Data Acquisition:

Airborne Laser Scanner (ALS) data was acquired from a fixed wing aircraft in

2015, using Aerial Surveys' Optech Orion H300 LiDAR system.

Survey Specification:

 Scanner: Optech Orion H300

 Flying height: 1200m AMGL

 Scan Angle: +/- 19 degrees

 Scan Frequency: 42.4Hz

 Pulse Rate 70kHz

 Swath Overlap: 35%

 Points Per Sqm: 1.0

Data processing:

The LiDAR sensor positioning and orientation (POS) was determined using the collected GPS/IMU datasets and Applanix POSMMS software.

Base Station Positions:

WHKT 37 58 54.07040 S 177 00 49.96000 E 231.871 Ell Height

TRNG 37 43 43.72352 S 176 15 39.15815 E 151.13 Ell Height

Antenna Height:

WHKT .002 Bot of Mount

TRNG .055 Bot of Mount

The POS data was combined with the LiDAR range files and used to generate LIDAR point clouds in NZTM and ellipsoidal heights. This process was undertaken using Optech LMS LiDAR processing software. The data was checked for completeness of coverage. The relative fit of data in the overlap between strips was also checked.

The height accuracy of the ground classified LiDAR points was checked using open land-cover survey check site data collected by Opus International Consultants Ltd. This was done by calculating height differences statistics between a TIN of the LiDAR ground points and the checkpoints. The standard deviation statistic is 0.029 m; a RMS of 0.045 m and the average difference is -0.032 m.

The positional accuracy of the LiDAR data has been checked by overlaying Opus International Consultants Ltd surveyed data over the LiDAR data displayed coded by intensity. The data was found to fit well in position.

The point cloud data was then classified withTerraSolid LiDAR processing software into ground and above ground returns using automated routines tailored to the project landcover and terrain.

All product deliverables were initially supplied in terms of NZTM and Muturiki 1953 height datum.

Re-processing:

In 2016 the data was reprocessed by Aerial Surveys for LINZ relative to the NZVD2016 vertical datum, and supplied as 1:1000 nominal scale (2500 720m high x 480m wide subtiles per full NZ Topo50 sheet). Lakes and rivers were hydroflattened in the bare earth digital elevation model.The deliverables to LINZ were:

1m gridded bare earth digital elevation model (DEM)

1m gridded digital surface model (DSM)

Classified point cloud