Lecture 4: Intro to the Vector Data Model and to Map Layout Lecture 3b Introduction to GIS Lecture 4: Intro to the Vector Data Model and to Map Layout By Weiqi Zhou, University of Vermont Thanks are due to Prof. Troy, upon whose lecture much of this material is based.

Lecture 3b Introduction to GIS 1. Vector Data Model

Introduction to GIS Intro to Vector Three basic “feature” or “object” types in the vector data type: Point Arc Polygon A given layer holds a given feature type

Point layer A point layer: a bunch of (x,y) coordiantes Introduction to GIS Point layer A point layer: a bunch of (x,y) coordiantes Image source: ESRI Arc Info electronic help

Line (Arc) layer Points define lines (arcs) Introduction to GIS Line (Arc) layer Points define lines (arcs) Feature is the ARC, not the line segments Line segments Verticies Arcs meet at the nodes Node Image source: ESRI Arc Info electronic help

Introduction to GIS Line (Arc) layer Each point has a unique location

Polygon layer In a polygon layer, lines (arcs) define areas Introduction to GIS Polygon layer In a polygon layer, lines (arcs) define areas Lines (Arcs) Points Closed region Boundaries: line segments Area of homogenous phenomena

Polygons VS Rings Which one is polygon? Polygon Ring Introduction to GIS Polygons VS Rings Which one is polygon? Polygon Ring

Introduction to GIS Vector: Topology Definition1: Explicit encoding of spatial relationships between objects: the spatial location of each point, line and polygon is defined in relation to each other Definition2: Topology is a collection of rules and relationships that enables the geodatabase to more accurately model geometric relationships found in the world.

Vector: Topology Defines spatial relationships Rules & relationships Introduction to GIS Vector: Topology Defines spatial relationships Rules & relationships Model geometric relationships

Why Topology Two major purposes Allows for powerful analysis tools Introduction to GIS Why Topology Two major purposes Allows for powerful analysis tools Quality control mechanism

Types of Vector Topology Introduction to GIS Types of Vector Topology Arc-node topology Polygon topology Route topology Region topology

Arc-node & Node Topology Introduction to GIS Arc-node & Node Topology Connectivity analysis Arc-node Topology Arc-node List Direction Image source: ESRI Arc Info electronic help

Polygon-arc Topology The order does matter! Polygon-arc Topology Introduction to GIS Polygon-arc Topology Polygon-arc Topology Polygon-arc List The order does matter! Image source: ESRI Arc Info electronic help

Polygon-arc Topology Adjacency External polygon Introduction to GIS Image source: ESRI Arc Info electronic help

Route Topology Define paths base on arcs Introduction to GIS Image source: ESRI Arc Info electronic help

Regions Topology Regions: A list of polygons Introduction to GIS Image source: ESRI Arc Info electronic help

Regions Topology Designed for complex analyses Introduction to GIS Regions Topology Designed for complex analyses Example: a region of forest fire damage (multi-temporal) Image source: ESRI Arc Info electronic help

Example: State of Hawaii (a region) < -- > islands (polygons) Introduction to GIS Regions Topology Designed for complex analyses Example: State of Hawaii (a region) < -- > islands (polygons) Image source: ESRI Arc Info electronic help

Quality control and topology Introduction to GIS Quality control and topology Ensuring data quality and “logical consistency” Define complex and nuanced spatial rules Single layer quality control Mutli-Layer quality control

Quality control and topology Introduction to GIS Quality control and topology Single layer quality control slivers Undershoot Dangles overshoot Not sharing border

Quality control and topology Introduction to GIS Quality control and topology Mutli-Layer quality control: Defining spatial rules between layers Polygon rules: e.g. Must Be Covered by Feature Class of Line rules: e.g. Must not Self Intersect Point rules: e.g. Must be Properly Inside Polygons ArcCatalog includes new tools for defining and validating topology rules (Book: Building a geodatabase)

Topology rules: Example Introduction to GIS Topology rules: Example Say we have the following layers: property lots, sidewalk, building footprints, zoning map We can specify topological rules, like: Lots must be enclosed polygons Buildings must be entirely within a lot Sidewalks must be outside a lot polygon and entirely within the public right of way Lots must fall entirely within a single zone All lots must have access to a right of way

Lecture 3b Non-topological data model Introduction to GIS Spaghetti Data Model Non-topological data model Collections of line segments and points Only stores features coordinates No real connection, topology or relationships Not for spatial analysis Generally come from CAD files or digitizing Can “clean” these data, using user-defined tolerances

2. Map Layouts and Cartographic Representation Lecture 3b Introduction to GIS 2. Map Layouts and Cartographic Representation

Lecture 3b Introduction to GIS Map Compilation X Map? Map Elements?

Map Compilation Title Legend Neatline Data frame North arrow Scale bar Lecture 3b Introduction to GIS Map Compilation Title Legend Neatline Data frame North arrow Scale bar Notes

Lecture 3b Introduction to GIS Layouts Create a map for layout in ArcMap Layout view View>>Layout view.

Map Compilation Legend Geographic features Other map elements Title Lecture 3b Introduction to GIS Map Compilation Geographic features Other map elements Legend Title North arrow Scale bar Author Neatline Source of data Other objects…

Lecture 3b Introduction to GIS Layouts Legends are edited in the Legends property window: Accessed by double clicking the legends. Give a title, e.g. land use Symbol editing

Layouts Legends editing: Items Item Style Symbol Introduction to GIS Lecture 3b Introduction to GIS Layouts Legends editing: Items Item Style Symbol

Lecture 3b Introduction to GIS Layouts Legends editing: Frame Frame

Layouts Legends editing: Size and position Size&Position Lecture 3b Introduction to GIS Layouts Legends editing: Size and position Size&Position

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

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

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

MXD Files Mxd files are project files Save your layout Lecture 3b Introduction to GIS MXD Files Mxd files are project files Save your layout All other preferences Data is not included With an extension .mxd To save: File>>save (As)

Layer Files Save symbology and setting Lecture 3b Introduction to GIS Layer Files 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

Lecture 3b Introduction to GIS Layer Files Use layer files when you have lots of non-numeric categories

Layer Files Create a layer file in ArcCatalog Introduction to GIS Lecture 3b Introduction to GIS Layer Files Create a layer file in ArcCatalog

Layer Files Create a layer file in ArcMap Introduction to GIS Lecture 3b Introduction to GIS Layer Files Create a layer file in ArcMap

Layer Files Import a layer file’s symbology in properties Lecture 3b Introduction to GIS Layer Files Import a layer file’s symbology in properties