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.