GIS Tutorial 1 Lecture 2 Map design

Outline Choropleth maps Colors Vector GIS display GIS queries Map layers and scale thresholds Hyperlinks and map tips GIS TUTORIAL 1 - Basic Workbook

Lecture 2 Choropleth maps

Choropleth maps Color-coded polygon maps Use monochromatic scales or saturated colors Represent numeric values (e.g. population, number of housing units, percentage of vacancies) GIS TUTORIAL 1 - Basic Workbook

Choropleth map example Map using color or pattern to show different values over space (uses a color ramp) GIS TUTORIAL 1 - Basic Workbook

Choropleth map example Percentage of vacant housing units by county GIS TUTORIAL 1 - Basic Workbook

Classifying data Break points Process of placing data into groups (classes or bins) that have a similar characteristic or value Break points Breaks the total attribute range up into these intervals Keep the number of intervals as small as possible (5-7) Use a mathematical progression or formula instead of picking arbitrary values Break points GIS TUTORIAL 1 - Basic Workbook

How to classify ranges in ArcMap GIS TUTORIAL 1 - Basic Workbook

Classifications Natural breaks (Jenks) Picks breaks that best group similar values together naturally and maximizes the differences between classes Generally, there are relatively large jumps in value between classes and classes are uneven Based on a subjective decision and is the best choice for combining similar values Class ranges specific to the individual dataset, thus it is difficult to compare a map with another map Because the class ranges are specific to the individual dataset, it is difficult to compare a map with another map and to choose the optimum number of classes, especially if the data is evenly distributed. GIS TUTORIAL 1 - Basic Workbook

Classifications Quantiles Places the same number of data values in each class Will never have empty classes or classes with too few or too many values Attractive in that this method produces distinct map patterns Analysts use because they provide information about the shape of the distribution. Example: 0–25%, 25%–50%, 50%–75%,75%–100% http://en.wikipedia.org/wiki/Data_classification GIS TUTORIAL 1 - Basic Workbook

Classifications Equal intervals Divides a set of attribute values into groups that contain an equal range of values Best communicates with continuous set of data Easy to accomplish and read Not good for clustered data Produces map with many features in one or two classes and some classes with no features GIS TUTORIAL 1 - Basic Workbook

Classifications Use mathematical formulas when possible. Exponential scales Popular method of increasing intervals Use break values that are powers such as 2n or 3n Generally start out with zero as an additional class if that value appears in your data Example: 0, 1–2, 3–4, 5–8, 9–16, and so forth GIS TUTORIAL 1 - Basic Workbook

Classifications Use mathematical formulas when possible Increasing interval widths Long-tailed distributions Data distributions deviate from a bell-shaped curve and most often are skewed to the right with the right tail elongated Example: Keep doubling the interval of each category, 0–5, 5–15, 15–35, 35–75 have interval widths of 5, 10, 20, and 40. GIS TUTORIAL 1 - Basic Workbook

Original map (natural breaks) U.S. population by state, 2000 GIS TUTORIAL 1 - Basic Workbook

Equal interval scale Not good because too many values fall into low classes GIS TUTORIAL 1 - Basic Workbook

Quantile scale Shows that an increasing width (geometric) scale is needed GIS TUTORIAL 1 - Basic Workbook

Custom geometric scale Experiment with exponential scales with powers of 2 or 3. GIS TUTORIAL 1 - Basic Workbook

Normalizing data Divides one numeric attribute by another in order to minimize differences in values based on the size of areas or number of features in each area Examples: Dividing the number of vacant housing units by the total number of housing units yields the percentage of vacant units Dividing the population by area of the feature yields a population density For example, dividing the 18- to 30-year-old population by the total population yields the percentage of people aged 18–30. Similarly, dividing a value by the area of the feature yields a value per unit area, or density. GIS TUTORIAL 1 - Basic Workbook

Nonnormalized data Number of vacant housing units by state, 2000 GIS TUTORIAL 1 - Basic Workbook

Normalized data Percentage vacant housing units by state, 2000 GIS TUTORIAL 1 - Basic Workbook

Nonnormalized data California population by county, 2007 GIS TUTORIAL 1 - Basic Workbook

Normalized data California population density, 2007 GIS TUTORIAL 1 - Basic Workbook

Normalize Data to conform to a standard Right-click the layer you want to draw showing a quantitative value in the table of contents and click Properties. Click the Symbology tab. Click Quantities and click graduated colors. Click the Value drop-down arrow and click the field that contains the quantitative value you want to map. Click the Normalization drop-down arrow and click a field to normalize the data. ArcMap divides this field into the Value to create a ratio. Normalize Data to conform to a standard GIS TUTORIAL 1 - Basic Workbook

To Create More Meaningful Text in Legends 1. Left click to highlight the layer in the TOC 2. Type the desired text 3. When the legend is added on the layout, the new text will display TOC TOC Layout View GIS TUTORIAL 1 - Basic Workbook

OR- To Create More Meaningful Text in Legends 1 In Layout View, right click the legend box 2 Select Convert To Graphics 3 Right click the Graphics text box legend, select Ungroup 4 Double left click text, then type desired text 1 2 4 3 Layout View GIS TUTORIAL 1 - Basic Workbook

To sort value ranges in descending order: Right-click the layer you want to draw showing a quantitative value in the table of contents and click Properties. Click the Symbology tab. Click Quantities and click graduated colors. Click the Value drop-down arrow and click the field that contains the quantitative value you want to map. Click the Range tab and click Reverse Sorting. ArcMap places the ranges in descending order. Select OK To reverse the symbol color: Select the symbol tab Select Flip Symbols Symbol- Flip Symbols Result Range- Reverse Sorting GIS TUTORIAL 1 - Basic Workbook

Other Types of Thematic Maps: Graduated Symbols GIS TUTORIAL 1 - Basic Workbook

Other Types of Thematic Maps: Proportional Symbols GIS TUTORIAL 1 - Basic Workbook

Other Types of Thematic Maps: Dot Density GIS TUTORIAL 1 - Basic Workbook

Other Types of Thematic Maps: Unique Values GIS TUTORIAL 1 - Basic Workbook

Lecture 2 colors GIS TUTORIAL 1 - Basic Workbook

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 GIS TUTORIAL 1 - Basic Workbook

Color wheel Device that provides guidance in choosing colors Use opposite colors to differentiate graphic features Three or four colors equally spaced around the wheel are good choices for differentiating graphic features Use adjacent colors for harmony, such as blue, blue green, and green or red, red orange, and orange GIS TUTORIAL 1 - Basic Workbook

Light vs. dark colors Light colors associated with low values Dark colors associated with high values Human eye is drawn to dark colors In the above example, the first set of all dark lines are static. The middle example leads the eye in a downward direction (dark to light). Reversing the values of the lines leads the eye upward. GIS TUTORIAL 1 - Basic Workbook

Contrast The greater the difference in value between an object and its background, the greater the contrast In the above examples, the lighter value recedes into the light background. The design with the greatest contrast makes the darker object more dominant. GIS TUTORIAL 1 - Basic Workbook

Monochromatic color scale Series of colors of the same hue with color value varied from low to high Common for choropleth maps The darker the color in a monochromatic scale, the more important the graphic feature Use more light shades of a hue than dark shades in monochromatic scales The human eye can better differentiate among light shades than dark shades GIS TUTORIAL 1 - Basic Workbook

Monochromatic map Values too similar GIS TUTORIAL 1 - Basic Workbook

Monochromatic map A better map, more contrast GIS TUTORIAL 1 - Basic Workbook

Dichromatic color scale An exception to the typical monochromatic scale used in most choropleth maps Two monochromatic scales joined together with a low color value in the center, with color value increasing toward both ends Uses a natural middle point of a scale, such as 0 for some quantities (profits and losses, increases and decreases) GIS TUTORIAL 1 - Basic Workbook

Dichromatic map Symmetric break points centered on 0 make it easy to interpret the map GIS TUTORIAL 1 - Basic Workbook

Color tips Colors have meaning Cool colors Warm colors Political and cultural Cool colors Calming Appear smaller Recede Warm colors Exciting Overpower cool colors GIS TUTORIAL 1 - Basic Workbook

Color tips Do not use all of the colors of the color spectrum, as seen from a prism or in a rainbow, for color coding If you have relatively few points in a point layer, or if a user will normally be zoomed in to view parts of your map, use size instead of color value to symbolize a numeric attribute GIS TUTORIAL 1 - Basic Workbook

Color tips If you have many polygons to symbolize, it is better to use polygon centroid points with color rather than polygon choropleth maps. City of Pittsburgh housing units by block (quantile) GIS TUTORIAL 1 - Basic Workbook

Changing colors in ArcMap Choose color, more colors… GIS TUTORIAL 1 - Basic Workbook

Learn more about GIS colors Website http://colorbrewer2.org/ Books Brewer, Cynthia A. 2008. Designed Maps: A Sourcebook for GIS Users. Redlands: ESRI Press Brewer, Cynthia A. 2005. Designing Better Maps: A Guide for GIS Users. Redlands: ESRI Press GIS TUTORIAL 1 - Basic Workbook

Lecture 2 Vector gis display GIS TUTORIAL 1 - Basic Workbook

Points, lines, polygons Point Line Polygon x,y coordinates starting and ending point and may have additional shape vertices (points) Polygon three or more lines joined to form a closed area GIS TUTORIAL 1 - Basic Workbook

Feature attribute tables Store characteristics for vector features Layers can be displayed using attributes GIS TUTORIAL 1 - Basic Workbook

Displaying points Single symbols All CAD calls GIS TUTORIAL 1 - Basic Workbook

Displaying points Same features, different points Based on attributes GIS TUTORIAL 1 - Basic Workbook

Displaying points Industry specific (e.g. crime analysis) Good for large scale (zoomed in) maps GIS TUTORIAL 1 - Basic Workbook

Displaying points Industry specific (e.g. schools) Not good for multiple features at smaller scales Simple points better for analysis GIS TUTORIAL 1 - Basic Workbook

Displaying points Quantities Use exaggerated sizes GIS TUTORIAL 1 - Basic Workbook

Displaying lines For analytical maps, most lines are ground features and should be light shades (e.g. gray or light brown) GIS TUTORIAL 1 - Basic Workbook

Displaying lines Consider using dashed lines to signify less important line features and solid lines for the important ones GIS TUTORIAL 1 - Basic Workbook

Displaying polygons Consider using no outline or dark gray for boundaries of most polygons Dark gray makes the polygons prominent enough, but not so much that they compete for attention with more important graphic features Map on the right is population by Census block (2000), City of Pittsburgh GIS TUTORIAL 1 - Basic Workbook

Displaying polygons Consider using texture for black and white copies Map displays population for Allegheny County, PA municipalities (2000) GIS TUTORIAL 1 - Basic Workbook

Graphic hierarchy Assign bright colors (red, orange, yellow, green, blue) to important graphic elements Features are known as figure All features in figure GIS TUTORIAL 1 - Basic Workbook

Graphic hierarchy Assign drab colors to the graphic elements that provide orientation or context, especially shades of gray Features known as ground Circles in figure, squares and lines in ground GIS TUTORIAL 1 - Basic Workbook 59

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 GIS TUTORIAL 1 - Basic Workbook

Graphic hierarchy example GIS TUTORIAL 1 - Basic Workbook

Lecture 2 Gis queries GIS TUTORIAL 1 - Basic Workbook

GIS queries Powerful relationship between data table and vector-based graphics—unique to GIS Records from a feature attribute table are selected by using query criteria Query will automatically highlight the corresponding graphic features GIS TUTORIAL 1 - Basic Workbook

Simple attribute queries Simple query criterion <data attribute>< logical operator><value> NatureCode ='DRUGS' DATE >= '20040701' % wild card % symbol stands for zero, one, or more characters of any kind NAME like ' BUR%' Selects any crime with names starting with the letters BUR, including burglaries (BUR), business burglaries(BURBUS), and residential burglaries (BURRES) GIS TUTORIAL 1 - Basic Workbook

Simple attribute queries GIS TUTORIAL 1 - Basic Workbook

Compound attribute queries Compound query criteria Combine two or more simple queries with the logical connectives AND or OR "NATURE_COD" = 'DRUGS' AND "DATE" > 20040801 Selects records that satisfy both criteria simultaneously Result are drug crimes that were committed after August 1, 2004 GIS TUTORIAL 1 - Basic Workbook

Compound attribute queries GIS TUTORIAL 1 - Basic Workbook

Layer groups, scale thresholds Lecture 2 Layer groups, scale thresholds

Layer groups Organizes layers Groups and names logically GIS TUTORIAL 1 - Basic Workbook

Map Layer file (.lyr) Display certain characteristics of a dataset Show street subset that is classified by small, medium, or large Dataset properties such as color & line width are saved and applied to similar datasets. To create layer file right click layer Select Save as layer file -type layer filename GIS TUTORIAL 1 - Basic Workbook

Group Layer (.lyr) To create a Group Layer: Right click the data frame text and Select New Group Layer Select the New Group layer & Add Data (i.e.rail & interstate) Right click the New Group layer text and select Save as Layer File In the save layer pop up window, type the name of the new layer file i.e. Transportation Group.lyr GIS TUTORIAL 1 - Basic Workbook

Minimum scale threshold When zoomed out beyond this scale, features will not be visible Tracts not visible when zoomed to the USA GIS TUTORIAL 1 - Basic Workbook

Minimum scale threshold Tracts displayed when zoomed in GIS TUTORIAL 1 - Basic Workbook

Maximum scale threshold When zoomed in, features will not be visible State population will disappear when zoomed in to a state GIS TUTORIAL 1 - Basic Workbook

Hyperlinks and map tips Lecture 2 Hyperlinks and map tips

Hyperlinks Links images, documents, Web pages, etc. to features on a map GIS TUTORIAL 1 - Basic Workbook

Map tips Provide an additional way to find information about map features Pop up as you hover the mouse pointer over a feature GIS TUTORIAL 1 - Basic Workbook

Summary Choropleth maps Colors Vector GIS display GIS queries Map layers and scale thresholds Hyperlinks and Map tips GIS TUTORIAL 1 - Basic Workbook