mapping GIS data Flashcards
HSV
hue, saturation, and value, method for discussing the use of color in portraying features on a map
hue
shade of color via wavelength of light
saturation
intensity of color represented as a percentage
value
light or dark represented as a percentage
alpha
opacity of a color used with HSV or RGB method
divergent color set
can show variation around a significant middle value, a multi color gradient
connotation
emotional impact associated with a specific color or symbol, culturally specific
nominal data
name or identify objects portrayed by labels
categorical data
separate features into groups or classes stored as text or codes, represented by a unique values map
ordinal data
categories ranked by some quantitative measure represented by unique values maps or graduated color maps
quantitative data
phenomena that fall on a regularly spaced interval like rainfall or distance
ratio data
has a meaningful 0 point indicating absence
interval data
no meaningful 0 point, anything with negative values, do not support multiplication or division
classified maps
show quantitative data arranged in classes with specific ranges
graduated symbol maps
show quantitative point or line data with increasing symbol size using classes
proportional symbol map
show quantitative point or line data with increasing symbol size with no classes
graduated color/choropleth maps
show quantitative polygon data using colors with varying saturation or value
modifiable arial unit problem (MAUP)
occurs when measurements are being aggregated over arbitrarily defined areas, solved by normalizing data or dot density maps
normalize data
divide each value by a specified variable to avoid MAUP and standardize the data
dot density map
uses randomly placed dots inside each polygon to show the magnitude of a value in the attribute table
chart map
shows multiple attributes using graduated symbols of pie or bar graphs
bivariate choropleth map
shows multiple attributes of two numeric variables with multiple colors
thematic raster
shows features or quantities with the stretched display method or the classified display method
classified display method
divides values into a small number of bins
stretched display method
scales image values to a color ramp with 256 shades
Tobler’s law
geographic values close to each other tend to be more similar than those further apart
image raster
include aerial photography and satellite data as RGB composite
color map
a restricted set of colors stored as RGB proportions using less space than general RGB
classification
classifying a range of data into a smaller number of groups each of which can be represented
jenks method
set of class breaks at naturally occurring gaps in the data, good for unevenly distributed data
equal interval classification
divides values into a specified number of classes with equal size, good for ratio data
defined interval classification
user specifies the size of class interval so the number of classes depends on the range of values, good for desired breaks
quantile classification
puts about the same number of features in each class, best for uniformly distributed data
geometric interval
bases class intervals on a geometric series in which each class is multiplied by a constant coefficient, good for continuous data
standard deviation
apportions values based on statistics of the field, best for normally distributed data
source data
original data on which a layer is based
layer properties
info in the layer such as symbols or feature labels
layer file
stores the location of the referenced data set and the layer properties
style
a set of symbols with a related theme
