Tagged: land geodesy - Page 2

This layer contains the DSM for LiDAR data from the Wellington region captured in 2013.
The DEM is available as layer Wellington LiDAR 1m DEM (2013).
The index tiles are available as layer Wellington LiDAR Index Tiles (2013).
The LAS point cloud is available from OpenTopography.

Lidar was captured for Greater Wellington Regional Council by Aerial Surveys in 2013. The datasets were generated by Landcare Research. The survey area includes Wellington, Porirua, Lower Hutt, Upper Hutt, Wairarapa, and Kapiti. Data management and distribution is by 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 1km x 1km tile layout

Data was collected at >1 pulse/square metre pulse density. Attributes include:
-Elevation
-Intensity values
-Return number
-Adjusted GPS time
-Classification

Vertical datum is NZVD2016

For further information about this dataset, see the Kaikoura earthquake information.

It is likely that many of these coordinates will be updated multiple times as marks move due to aftershocks and ongoing post-seismic deformation. It is therefore critical that the datum version and coordinate epoch date are recorded with any coordinates sourced from this dataset, along with the date the coordinates were accessed or downloaded.

These coordinates are computed from Continuously Operating Reference Station (CORS) data and geodetic surveys undertaken after the 14 November 2016 Kaikoura earthquake. They reflect earthquake movements up until the epoch date that is associated with each coordinate. Where possible, coordinates sourced from this dataset for use as control or calibration points in a project should be at the same or similar epochs. If not, post-seismic deformation may mean that new observations or coordinates do not fit well with these coordinates. Coordinates used as control or calibration points should also be well-distributed over the project area, so that any discrepancies resulting from the survey date being significantly different from the coordinate epoch date can be identified. If such discrepancies are identified, it may be necessary to use the LINZ PositioNZ-PP online processing service to generate control coordinates at the same (or nearly the same) epoch as the survey date.

Coordinates were calculated using SNAP v2.5.48. The origin of non-CORS coordinates is PositioNZ CORS that have been updated to include earthquake movements.

The 95% confidence interval uncertainties of coordinates are 0.02m horizontally and 0.03m vertically, relative to the PositioNZ network, at the epoch specified. In areas experiencing significant ongoing seismic activity, coordinates at the same mark at other epochs may differ by more than these uncertainties.

These coordinates are suitable for use in surveys and other geospatial positioning activities in the area impacted by the Kaikoura earthquake.

The deformation model associated with the NZGD2000 datum was updated, nominally at 1 August 2013. The actual update of LINZ data took place on 14-15 December 2013. This update involved reverse patches, which means that the "reference coordinates" of features were updated. The main updates relate to the Christchurch earthquakes. The patch also updated coordinates affected by other South Island earthquakes since 2000.

These updates have been incorporated into Landonline and resulted in spatial updates to all features in the affected areas.

This data set contains contours indicating the extent and magnitude of the coordinate changes to assist in assessing the impact of this update on client data sets. This dataset is also available as a multipolygon.

For more information see here

Coordinates computed from surveys undertaken after the 14 February 2016 Canterbury earthquake. These should be consistent with any observations made after this earthquake (neglecting any localised deformation such as that due to liquefaction).

For further information about this dataset, see the Canterbury earthquake information.

These coordinates are only provisional. Analysis is ongoing as further data is collected. Coordinates were calculated using SNAP v2.5.33. Stations were constrained using coordinates of distant PositioNZ continuous GNSS stations that were unaffected by the earthquake.

The standard deviations of coordinates are 0.01m horizontally and 0.02m vertically, relative to the PositioNZ network.

Coordinate changes due to the earthquake have been calculated by comparing pre and post-earthquake coordinates. Pre-earthquake coordinates were calculated relative to public and private continuous GNSS stations. These continuous GNSS stations had data processed for several days early in 2016 (before the earthquake). Other pre-earthquake geodetic data was then readjusted with the continuous GNSS data. Note that this means these coordinate changes may differ slightly from those that would be calculated by comparing the post-earthquake coordinates with those currently in the Geodetic Database.

These coordinates are suitable for use in surveys and other geospatial activities in Canterbury and Christchurch.

The deformation model associated with the NZGD2000 datum was updated, nominally at 1 August 2013. The actual update of LINZ data took place on 14-15 December 2013. This update involved reverse patches, which means that the "reference coordinates" of features were updated. The main updates relate to the Christchurch earthquakes. The patch also updated coordinates affected by other South Island earthquakes since 2000.

These updates have been incorporated into Landonline and resulted in spatial updates to all features in the affected areas.

This data set contains contours indicating the extent and magnitude of the coordinate changes to assist in assessing the impact of this update on client data sets. This dataset is also available as a polyline.

For more information see here

The relationship between the GRS80 ellipsoid and the New Zealand Vertical Datum 2016 (NZVD2016) is modelled by the New Zealand Quasigeoid 2016 (NZGeoid2016). The relationship value is represented by the attribute “N”, in metres.

This relationship and NZVD2016 is formally defined in the LINZ standard LINZS25009.

NZGeoid2016 can be used to convert New Zealand Geodetic Datum 2000 (NZGD2000) ellipsoidal heights to NZVD2016 normal-orthometric heights.

The conversion value is represented by the attribute “N”, in metres.

NZGeoid2016 is published on a one arc-minute grid (approximately 1.8 kilometres) over the New Zealand continental shelf (160° E to 170° W, 25° S to 60° S).

NZGeoid2016 was calculated by enhancing the EIGEN-6C4 global gravity model with, terrestrial, ship-track, satellite and airborne gravity data. GPS-levelling observations were not used to compute NZGeoid2016.

Users may also be interested in transforming heights to any of the 13 historic local vertical datums used in New Zealand using the appropriate datum relationship grid displayed in the NZ Height Conversion Index.

More information on these transformations is available on the LINZ website.

The Canterbury region of New Zealand experienced a sequence of significant earthquakes during 2010 and 2011. These earthquakes occurred on 2010-09-04, 2011-02-22, 2011-06-13 and 2011-12-23. The coordinates in this layer account for all significant movements relating to these, so should be consistent with any observations made after the last earthquake to affect a given area (neglecting localised deformation such as that due to liquefaction).

Users may also be interested in the more comprehensive data in the companion layer Canterbury Earthquake Geodetic Marks (2010, 2011) - Comprehensive.

These coordinates are only provisional. Analysis is ongoing as further data is collected. Coordinates were calculated using SNAP v2.3.61. Stations were constrained using coordinates calculated by GNS Science. Some coordinates were calculated from data provided by Christchurch City Council. No precise levelling data has been used.

The estimated accuracy is 0.02m horizontally and 0.03m vertically.

The deformation model igns2011_working.grd calculated from a model (v4) provided by GNS Science on 28 April 2011 was used to remove secular deformation.

These coordinates are suitable for use in surveys and other geospatial activities in Canterbury and Christchurch.

For further information about this dataset, see the Canterbury earthquake information on the LINZ website.

The Canterbury region of New Zealand experienced a sequence of significant earthquakes during 2010 and 2011. These earthquakes occurred on 2010-09-04, 2011-02-22, 2011-06-13 and 2011-12-23. Precise-levelling surveys have been carried out throughout Canterbury and Christchurch to re-establish heights after these earthquakes.

Users may also be interested in the horizontal coordinates derived from GNSS data in the companion layers Canterbury Earthquake Geodetic Marks (2010, 2011) - Comprehensive and Canterbury Earthquake Geodetic Marks (2010, 2011) - Simple

Horizontal Accuracy (standard deviation) approx 1m.
Vertical Accuracy of Lyttelton Vertical Datum 1937 heights (standard deviation) 0.005m.

Heights generated from precise levelling data undertaken to a misclose standard (mm) of 5*sqrt(k) where k is the distance in kilometres. Precise levelling in the Christchurch area was undertaken after the 23 December 2011 earthquake. Other areas were levelled after the most recent earthquake to have affected heights in that area. Heights therefore represent the position of marks accounting for all four substantial Canterbury earthquakes.

These heights are only provisional. Analysis is ongoing as further data is collected.
Heights calculated using SNAP v2.3.64.
Heights were constrained using the pre-earthquake heights at geodetic codes AC9B, AFAQ, AG32 and B853. GNSS observations and modelling indicates that the height change of these marks was negligible.
Some heights were calculated from precise levelling data provided by Christchurch City Council.

These coordinates are suitable for use in surveys and other geospatial activities in Canterbury and Christchurch.

For further information about this dataset, see the Canterbury earthquake information on the LINZ website.

This layer contains the DEM for LiDAR data from the Waikato west coast and Hauraki Plains captured in 2015.
The DSM is available as layer Waikato - West Coast and Hauraki Plains LiDAR 1m DSM (2015).
The index tiles are available as layer Waikato - West Coast and Hauraki Plains LiDAR Index Tiles (2015).
The LAS point cloud and vendor project reports are available from OpenTopography.

Lidar was captured for Waikato Regional Council by Aerial Surveys in February and March 2015. The datasets were generated by Aerial Surveys and their subcontractors. Data management and distribution is by 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

Point density is 2 points/square metre.

Vertical datum is NZVD2016.

The national airborne gravity dataset is comprised of more than 50,000 linear km of flight observations, covering the three main islands of New Zealand and up to 10km offshore.

This dataset provides a 1 arc minute raster image of the Bouguer anomalies, which have been downward continued to the ground surface (McCubbine et al, 2017).

The national airborne gravity dataset was collected as a joint project between Land Information New Zealand (LINZ), GNS Science (GNS) and Victoria University of Wellington (VUW). The airborne survey was completed in a total of eight months, over two campaigns: August – October 2013, and February – June 2014.

Users may also be interested in other layers created for the free-air anomalies at ground surface and the along track observations from the gravity flight lines at flight elevation NZ Airborne Gravity Free-Air Anomalies at Ground Surface (2013-2014) and NZ Airborne Gravity Flight Lines at Elevation (2013-2014).

McCubbine, J. Stagpoole, V. Caratori-Tontini, F. Amos, M. Smith, E. and Winefield, R. (2017). Gravity anomaly grids for the New Zealand region. Manuscript submitted for publication New ZealandJournal of Geology and Geophysics.