W2

Question 1

What is nominal level data

Answer 1

identifies one entity from another (categories)
- ex. vegetation
- not ranked or quantified

Question 2

What is ordinal level data?

Answer 2

Data is ranked along a scale
- cannot apply arithmetic operations

Question 3

What is interval level data?

Answer 3

Data values are quantitative and are on a measurement scale based on a arbitrary zero point (ratios between values do not make sense)
- ex. temperature scale and longtitude

Question 4

What is ratio level data?

Answer 4

Data values with a true origin
- ratios between values make sense
- ex. distance

Question 5

What are the three data types stored in GIS

Answer 5

Integers, floating point values, strings

Question 6

How are numbers arranged in the binary system?

Answer 6

In columns that represent powers of 2

Question 7

How many bits in a byte

Answer 7

8
- sometimes a bit is reserved to store the sign (+/-) (this is called a signed byte

Question 8

What are several bytes strung together called?

Answer 8

a word

Question 9

How does the binary system work

Answer 9

All computations are carried out using binary arithmetic

Electronic circuits can represent and process data using binary signals, where “on” represents 1 and “off” represents 0.

Question 10

How many numbers can be represented in a byte

Answer 10

256

Question 11

What are the two types of integers and how many bytes do they have?

Answer 11

short (2 bytes)
long (4 bytes)

Question 12

How many bytes can floating point value data have

Answer 12

4 or 8

Question 13

What is precision in terms of bits

Answer 13

Precision is a function of # of bits used to code the word

Question 14

How many bytes does string data have?

Answer 14

Each character is stored as one byte (takes up alot of memory)

Question 15

Why would be integer data be better than float?

Answer 15

• to keep storage size small if higher precision is not required

Question 16

Define geographic scale

Answer 16

general scope or extent of things

Question 17

Define cartographic scale

Answer 17

Scale of a feature on a map with respect to the real world a map

Question 18

Define data scale

Answer 18

Data is collected or digitized at some scale or resolution

Question 19

What is resolution

Answer 19

Smallest details that can be distinguished in a dataset

Question 20

What dictates scale for vector data

Answer 20

precision of coordinates

Question 21

What dictates scale for raster data

Answer 21

resolution

Question 22

What are some issues with converting data from raster to vector

Answer 22

• Needs a lot of storage
• Can look shaky (you can smooth it but will create distortion)

Question 23

What are some issues with converting data from vector to raster

Answer 23

Depending on scale you might lose precision

Question 24

Describe latitude and longitude

Answer 24

• metric, standard, stable
• Uses a well-defined and fixed reference frame
• most universal and commonly adopted system of referencing global geographic locations
• has the potential for very fine spatial resolution
• supports other forms of spatial analysis

Question 25

What is a great circle

Answer 25

shortest distance between two points
- due to sphere shape this is actually a curved line

Question 26

Define datum and ellipsoid

Answer 26

Ellipsoid: approximates the geoid (shape of earth)
Datum: defines the position of the ellipsoid on the earth (means that different datums mean two different coordinate values)

Question 27

What are projections

Answer 27

Method of converting geographic space to cartesian space
- need to portray the curved surface of the earth as a flat (map) surface
- described by parameters