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final exam Flashcards

1
Q

large scale vs small scale map

A

large scale = small places
small scale = large places

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2
Q

what is a feature?

A

representation of a real-world object on a map

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3
Q

What model is best for storing discrete data?

A

vector

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4
Q

what is a table?

A

A database or file containing information about a set of geographic features

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5
Q

line vectors have…

A

nodes on ends, vertices in the middle

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6
Q

how does triangulation work for GPS?

A

GPS receiver measures its distance from 3 satellites (with known locations) to determine location of the receiver

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7
Q

How does a GPS determine its distance from satellites?

A

time difference from when each satellite sends a code and the GPS receives it

distance = speed of light x time difference

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8
Q

RGB 255, 255, 255 makes

A

white

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9
Q

I am classifying Eckerd’s trees as “very healthy, healthy, some dead limbs, and dead”. What type of data is this?

A

ordinal (they are on a scale)

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10
Q

In terms of rasters, what is “stretching” and why would I want to stretch an image raster?

A

What: extend the colors/shades of a raster so more is visible

Why: good for a rasters where most of the values are similar

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11
Q

If you are making a map of population density, when would jenks classification be better than equal interval?

A

when trying to show differences in population density

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12
Q

nominal data

A

names

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13
Q

categorical data

A

groups

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14
Q

ordinal data

A

in order (ex. poor, fair, good)

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15
Q

interval data

A

has a scale with no meaningful 0

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16
Q

ratio data

A

has a scale with a meaningful zero (no negatives)

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17
Q

what is a chloropleth map?

A

thematic map in which a set of pre-defined areas is colored or patterned in proportion to a statistical variable (e.g. pop density per capita income)

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18
Q

when would you symbolize using single symbol/color?

A

nominal

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19
Q

When would you symbolize using unique values?

A

categorical and ordinal data

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20
Q

when would you symbolize using graduated colors/symbols?

A

continuous data

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21
Q

RGB vs CMYK

A

RGB makes white when all combined while CMYK makes black

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22
Q

Modifiable areal unit problem (MAUP)

A

what: arbitrary aggregation units like states or counties may influence values = maps reflect influence of size not the data being mapped

how to fix: normalize by area, populations, etc. or use grids

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23
Q

raster types: discrete

A

represents objects such as roads or land use (relatively few values)

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24
Q

raster types: continuous

A

represents measurement that occurs everywhere (thousands or millions of potential values)

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25
Q

B&W maps

A

1) no more than 5 gray levels
2) use different patterns instead of colors
3) color balance rules still apply (mostly light patterns, emphasize small areas with dark ones)

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26
Q

What is a graticule grid and why would you use one?

A

what: shows coordinates like lat/long

Why: show where map is on globe

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27
Q

map objectives

A

1) how map will be viewed and why
2) what you want to convey
3) privacy issues

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28
Q

geographical coordinate system vs projection

A

GCS is unprojected data

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29
Q

what is a datum?

A

a way to fit a projection to the earth taking into account that earth us a spheroid and geoid

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30
Q

what projection type is used for polar regions?

A

azimuthal

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31
Q

mercator projection

A

most accurate at equator
- used for navigation

preserves: shape & distance
loses: area

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32
Q

cylindrical projections

A

distortion absent where cylinder touches globe (and increases as you move away)

preserves: shape & direction
loses: area & distance

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33
Q

conic projections

A

distortion absent at standard parallels (and increases as you move away)

preserves: area & distance
loses: direction & shape

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34
Q

azimuthal projection

A

distortion absent where plane touches poles (and increases as you move away)

preserves: area or distance
loses: direction & shape

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35
Q

what is a compromise projection?

A
  • Sacrifices area, shape, distance and direction a little bit so that all are somewhat represented
  • Usually used for maps of large areas (aka small scale) like all of the world
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36
Q

what are UTMs?

A

universal transverse mercator
- world divided into 60 zones that are 6 degrees wide
- distortion is minimal in each zone
- best for maps covering small areas in one zone

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37
Q

what is the state plane system?

A

states divided into one or more zones identified by unique FIPS numbers

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38
Q

define projection vs project tool

A

define projection: creates/changes only CS label (does not change coordinates)

project: changes coordinates in the file

39
Q

When would you want to “define” a projection?

A

If you receive a shapefile or feature class and it has no information about its coordinate system

40
Q

which item in a geodatabase is most analogous to a shapefile?

A

feature class

40
Q

what is metadata?

A

Information about a data set that helps the user assess its purpose and quality

includes: tags, summary, description, credits

41
Q

feature class vs feature dataset

A

feature class is within a feature dataset

42
Q

shapefile vs geodatabase

A

shapefiles are spaghetti models while geodatabases are topological models

43
Q

what does merging do?

A

two similar types of features are combined (results in combo table)

44
Q

what does appending do?

A

adds additional features to an existing data set

45
Q

what does it mean to dissolve?

A

removes boundaries of features with the same value in the specified attribute fields

46
Q

what is a raster and why use them?

A

what: array of values in cells or pixels representing squares on the ground

why:
- better a storing certain kinds of data (elevation, images)
- better for analyzing certain kinds of data
- often faster analysis than vectors

47
Q

what is a raster pyramid?

A

successively lower resolution copies are created by making 4 adjacent cells into 1 with each copy being efficient for different scales of display
- speeds up display of rasters

48
Q

how do you georeference a raster?

A

identify pairs of ground control points visible in the raster and in a reference dataset -> transformation then calculates real world coordinates from the control point pairs and applies it to the raster

49
Q

when are attribute tables created for rasters and what is in them?

A

when: discrete raster with limited number of unique values

what: value, count, and explanatory fields

50
Q

two types of tables

A

1) standalone
2) attribute

51
Q

standalone tables

A
  • store tabular data
  • not associated with spatial data
52
Q

attribute tables

A
  • store attributes of map features
  • associated with spatial data layer
53
Q

target vs join table

A

target receives info while join provides info

54
Q

data types

A

1) short (whole numbers)
2) long (whole numbers)
3) float (decimals)
4) double (decimals)
5) text
6) date
7) BLOB (images, documents, etc)

55
Q

what is a domain and what are the types?

A

rules about what can be placed in a field

1) range
2) coded

56
Q

what is a range domain?

A

specify range of numeric values permitted

57
Q

what is a coded domain?

A

provide lists of values to pick from

58
Q

statistics vs summarize

A

stats provides stats on 1 variable while summarize would provide stats by subfield

59
Q

what is a simple query?

A

allows you to chose a subset of things based on their attributes (e.g. select states with more than 1mil ppl)

60
Q

What is snapping tolerance?

A

When the editing cursor falls inside the tolerance, it jumps to the precise location so the next point falls in the same spot

61
Q

What are the advantages of using Auto complete polygon when editing?

A
  • It eliminates silvers (gaps and overlaps)
  • It produces a coincident boundary
  • It is faster
62
Q

In terms of GIS, what is topology?

A

what is on your map matching what is on the ground

63
Q

When would end snapping be better than vertex snapping?

A

Ensuring that new streams connect to the ends of existing streams

64
Q

If I wanted to select all buildings that are within 100 meters of Zeta pond, what would work best?

A

A spatial query

65
Q

What is wrong with this attribute query: Building_name = Seibert OR James

A

SQL requires the field to be mentioned both times (Building_name = Seibert OR Building name = James)

66
Q

If I had a feature class of all roads in Pinellas county and I wanted to end up with just the roads on Eckerd’s campus (and have none extend past the property line), should I do a spatial selection or a Clip. Explain why.

A

Clip is correct because I want the roads to end at our property line

67
Q

AND vs. OR

A

AND = things that are both a & b
OR = things that are either a or b, but not both

68
Q

I had a cave feature class and a states feature class. If I wanted a feature class that lists each cave, its attributes, and the state it occurs in, which type of tool would I use?

A

Spatial join

69
Q

I have the range of the White Ibis and the range of the Glossy Ibis. I want a feature class of where these two species overlap and the attributes associated with each. Which overlay tool is best?

A

intersection

70
Q

We have the country and the volcano feature classes. If I want to know which country each volcano is closest to I could do a spatial join.

What is the:
Target feature?
Join feature?

A

target = volcano
join = country

71
Q

If I have a geology feature class and a soils feature class and I do a union, will I end up with more or fewer polygons?

A

more polygons

72
Q

On screen “digitizing”

A

convert raster images into vector features by looking at the image loaded into the GIS and tracing each feature or object

73
Q

dangles are created when

A

a node at either end is not connected to another line feature

74
Q

interactive query

A

select with mouse

75
Q

attribute query

A

specifies a certain condition based on fields in the attribute table and selects the records that meet the criteria

76
Q

spatial query

A

select based on spatial relationships

77
Q

oder of precedence (boolean operators)

A

evaluated from left to right
- parenthesis used to indicate what should be evaluated first

78
Q

SQL stands for

A

structured query language

79
Q

limits of spatial queries

A
  • can only select entire features
  • cannot specify boundaries (e.g. would select entire river, not just those/parts within a certain state)
80
Q

cardinality

A

Each record in the target feature class can only have one row of information from the join feature class appended to it

81
Q

2 basic cardinality approaches

A

one to one: each join feature will be copied once to the target feature class

one to many: creates copies of each target feature until enough are available to append with every matching join feature

82
Q

union

A

combine all features in 2 data layers

83
Q

clip

A

limit a feature class to just the extent of a shape

84
Q

intersection

A

only want locations where the 2 data layers both occur

85
Q

erase

A

removes portion of the input layer

86
Q

buffer

A

delineate areas that fall within a certain distance of a set of features

87
Q

dissolve

A

merge features when they share the same attribute value(s)

88
Q

what is a sliver and how can you avoid them?

A

inaccurate boundaries or logical inconsistencies may produce small extraneous polygons or lines called slivers

Slivers can be minimized by specifying an XY tolerance during an overlay operation

89
Q

how to increase topology when editing

A

Use tools like snapping, autocomplete polygon, split polygon

90
Q

snapping

A

Automatically connects features -> moves the editing cursor exactly to the same point once it gets close.

91
Q

dangle

A

when two lines fail to connect

92
Q

What happens to area and perimeter/length when you use geoprocessing tools using feature classes in a geodatabase?

A
  • Overlay often changes the shape, area, perimeter, and length of features
  • The geodatabase fields Shape_Length and Shape_Area are automatically updated
  • User-defined geometry fields, such as an ACRES field, must be updated manually using the Calculate Geometry Attributes tool

GIS (1 decks)

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