Introduction to GIS Lecture 2: Part 1. Understanding Spatial Data Structures Part 2. Legend editing, choropleth mapping and layouts Part 3. Map layouts Parts 1 and 2 by Austin Troy, Part 3 by Austin Troy and Brian Voigt

Introduction to GIS Part 2. Spatial Data Structures By Austin Troy

Introduction to GIS Representation Entities Fields Bona Fide Fiat

Introduction to GIS Representation Entities Fields Vector Raster

Introduction to GIS Points (no dimensions) Lines, or “arcs” (1 dimension) or Areas, or “polygons” (2 or 3 dimensions) Vector

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 Moving between vector and raster

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

Introduction to GIS Mapping of Attribute Data Two basic approaches for visually displaying attribute data: 1.Quantities approach 2.Category approach

Introduction to GIS Mapping of Attribute Data Quantity approach: applies to numeric >> ordinal Category approach: text values; order is irrelevant

Introduction to GIS Mapping of Attribute Data Category approach, example: vegetation type

Introduction to GIS Mapping of Attribute Data Quantity approach, example: population

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 TOC >> layer properties>>symbology tab>>Categories>> Unique values Choose values field that contains the attribute Click the “Add all values” button

Introduction to GIS Mapping Categories

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 Mapping Categories--grouping 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 In Arc GIS layer properties>>symbology, we choose Quantities>>graduated color We then choose a value to represent In this case we choose median house value It automatically chooses five classes for the data

Introduction to GIS Graduated Color The resulting map shows high housing value areas with dark colors and low with light

Introduction to GIS Graduated Color Now with 3 classes for same variable

Introduction to GIS Graduated Color …and 15 classes

Introduction to GIS Graduated Color Classification interface These are the breaks it makes, based on the distribution of the data largesmall Classification method (default= Jenks)

Introduction to GIS Graduated Color Equal interval method What kind of data is 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 Problematic example: skewed data (# of vacant structures)

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 Notice how with natural breaks there are now more classes on the left side, where most of the data are. Natural breaks uses Jenks Goodness of Fit statistic to adjust class boundaries

Introduction to GIS Graduated Color This map, 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 Quantile output

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 CFCC, 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

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 more classes of symbols that are industry standar

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

Charts displayed geographically 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 Part 3. Map Layouts By Brian Voigt and Austin Troy

Introduction to GIS Layouts You can very simply create a map for layout in Arc GIS by simply clicking View>>Layout view. Layouts are designed to 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 Map Elements?

Introduction to GIS Title Legend Neatline North arrow Scale bar Notes Data frame Map Compilation

Introduction to GIS Layouts Create a map for layout in ArcMap Layout view View>>Layout view. 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 Layouts Introduction to GIS Give a title, e.g. land use Symbol editing Legends are edited in the Legends property window: Accessed by double clicking the legends.

Introduction to GIS Layouts Introduction to GIS Legends editing: Items Item Style Symbol

Introduction to GIS Layouts Editing legend item type

Introduction to GIS Layouts Introduction to GIS Legends editing: Frame Frame

Introduction to GIS Layouts Introduction to GIS Legends editing: Size and position Size&Position

Introduction to GIS ArcMap: data frame More than one frames can be shown in layout view Introduction to GIS Frame 1 Frame 2

Introduction to GIS Data frames can be used for context

Introduction to GIS Or for detailed inset maps All lecture material by Austin Troy (c) 2008 except where noted

Introduction to GIS

Layouts: data frame Create a new view or “data frame” in ArcMap Introduction to GIS

Layouts: data frame Access and edit data frame properties Introduction to GIS

MXD Files Introduction to GIS Mxd files are project files – Save your layout – All other preferences – Data is not included – With an extension.mxd File >> Save (As)

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