ENGO 351 FINAL Flashcards
Diagram structure of basic GIS components
DATABASE(data stored) – DATA MANAGER(operations like insert, retrieve, delete update) < analyzer RS, Interface LS — People.
List the elements needed to define a coordinate system for an n-D space. Draw an example
for n=2 (i.e., a planar surface). [20]
- Origin
- Axis
- Units of measurement for the axis
(included drawing) x and y with two coordinates for it.
Explain the difference in the definition of (a) the cardinal versus (b) the rational level of
measurement. Give an example attribute along with some values for each level. [20]
CARDINAL - Arbitrary origin / unit
ex// Degrees Celsius
RATIONAL - Absolute origin, arbitrary unit
ex// Weight (kg)
Draw a line between two points on a GNOMONIC projection. is there any distortions? whats preserved?
two points are on a straight line in this projection. direction is conserved. Still mostly straight lines as is azimuthal.
Draw a line between two points on a CONIC projection. is there any distortions? whats preserved?
This projection preserves distance with the meridians. the line would be distorted outwards most likely as that’s the way the map distorts.
Draw a line between two points on a MERCATOR projection. is there any distortions? whats preserved?
Vertical lines are not distorted. but horizontal are unless on the equator. This preserves Angles and shapes. why its best for maps.
Define Loxodrome.
A line on the Earth surface with constant azimuth.
define spherical triangle.
A (spherical) shape defined by three points on the sphere and three edges, which are part of
the great circles connecting them (in pairs).
define projective surface (of a map projection).
An intermediate surface to project the spherical surface (Earth) onto a plane (map)
You are asked to build a geographic database of the UNB Campus buildings. Each
building is a geographic entity of interest.
(a) Name four (4) dimensions for each building. [10]
(b) List one or two attributes per dimension. [5]
(c) Specify the level of measurement of each attribute.
Dimension Attributes Level of Measurement
Identifier building ID Nominal (naming)
building Name Nominal
Spatial Location Rational(coords)
Direction Ordinal
Thematic # of floors Rational
use Nominal
Temporal year of construction Rational
years to build Cardinal
The air-humidity and the city-population …
[ ] refer to the rational and the cardinal level of measurements, respectively
[ ] refer to the cardinal and rational level of measurements, respectively
[ ] both refer to the rational level of measurements
[ X ] both refer to the rational level of measurements
- A loxodrome on a gnomonic projection is … [5] (Choose one)
[ ] always a straight line
[ ] always a curved line
[ ] sometimes a straight and some others a curved line
[ X ] sometimes a straight and some others a curved line
- Assume two lines of length equal to 1cm on a Mercator Projection. The first is drawn in
New York area and the second in Fredericton area. [5] (Choose one)
[ ] the first corresponds to a longer distance on earth
[ ] the second corresponds to a longer distance on earth
[ ] they both correspond to the same distance on earth
[ X ] the first corresponds to a longer distance on earth
- Assume two points on the equator with a difference in longitude equal to 180o
(on a
spherical Earth). [5] (Choose one)
[ ] There is a single
[ ] There are only two alternative
[ ] There are multiple alternative (i.e., more than two)
…shortest path(s) connecting the two points.
[ X ] There are multiple alternative (i.e., more than two)
…shortest path(s) connecting the two points.
“Gnomonic projection represents shortest paths on the spherical surface by straight
line segments”. Explain why.
The intersection of the projective surface with the plane containing the great circle
results to a line (as the intersection of two – non parallel – planes in space is a line).
