World File (tfw, tifw, wld, jgw, pgw, sdw, eww, blw, dmw, bpw, gfw)
World files contain the affine relationship between source image coordinates (pixel locations) and real-world reference coordinates (lat/long or other real-world coordinate units). World files simply contain a computed relationship between source image coordinates and reference coordinates. It consists of the pixel sizes in x and y direction, rotations about x and y axis and x and y coordinates of the center of the upper left pixel. Reference points cannot be loaded from a world file because they do not exist in the file. World files do not support storing coordinate system information. You may export the coordinate system information as an external WKT or PRJ file using the Export Coordinate System function.
Blue Marble Reference File (rsf)
The Blue Marble Reference Settings File saves the complete reference point list information such that it can be loaded again in the future. Within a Blue Marble Reference File, the first line contains the version of the file format (not to be confused with the version of the software) and the total number of points in the file. The remaining lines contain, in each line, the point ID, the x (row) pixel, the y (column) pixel, the z (elevation) value which is usually 0.00, followed by the ground coordinates expressed as Latitude or Northing (Y), Longitude or Easting (X) and Elevation (Z). The last value indicates whether the point described on that line is included in the solution, 0 = not included and 1 = included. Blue Marble Reference files support storing coordinate system information and control points.
MapInfo TAB File (tab)
MapInfo Table file formats save the complete reference point list information such that it can be loaded again in the future. MapInfo TAB files support storing coordinate system information and control points.
Supported projections when saving a coordinate system to TAB:
- Albers Equal-Area
- Azimuthal Equidistant
- Hotine Oblique Mercator
- Hotine Oblique Mercator 1pt
- Lambert Conic Conformal
- New Zealand Map Grid
- Swiss Oblique Mercator
- Stereographic Transverse Mercator
ER Mapper Raster File (ers)
The ER Mapper header file is an ASCII file describing the raster data in the data file. The entire header file holds information about the data source and is contained in the DatasetHeader block. There are two compulsory sub-blocks, the CoordinateSpace block (to define the coordinate space and location) and the RasterInfo block (to define the characteristics of the data in the accompanying data file). The RasterInfo block my contain a number of optional sub-blocks. To completely define coordinate information in an ER Mapper header file you need to include the following data: datum, projection, coordinate type, units, X and Y dimensions for cell size, registration cell X and Y values, registration cell coordinates, and possibly null cell value. Coordinate information is frequently, but not always, given for the upper left corner of an image. This would be registration cell X and Y values of 0.0 and 0.0. For most projections registration coordinates are entered as eastings and northings, the coordinate type will be "EN", and units will be meters (or occasionally feet). If you are using latitude and longitude the projection is Geodetic, coordinate type will be "LL" and the X and Y dimensions for the cell size will be in decimal degrees.
ER Mapper files support storing a limited number of pre-defined coordinate systems. Check the coordinate system details to ensure the ER Mapper identifier exists as the issuer for the coordinate system to be saved. The file will still be exported however the coordinate system will not be saved with the reference file.
ER Mapper reference files do not support rotated images. When attempting to export a reference file with a rotated image ER Mapper will not be listed.