24 mm lens was used to acquire ground-level imagery of the structure. Pictures were visually assessed prior to processing in PhotoScan to exclude any that were blurry and/or overexposed. The image alignment or bundle adjustment was performed using ‘High’ accuracy, a key point limit of 60000, no tie point limit, and generic preselection. After the sparse point cloud was created, the bounding box was adjusted to enclose the area of interest and the camera parameters were optimized. Gradual selection was used to remove tie points with relatively high uncertainties. The sparse point cloud was scaled using three markers with known dimensions that were placed in the area of interest, and which remained stationary throughout the entire photo survey. The dense point cloud was computed using the ‘Medium’ setting, as attempts to use the ‘High’ setting were unsuccessful due to insufficient memory. The dense point cloud was then used to compute the mesh model using the ‘High’ setting. The model was then exported to the .obj and .mtl files and .pdf file that are provided here. The .obj Bear Trap model can be viewed using Meshlab and the .pdf can be viewed using Adobe Acrobat Reader, both of which are cross-platform and freely available. Instructions are provided in the readme file that accompanies this dataset. The image survey of the Bear Trap was conducted as part of the Vaigat Iceberg-Microbial Oil Degradation and Archaeological Heritage Investigation (VIMOA) project, ...