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Flashcards in Module 6 Deck (26)
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1
Q

The main goal of any map

A

the goal of any map is to communicate the spatial information portrayed on the map as effectively and efficiently as possible – reading a map should be both an enjoyable and enlightening experience

2
Q

The Cartographic Process:5

A
  1. think about what the distribution of phenomenon might look like
  2. decide on the purpose of the map and the intended audience
  3. collect data that are appropriate for the purpose of the map
    - what projection would be best
  4. design and construct the map using appropriate cartographic principles
  5. determine if the map reader understands the map content
3
Q

the most important components of the map is the..

A

..the spatial data itself, which should be the focus of the product; surround it with secondary components

the legend is the 2nd most important component of the map –the legend is the tool by which you interpret the symbols that display the data

4
Q

geospatial metadata

A

▪ geospatial metadata provide information about the data used to create the map or perform GIS analysis
▪ it can be used to represent the who, what, when, where, why, and how of the resource
▪ when maps are produced from a variety of different data sources, or if the data has undergone substantial manipulation, documenting the geospatial metadata is even more important – known as geo-lineage
▪ in practice, very few maps provide this information hindering the ability of the map user to fully understand the potential limitations or benefits of the map

5
Q

in 1854, John Snow produced one of the most important _____ maps, using black bars to identify the location of each death due to cholera in London – the high point density on Broad Street led to the discovery of a central source of the outbreak

A

point

6
Q

apparent (perceptual) scaling vs absolute scaling

A

tries to take into account the human tendency to underestimate the size of larger circles

method with suggests that only the actual zscore should be presented because it accurately represents the data
▪ the argument here is that cartographers should tell the truth and exclude compensation for human perception failings

7
Q

flow maps

A

flow maps use proportional line symbols to represent the scale of a phenomena as it moves through a linear network flow maps use proportional line symbols to represent the scale of a phenomena as it moves through a linear network

  • The thickness of the line is used to represent the z-value, and can follow the same sizing approaches as used for point data
  • The thickness of the line is used to represent the z-value, and can follow the same sizing approaches as used for point data(
8
Q

Isarithmic mapping

A

uses isolines(lines of equal value) to model smooth, continuous phenomena

9
Q

isopleth maps

A

▪ isopleth maps use conceptual data points to create statistical surfaces – although they look like isometric maps, they are created in a different way
-have to come up with a rate, like #people/km, so that its equal across geographic locations

10
Q

▪ in any isoline map, the choice of the isoline ______ is important – it is analogous to the spatial resolution of raster data or digital imagery

A

interval

▪ too few isolines will miss important details, and in places of small difference may be so widely spread apart that the reader can’t notice their importanc

.too many isolines will result in redundancy and clutter on the map

11
Q

chloropleth mapping

A

choropleth mapping is performed by mapping spatial data that are constrained to lie within a definable administrative unit

▪ the size and shape of the administrative units can create special problems when performing choropleth mapping – large units tend to dominate over smaller units – good choropleth maps try to keep the units roughly the same size
▪ when keeping the units similarly sized is not an option, Standardization can be used to take into account the size of the administrating unit

12
Q

the natural breaks method

A

the natural breaks method examines a histogram of the original dataset to determine logical breaks (often seen as gaps) in the data distribution

13
Q

equal interval method

A
▪ the equal interval (or equal steps) method forces each class to occupy an equal interval along the x-axis when the data are arranged in histogram form 
▪ when it is not necessary to include specialized natural breakpoints, it is good cartographic practice to create all of the class intervals so that they have the same width
14
Q

Quantile method

A

▪ the quantile method ranks and orders the observations in the dataset and then places equal numbers of observations in each class
▪ if 4 classes are used, then it is a quartile map; if 5 classes are used, then it is a quintile map, etc.

15
Q

mean ± standard deviation method

A

▪ the mean ± standard deviation method creates class boundaries by repeatedly adding or subtracting the standard deviation from the mean of the dataset

16
Q

maximum breaks method

A
▪ the maximum breaks method orders the data from low to high and the differences between each adjacent value is computed – the largest differences act as the class breaks 
▪ because this method only looks for the largest breaks in the dataset, it often misses natural clusters of data along the histogram
17
Q

Different Breaks Methods: 6

A
  1. Natural
  2. Equal Interval
  3. Quantile
  4. mean ± standard deviation
  5. Maximum breaks
  6. Personal decision: manual breaks
18
Q

sequential colour schemes

A

are ideal for mapping ordered data that progresses from low to high

19
Q

diverging colour schemes

A

put equal emphasis on midrange values and extremes at both ends of the data range
ex:▪ the red-yellow-blue scheme is commonly used for temperature maps

20
Q

spectral progression colour schemes

A

are composed of the sequence of colours associated with the electromagnetic spectrum
▪ for many years spectral schemes were discouraged by cartographers because they do not represent a logical, linear order
▪ however, recent tests show that humans can readily interpret this colour scheme, especially persons with various types of colour blindness

21
Q

Photomaps

A

▪ it is common today to create maps that contain remotely sensed imagery as the background information in the map

▪ photomaps, image maps, and orthophotomaps have important geometric properties that should be considered when using them in a GIS

▪ however, because the photos/images do not contain any inherent spatial reference system, they cannot be relied upon for accurate measurement of areas, distances, or directions
▪ typically ,error increases from the centre of the photo towards the edges

22
Q

Controlled Photomap

A

▪ when individual aerial photographs have been geometrically rectified to a map projection using ground control points and digital image rectification techniques, we can produce a controlled photomap (or controlled image maps for rectified satellite images)
▪rectification is a process of stretching the photo or image so that each point shown falls where is should on Earths surface
▪ it removes much of the error that is seen in these images, but not all of it
▪ very necessary for oblique photographs, although the results can look odd

23
Q

rectification

A

is a process of stretching the photo or image so that each point shown falls where is should on Earths surface

▪ topographic relief plays a significant role in the error seen in aerial photographs and satellite imagery –
this error cannot be fixed by geometric rectification techniques

24
Q

T OR F:

Rectification can fix the error caused by topographic relief in aerial photographs?

A

F

topographic relief plays a significant role in the error seen in aerial photographs and satellite imagery –
this error cannot be fixed by geometric rectification techniques

▪ it is possible to remove these relief effects by a process using ground control points, ,digital terrain matrices, and fundamental photogrammetric techniques, yielding an orthophoto or orthoimage

25
Q

orthophoto or orthoimage

A

Image in which relief effects have been removed

26
Q

▪ if your analysis does not require accurate measurement of _____ , _____, and ______ , there is no need for orthorectification

A

distance,direction,area