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Lecture Four

Vector-Based Spatial Analysis:Tools

Processes

Geographic Information Systems GEOG4340 2013winter

Cheng. Q. , Earth and Space Science and Engineering, qiuming@yorku.ca

Reading materials: Chapter 6 of Intro GIS by J. R. Jensen and R.R. Jensen

Polygons

Files Coordinate filesLanduse.PATLanduse.AATLanduse.NAT

Arcs

Files Coordinate filesStreet.AATStreet.NAT

Points Files Coordinate files

Well.PAT

Topological Data Model

Feature attribute tables

•Point Attribute Table – PAT•Arc Attribute Table – AAT•Node Attribute Table – NAT•Polygon Attribute Table – PAT

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Topological relationships

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A coverage is a data model for the storage of vector data. It generally represents a single setof geographic objects such as roads, parcels, soil units or forest stands in a given area. A coverage supports the georelational model–it contains both the spatial (location) and attribute (descriptive) data for geographic features.

Coverage data model

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Reference locationpoint locations Node attribute tab

Arc attribute tab

Label file

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Shapefiles are a simple, non-topological format for storing vector data and attribute data. It generally represents a single set of geographic objects such as roads, parcels, soil units or forest stands in a given area. A shapefile does not support the georelational.

Shapefile data format

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3 4

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n Landuse.shp Map of same features

n Landuse.shx Exchange file

n Landuse.dbf DBS file for attr. table

Shapefile data format

No shape id1 12 23 34 45 56 6

Landuse.shp Landuse.dbf

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Geodatabase of ArcGIS is object-based georelational spatial database. It works for storing vector data, attribute data and raster data. It generally represents multiple sets of geographic objects such as roads, parcels, soil units or forest stands in a given area and support the georelations among these sets.

Geodatabase

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GIS Database

Processes

Information

Interpretation

Spatial Analysis KnowledgeDecision SupportProcesses and Basic Tools

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Create Buffer Zones Around Vectors

Points

Lines

Polygons

Example of geoprocessing

Combine Vector Layers (Overlay Operation)

Layer

Operator

Operator

Layer A

Layer B

Layer C

ArcGIS Overlay Operation

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Combine Vector Layers (Overlay Operation)

New AttributeShowing nearest Points on B from A

Node - Node relationship

Spatial Join

Points A

Points B

Points A

Combine Vector Layers (Overlay Operation)

New AttributeShowing nearest Points on B from A

Node - Line relationship

Spatial Join

Points A

Line B

Points A

Combine Vector Layers (Overlay Operation)

Spatial Join

Points A

By shape

New AttributeShowing class of Poly B

Node - Polygon relationship

Poly B

Points A

Combine Vector Layers (Overlay Operation)

Table Join

Intersections

Line - Line relationship

Intersect

Line A

Line B

Points C

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Combine Vector Layers (Overlay Operation)

New line layerWith lines separated According to poly Class in Poly B

Line - Poly relationship

Overlay

Line A

Poly B

Line C

Combine Vector Layers (Overlay Operation)

New Point feature Of intersect of Line A and Poly B

Line - Poly relationship

Intersect

Line A

Poly B

Point C

Combine Vector Layers (Overlay Operation)

IntersectIdentityUnion New Poly combined

Poly A and Poly B

Poly - Poly relationship

Overlay

Poly A

Poly B

Poly C

Combine Vector Layers (Overlay Operation)

New Line FeatureCommon boundary of Poly A and Poly B

Poly – Poly Intersect

Intersect

Poly A

Poly B

Line C

Combine Vector Layers (Overlay Operation)

New Point FeatureIntersect of Poly A and Poly B

Poly – Poly Intersect

Intersect

Poly A

Poly B

Point C

Site for Wastewater Treatment Plant

Application and Vector-based Analysis

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Model of Processes

BufferRiver

Areas

Land

R_BufferOverlay Intersect

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Buffer150mPark

Res_BufSelected P

P_Buffer

Buffer 150mParcel

SelectResidential

OverlayUnion

Overlay Union

Res_Park

R_P_Flood

Flood_Z

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