GEOL 452/552 - GIS for Geoscientists I

Mapping GIS data3%4)"(&"-&)"5)*(6(,17*(7*(81)")(4-+(2)9/)(1-8(,-(:%&(%/(%;"7(-/(.%4)"(???( 3%4)"(@"-&)"5)*Categorical dataOrdinal dataRatio/Interval dataIf non-numericIf numericGraduated color(polygons)Graduated symbol(points, lines)Dot DensityChart maps910Nominal DataLabels• Describes names of feature• Nominal data = names(words, computer-speak: “strings”)• name of state, land owner, etc.• “Name”: codes or indices (e.g. FIPS for counties, soil-codes, zipcodes)• Single symbol maps: same symbol / appearance• Labels: very simple way to show a feature’s attribute value astextCategorical Data•Places features into distinctcategories based on an attribute/field (here: Road types)•Different values (names, types)within each category (“Freeway”)•Examples: Landuse, types of crop oranimals, geologic units•ArcGIS: Symbolize as Unique values(limited number of types of objects)Geologic units1112

Making a unique values (Categories) map• Value field will show you all attribute fields•It’s up to you to select an attribute that contains categoricaldata (NOT numbers)• Assigns a symbol (here: type of line) to each value 13Numerical DataDeals with numbers (Zip code? No!)• Type A: Ordinal = rank (or order) (1., 2., 3., etc.)• Examples: Rankings of: state by population,universities, grades, taste• Type B: Decimal numbers (5.1, 2.3) or integers (5, 1, 8)• Examples: Length, Temperature, $, population,rainfall• Interval vs ratio type: ratio needs a meaningful “0point “(Celsius system vs. Fahrenheit or pH)14Mapping numerical data• Interval and ratio data: need to make classes beforemapping (need find class boundary, more next lecture)• Show as variations in symbol size, thickness, or color(lightness, hue) or combinationsTypes of maps symbolized as Quantitiesclass boundaries: 14, 18, 23 and 301516