Canterbury - Christchurch and Ashley River LiDAR Index Tiles (2018-2019)

Canterbury - Christchurch and Ashley River LiDAR Index Tiles (2018-2019)

Toitū Te Whenua Land Information New Zealand

2018-07-20

This layer contains the Index Tiles for LiDAR data in the Canterbury Region surronding Christchurch and the Ashley River between 2018 and 2019.

- The DEM is available as layer [Canterbury - Christchurch and Ashley River LiDAR 1m DEM (2018-2019)](https://data.linz.govt.nz/layer/104497).

- The DSM is available as layer [Canterbury - Christchurch and Ashley River LiDAR 1m DSM (2018-2019)](https://data.linz.govt.nz/layer/104498).

- The LAS point cloud and vendor project reports are available from [OpenTopography](https://portal.opentopography.org/datasets?loc=New%20Zealand).

LiDAR was captured for Environment Canterbury Regional Council by Aerial Surveys from 20 July 2018 to 01 March 2019. These datasets were generated by Aerial Surveys and their subcontractors. Data management and distribution is by Toitū Te Whenua Land Information New Zealand.

Data comprises:

- DEM: tif or asc tiles in NZTM2000 projection, tiled into a 1:1,000 tile layout

- DSM: tif or asc tiles in NZTM2000 projection, tiled into a 1:1,000 tile layout

- Point cloud: las tiles in NZTM2000 projection, tiled into a 1:1,000 tile layout

Pulse density specification is at a minimum of 2.14 pulses/square metre.

Vertical Accuracy Specification is +/- 0.2m (95%).

Horizontal Accuracy Specification is +/- 1.0m (95%).

Vertical datum is NZVD2016.

Data Acquisition:
Airborne Laser Scanner (ALS) data was acquired from a fixed wing aircraft from 20 July 2018 to 01 March 2019, using Aerial Surveys Optech Orion H300 and Optech Galaxy Prime LiDAR systems.

Please refer to survey reports for survey specifications.

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

Please refer to survey reports for benchmark and base station information.

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.

Please refer to survey reports for height accuracy summary statistics.

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.

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 supplied in terms of NZTM map projection and NZVD2016 vertical datum.

Classification of the point cloud followed the classification scheme below:
1 - Unclassified
2 - Ground
7 - Noise
12 - Overlap
14 - Above Ground

Above_Ground (14) points was reclassified by LINZ as Unassigned classification (1) before providing the classified point cloud data to Open Topography.

Lakes and large 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

-43.675837782 172.388784786 -43.1952142971 172.815703391

https://data.linz.govt.nz/layer/104499-canterbury-christchurch-and-ashley-river-lidar-index-tiles-2018-2019/

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