|
EPSG Coordinate Reference Systems |
|
Some GeoDLL functions use instead of the GeoDLL numbering for the Coordinate System and Reference System directly so called EPSG codes. If it is a valid EPSG code that is also supported by GeoDLL, the library automatically makes the necessary intern settings.
EPSG is the acronym for "European Petroleum Survey Group Geodesy". This is a working group of the European oil and gas exploration companies. The EPSG and their successors OGP "International Association of Oil and Gas Producers" have made it to their task to build a system with globally unique identitfiers (EPSG codes) for geodetic data, such as Coordinate Reference Systems, Reference Ellipsoids or Map Projections.
The library determines the equivalent to an EPSG Coordinate Reference System appropriate settings for the Coordinate System and the Reference System stored in GeoDLL .It is expressly noted, that not always exactly the same parameters for Coordinate Transformations and Reference System Transitions are used by GeoDLL, as they are present in the EPSG database. The reason for this is that some EPSG parameter sets do not meet the quality standards of KilletSoft products. GeoDLL mostly uses parameter sets which have been published by the respective survey administrations or have made firsthand available to KilletSoft by them or even have been purchased from them. KilletSoft has created its own high-quality data collection of exact geodetic parameter sets over the past years. Since the EPSG coding is used in many GIS systems and thus has obtained a high level of awareness, we provide the direct input of the EPSG codes to simplify the selection of the required Coordinate Systems and Reference Systems.
It does not always make sense to use the reference system preset in GeoDLL using an EPSG code. An EPSG code usually refers to a Coordinate System and to one of many possible Reference Systems. In GeoDLL, only one widely used Reference System for the respective Coordinate System is preset when using an EPSG code. Depending on the specific case, a Reference System other than the default one must be selected. This is necessary, for example, if several variants of different epochs and resolutions are available for the Reference System.
Example: For the DHDN [Deutsches Hauptdreiecksnetz] (German Main Triangle Network), there are time-related variants (1995, 2001, 2007) as well as spatially-related variants (Federal States, South, Center, North, etc.) available.
Functions using EPSG coding: List with supported EPSG-Codes
The Support of EPSG codes in GeoDLL is still under construction. So far, the EPSG code of the global and the European and North-American Coordinate Reference Systems are supported. If you want to have more EPSG codes that are to be supported by GeoDLL, please send us an Email in which you list the required EPSG codes. We will strive to implement this codes in one of the next updates.
|