Datums [Jan. 3, 2012, 12:45 a.m.]
At the end of this lesson, you will be able to:
- describe what a datum is in your own words
- differentiate a sphere from an ellipsoid
-
calculate the flattening ratio, equator to polar circumference, of an ellipsoid
- f = (a - b) / a
- flattening, a = equitorial radius, b = polar radius
Topic Overview
- Point of reference
- Clarke 1866
- NAD27
- NAD83
- GRS80
- WGS84
- Map Scale
- representative fraction
- 1:40,000,000 (meters)
- Other common scales
Reference
- Wikipedia: Datum (Geodesy)