Topic 03

Question 1

communicating geographic information

Answer 1

representations of things in the real world

nothing objective about the data we work with

information communicated throughbsymbols, language

what to represent? how to represent it?

Question 2

entities

Answer 2

discrete objects/data

Question 3

fields

Answer 3

continuous data

Question 4

discrete

Answer 4

point locations, regions, well-defined boundaries
efficient representation
problematic for many natural phenomena

efficient representation

Question 5

continuous

Answer 5

continuously variable field

measureable at any point

works well for natural phenomena
elevation, precipitation

Question 6

raster and vector (discrete continuous)

Answer 6

raster = continuous
vector = discrete

Question 7

raster data file structure

Answer 7

32 bit = single precision
64 bit = double precision

Question 8

quadtree encoding

Answer 8

speeds up certain commands
decreases the amount of storage

Question 9

raster file compression

Answer 9

JPEG
lossy compression
Lossless

doesnt lose any of the data
LWZ = compression within GIS

Question 10

vector data model

Answer 10

points, lines, polygons
connections via vertices and nodes
attributed assigned to each entity

are lines with starting and ending points

Question 11

node vs vertices

Answer 11

node = end points

vertices = intermedaite points

Question 12

topology

Answer 12

qualitative properties of things

spatial relationship

adjacency, containment, connectivity

Question 13

georelational vector data model

Answer 13

stores geometry and atribute in multiple tabs

shapefiles

relies on tables to store geometry

table with coordinate arc list

then has a table identifying the polygons and the arc lines that define it

Question 14

object based data model

Answer 14

object relational model

esri geodatabase

generic model where a single entity is used to describe each type of the object in the GIS database

Question 15

advanatges and of object based data model

Answer 15

ad = allows to aggregate feastures easily

Question 16

hybrid models

Answer 16

ESRI employs a hybrid model that uses both

object relational

Question 17

raster model

Answer 17

space is divided up into a regular array of cells/shapes

usually for continuous fields

space divided into equal pieces or pixels

attributes are assigned to each cell

Question 18

tesselation

Answer 18

breaking up to continuous data ito regular shapes (square pixels)

Question 19

properties of rasters

Answer 19

cell size and shape
cell values
cell bit depth

8 bit, 16 bit, 32 bit

Question 20

raster bands

Answer 20

single vs multiple band images

Question 21

sptial reference sysetem (raster)

Answer 21

location of raster (loaded into metadata)

Question 22

environmental scale

Answer 22

refers to texten of the map or size of the object under investigation

large scale projects covers a large area

Question 23

cartographic scale

Answer 23

refers to the representative fraction of te mp

large scale map covers small geographic area

Question 24

TF the scale of a cited map is never completely accurate

Answer 24

true

Question 25

graphical scale bars are handy bc why

Answer 25

they will shrink and grow along with the map rather then saying 1:50 for example and it being shrunken

Question 26

what two ways can spatial scale be represented

Answer 26

two independent components extent (total area) resolution (smallest discernible object)

Question 27

spatial resolution

Answer 27

raster = size of pixel or smallest feature that can be identified vector = # number of vertices used to define a line

Question 28

changing scales = 1 of the following

Answer 28

change in extent (precision or grain remains constant) change in grain (extent remains constant) change in both precision/grain and extent

Question 29

analytical scale

Answer 29

scale of available data and capabilities of the computer software cannot detect patterns of phenomena that are occurring at a finer resolution then the data itself constrained by extent and resolution

Question 30

measurement scales

Answer 30

NOIR + cyclic wind direction and phenology

Question 31

accuracy

Answer 31

closeness to the truth

Question 32

precision

Answer 32

level of exactness ability to reproduce the same results measurement of random errors

Question 33

bias

Answer 33

systematic distortion in measurement.observations faulty equipment, blunders, subjectivity