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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.

World files do not specify a coordinate system.
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

http://en.wikipedia.org/wiki/World_file

 
Last modified:: 2019/10/08 11:11