Orthophotography within the Canterbury Region captured in January 2020. Coverage encompasses Ashburton, Methven, Lake Clearwater and Camp Huts, Mount Somers, Lauriston, Rakaia, Chertsey, Mayfield, Hinds, Hakatere Ocean and Rangitata Huts.
Imagery was captured for Environment Canterbury by Aerial Surveys Ltd, Unit A1, 8 Saturn Place, Albany 0632, New Zealand.
Data comprises: • 5324 ortho-rectified RGB GeoTIFF images in NZTM projection, tiled into the LINZ Standard 1:500 tile layout • Tile layout in NZTM projection containing relevant information.
The supplied imagery is in terms of New Zealand Transverse Mercator (NZTM) map projection. Please refer to the tile index layer for specific details, naming conventions, etc.
Imagery supplied as 7.5cm pixel resolution (0.075m GSD), 3-band (RGB) uncompressed GeoTIFF. The final spatial accuracy is ±0.15m at 95% confidence level in clear flat areas.
Index tiles for this dataset are available as layer [Ashburton 0.075m Urban Aerial Photos Index Tiles (2020)](http://data.linz.govt.nz/layer/106783)
Data Acquisition The aerial photography for this project was captured within the 2019/20 flying season (September 2019 – April 2020).
Camera and Flying Height All photography was captured using Vexcel's digital UCE camera fitted with the 100 mm lens. Urban areas flown at an altitude of approximately 4,732 ft (1,441 m) with the lowest ground GSD set at 0.075 m.
Capture Dates The aerial imagery was captured on the following dates: 16 and 17 January 2020.
Sun Angle Imagery captured with a minimum sun angle of +45 degrees. The sun angle of the imagery used for the ortho-rectification ranged from 44.4 to 66.5 degrees. One run of the Lauriston township was captured with a sun angle between 44.4 to 44.6 and this has been approved by Council.
Flight Planning The flight survey number for this project is: SN14089 Ashburton Urban 7-5cm UCE V2 comprising 59 runs, 1,276 frames
All urban imagery captured in stereo: forward overlap 60%, min 54%; side overlap 35%, min 15%. Ashburton CBD area imagery captured in stereo: forward overlap 80%; side overlap 80%.
Environmental Specification Imagery captured with no cloud or cloud shadow within the area of interest. Imagery for all harbour, coastal and tidal areas acquired during low tide periods, being two hours either side of low tide. Rivers captured at time of low river flow.
Urban Building Displacement Specification Urban 0.075 m GSD imagery – using the UCE camera and by flying with 60% forward overlap and with 35% sidelap (standard stereo coverage), maximum 1.1 m building lean per 3 m height within the image model area. Imagery over the Ashburton CBD area captured with 80% forward overlap and 80% sidelap to achieve maximum 0.37 m building lean per 3 m height within the image model area and produce a near true ortho product.
Ground Control A combination of existing control and LINZ benchmarks were used for aerial triangulation for this project.