# Projection Type

Represents a map projection. Projections can be defined using the predefined options (UTM, Geodetic etc), using a WKT specification, using an EPSG code or using a Proj4 specification.

WKT specifications must follow the WKT standard syntax. See the example below:

```  PROJCS["SUTM21",
GEOGCS["SOUTH AMERICAN 1969",
SPHEROID["INT67",6378160,298.25]],
PRIMEM["Greenwich",0],
UNIT["degree",0.0174532925199433]],
PROJECTION["Transverse_Mercator"],
PARAMETER["latitude_of_origin",0],
PARAMETER["central_meridian",-57],
PARAMETER["scale_factor",0.9996],
PARAMETER["false_easting",500000],
PARAMETER["false_northing",10000000],
UNIT["Meter",1]]```

The Proj4 syntax must also follow the Proj4 specification syntax. Example:

`  [ +proj=latlong +ellps=GRS80 +towgs84=-199.87,74.79,246.62 ]`

## GUI Editor

Graphical representation of the projection editor

## EGO Script

A constant representing a projection in a EGO Script can be defined in two different ways:

### Using ERMapper parameters

`[| "COORDINATE_TYPE", "ERMAPPER_PROJECTION", "ERMAPPER_DATUM", "ERMAPPER_UNIT" |]`

All parameters are case-insensitive and must be surrounded by double quotes.

Example:

`[| "LATLONG", "GEODETIC", "WGS84", "METERS" |]`

### Using a WKT (Well-Known Text) description

`[| "COORDINATE_TYPE", WKT_PROJECTION |]`

The syntax used to the represent the WKT_PROJECTION can be found here.

It is worth nothing that only the COORDINATE_TYPE must be surrounded by double quotes.

Example:

```[| "LATLONG",
PROJCS["unnamed",
GEOGCS["WGS 84",
DATUM["WGS_1984",
SPHEROID["WGS 84",6378137,298.257223563,
AUTHORITY["EPSG","7030"]],
TOWGS84[0,0,0,0,0,0,0],
AUTHORITY["EPSG","6326"]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.0174532925199433,
AUTHORITY["EPSG","9108"]],
AUTHORITY["EPSG","4326"]],
PROJECTION["Transverse_Mercator"],
PARAMETER["latitude_of_origin",0],
PARAMETER["central_meridian",90],
PARAMETER["scale_factor",0.9996],
PARAMETER["false_easting",500000],
PARAMETER["false_northing",-2000000],
UNIT["METERS",1]]]
|]```

### Using a Proj4 description

`[| "COORDINATE_TYPE", [ PROJ4_PROJECTION ] |]`

The syntax used to the represent the PROJ4_PROJECTION can be found here.

Example:

```[| "LATLONG",
[ +proj=longlat +ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +no_defs ]
|]```

### Using a EPSG code

`[| "COORDINATE_TYPE", EPSG_CODE ] |]`

Example:

```[| "LATLONG",
7030
|]```

A COORDINATE_TYPE is also case-insensitive and must be represented using keywords “en” (Easting/Northing), “latlong” (Latitude/Longitude) and “none”. The latter can be used to automatically derive the coordinate type based on the projection parameters.

## Automatic Conversions

• Converted to: None.