World File

A raster may have an associated World File which defines the position of the Raster.

The World File contains 6 lines of text as follows:

• A: X-dimension of a pixel in map units.
• D: Rotation parameter.
• B: Rotation parameter.
• E: Negative of y-dimension of a pixel in map units.
• C: X-coordinate of center of upper left pixel.
• F: Y-coordinate of center of upper left pixel.

MapLink Pro Studio and the Raster Data Layer will use a World File if it is present.

The World File will not be used if the Rotation parameters are not 0 as these mean that the raster is rotated.

A World file is very dependent on the map units used within the file and with any associated map or coordinate system.

For example a World file for a raster in a UTM projection the following is true:

• D and B are always zero
• C is the Easting UTM coordinate.
• F is the Northing UTM coordinate.
• Units are always metres per pixel.

Note:

When loading a raster image into a Raster Data Layer using the addRasterWithWorldFile function with the underlying map being the shipped VMAP0 World map, the map units are DEGREES, so the A and E values are calculated thus:

• A: x-dimension of a pixel = degrees / pixels
• E: Negative of y-dimension of a pixel in map units = -degrees / pixels