Conceptual Foundations

Question 1

Georeferencing

Answer 1

Associating a map (such as a pdf without spatial information) or image (such as an aerial image without spatial information) with spatial points

Question 2

Control points

Answer 2

Consisting of multiple points, points come in pairs that match the spatial location with a point on an unreferenced image or map

Question 3

Spatial Reference System (SRS) or Coordinate Reference System (CRS) is a coordinate

Answer 3

Based local, regional or global system used to located geographical entities

Question 4

International Terrestrial Reference System (ITRS)

Answer 4

It is a three dimensional coordinate system with a well-defined origin (the center of mass of the Earth) and three orthogonal coordinate axes (X,Y,Z)

Question 5

Map Projection

Answer 5

Transforming coordinates from a curved earth to a flat map UTM

Question 6

Universal Transverse Mercator (UTM)

Answer 6

A global coordinate system - UTM zones are 6 degrees

Question 7

Horizontal Datum

Answer 7

Model of the Earth as a spheroid (2components, reference ellipsoid and a set of survey points both the shape of the spheroid and its position relative to the earth

Question 8

Vertical Datum

Answer 8

Set of control point for elevations of surfaces and features on the Earth - could be based on tidal, seas levels, gravimetric, based on a geoid

Question 9

NAVD88

Answer 9

Gravity based geodetic datum in North America

Question 10

Geodetic Datum

Answer 10

Set of control points whose geometric relationships are known, either through measurement or calculation

Question 11

WGS84

Answer 11

World Geodetic System - reference coordinate system used by the Global Positioning System (GPS)

Question 12

SRID Integer

Answer 12

Spatial reference system ID numbers, including EPSG codes defined by the International Association of Oil and Gas Producers

Question 13

4 Distortions

Answer 13

1. Distance
2. Direction
3. Shape
4. Area

Question 14

Mercator Projection

Answer 14

Preserves shape and direction, area gets distorted - projecting earth onto a cylinder tangent to a meridian

Question 15

Azimuthal Equidistant

Answer 15

Planar (tangent) - used for air route distances - distances measured from the center are true - distortion of other properties increases away from the center point

Question 16

Cylindrical equal-area projections

Answer 16

Preserves area, shape and distance gets distorted near the upper and lower regions of the map - straight meridians and parallels - meridians are equally spaced and the parallels are unequally spaced

Question 17

Conic Projections

Answer 17

Preserves directions and area in limited areas - distorts distances and scale except along standard parallels - generated by projecting a spherical surface onto a cone