Points (no dimensions) Lines, or “arcs” (1 dimension) or Areas, or “polygons” (2 or 3 dimensions) Vector
Introduction to GIS Point layer X,Y coordinates Introduction to GIS 05 1 1234 2 3 4 5 Point IDLocation 14,3 22,2 31,4 44,1 1 2 3 4 Examples: Stream gauge / wave buoy, stoplight, survey location / respondent, residence / business, etc.
Introduction to GIS Line (Arc) layer Points define lines (arcs) Introduction to GIS Image source: ESRI Arc Info electronic help Line segment Vertex Node Feature is the ARC, not the line segments Arcs meet at the nodes Arc
Introduction to GIS Line (Arc) layer Each point has a unique location Introduction to GIS
Polygon layer In a polygon layer, lines (arcs) define areas Introduction to GIS Lines (Arcs) Points Boundaries: line segments Area of homogenous phenomena Closed region
Introduction to GIS Raster Grids, or pixels Cell size is constant Area of each cell defines the resolution Raster files store only one attribute, in the form of a “z” value, or grid code.
Introduction to GIS Raster and Vector representations of the same terrain Raster: great for surfacesVector: limited with surfaces
Introduction to GIS Raster and Vector representations of the same land use:
Introduction to GIS Vector vs. Raster: bounding Raster: bad with bounding Vector: boundary precision
Introduction to GIS Vector vs. Raster: Sample points Cancer rates across space
Introduction to GIS Vector / Raster Representation Points
Introduction to GIS Vector / Raster Representation Lines
Introduction to GIS Vector / Raster Representation Polygons
Introduction to GIS WHEN TO USE RASTER OR VECTOR???
Introduction to GIS Raster and Vector Analytic advantage and disadvantages Technical advantages and disadvantages Specific Usages Tossups
Introduction to GIS Part 2. Legend editing, choropleth mapping By Austin Troy & Brian Voigt
Introduction to GIS Mapping Attribute Data Two basic approaches for visually displaying attribute data: 1.Quantities approach 2.Category approach
Introduction to GIS Mapping Attribute Data Quantity approach: applies to numeric >> ordinal Category approach: text values; order is irrelevant
Introduction to GIS Mapping Attribute Data Quantity approach, example: population
Introduction to GIS Mapping Attribute Data Category approach, example: vegetation type
Introduction to GIS Mapping Categories Examples: vegetation types, land use, soil types, geology types, forest types, party voting maps, land management agency, recategorizations of numeric data (“bad, good, best” or “low, medium, high’). Can you think of any others?
Introduction to GIS Mapping Categories Access layer properties: 1.right-click layer in the TOC 2.double-click layer in TOC Symbology tab >>> Categories >>> Unique values Set Value Field to desired attribute Click the Add All Values button
Introduction to GIS Mapping Categories Often categories must be aggregated and redefined: this land use map had over 110 categories that were condensed to 12
Introduction to GIS Grouping Categories In this case 1262, 1263, 1264, 1265, etc. refers to different subcategories of commercial land use Can then save symbology as.lyr or in.mxd
Introduction to GIS Quantity Mapping Also known as “choropleth mapping” For points, lines and polygons: graduated color, or color ramping For lines and points can also do graduated symbol
Introduction to GIS Graduated Color Layer Properties >>> Symbology >>> Quantities >>> Graduated colors Set the Value field to desired attribute In this case we choose median house value It automatically assigns five classes for the data
Introduction to GIS Graduated Color The map shows high value housing with dark colors and low value housing with light colors
Introduction to GIS Graduated Color Same map, but this time with 3 classes
Introduction to GIS Graduated Color …and with 15 classes
Introduction to GIS Graduated Color Classification interface These are the class breaks (based on the distribution of the data) largesmall Classification method (default= Jenks)
Introduction to GIS Graduated Color Classification Method: Equal Interval What kind of data does this work for?
Introduction to GIS Graduated Color Here’s what the same distribution looks like with only 5 equal intervals.
Introduction to GIS Graduated Color Data representing # of vacant structures Potential problem(s) with this method of classification
Introduction to GIS Graduated Color This map of vacant properties tells us almost nothing, because almost all the records fall into the first class
Introduction to GIS Graduated Color Natural Breaks: Notice how there are now more classes on the left side, where most of the data are. Minimize each class’s average deviation from the class mean, while maximizing each class’s deviation from the means of the other groups Reduce the within class variance and maximize the between class variance
Introduction to GIS Graduated Color This map of vacant properties, made with Natural Breaks, is more intelligible
Introduction to GIS Graduated Color Quantile method: sets the class boundaries so as to maximize the perceived variation in the map; equal number of data points in each class
Introduction to GIS Graduated Color Map of vacant properties using the Quantile classification method
Introduction to GIS Graduated Color Graduated color can also be applied to points. Here are houses display by sales price Natural breaks Equal interval
Introduction to GIS Graduated Symbol In this case housing price is expressed by symbol size
Introduction to GIS Graduated Symbol The same thing can also be done with lines—for instance, traffic volumes
Introduction to GIS Symbol Styles We can also choose to “match to symbols in a palette” and then apply the “transportation.style” palette to the FCC, or road category, attribute in our roads layer Introduction to GIS Results in this map Must click here to match Choose your style palette here
Introduction to GIS Symbol Styles One could also manually create symbol styles for each street type. Clicking on each symbol in either the TOC or properties windows brings up a manual symbol selector. You can assign a separate one to each category. Introduction to GIS Includes many classes of industry standard symbols
Introduction to GIS Symbol Styles There are also a huge variety of industry-specific point symbols that can be either assigned through matching symbols to a predefined style or manually assigning those symbols Introduction to GIS
Displaying Charts Attributes for point, line or polygon features can also be displayed as charts on the map Introduction to GIS
Normalization Show an attribute normalized by another attribute or expressed as a percentage of total. Here we have number of vacancies per tract as a percentage of total households. Introduction to GIS numerator denominator
Introduction to GIS Layer Files Introduction to GIS Save symbology and setting Primarily for saving legend setting Opening a layer file will open the data layer with all the preferences saved With an extension.lyr
Introduction to GIS Layer Files Introduction to GIS Use layer files when you have lots of non-numeric categories
Introduction to GIS Layer Files Introduction to GIS Create a layer file in ArcCatalog
Introduction to GIS Layer Files Introduction to GIS Create a layer file in ArcMap
Introduction to GIS Layer Files Introduction to GIS Import a layer file’s symbology in properties
Introduction to GIS Part 3. Map Layouts By Brian Voigt and Austin Troy
Introduction to GIS Map Layout You can create a map for layout in Arc GIS by selecting View >>> Layout view. Layouts are designed to be cartographically acceptable, which means they must have the key elements of a printed map, such as scale bars, north arrows, legends and titles These can be added from the Insert menu
Introduction to GIS Map Compilation Map? X What’s missing?
Introduction to GIS Title Legend Neatline North arrow Scale bar Notes Data frame Map Compilation
Introduction to GIS Map Compilation Geographic features Other map elements – Legend – Title – North arrow – Scale bar – Author – Neatline – Source of data – Other objects…
Introduction to GIS Map Layout: Data frame Create a new view or “Data Frame” in ArcMap Introduction to GIS
ArcMap: Data Frame More than one frame can be shown in layout view Introduction to GIS Frame 1 Frame 2