Intro to GISIntro to GIS

October 24, 2006October 24, 2006

AnnouncementsAnnouncements

Second Midterm Quiz is next week (covers Second Midterm Quiz is next week (covers chapters 6, 9, 10, 12 plus lectureschapters 6, 9, 10, 12 plus lectures

Oslo Project descriptionOslo Project description GIS Club Activity: Presentation by GIS Club Activity: Presentation by

Thorbjørn Geirbo, today at 14.15 in the Thorbjørn Geirbo, today at 14.15 in the GIS Lab (HHH 035)GIS Lab (HHH 035)

GIS Day: Wednesday, November 15th.GIS Day: Wednesday, November 15th.

Oslo Project Oslo Project Examples from 2004Examples from 2004

Tilgjengelighet til legesentre i Bydel GrorudTilgjengelighet til legesentre i Bydel Grorud Innvandrernes bosettingsmønsterInnvandrernes bosettingsmønster Distinksjoner i Oslo: En Bourdieusk alanyse av Distinksjoner i Oslo: En Bourdieusk alanyse av

ulikehet ved hjelp av geografiske ulikehet ved hjelp av geografiske informasonssystemerinformasonssystemer

Sosiale skiller i OsloSosiale skiller i Oslo Sosiale ulikheter i OsloSosiale ulikheter i Oslo Inntekt og boligstruktur i Oslo: med fokus på Inntekt og boligstruktur i Oslo: med fokus på

bydel Gamle Oslobydel Gamle Oslo Privatisering og innntektsnivå i bydel Vestre Privatisering og innntektsnivå i bydel Vestre

AkerAker

Examples from 2005Examples from 2005

Barnehagedekning i bydel St. HanshaugenBarnehagedekning i bydel St. Hanshaugen En treffsted for alle unge? Tilgjengelighet til En treffsted for alle unge? Tilgjengelighet til

fritidsklubber i Nordstrand og Østensjø bydelerfritidsklubber i Nordstrand og Østensjø bydeler Romlig analyse av sosiale forskjeller; Romlig analyse av sosiale forskjeller;

segregering på Grünerløkka?segregering på Grünerløkka? Vestre Aker – mer enn bløtkakevillaer og Vestre Aker – mer enn bløtkakevillaer og

Jaguarer (en casebasert diskusjon av GIS som Jaguarer (en casebasert diskusjon av GIS som geografisk analyseverktøy)geografisk analyseverktøy)

Last Week’s LectureLast Week’s Lecture

Database – an integrated set of data on a Database – an integrated set of data on a particular subjectparticular subject

Databases offer many advantages over Databases offer many advantages over filesfiles

Relational databases dominateRelational databases dominate

A DBMS contains:A DBMS contains:

Data definition languageData definition language Data dictionaryData dictionary Data-entry moduleData-entry module Data update moduleData update module Report generatorReport generator Query languageQuery language

Advantages of Databases Advantages of Databases

Avoids redundancy and duplicationAvoids redundancy and duplication Reduces data maintenance costsReduces data maintenance costs Applications are separated from the dataApplications are separated from the data

Applications persist over timeApplications persist over time Support multiple concurrent applicationsSupport multiple concurrent applications

Better data sharingBetter data sharing Security and standards can be defined and Security and standards can be defined and

enforcedenforced

SQLSQL

Structured (Standard) Query Language – Structured (Standard) Query Language – (pronounced SEQUEL)(pronounced SEQUEL)

Developed by IBM in 1970sDeveloped by IBM in 1970s Now Now de factode facto and and de jurede jure standard for accessing standard for accessing

relational databasesrelational databases Three types of usageThree types of usage

Stand alone queriesStand alone queries High level programmingHigh level programming Embedded in other applicationsEmbedded in other applications

Types of SQL StatementsTypes of SQL Statements

Data Definition Language (DDL)Data Definition Language (DDL) Create, alter and delete dataCreate, alter and delete data CREATE TABLE, CREATE INDEXCREATE TABLE, CREATE INDEX

Data Manipulation Language (DML)Data Manipulation Language (DML) Retrieve and manipulate dataRetrieve and manipulate data SELECT, UPDATE, DELETE, INSERTSELECT, UPDATE, DELETE, INSERT

Data Control Languages (DCL)Data Control Languages (DCL) Control security of dataControl security of data GRANT, CREATE USER, DROP USERGRANT, CREATE USER, DROP USER

Spatial RelationsSpatial Relations Equals – Equals – same geometriessame geometries Disjoint – Disjoint – geometries share common pointgeometries share common point Intersects – Intersects – geometries intersectgeometries intersect Touches – Touches – geometries intersect at common boundarygeometries intersect at common boundary Crosses – Crosses – geometries overlapgeometries overlap Within– Within– geometry withingeometry within Contains – Contains – geometry completely containsgeometry completely contains Overlaps – Overlaps – geometries of same dimension overlapgeometries of same dimension overlap Relate – Relate – intersection between interior, boundary or intersection between interior, boundary or

exteriorexterior

Spatial MethodsSpatial Methods

DistanceDistance – shortest distance – shortest distance Buffer Buffer – geometric buffer– geometric buffer ConvexHulConvexHulll – smallest convex polygon geometry – smallest convex polygon geometry Intersection Intersection – points common to two geometries– points common to two geometries Union Union – all points in geometries– all points in geometries DifferenceDifference – points different between two – points different between two

geometriesgeometries SymDifferenceSymDifference – points in either, but not both of – points in either, but not both of

input geometriesinput geometries

Spatial SearchSpatial Search

Buffering is a spatial retrieval around Buffering is a spatial retrieval around points, lines, or areas based on distance.points, lines, or areas based on distance.

Overlay is a spatial retrieval operation that Overlay is a spatial retrieval operation that is equivalent to an attribute join.is equivalent to an attribute join.

IIdentifydentify

RecodeRecode

OR

Data Data overlayoverlay

Overlay

Types of overlay operationsTypes of overlay operations

AndAnd OrOr MaxMax MinMin

BufferBuffer (raster) (raster)

+ 1

Buffer (vector)Buffer (vector)

Complex Retrieval: Map Complex Retrieval: Map AlgebraAlgebra

Combinations of spatial and attribute Combinations of spatial and attribute queries can build some complex and queries can build some complex and powerful GIS operations, such as powerful GIS operations, such as weighting.weighting.

ReviewReview

A geographic database contains both A geographic database contains both spatial and tabular data. The spatial data spatial and tabular data. The spatial data contains feature shape and location contains feature shape and location information, while the tabular data information, while the tabular data contains the attributes for the features. contains the attributes for the features. Often, feature attributes are contained in Often, feature attributes are contained in multiple tables.multiple tables.

Making Maps With Making Maps With GISGIS

IntroductionIntroduction

Output is the pinnacle of GIS projectsOutput is the pinnacle of GIS projects Two main types of outputTwo main types of output

MapsMaps Visualizations (see chapter 13)Visualizations (see chapter 13)

Maps are good at summarizing and Maps are good at summarizing and communicatingcommunicating

What is a map?What is a map?

““A graphic depiction of all or part of a A graphic depiction of all or part of a geographic realm in which the real-world geographic realm in which the real-world features have been replaced by symbols features have been replaced by symbols in their correct spatial location at a in their correct spatial location at a reduced scale.”reduced scale.”

power line

Map function in GISMap function in GIS

StorageStorage Temporary communicationTemporary communication Intermediate check of dataIntermediate check of data Final reportFinal report

GIS Processing GIS Processing TransformationsTransformations

Characteristics of MapCharacteristics of Map

Two main typesTwo main types TopographicTopographic ThematicThematic

Some map problemsSome map problems Can miscommunicateCan miscommunicate Each map is just one of all possible mapsEach map is just one of all possible maps Complex maps can be difficult to understandComplex maps can be difficult to understand

Topographic Map

Thematic Map

Map TypesMap Types

Point dataPoint data Line dataLine data Area dataArea data Volume dataVolume data Time dataTime data

Choosing a Map TypeChoosing a Map Type

Cartographers have designed hundreds of Cartographers have designed hundreds of map types: methods of cartographic map types: methods of cartographic representation.representation.

Not all GISs allow all types.Not all GISs allow all types. Most have a set of basic typesMost have a set of basic types Depends heavily on the dimension of the Depends heavily on the dimension of the

data to be shown in the map figure.data to be shown in the map figure.

Choosing the Wrong TypeChoosing the Wrong Type

Fairly common GIS error.Fairly common GIS error. Due to lack of knowledge about Due to lack of knowledge about

cartographic options.cartographic options. Can still have perfect symbolization.Can still have perfect symbolization. Possibility of misinformationPossibility of misinformation Definite reduction in communication Definite reduction in communication

effectiveness.effectiveness.

Choropleth Choropleth Class Class

SchemesSchemes

Choosing TypesChoosing Types Check the dataCheck the data

ContinuousContinuous DiscreteDiscrete Accuracy & PrecisionAccuracy & Precision ReliabilityReliability

Dimension (Point, Line, Area, Volume)Dimension (Point, Line, Area, Volume) Scale of MeasurScale of Measureement (Nominal, ordinal, etc.)ment (Nominal, ordinal, etc.) GIS capabilityGIS capability Is there aIs there a need to supplement GIS software need to supplement GIS software? (e.g. with a ? (e.g. with a

drawing package)drawing package)

Maps and CartographyMaps and Cartography

Map – ‘digital or analog output from a GIS Map – ‘digital or analog output from a GIS showing information using well established showing information using well established cartographic conventions’cartographic conventions’

Cartography is the art, science and Cartography is the art, science and techniques of making mapstechniques of making maps

The Need for DesignThe Need for Design

To appear professional and avoid errors, To appear professional and avoid errors, GIS maps should reflect cartographic GIS maps should reflect cartographic knowledge about map design.knowledge about map design.

A map has a visual grammar or structure A map has a visual grammar or structure that must be understood and used if the best that must be understood and used if the best map design is desired.map design is desired.

Cartographic conventionCartographic conventions should be s should be followedfollowed (e.g. forests should be green). (e.g. forests should be green).

Map DesignMap Design

Good map design requires that map Good map design requires that map elements be placed in a balanced elements be placed in a balanced arrangement within the neat line.arrangement within the neat line.

A GIS map is designed in a process called A GIS map is designed in a process called the design loop.the design loop.

Primary goals in map design: to share Primary goals in map design: to share information, highlight patterns and information, highlight patterns and processes, and illustrate results.processes, and illustrate results.

To be effective, To be effective, a map a map must must be correctly designed and be correctly designed and

constructed.constructed.

The Parts of a Map: Map ElementsThe Parts of a Map: Map Elements

The United States of America

Alaska

Lambert Conformal Conic ProjectionSource: U.S. Dept. of State

0 41 2 3

hundreds ofkilometers

0 4 0 4

Washington,D.C.National Capital

Legend

Scale

CreditsNorth ArrowPlace nameInset

Ground

Figure

Neat line Border Title

Hawaii

TitleLegend

Projection

Grid

Data Source

Inset map

Map Body

Author

North Arrow

Scale

Bertin's Graphic Bertin's Graphic PrimitivesPrimitives

Visual balance is key!Visual balance is key!

Visual balance is affected by:Visual balance is affected by: the "weight" of the symbolsthe "weight" of the symbols the visual hierarchy of the symbols and the visual hierarchy of the symbols and

elementselements the location of the elements with respect to the location of the elements with respect to

each other and the visual center of the each other and the visual center of the map.map.

Visual centerVisual center

5% of height

5% of height

Landscape Portrait

Visual LayoutVisual Layout

Title Here

Title Here

Eye expects (1) balance and (2) alignment

Text: Selection and PlacementText: Selection and Placement

Kristiansand

BM 232

US Route

66

200

L a

ke

M u d

POINT LINE AREASome cartographic label placement conventions. Points: right and above preferred with no overlap.

Lines: Following the direction of the line, curved if a river. Areas: On a gently curved line following the shape of the figure and upright.

Bæ

rum

Osl

o

Text placementText placement

TrondheimTrondheim

Trondheim

Trondheim

Bogstadvann

Path right

Path Down

Symbol “weight”Symbol “weight”

Line weight Pattern Shading Hue

Map Design and GISMap Design and GIS

When a GIS map is the result of a When a GIS map is the result of a complex analytical or modeling process, complex analytical or modeling process, good design is essential for good design is essential for understanding.understanding.

The map is what distinguishes GIS as a The map is what distinguishes GIS as a different approach to the management of different approach to the management of information, so extra care should be taken information, so extra care should be taken to improve the final maps that a GIS to improve the final maps that a GIS generates in a GIS task.generates in a GIS task.

Limitations of Paper MapsLimitations of Paper Maps

Fixed scaleFixed scale Fixed extentFixed extent Static viewStatic view Flat and hence limited for 3D visualizationFlat and hence limited for 3D visualization Only presents ‘complete’ world viewOnly presents ‘complete’ world view Map producer-centricMap producer-centric

ConclusionsConclusions

Cartography is both an art and a scienceCartography is both an art and a science Maps are fundamental to GIS projectsMaps are fundamental to GIS projects Modern advances in cartography make it Modern advances in cartography make it

easy to produce good and bad mapseasy to produce good and bad maps New technology and especially the New technology and especially the

Internet has change the content and Internet has change the content and techniques of GIS-based cartographytechniques of GIS-based cartography

Multivariate Mapping

Part II: Working with Part II: Working with Attributes in ArcGISAttributes in ArcGIS

Issues to discussIssues to discuss

how attribute data is stored in a table of how attribute data is stored in a table of rows and columns rows and columns

how attribute data is associated with how attribute data is associated with features features

tabular field types supported in ArcGIS tabular field types supported in ArcGIS types of table relationships types of table relationships how tables can be related to each other how tables can be related to each other how to join tables based on a common field how to join tables based on a common field

Anatomy of a TableAnatomy of a Table

Each table in a database has the same basic format: Each table in a database has the same basic format: an array of rows and columns. Rows are also called an array of rows and columns. Rows are also called records, and columns are also called fields. records, and columns are also called fields.

Some tables, like a feature class's default feature Some tables, like a feature class's default feature attribute table, have a preset number of columns. For attribute table, have a preset number of columns. For instance, a polygon coverage's feature attribute table instance, a polygon coverage's feature attribute table has four standard columns: Area, Perimeter, has four standard columns: Area, Perimeter, Coverage#, and Coverage-ID, while a line Coverage#, and Coverage-ID, while a line shapefile's feature attribute table has only one shapefile's feature attribute table has only one default column, named Shape. Other tables are default column, named Shape. Other tables are completely user-defined. completely user-defined.

The table has three user-added columns: Name, Country, The table has three user-added columns: Name, Country, and Population. ArcMap automatically adds a third column and Population. ArcMap automatically adds a third column (FID) for display purposes. The name of this column may (FID) for display purposes. The name of this column may be different depending on the type of data source. For be different depending on the type of data source. For example, it is called FID for a coverage or shapefile, example, it is called FID for a coverage or shapefile, OBJECTID for a geodatabase feature class, and Order_ID OBJECTID for a geodatabase feature class, and Order_ID for a grid. for a grid.

Because some databases and some operations do not Because some databases and some operations do not support fields with blanks in their names, you should avoid support fields with blanks in their names, you should avoid creating fields that contain them. In addition, every column creating fields that contain them. In addition, every column in a table should have a unique name but columns in the in a table should have a unique name but columns in the same table can have a variety of formats. NOTE: same table can have a variety of formats. NOTE: Norwegian “æ å ø” can also create problems, as can Norwegian “æ å ø” can also create problems, as can decimal formats (10,1 versus 10.1).decimal formats (10,1 versus 10.1).

Tabular data field typesTabular data field types

Tables are capable of storing date, number, and Tables are capable of storing date, number, and text values, but most tabular formats have several text values, but most tabular formats have several different field types to store this information. different field types to store this information.

Choosing the best field type for the values to be Choosing the best field type for the values to be stored is an important consideration. Also, the stored is an important consideration. Also, the available field types can vary between tabular available field types can vary between tabular formats. In general, you can store numbers, text, formats. In general, you can store numbers, text, and dates. Specifically supported formats in and dates. Specifically supported formats in ArcCatalog include short integer, long integer, ArcCatalog include short integer, long integer, float, double, text, date, object-id, and blob. float, double, text, date, object-id, and blob.

Information stored in tables is organized by fields and field types. When defining a table's fields, be aware that each database has its own rules defining what names and characters are permitted.

ArcGIS Tabular FormatsArcGIS Tabular Formats ArcGIS supports the use of multiple formats for storing ArcGIS supports the use of multiple formats for storing

and managing tabular data. Each of ArcGIS software's and managing tabular data. Each of ArcGIS software's primary spatial formats has its own native format. primary spatial formats has its own native format. Coverages use INFO-formatted tables; shapefiles store Coverages use INFO-formatted tables; shapefiles store their attributes in dBASE (.dbf) format; geodatabases their attributes in dBASE (.dbf) format; geodatabases rely on the format of their supporting RDBMS (Oracle, for rely on the format of their supporting RDBMS (Oracle, for example). example).

Deciding on the proper format in which to store attribute Deciding on the proper format in which to store attribute information is an important part of database design and information is an important part of database design and can affect the efficiency with which you are able to can affect the efficiency with which you are able to access feature attributes. To facilitate sharing data that's access feature attributes. To facilitate sharing data that's in different formats, ArcCatalog and ArcToolbox contain in different formats, ArcCatalog and ArcToolbox contain tools to convert between the various tabular formats. In tools to convert between the various tabular formats. In addition, some formats, such as the coverage, can link to addition, some formats, such as the coverage, can link to independent tables regardless of their format. independent tables regardless of their format.

Tabular information can be stored in a variety of formats. In this case, feature information is stored in the coverage feature attribute table, data about the owners is stored in dBASE format, and tax information is stored in a relational database format.