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GRASS Help System |
The geographic coordinates associated with digitized points (defining line segments and nodes) will be added to a GRASS data file in the order in which they are digitized. If two node points fall within the geographic snapping threshold of one another, the node that appears second in the data file will snap to the one that is listed first. In GRASS, the default snapping threshold is .04 map inches (in terms of distance on the map). The snapping threshold can also be expressed as actual ground distance in database mapping units (e.g., in meters for a UTM database). When expressed in database mapping units, the number given for the snapping threshold will be dependent on the scale of the map.
Please refer to Setting the Snapping Threshold Value for important information on setting the snapping threshold.
See "Cartographic Issues in the Development of a Digital GRASS Database" from which the information in this section was obtained, for further information on map development issues.