Cartographic Principles & Map Projections Flashcards
What a projected coordinate system?
It converts locations on the Earth’s curved surface onto a flat surface.
What are the three types of projection?
Cylindrical, conical, and azimuthal/
What are the characteristics of a cylindrical projection?
Can be “unrolled” into a flat plane without folding, tearing, etc.
What is a characteristic of a conical projection?
It can be curved, but only in one direction.
What kind of projection stays true to the earth’s axis of rotation?
Normal
What known as a transverse projection?
One with a developed surface axis that runs perpendicular to the earths axis of rotation.
What is known as a tangent projection?
One in which the developable surface touches, but doesn’t intersect the Earth.
What is known as a secant projection?
One in which the developable surface intersects the surface.
What are the two radians?
Longitude and latitude (x,y)
How does map projection actually work?
Input unprotected
(lat/long), apply a pair of functions (x,y), and output a position in projected coordinates.
How does one minimize distortions which is characteristic of maps?
By using compromising projections that attempt to balance properties.
What are the three types of compromise projections?
ConFORMAL, equal-area, equiDISTANT
Where is distortion seen in an equal area projection?
Shape
Where is distortion seen in a conformal projection?
Area
What is a Mercator projection classified as?
A conformal normal cylindrical projection
Where does a Mercator projection distort?
At the polls where spacing of parallels increase.
What are known as rhumb lines?
Lines of constant bearing
What are the characteristics of a gnomic projection?
Azimuthal (causes distortion in everything), straight lines depict great circles (makes it good for aviation)
What is a lambert conformal conic projection good for?
Large east-west extents in mid-latitudes, w latitudinal range less than 35 degrees.
What applications are conformal projections best for?
Cadasters, topographic maps, weather, and military.
What are equal-area projections best applied for?
Land-use and density/concentration.
What kind of projections are best for tropic areas of N-S extent?
Cylindrical
What kind of projections are best for mid latitude areas of E-W extent?
Conical
What kind of projections are best for the polar regions?
Azimuthal
What is georeferencing?
The process of defining position w respect to a reference frame (also known as geo coding or geolocating)
What are the requirements of georeferencing?
Uniqueness (1 coord. per location), interoperability (shared meaning among users), and persistence (does not req frequent updates)
What are the two types of metric (coordinate system) georeferencing?
Geographic Coordinate System (locations on a sphere) and Projected Coordinate System (locations on a plane)
What is the Universal Transverse Mercator?
Not strictly a projection rather, a coordinate system based on a series of Transverse Mercator projections.
What’s the difference between the transverse Mercator and universal transverse Mercator?
Transverse uses tangent lines and universal uses lines of secancy
What are the characteristics of the UTM system?
Earth is divided into 60 zones with 6 degrees of longitude wide that are labeled from 1 to 60 starting from the international date line, each zone has a central n-s meridian and they are divided into letter zones
What does the UTM coordinate system consist of?
Zones w their own coordinate system in meters defined by an x coordinate (wasting),a y coordinate (northing), and an origin.
What is an origin?
It’s the intersection of equator and central meridian.
What is known as a false easting?
When the central meridian gives an arbitrary x value of 500,000
What is a graticule?
A grid of mapped latitude and longitude lines.
What is known as geodesy?
The study of the shape of the earth
What is a geoid?
An equi-potential gravitational surface that is not measured nor regular.
What is known as an ellipsoid?
Similar to a geoid but flat and constant
What is known as the datum?
The coordinate system defined by an ellipsoid positioned w respect to the earth
