Geospatial data and 3D representation of Maungataketake, Auckland, New Zealand

Context

Maungataketake (Ellett’s Mountain) was a volcanic cone on the shore of the Manukau Harbour, Mangere, New Zealand. In the second half of the twentieth century the mountain was quarried away. Maungataketake was a terraced Māori Pā, and archaeological excavations (only now in the process of being published) were undertaken there between 1972 and 1975, and in 1982, prior to its complete destruction. There is aerial imagery of the mountain available that depicts the mountain prior to quarrying. With these data a 3D model of the site was made using photogrammetry, which was also used to create a digital surface model (DSM) and contour map of the mountain. The resulting data is provided here and is aimed for further geospatial applications. In addition, the resolution of the provided DSM has analogues for the wider region and therefore could be incorporated to represent the landscape pre-destruction. Further to this a representation of the 3D model may be found on SketchFab.

Method

The photogrammetry model was created in Agisoft Metashape version 1.5.4. Ten aerial images were used of Maungataketake and the surrounding area, captured on 19^th August 1960. These images were downloaded from http://retrolens.co.nz and are licensed by LINZ CC-BY 3.0. The model was aligned and the spare point cloud filtered by gradual selection with the following parameters: projection error = 0.2; reconstruction uncertainty = 10; projection accuracy = 2.5. The dense cloud was processed with depth maps of ultra high quality and aggressive filtering. The resulting points cloud was edited to remove outlying points and processed into a 3D model.

The resulting 3D model was manually edited to remove faces representing trees on Maungataketake only, but not the surrounding area. This was done as to obtain representative surface contours of the mountain. The model was georeferenced by the identification of points on the landscape present on the 1960 composite image and contemporary satellite imagery. A 0.5 m DSM and contours at 1 m resolution were calculated of Maungataketake.

Contents of dataset

• A geodatabase with:
  • Control points used for georectification
  • 1 m contours without elevation of Maungataketake
  • 1 m contours with elevation of Maungataketake
  • 0.5 m composite aerial image
  • 0.5 m DSM of area covering control points
  • 0.5 m DSM of Maungataketake
• Aerial photographs Crown_583-1924_22-26, Crown_583_1925_22-26
• Licence for aerial photographs from http://retrolens.co.nz
• Attributes of aerial photographs