Canterbury - Cheviot LiDAR 1m DEM (2015)

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 Cheviot
Date of Capture: 1/4/15
Base Station Type/Owner: Global Surveys
Bench Mark: GSCV
Base Station Position: 42 48 46.88210 S 173 16 44.94167 E 85.7327 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)