1.   This allows the map data to be replaced by probability distributions of known form and parameters.

2.   Geometric correction and registration are necessary if Landsat imagery is to be used for cartographic purposes, or is being used in conjunction with map data.

3.   The Ordnance Survey of Great Britain is also providing a limited amount of digital map data and DEMs.

4.   An invaluable site for finding map data is GLIS, the U.S. Geologic Survey Global Land Information System.

5.   Agency spokesmen have questioned whether civilian users need the detailed map data.

6.   Most navigation systems use map data on CD-ROMs, each covering part of the country.

7.   Similarly, many users of map data are content to work with old paper maps rather than pay for satellite images.