spatial symbology thematic data &. thematic data language and style interrelates thematic data...
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Spatial Symbology
Thematic Data
&
Thematic Data
Language and style interrelates thematic data and spatial symbology
Understanding this language allows us to: Use appropriate cartographic symbolization and
standards Communicate messages better Critique maps using an analytical framework Make better maps
Analytic Framework
Spatial Dimension Spatial Characteristic Level of Measurement Visual Variables
Spatial Dimension
Point Line Area Volume Space-Time
Point
X Y
Geographic Coordinates
Spatial Dimension
.
0 dimensional
A Point has no extent
or area
Spatial Dimension
Dot DistributionMap
Proportional Symbol
Map
Spatial Dimension
LineSeries of
Y
X 1 Dimension
Length
Qualitative Thematic Line Map
Quantitative Thematic Line Map
Is a line always a line?
Enclosed Series of X, Y
Spatial DimensionFound on base mapsnot thematic overlays
Area
2 Dimensional
Length & Width
Spatial Dimension
Feature Model of Space
Maps as graphic representations
Spatial DimensionVolume
3 Dimensions
Surface
X Y Z
Area
+ Thematic Overlay
Nominal Area Map
Qualitative
“Z” on thematic overlay
Choropleth Map
“Z” on thematic overlay Quantitative Volumetric Map
X, Y, Z
Space-Time
4 Dimensions
Spatial Dimension
Time
+
=
Spatial Characteristic
Discrete Continuous Sequential
Discrete Phenomenon
Distinct locations in space
Does the phenomenon occur throughout an area?
Spatial Dimension
Point Phenomena=
no
Continuous Phenomenon
Does the phenomenon occur throughout an area?
YES
=Area or Volumetric Phenomena
Spatial Dimension
Sequential Phenomena Series of points in a sequence Spatial Dimension = Line
Level of Measurement
Nominal
Ordinal
Interval
Ratio
non-numeric
non-numeric
numeric
numeric
Qualitative
Quantitative
Quantitative
Quantitative
NominalLeast Accurate
No Ordering
Distinctionin Category
Ordinal Categorization & Ranking
No Numerical Differences in Kind
Interval
No Zero Point, Can’t Make Ratio Claim
Numerical Difference Between Categories
Ratio
Same as Interval
But
Non-Arbitrary Zero Point
Visual Variables
Point
Line
Area
Form Size Color Value Texture Orientation
Qualitative or Quantitative ?
Spatial Dimension?
Visual Variable?
Level of Measurement?
Volume
Spatial Characteristic? Continuous
Interval
Color
Appropriate use of Visual Variable?
Color = qualitative
Spatial Dimension?
Visual Variable?
Level of Measurement?
Point
Spatial Characteristic? Discrete
Ratio
Size Appropriate use of Visual Variable?
Size = quantitative
Spatial Dimension?
Visual Variable?
Level of Measurement?
Volume
Spatial Characteristic? Continuous
Ordinal
Color
Appropriate use of Visual Variable?
Color = qualitative
Spatial Dimension?
Visual Variable?
Level of Measurement?
Volume
Spatial Characteristic? Continuous
Nominal
Color
Appropriate use of Visual Variable? Color = qualitative
Spatial Dimension?
Visual Variable?
Level of Measurement?
Point
Spatial Characteristic? Discrete
Ratio
Color
Appropriate use of Visual Variable?
Color = qualitative
Size
Size = Quantitative
Sequential
Line