World files provide information for image calibration.
A World file has the same filename as the main image file. For example,
a file called USA.jgw
could accompany an
image named USA.jpg
, and contain the coordinates
of the image in seconds of arc.
An example of a World file content is as follows:
1.50000000000000 (X pixel size)
0.00000000000000 (translation)
0.00000000000000 (rotation)
-1.50000000000000 (Y pixel size)
1934001.50000000000000 (X coordinate of the upper left pixel)
1187698.50000000000000 (Y coordinate of the upper left pixel)
The Map Builder ignores the
translation and rotation parameters.
When loading images in GIF, JPG, PNG, or TIF format,
the Map Builder scans the directory to
see if a World file exists, and if so, predefines the image bounds
accordingly in the importation dialog box.
For GIF, JPG, PNG, and TIF formats, the world file extensions
checked are in the form .tifw
or .tfw
, .gifw
or .gfw
, .jpgw
or .jgw
, and .pngw
or .pgw
respectively.