Conceptual Foundations 2

Question 1

Choosing a projection: Latitude

Answer 1

Low-latitude areas (near equator) use a conical projection; Polar regions use a azimuthal planar projection

Question 2

Choosing a projection: Extent

Answer 2

Broad in East-West (e.g., the US) use a conical projection; Broad in North-South (e.g., Africa) use a transverse-case cylindrical projection

Question 3

Choosing a projection: Thematic

Answer 3

If you are doing an analysis that compares different values in different locations, typically an equal-area projection will be used

Question 4

Discrete Features

Answer 4

A feature that has a definable boundary, begins and ends, for example a highway or lake

Question 5

Continuous Phenomena

Answer 5

Each location is a measure of something, for example elevation
A. Measure of concentration level
B. Measure of a value in terms of a fixed point (like elevation in terms of sea level)

Question 6

Geoid

Answer 6

Is the shape that the surface of the oceans would take under the influence of Earth’s gravitation and the rotation alone, in the absence of other influences such as winds and tides- used to reference heights, by registering ocean’s water level at coastal places using tide gauges- this is how the mean sea level is determined

Question 7

Reference Ellipsoid

Answer 7

Is a mathematical defined surface that approximates the geoid, the truer figure of the Earth, or other planetary body

Question 8

Oblate Ellipsoid

Answer 8

Fits the geoid to a first order approximation - formed when an Ellipsoid is rotated about its minor axis

Question 9

Sphere

Answer 9

As can be seen from the dimensions of the Earth Ellipsoid, the semi-major axis a and the semi-minor axis b differ only by a bit more than 21 kilometers

Question 10

First (direct) geodetic problem

Answer 10

Given a point (in terms of its coordinates) and the direction (azimuth) and distance from that point to a second point, determine (the coordinates of) that second point

Question 11

Second (inverse) geodetic problem

Answer 11

Given two points, determine the azimuth and length of the line (straight line, arc or geodesic) that connects them

Question 12

Geomatics

Answer 12

Science and technology of gathering, analyzing, interpreting, distributing and using geographic information ( includes surveying, mapping, remote sensing, GID, GPS)