Otago 0.4m Rural Aerial Photos Index Tiles (2013-2014)

The project area covered the Waitaki DC districts (Otago region).

The Aerial Surveys project number for this project is PGRM2458.

Digital imagery was collected between 29 October 2013 - 13 March 2014, using Aerial Survey's Microsoft UCLp large-format digital cameras. The imagery was collected flying at 4,700 metres above ground.

Data Processing
All aspects of the data processing from imagery processing, to DTM creation and ortho production and product deliverables was undertaken in-house by Aerial Surveys staff.

Map Projection:
All spatial data for this project provided in terms of New Zealand Transverse Mercator (NZTM) map projection. The datum is New Zealand Geodetic Datum 2000. The height datum is orthometric Lyttleton 1937 (sea level). The products are tiled into NZTopo50 map sheet tiles as noted below.

Image Processing & Aerial Triangulation:
All imagery has gone through QA checks ensuring there is no cloud cover and cloud shadow. During aerial acquisition the aircraft on-board GPS navigation data & ground base station data collected & post processed. Imagery processed to level3 and checked for colour correctness/radiometry and even tonal balance across each project area. The aerial triangulation brings together the GPS data & imagery using a two part process which stitches the imagery together using tie point matching for the relative orientation phase & observing ground control points for the absolute orientation phase. A final report is generated to check RMSE values are within specification.

Ortho Specification:
Ortho rectification is the process of removing (from the image) the effects of camera tip/tilt & displacement caused by terrain relief. During this process each frame is 'draped' over the terrain model & the photograph then becomes 'scaled' & 'levelled' & in terms of true ground coordinates. The generation of seamlines between frames follow natural physical features such as ridges, valleys, roads and rivers. The seamlines are used for the final ortho mosaic that stitches the imagery together using feather mosaicking techniques along with the final extraction of the ortho image tiles. The 0.4m GSD imagery processed as RGBI with RGB extracted after the final ortho mosaic process. Some manual colour adjustment made over coastal sea areas in the RGB.