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49 Cards in this Set
- Front
- Back
reference maps
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show detailed geographic information
1. Portrays information as accurately as possible 2. Designed to extract precise information 2. May display many different kinds of information 3. Are used for multiple purposes |
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thematic maps
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–show selected features or concepts
-generally have a theme or message 1. Precise information less important 2. Designed to visualize general patterns 3. Display a limited amount of information 4. Are used for a single, or limited, purpose |
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Quantitative Map
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displays the spatial aspects of numeric data
Example: number of people in Wisconsin by county (often referred to as “statistical” maps) |
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Cloropleth map
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show raw or standardized data
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Visual Variables
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“Graphic Variations” of a particular graphic element
•ability to distinguish between features having a common graphic element (shape, hue, size, orientation,chroma(saturation)) |
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Traditional Graphic elements (symbols)
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point, line, area
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Secondary Visual Variables
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arrangement, texture, orientation
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Legibility
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Symbols and text must be easy to read and understand • Map scale • Size Limitations • Media |
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Visual Contrast
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•Must be able to distinguish between symbols and components
•Possibly most important principle of graphic design •Visual Interest |
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Ways to achieve contrast
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different saturations of grey
color contrast line widths |
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Figure -Ground organization
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Perceptual grouping of objects in a scene as figure (in front) and ground (in back)
*More important information should be firgure. |
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Interposition
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used to develop figure-ground relationships. one objects appears over another
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Land water contrast
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shading, line width, graticule in water, coastal vignetting
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Coastal vignetting
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alter brightness along coastline, (use from line, stillpling, or darkening coast land or water)
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Visual Hierarchy
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•Organizational Hierarchy
•Intellectual order reflected in visual prominence |
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Map Composition
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Refers to the layout and arrangement of basic map components
(legend, neat line, north arrow, etc) |
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typography
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the study and development of type
•type design •type morphology (shape) and characteristics •arrangement and spacing •readability and legibility |
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Serif
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•Finishing strokes added to the end of the main strokes of the letter
•In running text, serif style type is generally easier to read (Times new Roman) |
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Type Size and Legibility
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Font size expressed in points (72 pts. in 1 inch) (foundry block) • Legibility • never smaller than 5 pts. • rarely less than 6 pts. |
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fonts to avoid
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all caps
decorative |
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preferred position for labeling points
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1- top right
2- top left 3- bottom right 4- bottom left |
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line labels
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•ideal position is above line, along a horizontal stretch
•try to place labels so that words flow in direction of river •avoid positioning type upside down •should / may follow curve of feature - instead of stretching word, label multiple times (for aerial follow all of these rules, but DO stretch to cover feature) |
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Continuous Data
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Data that occur everywhere on the earth’s surface
Ex) temperature, elevation, barometric pressure |
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Discrete Data
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data that occur only at specific locations on the earth’s surface
Ex: cities, cellular towers |
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Proportional (Graduated) Symbol Mapping
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•typically use discrete data (non-continuous)
•size of symbol relates to values being mapped (usually graduated circles) |
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Mathematical Scaling:
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areas of circles are directly proportional to the data values
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Perceptual Scaling
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size of circle is increased to account for underestimation of data values
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Range Graded
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number of classes (?)
depicts the circles in relation to ranges of data. The information is classified as equal quantiles, breaks, natural breaks, and minimum variance. |
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Continuous Scaling
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no classes; # dot sizes = # observations
(so the key would show guidelines for comparison ) |
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nested vs linear legends
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nested- symbols shown overlapping
linear- symbols in a line/row |
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how to reduce symbols overlapping in maps
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Reduce number of points • Adjust dot size • Consider making series of maps • Adjust symbol specifications |
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Dot Density Mapping
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For mapping discrete data • Communicates spatial density • Reveals overall pattern at the expense of specific value extraction |
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Point classification
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1. One to One relationship (one dot = one person)
2. One to Many relationship (one dot = 1000 people) possibly most important factor |
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Choropleth Map
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(choro = place, pleth = value)
• Quantitative thematic map in which discrete data are aggregated and mapped by enumeration unit. areal symbols shaded, or colored, according to value |
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Enumeration unit:
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an area used to collect, aggregate, and map data
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Data Standardization
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standardizes data based on another variable (eg. area & population -pop density)
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data classification
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-simplifies data
•Typically 5-7 classes |
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Techniques for Determining Class Breaks
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Equal Interval (equal arithmetic breaks) • Quantiles • Natural Breaks • Jenks Optimization Routine |
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Equal interval
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Data classed according to equal numeric breaks (or equal intervals)
example: 10-20, 20-30 (interval = 10, range = 20) Does not take distribution into account- some classes may include no observations |
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Quantiles
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Equal number of observations in each class
no empty sets, but units with same values may be separated into different classes. |
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Natural Breaks
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when data is is spread out, visual clusters determine breaks
takes distribution into account, but can be very subjective |
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Jenks Optimization Routine
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Developed in the 1970’s • Attempts to establish “optimal” class breaks based on the spread of data • Mathematical approach • Minimizes difference within classes • Maximizes difference between classes |
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ColorBrewer
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an online tool that assists cartographers choose appropriate colors for thematic maps
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Diverging Schemes
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one color shows negative numbers, another shows positives, with darker colors at poles. Can be used for blue/red political mapping.
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Sequential Schemes
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color scheme that sequences from light to dark, used in chloropleth- light represents low values, dark represents high values
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HSV
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used for color pickers in computers
HSL and HSV are the two most common cylindrical-coordinate representations of points in an RGB color model, which rearrange the geometry of RGB in an attempt to be more perceptually relevant than the cartesian representation. |
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RGB
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The RGB color model is an additive color model in which red, green, and blue light are added together in various ways to reproduce a broad array of colors.
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CMYK
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The CMYK color model (process color, four color) is a subtractive color model, used in color printing, and is also used to describe the printing process itself. CMYK refers to the four inks used in some color printing: cyan, magenta, yellow, and key black.
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Qualitative Map
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purpose is to show the spatial distribution of “what”, or “what kind”
Example: location of churches |