The map definition file contains a list of CRSs, not included in epsg.db.
The file name is mapdef.dat and it is located in the system folder of the application
C:\Program Files\CARIS\<application>\<version>\system
Do not edit the default file. Create a copy of theଠ file and use the copy for custom map definitions. |
International foot = 0.3048m |
US survey foot = 0.30480061m (1200/3937 per US SPCS 1927) |
Lines that start with # are comments.
Map definition entries are collected in groups. The group name, enclosed in square brackets, is on a line by itself, followed by an unlimited number of definitions, one per row. Each definition can be no longer than 400 characters.
Definition fields are separated by commas. The first five fields are required. The remaining fields (the numeric fields) depend on the CRS and projection. If a numeric field is not required, enter a value of 0. You cannot leave a field out.
Each definition line has the following format:
Field | Type | Maximum | Description | Example |
Key | Char | 20 characters | The map definition key. Must be unique. |
|
Description | Char | 80 characters | A description for the definition. Must be enclosed in double quotes. Must contain no commas. |
|
Coordinate system | Char | 4 characters | NEMR, NRMR, LLDG or CHMR (see table below) |
|
Ellipsoid | Char | 4 characters | From the datum file. See Datum File |
|
Projection | Char | 4 characters | Projection code. See the list below. |
|
Scaling latitude 1 | Real | 10 dec. places | The latitude of the geographic origin. |
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Scaling latitude 2 | Real | 10 dec. places | The latitude of the geographic origin. |
|
False North | Real | 10 dec. places | An offset applied to all northings. |
|
False East | Real | 10 dec. places | An offset applied to all eastings. |
|
Scaling factor | Real | 10 dec. places | The amount of distortion to be expected at the geographic origin. |
|
Latitude origin | Real | 10 dec. places | The latitude of the geographic origin. |
|
CMorLO | Real | 10 dec. places | Central meridian or longitude origin, depending on the projection. |
|
Skew azimuth | Real | 10 dec. places | The azimuth of a great circle which passes through a point of origin. |
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CARIS uses four horizontal coordinate systems:
Coordinate System | Description |
NEMR | The coordinates are expressed as Northings and Eastings of a projection in metres on the ground (hence Northings and Eastings in MetRes). Distances and bearings can be carried across adjacent map sheets with this coordinate system, meaning that a continuous database can be established. Its application includes the atlas grid and where precise measurements are required (e.g. port or waterway). |
NRMR | Coordinates expressed in metres on the map have no reference to a specific location on the ground (hence Non Registered, MetRes). This type of coordinate system is used when a map needs to be created for demonstration purposes only where the information necessary for relating the map to the real world (control points) is not necessary. |
LLDG | Coordinates are expressed in latitude and longitude in decimal degrees on a reference ellipsoid (hence Latitude and Longitude in Decimal deGrees). Data may be digitized in Latitude and Longitude by typing the coordinates or by batching a number of measurements and applying them at one time. Another method of obtaining data is to digitize in another coordinate system and then convert to LLDG. |
CHMR | Coordinates are expressed in metres at the chart scale (hence CHart in MetRes). All distances and bearings are relative to that chart. Thus a stored position near the top right-hand corner of the physical map would be similar to the actual map dimensions. This stored position can nevertheless be transformed to Northings and Eastings or geographic latitude and longitude as required. This coordinate system is used primarily for hydrographic charting. |