Data Acquisition:

Airborne Laser Scanner (ALS) data was acquired from a fixed wing aircraft on 1 April

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

Survey Specification:

 Scanner: Optech Orion H300

 Flying height: 1200m AMGL

 Scan Angle: +/- 20 degrees

 Scan Frequency: 34Hz

 Pulse Rate 75kHz

 Swath Overlap: 30%

 Points Per Sqm: 1.3

Data processing:

The LiDAR sensor positioning and orientation (POS) was determined using the collected GPS/IMU datasets and Applanix POSMMS software. This work was all undertaken in NZGD2000 coordinate system using the data collected from the following basestations:

Project: Ecan Hawarden

Date of Capture: 1/4/15

Base Station Type/Owner: Global Surveys

Bench Mark: GSAM

Base Station Position: 43 09 06.47086 S 172 43 45.04334 E 66.747 Ell Height

Ant Height : 0.00 Phase Center

Output LAS Projection: TM2000

Height: WGS84 Ellipsoid

Validation was carried out using the guidelines contained in the ICSM specification template as required for this program.

Vertical Accuracy Validation:

The height accuracy of the LiDAR points was checked using check points collected during the ground control survey

Horizontal Accuracy Validation

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

All product deliverables were initially supplied in terms of NZTM and Lyttelton 1937 height datum.

Classification of the point cloud followed the classification scheme below:

0 - Created, never classified

2 - Ground

12 - Flight line overlap points

14 - Above_Ground

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

Data hosted by OpenTopography was re-classified: the Above_Ground (14) points were reclassified as Unassigned classification (1)