GPS, Coordinate Systems, Projections & Feature Creation

Question 1

Georeferencing

Answer 1

Aligning Geographic data to a Coordinate System.

May involve shifting, rotating, scaling, skewing, warping, rubbersheeting or orthorectifying.

Question 2

Projections

Answer 2

The method by which the curved surface of the earth is portrayed on a flat surface

Question 3

Geocoding

Answer 3

Converting street addresses into spatial data, usually referencing address information from a street segment layer.

Question 4

Reverse Geocoding

Answer 4

Finding a street address from a point on the map.

Question 5

Orthorectification

Answer 5

The process of correcting the geometry of an image so that it appears as though each pixel were acquired from directly overhead. Uses elevation data to correct terrain distortion in aerial or satellite imagery.

Question 6

Heads-up Digitizing

Answer 6

Manual digitization by tracing over a feature.

Question 7

Datum

Answer 7

A system of coordinate positions on a surface. A geodetic datum is the basis for calculating positions on, above, or below the earth’s surface.

Question 8

Precision

Answer 8

Closeness of a repeated set of observations to each other.

Question 9

Accuracy

Answer 9

Closeness to true position.

Question 10

Sliver polygon

Answer 10

A small, narrow polygon that appears along the borders of polygons following the overlay of two polygons. May indicate topology problems.

Question 11

Union

Answer 11

All features that exist in either set are retained.

Question 12

Intersect

Answer 12

All features that overlap are retained.

Question 13

Address Locator

Answer 13

Defines the process for geocoding.

Question 14

Transformation

Answer 14

Converting the coordinates from one system to another.

Question 15

Geographic Coordinate System

Answer 15

Lat/Long. Uses a datum, prime meridian, and angular unit of measure (degrees, minutes, seconds).

Question 16

Projected Coordinate System

Answer 16

Uses a linear system of x,y,z. Relies on a Geographic Coordinate System, Map Projection, and linear units of measure.

Question 17

Decimal Degrees

Answer 17

Values of lat & long expressed in decimal format.

Question 18

Image Processing

Answer 18

Changing the values of an image for analysis or enhanced display.

Question 19

Density Slicing

Answer 19

Highlight areas that appear to be uniform in tone but aren’t. Often used for remote sensing of vegetation.

Question 20

Low/High Pass Filtering

Answer 20

Spatial filter that blocks high or low frequency radiation, resulting in a smoother or sharper image.

Question 21

Edge Enhancement

Answer 21

Emphasize the appearance of edges & lines