Otago - Coastal Catchments LiDAR 1m DSM (2021)
This layer contains the DSM for LiDAR data along the coast of the Otago Region, covering Milton, Catlins, Palmerston, Dunedin, Mosgiel, and Oamaru, captured between the 25 June to 1 October 2021.
- The DEM is available as layer [Otago - Coastal Catchments LiDAR 1m DEM (2021)]( https://data.linz.govt.nz/layer/109627 ).
- The index tiles are available as layer [Otago - Coastal Catchments LiDAR Index Tiles (2021)]( https://data.linz.govt.nz/layer/109629 ).
- The LAS point cloud and vendor project reports are available from [OpenTopography]( https://portal.opentopography.org/datasets?search=new%20zealand ).
LiDAR was captured for Otago Regional Council by AAM Ltd between 25 June to 1 October 2021. These datasets were generated by AAM 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 4 pulses/square metre.
Vertical Accuracy Specification is +/- 0.2m (95%)
Horizontal Accuracy Specification is +/- 1.0m (95%)
Vertical datum is NZVD2016.
Simple
Identification info
- Date (Creation)
- 2021-06-25
- Status
- Completed
- Point of contact
-
Role Organisation Electronic mail address Point of contact Toitū Te Whenua Land Information New Zealand
- Spatial representation type
- Grid
Spatial resolution
Equivalent scale
- Denominator
- 1000
- Topic category
-
- Elevation
Extent
- Geographic identifier
-
nzl
- Title
-
ANZMet Lite Country codelist
- Date (Publication)
- 2009-03-31
- Edition
-
Version 1.0
- Edition date
- 2009-03-31
- Citation identifier
- http://asdd.ga.gov.au/asdd/profileinfo/anzlic-country.xml#Country
- Cited responsible party
-
Role Organisation Electronic mail address Custodian ANZLIC the Spatial Information Council
Extent
))
- Maintenance and update frequency
- Not planned
Resource format
- Title
-
*.xml
- Date
- Edition
-
Unknown
- ANZLIC Jurisdictions
-
-
New Zealand
-
Resource constraints
- Classification
- Unclassified
Resource constraints
- Use limitation
-
Copyright of this work is owned by Otago Regional Council
© Otago Regional Council
- Use constraints
- Copyright
Resource constraints
- Use limitation
-
Released by Toitū Te Whenua Land Information New Zealand under Creative Commons Attribution 4.0 New Zealand (CC BY 4.0) with:
Following Attribution:
"Sourced from the LINZ Data Service and licensed by Otago Regional Council, for re-use under CC BY 4.0."
For details see: https://www.linz.govt.nz/data/licensing-and-using-data/attributing-elevation-or-aerial-imagery-data
- Use constraints
- License
- Language
- English
- Character encoding
- UTF8
Resource lineage
- Statement
-
Data Acquisition:
Airborne Laser Scanner (ALS) data was acquired from a fixed wing aircraft between 25 June to 1 October 2021, using AAM's Optech Galaxy Prime 473 LiDAR system.
Survey Specification:
Scanner: Optech Galaxy Prime 473
Flying Height: 1320 m - 1600 m AGL
Scan Angle: ±21 - 25 degrees
Scan Frequency: 66 Hz
Pulse Rate: 400 - 500 kHz
Swath Overlap: 22 - 25%
Swath Points Per M2: 4
Data Processing:
RTX processing was utilised to calculate the GPS trajectory. Trimble CenterPoint® RTX™ is a proprietary GPS, GLONASS, BeiDou, and QZSS enabled technology that provides high-accuracy GNSS positioning worldwide without the use of traditional local base stations or a VRS network. By combining real time data from a global reference station infrastructure with innovative positioning and compression algorithms, Trimble RTX technology computes centimeter-level positions based on satellite orbit and clock information. Trajectory processing provides the accurate position and orientation of the sensor, essential for georeferencing the dataset.
All initial processing was undertaken in UTM60S/ITRF2008. Reprojection and application of the
NZGD2000 deformation model converted the data to NZTM/NZGD2000 using concord software. To convert the point cloud heights from ellipsoidal to NZVD2016 heights, a geoid adjustment was performed using the NZGeoid2016 separation model.
WSP NZ Ltd undertook a field survey between 22 July to 6 October 2021 to acquire ground test points, assumed to be error-free, to validate the accuracy of the LiDAR data and derivative products. The test points were uniformly distributed across the area and located on clear ground. Comparison of the field test points with elevations interpolated from measured data, yielded the following accuracy assessment:
Data blocks: Catlins, Milton, Palmerston
Test point sites: 6, 19, 42
No. points: 190, 925, 2609
Mean difference: 0.005, 0.004, 0.000 m
St. Deviation: 0.041, 0.029, 0.033 m
Standard Error (RMS): 0.042, 0.029, 0.033 m
The mean elevation difference was removed from the supplied data. The Fundamental Vertical Accuracy for each block is therefore 8.2 cm for Catlins, 5.7 cm for Milton, 6.5 cm for Palmerston (RMS x 1.96), which are within the RMS specification of 20 cm at 95% confidence.
The expected horizontal accuracy was calculated by Flying Height Above Ground(1600 m)/10,000 therefore is 31 cm at 95% CI for all blocks, which is within the specification of 100 cm.
AAM uses proprietary automated ground classification routines in TerraScan, based upon algorithms tailored for major terrain/vegetation combinations, to initially classify the laser strikes into ground / non-ground classification and to generate an accurate ground surface. The ground classification is then manually reviewed and edited to reach ICSM level 2 standards. Following this process, non-ground classes are then classified using automated routines and macros. Water was also manually reviewed to ensure correct presentation in the downstream elevation products (DEM and DSM). The definition of the ground points may be less accuracte under vegetation.
Classification of the point cloud follows the classification scheme below:
1 - Unclassified
2 - Ground
3 - Low Vegetation
4 - Medium Vegetation
5 - High Vegetation
6 - Buildings
7 - Low Noise
9 - Water
17 - Bridge Deck
18 - High Noise
The DEM was generated using linear interpolation of a TIN from the ground points to define the bare earth ground surface. Hydroflattening was performed through breaklines that were drawn manually and the coastline was clipped to a polygon that was derived from the water points boundary, to give a clean presentation along the coast.
The DSM was generated using first return ground and non ground classes, excluding high and low noise.
The deliverables to LINZ were:
1m gridded bare earth digital elevation model (DEM)
1m gridded digital surface model (DSM)
Classified point cloud
All product deliverables supplied in terms of NZTM map projection and NZVD2016 vertical datum.
- Hierarchy level
- Dataset
- Other
-
dataset
Reference System Information
- Reference system identifier
- 2193
Metadata constraints
- Use limitation
-
Copyright of this work is owned by Toitū Te Whenua Land Information New Zealand
© LINZ
- Use constraints
- Copyright
Metadata constraints
- Use limitation
-
Released by Toitū Te Whenua Land Information New Zealand under Creative Commons Attribution 4.0 International (CC BY 4.0) with:
Following Attribution:
"Sourced from the LINZ Data Service and licensed for reuse under CC BY 4.0"
For details see https://www.linz.govt.nz/data/licensing-and-using-data/attributing-linz-data
- Use constraints
- License
Metadata
- Metadata identifier
- 2f569df8-0bd1-1072-e814-fa99f207594e
- Language
- English
- Character encoding
- UTF8
- Contact
-
Role Organisation Electronic mail address Point of contact Toitū Te Whenua Land Information New Zealand
Type of resource
- Resource type
- Dataset
- Name
-
dataset
- Date info (Revision)
- 2023-01-30
Metadata standard
- Title
-
ANZLIC Metadata Profile: An Australian/New Zealand Profile of AS/NZS ISO 19115:2005, Geographic information - Metadata
- Edition
-
1.1