GIS Presentation and Output -- charts -- maps

1. GIS Presentation and Output-- charts-- maps

2. Presentation: Charts Bar • charts can be used to display tabular data. • the types of charts available in ArcView are typical of these available in GIS desktop systems • most systems have dynamic (as opposed to static) charting: charts automtically updated as data in underlying tables changes: • 6 types in ArcView: area, bar, column, line, pie, scatter Area Line Column Pie Scatter

3. Presentation: Maps What’s a map? "a representation, normally to scale and on a flat medium, of a selection of material or abstract features on , or in relation to, the surface of the earth.”International Cartographic Association Aspatial model of the real world, but differentiated from it by: abstraction, focus, simplification, symbolization scale, projection, and purpose

4. What’s in a Map? • Abstraction • Imaginary features (i.e. political boundaries) as well as physical features • Past, present, and future (archaeological sites, current, and planned roads) features • Focus • Selection and classification of features in real world to include in the map • Simplification • Simplification of complex features such as coastlines • Exaggeration of features that are too small to show at the scale of the map • Symbolization • Use of symbols or graphic to represent classified objects (e.g. church) • Scale • The ratio of distance on a map, to the equivalent distance on the earth's surface. • Projection • Representing curved surface of the earth on a flat plane. Distortion is inevitable. • Purpose • To describe, measure, communicate/persuade

5. Types of Maps 1. Planimetric (e.g municipal base map) A map designed to portray the horizontal positions of features; vertical information is specifically ignored. 2. Topographic (e.g. USGS 7.5 minute quads) A map designed to portray features on the surface of the Earth, including relief (elevation), hydrography, and cultural features. 3. Cadastral (e.g municipal parcel map) A map representing boundaries of land parcels, ownership, land use, valuation, and other related information. 4. Image (e.g LANDSAT image ‘map’) A map representing a remotely sensed picture or reflection of all or part of the Earth's surface • may or may not be orthomorphically correct. 5. Thematic (see next slide for types and examples) • A map used to visualize spatial relationships and patterns among information pertaining to some theme or concept (e.g. income)

6. Types of Thematic Maps Thematic Map: A map used to visualize spatial relationships and patterns among information pertaining to some theme or concept (e.g. income) • Choropleth map: uses zones or polygons to display information using shading, dot, density, or other techniques. • e.g population change, ethnicity distribution • Proximal (dasymetric) map: shows zones of constant attributes, such as soil type or vegetation (similar to choropleth except that data determines boundary lines; no pre-defined polygons) • e.g zoning, soil map • Isopleth map (contour or isarithmic) : shows a contiuous three dimensional surface such as elevation using lines connecting points of equal value (contours). • e.g elevation, travel time contours from a point(s), land values, income • Point (dot) or symbol map: shows information relating to specific points using marker sysmbols whose size and/or frequency relates to magnitude of phenomena • housing sales, code violations, crimes

7. Making Better Maps: some general principles • keep it simple, but don’t rely on software defaults • show only the area under study (e.g. if Texas, don’t show AK or LA counties): use small insert map to show relative location • Plan for final printing/publication scale • allow for size reduction (e.g. for report or journal publication), • point symbols visually reduce at twice the rate of line features (a function of area) • put title at top using ‘thick line’ font: serif/sans-serif; case not critical • map labels • best in serif font (letters have ‘tails’), with first letter upper and rest lower case • place above and to the right of the feature (2nd choice: above to left) • use font size hierarchy to indicate relative importance: US,Texas, Dallas • water features traditionally labelled in italic font • Create good map in black and white, then add color (not the reverse!) • 1 in 10 people are colorblind • people will xerox your map anyway

8. Making Better Maps: color and symbolization • Color concepts • Hue: the actual color (red, blue, etc) • Saturation: how much of it • Value: the amount of black Use low saturation in background, high saturation in foreground • choice of shading Quantitative data • symbols should have visual progression corresponding to data values • for polygons, use monochromatic color ramp: same color (hue), different saturation or value • can highlight top and bottom with contrasting color if desired • if use different fill patterns, be sure “visual progression” is achieved • for point symbols, use different sizes of the same symbol Qualitative data • For polygons, use different colors (polychromatic), or different fill patterns • For point symbols, use same size of different symbols • To create a color ramp for any two colors, hold CTRL key while selecting colors • be sure legend is big enough to clearly show different fill patterns

9. Making Better Maps: some tricks to use • Always include “neatline” around outside: ArcView uses this for positioning • Select Layout/add neatline to add neatline around outside of entire graphic • Use the same theme twice (be sure to remove copy from legend) • e.g. place theme with thin black line on top of a copy of the theme with thick red line • e.g. have separate theme for outline of polygons • Use buffering to create special effects (in View, select Theme/Create buffers) • e.g. along a shoreline, create multiple buffers then color ramp them • e.g.buffer within a polygon border, then save as new theme, and shade appropriately • Controlling scale of maps in Layouts • use copy to create a second frame of identical size • Be sure distance units and map units are set in View/ Properties for any View used • Set scale option in “View Frame Properties” box (double click on frame to set this) • Controlling size of point and line symbols in Layout • In View, double click on theme in TofC to open its Legend Editor • Click Advanced button, click Scale Symbols check box, type in Reference (output) scale • for dot patterns, keep density constant and change size of dots (rather than converse): but most software won’t do this! • Color, or use fill pattern (dots or stipple) for oceans and large water bodies • Use graphics design package for major customization • Export entire layout to graphics package • Use package to create a custom graphic then bring in as a picture/graphic