Term

Definition
[image]
vector representations of continuous data
helpful in 3 dimensions 


Term

Definition
created infinite numbers of points
line drawn on interpolated values between points
once drawn smooth
 when points are few
 interpolate additional point value
 then interpolate isolines



Term

Definition
types of isolines = quantitative data types can be collected as points
many as specific names
Examples:
isobath
isocline
isohips 


Term

Definition
each line = 1 meter
context lines = multiples of isolines 


Term

Definition
[image]
spreadsheets
row & columns = forms cells
grid = rows
columns = tessellations
data unit = spatial (cell)  x,y = implicit
entity (object) info = explicity encoded
each cells must have numeral value
all about numbers
analytical modeling 


Term

Definition
natural world = continuous data
ideal spatial model to illustrate these surface



Term
Natural Surfaces Examples
Raster 

Definition
[image]
 Elevation
 Surfaces symbolized low & high using color ramps
 elevation
 ramp colors  rising & lowering elevation



Term
Color Ramps & Continuous Surfaces 

Definition
Color Ramps = stretched data
stretched data organized values into 256 classes 


Term
Color Ramps & Continuous Surfaces
Examples 

Definition
[image]
Hillshades = create classic cartographic product a shaded relief map
use as reference layer, to help ppl orient themselves within map 


Term

Definition
[image]
flat surface
appear 3D
Seldom
Digital
animated to different perspectives 


Term

Definition
nominal, ordinal, interval, ratio
numbers = data scale 


Term

Definition
telephone numbers
establish identity
race = individuals have numbers to identify him
not order & value 


Term
Ordinal Data Scale
Data Scale 

Definition
establish order
1st place, 2nd place, 3rd place
phone number is NOT ordinal 


Term
Interval Scale
Data Scale 

Definition
no absolute zero
negative values
degrees
100^{o}C
50^{o}C 


Term
Ratio Scale Data
Data Scale 

Definition
has absolute zero
no negative values
weight = 50 kg
direct composition 


Term
Why we should care?
Data Scale 

Definition
different types of analysis
different cartographic symbols
different inappropriate values 


Term
nominal or categorical data
{data classifications} 

Definition
qualitative: ordered but without a measurable range
no absolute values 


Term
ordinal data
{data classifications} 

Definition
relative NOT absolute value
deals with quantitative but without a measurable range
using numbers label ordinal
data often confusing 


Term
interval data
{data classificitions} 

Definition
quantitative: has NO absolute zero
subtraction works NOT division
class range = absolute zero
negative numbers 


Term
ratio scale data
{data classifications} 

Definition
quantitative: absolute zero so both
subtraction & division work
no negative values in classification 


Term

Definition
sorting or arranging entities into groups or categories
number of classes usually between 5 & 10,
more likely 5 than 10
classifcation methods vary depending on data
ArcGIS = # of classification 


Term
Equal Interval
{data classification} 

Definition
[image]
constant interval between classes # of observations will be different from class to class
Good = direct comparisons between different choropleth maps 


Term
Calculating Equal Interval


Definition
subtract minimum from maximum
divide result by # of classes
result = width of each class
add value with minimum value for first class
repeat until done 


Term
Quantile
{data classification} 

Definition
[image]
equal # of observation per class
same class = interval between classes = different



Term

Definition
divide count of features by # of classes
arrange features least to greatest
divide into classes = matches result of division equation 


Term
Jenks  Natural Breaks
{data classification} 

Definition
[image]
minimizes variance within a class
by dividing classes in areas
different sized class &
different # of observations 


Term
Mean & Standard Deviations
{data classification} 

Definition
[image]
classes = mean & deviations from the mean
best if data displays a nominal distribution 


Term
Calculating Mean and Standard Deviation 

Definition
 Calculate the mean of data
 Calculate the standard deviation of data
 Arrange your first class to straddle[stand] mean
 Then add classes at intervals of standard deviation both above and below the mean class



Term
Quantile  5 Classes using 7,1,18,20,6,14,19,13,21,25,2,23,1,15 

Definition
using 3 observation: (1,1,1) (2,2,6) (7,13,14) (15,18,19) (20,23,25) 


Term
Equal Interval  5 classes using 7,1,18,20,6,14,19,13,21,25,2,23,1,15 

Definition
(1,1,1,2,2) (6,7) (13,14,15) (18,19,20) (23,25) 


Term

Definition
 diagram or abstract geographical to distorted proportionally value of an attribute
 NOT that useful
 Trade off between Area error and shape error
 Hard to make a real shapes
 Do not use cartograms to show average values, per capita, values, etc
 People look what’s on the map but comparing to what’s in their head
 CANNOT show mean, average
[image] 


Term
World Population
{Cartogram} 

Definition
[image]
Area scale accurately represents selected variable
Contiguity is maintained
Shapes should remain recognized
World population is useful but not as continuity 


Term

Definition
[image]Look cool and artistic but hard to read
Election Count by counties NOT states 


Term

Definition
 Contiguous
 Non  Contiguous



Term

Definition
Maintained Recognized = shapes
Area scale accurately selected
Advantages:
Easy to read
Disadvantage:
Distortion can confuse reader
Shapes of internal numeration may recognition impossible
Difficult to produce through commercial GIS software
The circle population = contiguity
[image] 


Term
Non  Contiguous
{Cartogram} 

Definition
Not maintained
Area scale accurately recognized selected
Advantage:
Easy to construct GIS
True shapes of enumeration units
Disadvantage:
Separated
No compact
White spaces
Do not convey continuous nature of geographical space
Trade off between maintaining relative positive of enumeration unit and not overlapping
[image] 


Term
Restrictions on Cartogram 

Definition
Shape quality: cartograms useless? some approximation of true shape can be achieved
Each enumeration unit needs size, shape, orientation and contiguity…
Least important = communication 


Term
Data Limitation Cartogram 

Definition
Data must be ratio
Positive values in data sets with large range are problem.
Negative values cannot be mapped
Zero values eliminate the enumeration unit, creating map 


Term

Definition
Calculate total value for enumeration units based on single attribute
Compute proportional area of enumeration unit’s base on attribute value for each divided by total value
Draw, calculate and conform shapes and values 

