Canterbury - Waitaki 0.3m Rural Aerial Photos Index Tiles (2021)

Data acquisition:

Camera:
Imagery for this schedule was acquired using the Leica ADS100 line scanning camera with SH100 sensor head. The camera was fitted to a Leica PAV100 HP high performance gyro-stabilised mount.

Flight Planning:
Careful consideration was given during flight planning to geographic location, terrain, topographical characteristics of the area, acquisition efficiency, final output resolution and meeting the various requested orthophoto quality specifications.

Environmental Specification:
All imagery was captured without the presence of cloud or cloud shadow within the specified areas of interest. Rivers were captured during times of appropriate flow/stage height/rainfall restrictions as specified by the client. These criteria were set to avoid periods of high river flow (flooding), rather than to target abnormally low river flows.

Ground Control:
A total of 35 new ground control points were observed for use with the aerial triangulation and bundle adjustment in the schedule B area, and of the 92 new ground control points that fell within the schedule C area, 9 were selected and used in the aerial triangulation and bundle adjustment. Data from Global Survey’s and LINZ CORS sites, along with several existing LINZ benchmarks, were used in Leica Infinity software to process and check the ground control.

Data Processing:

Map Projection and Datum:
All spatial data for this project is supplied in the New Zealand Transverse Mercator (NZTM2000) projection in terms of the New Zealand Geodetic Datum 2000 (NZGD2000).

Image Processing:
Hexagon Geosystems Services India carryied out Orthophoto production. Leica Xpro software along with the QS2 distributed processing environment and inbuilt Hexagon Image Manager and Quality Manager2 were used during relevant phases of production.

Aerial Triangulation (AT):
No abnormalities or complications were encountered during this phase. All aerial triangulations are carried out to ensure accuracies in the region of 1xGSD value. This was achieved with adjusted RMS position residuals less than 30cm, ensuring excellent overall quality and spatial accuracy.

Orthophoto production:
Individual radiometric profiles were created and checked for each strip ensuring optimal results across the final ortho-mosaic. No complications were encountered during orthophoto generation, mosaicking and tiling. Various quality checks including accuracy, colour, contrast, sharpness, seamline positioning, refraction and generation artifacts were performed and found satisfactory on the final orthophoto tiles.

Peripheral Imagery:
The full extent of all captured imagery outside of the tiles covering the area of interest has been delivered. This imagery has been orthorectified with the same DEM used to generate the primary AOI orthophotos. As such, these DEMs may not cover the entire area of peripheral imagery and associated artefacts may be present.