Monday, September 28, 2009

Find the Joke

At work I've been writing a proposal for a new coordinate system (related to mapping of the company's facilities). I wrote a proposal just like this sixteen years ago and just to see if anyone actually read it, I embedded a joke in the "Glossary of Terms".

No one evvverrrr found it.

So now that the time has come time to polish that old gem, I've decided to test it again. Since y'all are much sharper than my company's management, let's just see if you can spot it. (I've spared you having to read the entire twelve-page proposal and just excerpted the section of the glossary that contains the quip.)


Eccentricity – eccentricity of an ellipsoid, œ = arccos(1 – f ), where f is the ellipsoidal flattening. (See “Flattening”.)

Ellipsoid – a flattened sphere, mathematically defined by the equation: [(x2 + y2)/a2] + z2/b2 = 1; where “a” is the semimajor axis and “b” is the semiminor axis. The two ellipsoids mentioned in this proposal are: the Clarke Spheroid of 1866 (used by NAD27) and the defined ellipsoid for the World Geodetic System of 1984 (WGS84).

Flattening – ellipsoidal flattening, f (the “flattening” of an ellipsoid defined by [(x2 + y2)/a2] + z2/b2 = 1) is defined as f = (a - b)/a = 1- cos(œ), where œ is the eccentricity of the ellipsoid. The referenced ellipsoid of GRS84 uses the inverse of the flattening (the reciprocal of f ) as a defining parameter.

Geodetic Coordinates – latitude and longitude referenced to a datum.

Geographic Information System (GIS) – computer software system designed to collect, manage, manipulate, analyze, and display spatially referenced data.

Latitude – geodetic latitude: the angle (φ) between the equatorial plane and a line that is normal to the reference ellipsoid. By convention points in the northern hemisphere are assigned positive values (0º ≤ φ ≤ 90º) and those in the southern hemisphere are assigned negative values (0º > φ ≥ -90º).

Longitude – the angle (λ), measured east or west of the Prime Meridian to the meridian passing through another position on the Earth’s surface. By convention points in the eastern hemisphere are assigned positive values (0º ≤ λ ≤ 180º) and those in the western hemisphere are assigned negative values (0º > λ > -180º).

Map Projection – mathematical mapping of points on the surface of the Earth to unique points on a plane, or ascribing to a map feelings which one denies of self.

North American Datum of 1927 (NAD27) – horizontal control datum for the United States, which was defined by a location and azimuth on the Clarke spheroid of 1866, with origin at the survey station “Meades Ranch”, Kansas.

North American Datum of 1983 (NAD83) – horizontal control datum for the United States, Canada, Mexico, and Central America, based on a geocentric origin and the Geodetic Reference System 1980 (GRS80). NAD83 was based on the adjustment of 250,000 points including 600 satellite Doppler stations. For land survey purposes, NAD83 is essentially synonymous with WGS84 (differing only in its definition for the “inverse of the flattening”: 298.257222101 [for NAD83] versus 298.257223563 [for WGS84] – a difference that affects long-term orbital computations, but has no practical effect when computing terrestrial positions). ...


The Flyer said...

Ahhh! So that's why Mercator made Greenland so big! It all makes sense now!

Bob said...

You found it! Good eye.

JP said...

Map Projection – ascribing to a map feelings which one denies of self.

Kinda like giving someone an Italy in the rear? Get it? Italy, boot...

Bob said...

Yep JP--
Cartography is all about feelings. Nothing more than feelings. Trying to forget my feelings for maps! Feeeeelinnngggs, wow, woe, woe feeeeelinnngggs...

Mrs. JP said...

Ah, good ole MP!
I think if they actually read it they'd get it. huh, kinda like something else we'd like others to read. Sorry, I brought my soap box along.