Soil Mapping Units
For the purposes of mapping, the soils were grouped on the basis of their characteristics into named soil series and soil phase units.
minimum mapping units For a given map scale, the size or dimension below which a long narrow feature is represented as a line and a small area as a point. For example, streams and rivers will be represented as lines if their width is less than .
Defense Mapping Unit (Singapore); Distance measuring unit
DMW
Daft, McCune, Walker ...
a minimum mapping unit corresponding to a vegetation stand derived automatically from satellite multispectral data using image segmentation; ...
Garmin mapping units come with permanently built-in basemaps, which typically include coverage of oceans, rivers, and lakes; principal cities, smaller cities, and towns; interstates, highways, and local thoroughfares; and railroads, airports, ...
A factor known as a minimum mapping unit comes into play. Minimum mapping unit asks the question of how small something is before it is not represented on the map.
For instance, it is very hard to distinguish anything smaller than about 1/50th of an inch on a map (the theoretical "minimum mapping unit").
quarter quad - One-quarter area of a four-sided quadrangle that depicts 7.5 minutes of latitude and 7.5 minutes of longitude on a side. Used as a standard surface area mapping unit by the U.S. Geologic Survey.
r.to.vect extracts vectors (aka, "arcs") from a raster file. These arcs may represent linear features (like roads or streams), or may represent area edge features (like political boundaries, or soil mapping units).
Using too small a cell size will significantly increase the storage space and processing time required, without adding precision to the map. To create an effective cell size, base the cells on map scale and on the minimum mapping unit of the other ...
 See also: Mapping, Information, Geographic, GIS, Area
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