GIS Lecture: Maps
Summary Thematic Maps (Choropleth) Use of Color Categorical Maps Graphical Hierarchy
Thematic vs. Categorical Thematic maps – Quantity - different amounts Categorical maps – Quality - different types
Thematic Maps
Classification Intervals Edit the classifications and layer properties
Original Map (Natural Breaks) Uninsured U.S. Population, 2005
Custom Map (Equal Intervals) Uninsured U.S. Population, 2005
Other Numeric Intervals Pittsburgh, PA: Neighborhood proportion under poverty and average BMI per neighborhood BMI ! 18.5 - 24.9 25.0 - 29.9 30.0+ Percentage in Poverty 0 - 12.5% 12.51% - 19.99% 20.0% - 39.99% 40.0% - 70.10% Data Sources: BRFSS data, 2000;City of Pgh City Planning Dept., U.S. Census 2000
Use of Color
Color Overview Colors have meaning Cool colors calming, Warm colors exciting Cool colors appear smaller than warm colors and they visually recede on the page, so red can visually overpower and stand out over blue even if used in equal amounts Colors have political and cultural meanings
Color Overview Hue is the basic color Value is the amount of white or black in the color Saturation refers to a color scale that ranges from a pure hue to gray or black
Color Overview Monochromatic color scale is a series of colors of the same hue with color value varied from low to high
Customized ramps Customize the Properties of a layer
Color Wheel Guidelines Use opposite colors - those directly across from one another to differentiate graphic features 3 or 4 colors equally spaced - good for differentiating graphic features Use adjacent colors for harmony - such as blue, blue green, and green or red, red-orange, and orange
Contrasting and Non-contrasting Colors
Dichromatic Color Scale Two monochromatic scales joined together with a low color in the center, color increasing toward both ends Natural middle-point, such as 0 for some quantities (profits and losses, increases and decreases)
Change Map Example
Color Spots White background allows color spot to be visualized
Color Spot Ramp
Categorical Maps
Categorical Map Example - Light Pole Owner
Categorical Map Example - Zoning
Categorical Map Example - Street sweeping days
Graphic Hierarchy
Graphic Hierarchy Assign bright colors to the most important graphic elements Such graphic elements are called “figure”
Graphic Hierarchy Assign drab colors to the graphic elements that provide orientation or context, especially shades of gray Such graphic elements are called “ground”
Graphic Hierarchy Place a strong boundary, such as a heavy black line, around polygons that are important to increase figure Use a coarse, heavy cross-hatch or pattern to make some polygons important, placing them in figure
Graphic Hierarchy
Summary Thematic Maps (Choropleth) Use of Color Categorical Maps Graphical Hierarchy