The ArcInfo Export file format is designed for interchange between ArcInfo systems. Due to the wide use of ArcInfo, though, it is also quite widely used as a de facto interchange standard. GIS systems such as MapInfo, SPANS, Laserscan Horizon, and Atlas*GIS can all read export format. Export files can be created in a number of different ways. The first choice is whether the files should be written as double or single precision, which refers to the number of bits (binary digits) allocated to storing the co-ordinates. Single precision is adequate for many purposes, but for large areas held at largish scales it may prove inadequate. Use of single precision in ArcInfo can also lead to co-ordinate creep due to rounding errors if data is frequently translated from one map projection to another. PC-ArcInfo and ArcView Versions 1 and 2, but not the current Version 3, can only read single precision export files. The second choice is whether or not the export files should be compressed. Both partial and full compression are available, but the import modules of non-ArcInfo GIS systems can often only read uncompressed ASCII export files. By default, we will provide uncompressed single precision export files. |
