GIS in Real Estate Phil Hurvitz CAUP-Urban Form Lab April 13, 2005.

GIS in Real Estate

Phil Hurvitz

CAUP-Urban Form Lab

April 13, 2005

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GIS in Real Estate

Overview

• What is GIS?

• How is GIS used outside of real estate

• Data models used in GIS

• Lab session_

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GIS in Real Estate

Overview

• What is GIS?



• Lab session

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GIS in Real Estate

What is GIS?

• GIS is a computer-based technology used for the – Capture– Storage– Manipulation– Analysis, and– Display

of spatially referenced data_

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GIS in Real Estate

What the hell does that mean?

• Anything you have ever seen, or could imagine on a map can be stored and analyzed with specialized software on a desktop PC

• (Examples to follow)…_

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GIS in Real Estate

Why use a GIS?

• An extension of the paper map, but much more than a map, as you will see

• GIS uses the analytical power of the computer to complete complex tasks

• Computer's storage power to manage large data sets. • Integration of many different types of data from many

different sources• GIS maps a variety of different data to the same

coordinate space (allows for combination of data)_

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GIS in Real Estate

What are the necessary parts to a GIS?

1. Trained personnel (the most expensive part)

2. Software (at the high end, ArcGIS, ~$25,000 per seat)

3. Data (many for free, some cost $$)

4. Computers (even a moderate desktop PC these days can perform dazzling things)

5. Ideas!_

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GIS in Real Estate

Overview

• What is GIS?



• Lab session

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GIS in Real Estate

GIS use examples in various disciplines

• Natural resource management

• Telecommunications

• “Traveling salesman” problem

• Risk management & emergency response

• Space exploration

• Urban form & Public Health

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GIS in Real Estate

Natural resource management

• Where are areas on a forest that meet a given complex set of criteria?

– “What parts of the forest are located:

– within 100 ft of a stream, – beyond 50 ft from a road,– on greater than 30% slope?”

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GIS in Real Estate

• on > 30% slope?

• closer than 100 ft to a stream, and• farther than 50 ft from a road,

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GIS in Real Estate

Telecommunications

• Cellular phone towers

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GIS in Real Estate

Telecommunications


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GIS in Real Estate

Telecommunications


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GIS in Real Estate

“Traveling salesman” problem

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GIS in Real Estate

Space exploration

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GIS in Real Estate

Urban form & Public Health

• Urban sprawl and automobile dependence– decreased activity levels– increased obesity rates

• Is urban spatial composition and configuration and indicator for obesity or other disease?

• Can communities be structured to promote an increase in activity levels?

• GIS is a central tool in quantifying the urban environment

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GIS in Real Estate

Walkability & Bikeability Modeling

• WBC Project, funded by CDCs

• Urban Form Lab (Anne Moudon, Chanam Lee)

• A GIS extension for obtaining environmental data in a household’s neighborhood– Urban features within walking/cycling distance– 200+ variables per household– Stat

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GIS in Real Estate

Walkability & Bikeability Modeling

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GIS in Real Estate

What is in the neighborhood?

3 banks

1 km radius

1 bar

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GIS in Real Estate

How do land uses cluster?

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GIS in Real Estate

Overview

• What is GIS?



• Lab session

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GIS in Real Estate

Spatial Data Model: Basic Data Types

• GIS are driven by spatial data

• 2 basic spatial (coordinate/geometric) data models exist

– vector: based on geometry of• points• lines • polygons

– raster: based on geometry of• grid cells (images, bitmaps, DEMs)_

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GIS in Real Estate

Vector Data ModelPoints: represent discrete point features

each point locationhas a record in thetable

airports are point featureseach point is stored as a

coordinate pair

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GIS in Real Estate

Vector Data ModelLines: represent linear features

roads are linear features

each road segmenthas a record in thetable

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GIS in Real Estate

Vector Data ModelLines: fundamental spatial data model

• Lines start and end at nodes• line #1 goes from node #2 to node #1

• Vertices determine shape of line• Nodes and vertices are stored as coordinate pairs_

node

node

vertex

vertex

vertex

vertex

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GIS in Real Estate

Vector Data ModelPolygons: represent bounded areas

each bounded polygonhas a record in thetable

landforms and water are polygonal features

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GIS in Real Estate

Vector Data Model

• Polygon #2 is bounded by lines 1 & 2• Line 2 has polygon 1 on left and polygon 2 on right_

Polygons: fundamental spatial data model

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GIS in Real Estate

Vector Data Model

• complex data model, especially for larger data sets• “arc-node topology,” only used for ArcInfo data sets_

Polygons: fundamental spatial data model

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GIS in Real Estate

Raster Data Model

• digital orthophoto

• digital elevation model (DEM)_

A few different types of raster data

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GIS in Real Estate

Raster spatial data model

• origin is set explicitly

• cell size is always known

• cell references (row/column locations)are known

• cell values are referencedto row/column location

• values represent numerical phenomena orindex codes for non-numerical phenomena_

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GIS in Real Estate

Raster Data Model

• Characteristics of the raster data model:– Rectangular grid of square cells

• – Shape of discrete polygonal features generalized by cells

• + Continuous (surface) data represented easily

• + Simple data structure_

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GIS in Real Estate

Raster Data Model

• Raster data are good at representing continuous phenomena, e.g.,

– Wind speed– Elevation, slope, aspect– Chemical concentration– Likelihood of existence of a certain condition– Electromagnetic reflectance (photographic or

satellite imagery)_

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GIS in Real Estate

• The “where” of GIS is determined by coordinate (map) data structures, but …

• The “what” of GIS is determined by tabular (relational database) data structures

• Thus, tabular data are just as important as coordinate data_

Relational Database Model & Attribute Data Structures

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GIS in Real Estate


•Attribute data are stored in database tables.

•Tables are composed of:

– fields

and

– records_

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GIS in Real Estate


• You may already be familiar with some types of relational databases

– dBase– rBase– MS Access– MS Excel (database functionality)– Oracle, INFORMIX, INGRES, SQL Server– MySQL, PostgreSQL– INFO (in ArcInfo)_

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GIS in Real Estate


•Each vector data source has an attribute table

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GIS in Real Estate


•Tables can be linked and joined (“related”) by use of common values in fields

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GIS in Real Estate


• Relationship between tabular and map data – one-to-one between features and records

• when a selection is made, both the record and feature are selected

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GIS in Real Estate

Overview

• What is GIS?



• Lab session

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GIS in Real Estate

Lab Session

• Open GIS software

• Download Seattle & King County data

• Perform query & display

• Create a map displaying a simple selection or analysis

GIS in Real Estate Phil Hurvitz CAUP-Urban Form Lab April 13, 2005.

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