DOC PREVIEW
UNC-Chapel Hill GEOG 070 - The Two Types of Data in GIS

This preview shows page 1-2-14-15-30-31 out of 31 pages.

Save
View full document
View full document
Premium Document
Do you want full access? Go Premium and unlock all 31 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 31 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 31 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 31 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 31 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 31 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 31 pages.
Access to all documents
Download any document
Ad free experience

Unformatted text preview:

The Two Types of Data in GISGIS Database ModelsSome Database DefinitionsAdvantages of Databases over FilesDisadvantages of Databases over FilesCharacteristics of DBMS (1)Characteristics of DBMS (2)Characteristics of DBMS (3)The Role of DBMS in GISTypes of DBMS ModelsHierarchical Data ModelHierarchical Data ModelRelational Data ModelRelational DBMS (1)A TableRelational DBMS (2)Relation Rules (Codd, 1970)NormalizationRelational JoinRelational JoinSpatial RelationsContains RelationTouches RelationSpatial MethodsConvex Hull and Difference MethodsIndexingGrid Index (multi-level)Point and Region QuadtreesR-treeMinimum Bounding RectangleDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005Spatial data: Describing where things areANDAttribute data: Describing what things are•Example: A point specified by UTM coordinates•Easting = 50,000 m•Northing = 5,000,000 m•Zone =17•This specifies the location of a point of the ground•The nature of the real-world feature located at this point would be recorded in the attribute data•Traditionally, geographic data and attributes were recorded on paper too (maps), and these had the same problems as a phone bookThe Two Types of Data in GISDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005• The approaches used for constructing GIS database management systems have depended upon the development of DBMS in computer science. This dates back to the 1970s when data entry used punch cards, and it has come a long way since then …• The first successful GIS Arc/INFO was really the marriage of two separate components:•The Arc spatial data processing component•The INFO relational database management systemGIS Database ModelsDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005Some Database Definitions• Database – an integrated set of data on a particular subject• Geographic (~spatial) database - database containing geographic data of a particular subject for a particular area• Database Management System (DBMS) –software to create, maintain and access databasesDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005Advantages of Databases over Files• DBs avoid redundancy and duplication• DBs reduce data maintenance costs• Applications are separated from the data– Applications persist over time– Support multiple concurrent applications• DBs facilitate better data sharing• Security and standards can be defined and enforced using DBsDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005Disadvantages of Databases over Files• Expense of databases• Complexity of databases• Performance of databases – especially with complex data types (including spatial data)• Integration with other systems can be difficult, especially if those systems don’t use the same data modelDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005Characteristics of DBMS (1)• Data model support for multiple data types– e.g MS Access: Text, Memo, Number, Date/Time, Currency, AutoNumber, Yes/No, OLE Object, Hyperlink, Lookup Wizard• Load data from files, databases and other applications• Indexed for rapid retrievalDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005Characteristics of DBMS (2)• Query language – SQL provides a structured way to ask questions of the data• Security – controlled access to data– Multi-level groups etc.• Controlled update using a transaction manager manages the updating process• Backup and recovery of data for when the unthinkable happens …• DBA tools for optimizing performance– Configuration, tuningDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005Characteristics of DBMS (3)• Applications that help make good use the data– CASE tools to help in formalizing logic– Forms builder to make structured input easy– Report writer to create customized output– Internet Application Server to serve data on the Web• Programmable API (application programming interface) to allow customizationDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005Geographic Information SystemDatabase ManagementSystem• Data load• Editing• Visualization• Mapping• Analysis• Storage• Indexing• Security• QueryDataSystemTaskThe Role of DBMS in GISDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005Types of DBMS Models• Hierarchical•Network• Relational - RDBMS• Object-oriented - OODBMS• Object-relational - ORDBMSÅ Our focusDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005UniversityLaw SchoolCollege of A&SMedical SchoolEngineeringPhysics GeographyAaronCongheDavidLarry….Hierarchical Data ModelUniversityUnitsDepartmentsFaculty andStaff•Suppose we are designing a model for faculty & staff data:David Tenenbaum – GEOG 070 – UNC-CH Spring 2005USAAlaska New York North CarolinaOrange CountyWestchester CountyHierarchical Data Model•Now, suppose we are creating a model for places in the USACountryStateCountyCarrboroChapel HillHillsboroughCity &TownNew York CityBrooklynThe BronxManhattanQueensStaten Isl.?David Tenenbaum – GEOG 070 – UNC-CH Spring 2005• The database is defined in terms of a tree structure which is inflexible and has trouble dealing with exceptions (i.e. all records need to follow the same uniform structure):1. We cannot define new linkages between records once the hierarchical tree is established2. We cannot define linkages laterally or diagonally in the tree, only vertically3. The only geographical relationships which can be encoded easily are “is contained within” or “belongs to”Disadvantages of the Hierarchical Data ModelDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005The relational model organizes data in a series of two-dimensional tables, each of which contains records for one kind of entity…555-6789Comm.David1021384…555-4321Geog.John1010789…Phone #MajorNamePID #Fields recordsRelational Data ModelThis model is a revolution in database management ÆIt replaced almost all other approaches in database management because it allows more flexible relationsbetween kinds of entitiesDavid Tenenbaum – GEOG 070 – UNC-CH Spring 2005Relational DBMS (1)• In a RDBMS, data is stored as tuples(pronounced tup-el), and is conceptualized as tables• Table – contains data about a class of objects– Two-dimensional list (array)– Rows = objects– Columns = object states (properties, attributes)David Tenenbaum – GEOG 070 – UNC-CH Spring 2005A TableRow = objectColumn = propertyTable = Object ClassObject classes which haveGeometry encoded are called feature classesDavid


View Full Document

UNC-Chapel Hill GEOG 070 - The Two Types of Data in GIS

Download The Two Types of Data in GIS
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view The Two Types of Data in GIS and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view The Two Types of Data in GIS 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?