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In 2022, Auckland Council contracted Aerial Surveys Ltd to supply 0.075 m GSD digital ortho imagery covering the Auckland region. Aerial photography was captured over the Auckland Region and the Hunua Ranges, totalling approximately 6,130 km2. Data Acquisition The aerial photography for this project was captured within the 2023/24 flying season (September 2023 –April 2024) and 2024/25 flying season (September 2024 – April 2025). The aerial imagery was captured on the following dates: 1 February 2024, 24 February 2024, 28-29 February 2024, 1 March 2024, 9-10 March 2024, 16 March 2024, 19-21 March 2024, 31 March 2024, 8 May 2024, 11 May 2024, 11-14 January 2025, 5-6 March 2025. Imagery Specification Ortho imagery: Three-band Spectral resolution: Near Infrared, Green, Blue Radiometric resolution: RGB 24 bit, RGBI 32 bit (8 bits per each band) Pixel resolution: 0.075 m GSD (7.5 cm) Tile index: Tile index for the project area Spatial accuracy: ±0.15 m @ 95% confidence level in clear flat open spaces (2 sigma) Aligned to LINZ 1:1,000 map sheet layout (480 m x 720 m) Tiles supplied: 18,230 (1:1,000 map sheet tiles) Image format: JPEG Note: Auckland Council can provide R-G-B-NIR imagery for the area in GEOTIFF format as well. Please contact us at [e-mail] to request the four-band imagery. Map Projection All spatial data for this project is provided in terms of New Zealand Transverse Mercator 2000 map projection (NZTM2000). The ellipsoidal datum is New Zealand Geodetic Datum 2000 (NZGD2000). The airborne GPS and ground control GPS data was converted from ellipsoidal heights into orthometric heights using the LINZ NZGeoid16 separation model. For this project, the orthometric vertical datum is New Zealand Vertical Datum 2016 (NZVD2016). Map Projection All spatial data for this project provided in terms of New Zealand Transverse Mercator 2000 map projection (NZTM2000). The ellipsoidal datum is New Zealand Geodetic Datum 2000 (NZGD2000). The airborne GPS and ground control GPS data was converted from ellipsoidal heights into orthometric heights using the LINZ NZGeoid16 separation model. For this project the orthometric vertical datum is New Zealand Vertical Datum 2016 (NZVD2016). Camera and Flying Height Most of the photography was captured using Vexcel's digital UltraCam Eagle Mark 3 (UCE-3) and UltraCam Eagle Prime (UCE-p) camera fitted with the 100 mm lens and flown at an altitude of approximately 4,732 ft (1,442 m) with the lowest ground GSD set at 0.075 m. These cameras are fitted to a GSM 3000 gyro-stabilised mount and IGI AEROcontrol GNSS/IMU positioning system. Some portions were flown using Vexcel's digital UltraCamLp (UCLp) camera fitted with the 70 mm lens and flown at an altitude of approximately 2,952 ft (900 m). Sun Angle Imagery captured with a minimum sun angle of +40 degrees subject to a 5-degree tolerance when capture is in progress. It was agreed (February 2024) to lower the sun angle to +30 degrees over rural areas and +40 degrees over urban/city areas. The sun angle of the imagery used for the orthorectification ranged from 24 to 75 degrees. Flight Planning The flight survey number for this project is SN14259. The flight plan is named ‘Auck_075cm_UCLp_v3’ and comprises 137 runs, 11,975 frames. All imagery captured in stereo: forward overlap 60%, min 54%; side overlap 35%, min 15%. Imagery over CBD and tall building areas captured in stereo: forward overlap 80%; side overlap 80%. The additional flight plan is named ‘Auckland-80x80-2022-23-7-5cm-UCE3’ and comprises 17 runs, 218 frames. Urban Building Displacement Specification Urban 0.075 m GSD imagery – using the UCE-3, UCEp and UCLp cameras and by flying with 60% forward overlap and with 35% sidelap (standard stereo coverage) will achieve <1 m building lean per 3 m height in the corners of the imagery used. Tall structures inwards of the corner of the frame will have less lean the closer to the nadir they are. <0.37 m building lean per 3 m of height in the corners of the imagery using increased 80/80 overlap in the CBD area. Very tall buildings have been further straightened using manual techniques. To help reduce building lean in the CBD area additional processing has been applied to produce true orthos for building verticality. Ground Control A combination of existing control and LINZ benchmarks were observed for use with the aerial triangulation and bundle adjustment. DTM for Ortho Production The digital terrain model used for this project was derived from LiDAR DTM data flown in 2015. Outside the LiDAR DTM a new DTM was collected from the 0.075 m GSD stereo imagery using photogrammetric techniques, largely automated pixel matching and autocorrelation process. The DTM data was merged seamlessly and accuracy checked to meet the ortho imagery specification. The DTM was further processed and edited suitable for the ortho production.