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Image World File
A world file is a plain text file used by geographic information systems to georeference raster map images. Small-scale rectangular raster image maps can have an associated world file for GIS map software which describes the location, scale and rotation of the map. These world files are six-line files with decimal numbers on each line.
This information is generally stored in another companion file, the Orbit Resource Descriptor File (ORD)
Structure
An world file is a plain text file used by Orbit to georeference an image file. The world file is always associated with an OMI file : it describes the location, scale and rotation of the map. These world files are six-line files with decimal numbers on each line.
More information can be found on: https://en.wikipedia.org/wiki/World_file.
Create
Create and edit these files using a text editor. Take care of spelling and file syntax.
Parameters
- Line 1: pixel size in the x-direction in map units/pixel
- Line 2: rotation about y-axis
- Line 3: rotation about x-axis
- Line 4: pixel size in the y-direction in map units
- Line 5: x-coordinate of the center of the upper left pixel
- Line 6: y-coordinate of the center of the upper left pixel
Examples of Associated World Files
| Format | Image Data File | Image World File |
|---|---|---|
| Orbit Multiresolution Image | .omi | .oiw |
| ECW | .ecw | - |
| Bitmap | .bmp | .bpw |
| Graphics Interchange Format | .gif | .gfw |
| JPEG | .jpg | .jgw |
| Portable Network Graphics | .png | .pgw |
| Mister Sid | .sid | .sdw |
| Tagged Image File Format | .tif(f) | .tfw |