Knowledge Base - Version 11.0
Recent Changes
This is documentation of an archived release.
For documentation on the current version, please check Knowledge Base.

Coordinate Reference Systems in Orbit

This page describes only the use and application of Coordinate Reference Systems in Orbit.
For a clear and short overview of the concepts of coordinate systems, datum and projections, read Coordinate Reference System in Theory.

CRS / SRS

A coordinate reference system (CRS) or spatial reference system (SRS) is a coordinate-based local, regional or global system used to locate geographical entities referring to a horizontal or vertical reference frame.. A coordinate reference system defines inter alia the representative volume of the earth, in case of projected systems the map projection method and the transformation between different spatial reference systems.
Coordinate reference systems can be referred to using a SRID integer, including EPSG codes defined by the International Association of Oil and Gas Producers.

Supported CRS

Up to now Orbit supports any combination Geographic, Geocentric and Metric projected coordinate systems 1).
If it is your wish to use Feet projected coordinate system, please let us know. It is on our wishlist for a future update.

EPSG Library

Orbit has the objective to support all coordinate systems as defined by the OGP (International Association of Oil and Gas Producers) and described in the EPSG library. Orbit respects the order of axes as defined by the EPSG Library

Custom CRS Definition

Orbit supports custom CRS definitions in addition to the EPSG library. These custom definitions are well-known text .prj files, structured as described by the Open GeoSpatial Consortium :

How to add a custom CRS definition

  1. Create your custom .prj file as described by the OGC, see above.
  2. Rename prj file to be structured as “<number>_<description>.prj”, for example “1031370_Belge 1972 - Belgian Lambert 72.prj”
    • the number should be larger than 1000000 (one million) and smaller than 2000000 (two million) to avoid overlap with existing EPSG codes or dynamic Orbit coordinate systems.
    • the description is optional
  3. Copy file to <Orbit installation directory>\program\system\crs
  4. Restart Orbit.
    The newly added CRS will be available via the CRS Window by entering its name as defined in the .prj file, its number as defined in the file name or via “Undefined Area” (CRS By Country).

Local CRS Definitions

Orbit adds on demand local CRS definitions as defined by their local entity, both for XY and Z.
Some examples :

Contact the Orbit support team to embed your local defined coordinate system.

Vertical CRS Definitions - Geoid or DEM

The powerful Orbit engine can be used to add any geoid model or dem via an Orbit raster file (.omi) or via a mathematical description.

To support your local geoid model in Orbit you can provide your geoid (raster) definition and specifications to the Orbit support team.
This can be as text/csv file (containing X,Y,Z) or any supported raster resource.
The Orbit team will process the required configuration files which can be added on the fly like a custom CRS definition.

Dataset CRS

Every single resource has a CRS.
If no Orbit dataset CRS is set, Orbit will read the resource assuming that dataset has the same coordinate system as the MapCanvas (see below). When combining resources with different coordinate system it is strongly recommended to define the coordinate system for every single resource.
Orbit supports imagery to be reprojected on the fly.

There are two ways to set the CRS of a dataset in Orbit :

The dataset CRS is saved in the Orbit Resource Descriptor file :

MapCanvas CRS

The MapCanvas CRS is the coordinate system that will be used as display coordinate system for all your listed datasets. If required datasets will be re-projected on the fly to be displayed on the MapCanvas.
But make a wise decision :

  • It will require processing power to reproject large vector datasets into another MapCanavas CRS. It is advised to use the CRS of the largest vector dataset or combination of datasets as MapCanvas CRS. This will reduce re-projection calculations and will speed up map rendering considerably.
  • Re-projecting means deforming. To retain your familiar “projection shapes” use again the same CRS for your MapCanavas as defined for your datastets.

The MapCanavas CRS can be changed quickly via the Set Coordinate Reference System Window which one opens with a single click on the current MapCanvas CRS in the middle of the MapCanvas Statusbar.

The MapCanvas CRS will follow automatically the CRS of the first checked / displayed dataset with a defined CRS.

The MapCanvas CRS will be saved in the workspace :

1)
Supported projection methods : Hotine_Oblique_Mercator, Krovak, Lambert_Conformal_Conic (_1SP, _2SP, _2SP_Belgium), Mercator_1SP, Oblique_Mercator, Oblique_Stereographic, Transverse_Mercator.
 
Last modified:: 2019/03/25 11:36