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How does ArcView, ArcInfo, and most other commercial software deal with positive west longitudes?

April 26, 2017arcinfo ArcView Commercial deal longitudes positive Software West

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How does ArcView, ArcInfo, and most other commercial software deal with positive west longitudes?

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ArcView and Arc/INFO and most other mapping software can only deal with positive east coordinate systems (without enhancements). Because of this, all our GIS datasets are stored in a positive east coordinate system. Thus when one is working with older Mars data or another body that is defined as positive west, you must convert the longitudes to emulate Earth. Recently, the Mars longitude system was standardized to use east. Thus older data will be west and new datasets will be east. See figures for examples. ——————————————————- | MARS (west) | | | | 180 <---(90)----- 0 | | and | | 0 -----(-90)-----> -180 | | | | | | | | | ——————————————————- Again ArcView 3.x prefers positive east 180 system (-180 to 180). So you must convert the coordinates (basically NEGATE ALL LONGITUDES for Mars to fit in a Earth based system). ArcMap versions 8 and up can use positive 180 and 360 (0 to 360) decimal degree systems.