GNTRANS

Geo++® GNTRANS is a model for coordinate transformations. It offers the possibility of regional, expanded coordinate transformations. Conventional local transformation generally give isolated results (“island solution”) due to the fact of different transformation parameters. In contrast to this, the transformation with GNTRANS is unique, preserve the adjacent metric properties, homogeneous and continuous. GNTRANS improves the quality, reliability and speed of transformations, allowing fast and efficient work in many fields of application.

Feel free to test GNTRANS available on Geo++ GNTRANS Demo-Server  (currently disabled!).

Range of Application

GNTRANS is suited for small and large transformation areas with homogeneous and inhomogeneous coordinate systems.

In addition GNTRANS can be applied for coordinate transform in problematic areas, where normally different sets of parameters have to be used (“island solution”). GNTRANS transforms areas considering the neighbourhoods and discontinuities (see graphic 1).

The transformation module produced with GNTRANS is used as unique transformation for all users in the covered area.

Additional and individual adaptations of existing GNTRANS modules, so called patches, are used to improve the accuracy, to locally adjust the transformation, or to adopt special user data.

GNTRANS enables the application of satellite-based surveying techniques as a fast and efficient method for direct determination of official coordinate system with the stated properties without difficult and inefficient transformations using identical points.

In Germany, for instance, GNTRANS is used to transform distorted coordinates of the official horizontal and vertical networks (STN, DHDN, DHHN, …) to ETRF89 and backwards.

Mode of Operation

GNTRANS uses unique, mathematical functional approach for modelling systematic parts of a transformation. Furthermore A stochastic prediction of remaining discrepancies is furthermore used considering existing discontinuities. The complete transformation is largely free of residuals at identical points.

gntrans-en
Graphic 1: example sketching isolated results I, II, III and a discontinuity between I and III

Properties

  • uniqueness/standardized
  • preservation of adjacent metric properties
  • homogeneous
  • continuity
  • consideration of discontinuities
  • bi-uniqueness (one-to-one mapping)

Pre-requisite

The one-time generation of an individual transformation module is based on a representative set of identical points with coordinates in the origin and target coordinate system. Information on discontinuities is considered in the modelling.

A German-wide GNTRANS model exists already. It is based on a set of of about 1200 identical 3D coordinates, about 340 additional 1D coordinates and uses the specially adopted quasi-geoid EGG97. The status of the data is from the year 2001. The accuracy of the transformation of GNTRANS can be different for individual state survey systems and depends on the actual transformation area . For the transformations the following standard deviations (1 sigma) are generally valid:


Plane
Height
DHDN-Area
5 cm
3 cm
STN-Area
1 cm
0.6 cm

The following document will show detailed information about all Germany state-wide coordinate systems (status 2001):

GNTRANS – state information

Remark: GNTRANS is an essential component of the DB_REF realization of DB Netz AG. The implemented height transformation and transformations starting in the national coordinate systems is the recommended way to generate DB_REF. The basic model provided with GNTRANS corresponds not with the latest transformation models provided by the individual states of Germany.

Programs

GNTRANS is basically provided as a command line tool. In addition GNTRANS is available as DLL (Dynamic Link Library) for easy integration in own applications. A windows applications with GUI (WINGNTRANS is offered with restricted functionality.

main_window2

WINGNTRANS GUI

The German wide transformation module GNTRANS is integrated in the track surveying and adjustment application Verm.essen of the company Technet GmbH and is provided to the user in the usual application environment. The planning and development system CARD/1 of IB&T Ingenieurbüro Basedow & Tornow GMBH also support the modul GNTRANS for the integrated Transformation of project data. GNTRANS is optionally available in the modules for coordinate transformation of WASY. The FME software distributed by Con terra uses optionally GNTRANS.

New transformation modules and patches can be generated with the Geo++® GNTRANS Generator (GNTRGEN) by the user himself. The GNTRANS Generator is an additional software package and usable with an additional license.

References

The German state Brandenburg uses for state-wide, bi-uniqueness transformation of horizontal and vertical coordinates from the old official coordinate system (STN) to the new unique 3D reference system ETRS89 the GNTRANS transformation method. The transformation module BRA2ETRS is provided to all users.

The Deutsche Bahn AG performs the transition from the old official coordinate systems to the new unique, homogeneous reference system DB_REF. Therefore a German-wide transformation module GNTRANS was developed. The transformation model makes unique, homogeneous, continuous adjacent metric preserving transformations between ETRF89, DB_REF and old official coordinate systems possible.

The Vermessungs- und Katasteramt Düsseldorf transfers point data of the cadastre from the old official coordinate system to the European unique 3D reference system ETRS89. For this purpose the German-wide transformation module GNTRANS and an additional GNTRANS patch for Düsseldorf improving the accuracy is used.

LGLN (Landesamt für Geoinformation und Landentwicklung Niedersachsen) (until 2011 LGLN) performed analysis of different transformation approaches. For these analysis several GNTRANS patches for the German-wide GNTRANS module were generated to improve the accuracy and were made available to LGLN. Finally the decision was made to use a special GNTRANS_NI for the transition to ETRS89.

AXIO-Net provider of GNSS reference station services (ASCOS in Germany offers their users the German-wide transformation module GNTRANS as well as GNTRANS patches as an additional transformation service in real-time. GNTRANS makes real-time surveying in the old official coordinate systems and DB_REF possible.

MPC/Mitsubishi Electric Corporation, respectively Jenoba Corporation, the provider of the GPS reference station services PAS in Japan uses GNTRANS. Effects of tectonic movements in Japan are modeled with the help of the GNTRANS. The GNTRANS module is available for the users of GPS reference station services and compensate the influences of tectonic movements in a real-time transformation.

Informationstechnikzentrum Bund (ITZ Bund) uses the GNTRANS API with additional GNTRANS patches in their own user interface GNTRANS WSV for horizontal coordinate transformations within the German Wasser- und Schifffahrtsverwaltung (WSV).

More links:

Link Description
The content of the linked website is the property of the respective owner.
LGLN State Survey Niedersachsen (until 2011 State Survey + Geospatial Basic Information Lower Saxony, LGN)
Mitsubishi Electric Distribution partner of Geo++® GNSMART for japan and the far east
AXIO-NET Trans GNSS data provider in Germany
WASY – WGEO Software intergration of GNTRANS
ITZ Bund GNTRANS WSV
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