Write Shift Vectors File

The four export format are listed on the dialog.

Report on Shifts

This option writes the shifts to a CSV file which can be easily viewed in Excel.
It exports the following data fields for each shift vector
  1. Shift Point number
  2. Reference Point number
  3. Shift Distance
  4. Shift Point Easting
  5. Shift Point Northing
  6. Ref Point Easting
  7. Ref Point Northing



Write ESRI Correction File.

Click here for details of the ESRI Shift File Format.

Write the FME Correction File.

Click here for details of the FME File Format.

NTv2 Transformation File. An NTv2 transformation grid file contains coordinate shift values at nominated grid nodes in a format known as NTv2 (National Transformation Version 2). This format was developed by the Geodetic Survey Division of Geomatics Canada, to implement the transformation of coordinates between NAD27 and NAD83 in Canada.

The format of the grid file (NTv2) is described in the following web page:

http://www.geom.unimelb.edu.au/gda94/UsersGuide.pdf

The format has been adopted by many countries (including Australia) to provide a means of transforming coordinates between different geodetic datums. Most data base systems have software to apply this transformation procedure.

A Grid Shift file contains one or more rectangular “sub grids". Each sub grid consists of nodes spaced at regular intervals of latitude and longitude. Each node has a shift value for both latitude and longitude components, as well as a value for the accuracy of each shift.

In its simplest form, a Grid Shift file defines a single sub grid, however it can contain more than one sub grid. If multiple sub grids are defined, the sub grids do not have to be contiguous. Sub grids of different densities can also overlap each other if certain rules are adhered to.

The program can build a NTv2 grid to reflect the differences between two cadastral mapping systems so that the associated layers in a data base can me moved to reflect the change in the cadastral layer.

The program will write a NTv2 sub grid for an area selected in a view port where the correction vectors have been calculated.

The mesh size can be set and for urban areas, a mesh size of 50 metres is recommended. A larger mesh size may be more appropriate for rural areas. Note that if you halve the mesh size, there are four times the number of elements, and if you quarter the mesh size, there are sixteen times the number of elements.

Create a viewport using the viewport option, select the viewport and the output file name and the file will be written. The viewport borders decide the total mesh size.

To test the file, restart the program with the layer to be adjusted. Apply the correction using Points/Advanced/Datum Change, then read in the reference layer. If the process has been carried out correctly. The two cadastral patterns will now be exactly superimposed on top of each other.


Geographics Shift Values

Tick to output Geographics values (Latitude, Longitude).
The values are in Decimal Degrees to 10 decimal places.
This only works for ESRI and FME files


Compute Shift Vectors
Edit Shift Vectors
Shift Vector Settings
Read Shift Vectors file
Write Shift Vectors file
Write Shift Vectors to an FME format file
Write Shift Vectors to an ESRI format file