ce 453 – horizontal / vertical reference systems and mapping

CE 453 – Horizontal / vertical reference systems and mapping

How Long was the route you designed?

Were the coordinates based on the:

• International foot? ( 1m= 3.2808399 ft)

(1 ft = 0.3048 m)

or the

• Surveyor’s foot (1 m = 3.2808333 ft)

(1m = 39.37”)

What difference would that make?

Effect over 20 miles

0.21 feet (check it out)

Effect across the State of Iowa

~ 3.2 feet

How long was the route you designed?

Were the distances measured along

• horizontal planes,

• spheroidal surfaces,

• geodetic surfaces, or

• Ellipsoidal surfaces?

How high was the route you designed?

Were elevations from datums established in 1927 or in 1988?

U.S. Reference datums - horizontalfor State Plane coordinate conversions

• NAD27 Clark ellipsoid of 1866 (ft)• NAD83 1980 GRS ellipsoid (metric)

• Later systems/sources include:• World Geodetic System(1984)• High Accuracy Reference System(HARN)• International Terrestial Reference Frame• Continuously Operating Reference Stations

Computing State Plane coordinates:Lambert projection

• 10 Equations to determine zone constants -• Basic components• Ellipsoid major axis• Eccentricity• Grid origin (Latitude and longitude of the zone)• Spot coordinates (latitude and longitude)• False northing and easting of zone

Mapping and data reference systems

The following sequence of slides is intended to introduce various data reference systems.

Several slides were obtained form a presentation from

David Doyle, National Geodetic Survey

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