The Geographic and Cartographic Framework Flashcards
4 Limitations of Maps
Abstraction & generalization
Scale
Projection
Spatial relationships
Scale Ratio
Map size to real-world size
Representative fraction
Verbal Scale
Words - 1 inch to 16 miles
Graphic Scale
Scale bar
Should not be more precise than the map
Works better for print than other scales
Large scale
shows less area, greater detail
Small scale
shows larger area, less detail
larger denominator in the ratio
Data Compilation: 2 types of data
Base data
Thematic/primary data
Internal Base Data
Geographic info of the mapped area itself
Often called the “base map”
Administrative boundaries, place names, water bodies, transportation routes, etc
External Base Data
Data with an explanatory function
Title, legend, scale, North arrow, grid, text
Sources of primary/thematic data
Field studies
Imagery/air photos
Stats
Published maps
Data portals
Interviews
How many themes should be illustrated on a map
one (1)
Generalization
Reduction of detail to enhance the point of your map through the selection, simplification, and symbolization process
Selection
Part of generalization.
Choosing categories of data to be presented
Choosing the amount of information
Simplification
Part of generalization.
Smoothing, grouping, classification, exaggeration, displacement
What to display on the map: Tables/Numbers or Spatial Distribution
Spatial distributions shown with symbols are more visually effective than just numbers
Phenomena
Features and attributes of the real world being mapped
Data
facts gathered by measuring, counting, calculating, or derivation
Portrayed on maps
What do maps display? Phenomena or Data
Data (spatial data)
Matching Data and Symbols: Levels of Measurment (classifications)
- Nominal - qualitative, lowest level of info
- Ordinal - order/rank, qualitative
- Interval or Ratio - quantitative
Jacques Bertin’s 4 levels of visual variables
Selective
Associative
Ordered
Quantitative
Bertin’s Visual Variables: Selective
Allows us to immediately isolate a group of signs based on a change in the variable
Everything except size
Jacques Bertin: Visual variables (not levels)
Position
Size
Shape
Value
Hue
Orientation
Texture
Bertin’s Visual Variables: Associtative
Allows grouping across changes in the variable
Shape especially
Position and Hue
Sometimes Orientation
Size = Dissociative
Berin’s Visual Variables:
Ordered
Variables have an immediate recognizable sequence
Position, size, value
Sometimes Texture
Bertin’s Visual Variables: Quantitative
Allows an estimation of the actual numerical difference between symbols
Size
Estimation, not percise
*Differences in magnitude are NOT immediatley perceptible with out looking at a legend
Patterns as a visual variable
Manipulating shape or orientation creates patterns
Controlled by arrangement and texture
Redundant Symbolization
Combining visual variables to provide redundancy within a symbol
More common in bivariate mapping
Visual Variables for Data Uncertainty
Transparency
Crispness
Resolution
(good for transitional areas too)
3 general types of symbols (not point/line/area)
Pictorial
Associative
Abstract
3 Types of Cartographic Errors
Source Errors
Processing Errors
Cartographic Design Errors
Cartographic Errors: Source Error
Found in data collection
Scale, projection, accuracy
Cartographic Errors: Processing Error
Results from the cartographic transformation of data
Rounding, interpolation, classification
Cartographic Errors: Cartographic Design Errors
Wrong thematic types
symbolization, use of color, generalization
