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Why are there multiple datums for the same place?
Because there are different ways to fit the mathematical model to the surface of the Earth, there are many different datums. Also, in the modern digital era, techniques have vastly improved and many modern datum are very similar to each other.
Why are different reference ellipsoids used for different datums?
Since reference datums can have different radii and different center points, a specific point on Earth can have substantially different coordinates depending on the datum used to make the measurement.
Who defines a datum?
Datums are the basis for all geodetic survey work. Near coastal areas, mean sea level (and other tidal datums) is determined by analyzing observations from a tide gauge. Scientists at the National Geodetic Survey are working on a long-term project to make accurate height measurement better, faster, and cheaper.
What’s the difference between latitude and longitude coordinates?
Latitude and longitude coordinates are used to express points within a geographic coordinate system, such as NAD27 or WGS84. Meters or feet are used with projected coordinate systems, such as Alaska Albers Equal Area Conic. The $64,000 Question – Why do I need to know all this stuff?
Do you know the datum of your Latitude and longitude?
When gathering latitude / longitude data for geographic reporting, knowing the datum is important, as you may need to convert your coordinates to the proper datum before using them Let’s look at a basic example using lat/long coordinates for the Golden Gate Bridge.
What’s the difference between a regional and a local datum?
These are commonly called Local or Regional Datum. (AGD was a regional datum for Australia.) The result of the use of Local Datums was that lines of longitude and latitude between different countries/regions would not connect evenly.
Which is the best description of a coordinate system?
A coordinate system is a way to describe positions on the surface of the Earth. The coordinates of a point can be expressed in several ways – as latitude and longitude, or as meters or feet. Latitude and longitude coordinates are used to express points within a geographic coordinate system, such as NAD27 or WGS84.