Map Projections and Coordinate Systems. Jan-Van Sickle Khang-tsung Chang ESRI Using ArcMap. Coordinate Systems. The location of a known point (Youghall, Colorado Mountains) is known on the ground Coordinates: 1937 : lat 40 ° 25’ 33.504’’N; Long 108 ° 45’ 55.378’’W
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ESRI Using ArcMap
The location of a known point (Youghall, Colorado Mountains) is known on the ground
1937: lat 40° 25’ 33.504’’N; Long 108° 45’ 55.378’’W
1997: lat 40° 25’ 33.39258’’N; Long 108° 45’ 57.78374’’W
1937: 2658.2 m
1997: 2659.6 m
A datum (spheroid) approximates the shape & size of the Earth in the examined area
Five Parameters were needed to define a datum (e.g., NAD27):
Whereas, locations of map features are based on plane coordinate system (x and y coordinates)
Does a flat Cartesian datum with two axes represent the real world (Earth) well?
Only, if the Earth was flat
Thus, across small areas, this approximation works well.
If the area gets to be large, distortions will be problematic
Find the distance between them
Distance = ((X1-X2)2 + (Y1-Y2)2)1/2
Distance = 3336.91 ft
Angle measured from Polar Axis
Cartesian only one pair can represent a point
(2) Use one tangent plane
Start with a surface that is not deformed upon flattening