Most fall between the two as compromises. To compare or edge-match maps in a GIS, both maps MUST be in the same projection. Coordinate Systems A coordinate system is a standardized method for assigning codes to locations so that locations can be found using the codes alone. Standardized coordinate systems use absolute locations. A map captured in the units of the paper sheet on which it is printed is based on relative locations or map millimeters.
Most systems make both values positive.
Some standard coordinate systems used in the United States are geographic coordinates universal transverse Mercator system military grid state plane To compare or edge-match maps in a GIS, both maps MUST be in the same coordinate system. UTM zones in the lower 48 Military Grid Coordinates GIS Capability A GIS package should be able to move between map projections, coordinate systems, datums, and ellipsoids. County index grid Improving Existing GIS Coordinate Control Rectify GIS data to orthophotography Building complex features Simple geographic features can be used to build more complex ones. Areas are made up of lines which are made up of points represented by their coordinates. Basic properties of geographic features GIS Analysis Much of GIS analysis and description consists of investigating the properties of geographic features and determining the relationships between them.