PROCESS IN DATA SYSTEMS PLANNING DATA INPUT DATA STORAGE DATA ANALYSIS DATA OUTPUT ACTIVITIES USER NEEDS.

PROCESS IN DATA SYSTEMSPROCESS IN DATA SYSTEMS

PLANNING

ACTIVITIES

USERNEEDS

DATAINPUT

DATA STORAGE

DATA ANALYSIS

DATA OUTPUT

DATA STRUCTURESDATA STRUCTURES

Non spatialNon spatial FinanceFinance LibraryLibrary CommunicationCommunication TransportationTransportation

SpatialSpatial earthearth coordinatescoordinates

DATA STRUCTURESDATA STRUCTURES

NON SPATIALNON SPATIAL Management Management

Information Information SystemSystem

Decision Support Decision Support SystemSystem

Office Otomation Office Otomation SystemSystem

Artificial Inteligent Artificial Inteligent SystemSystem

SPATIALSPATIAL Environmental Info Environmental Info

SystemsSystems Infrastructural Info Infrastructural Info

SystemsSystems Cadastral Info Cadastral Info

SystemsSystems Social-economic Social-economic

Info SystemsInfo Systems

GIS DATA STRUCTURESGIS DATA STRUCTURES

traditional computer file structures that traditional computer file structures that allow for the storing, ordering and allow for the storing, ordering and searching of pieces of datasearching of pieces of data

higher level of organisation in the higher level of organisation in the computer called data base structures computer called data base structures allow more complex methods of managing allow more complex methods of managing datadata

GIS: GIS: graphic data structuregraphic data structure,, multiple multiple graphic data layers and their databasesgraphic data layers and their databases

SPATIAL SPATIAL DATADATA

POINTSPOINTS LINESLINES AREASAREAS can be represented by their respective can be represented by their respective

symbolssymbols SURFACESSURFACES most often represented either by point most often represented either by point

elevationselevations or other computer structuresor other computer structures, ,

POINT FEATURESPOINT FEATURES

Trees, houses, road intersections, and Trees, houses, road intersections, and many more.many more.

Each feature is said to be discrete in that Each feature is said to be discrete in that it can occupy only a given point in space it can occupy only a given point in space at any time.at any time.

These objects are assumed to have no These objects are assumed to have no spatial dimension. Each can be referenced spatial dimension. Each can be referenced by its locational coordinatesby its locational coordinates

LINEAR (LINE) FEATURESLINEAR (LINE) FEATURES

They are conThey are concceptualized as occupying eptualized as occupying only a single dimension in our coordinate only a single dimension in our coordinate space.space.

Roads, rivers, regional boundaries, fences, Roads, rivers, regional boundaries, fences, hedgerows, or any kind of object that is hedgerows, or any kind of object that is fundamentally long and very skinny.fundamentally long and very skinny.

Other lines such as political boundaries, Other lines such as political boundaries, have no width dimension to be concerned have no width dimension to be concerned about. In fact they are not physical about. In fact they are not physical entities at all, but rather, a construct of entities at all, but rather, a construct of political convention and agreement.political convention and agreement.

LINEAR (LINE) FEATURESLINEAR (LINE) FEATURES

They allow us to measure their spatial They allow us to measure their spatial extent by simply finding out how long they extent by simply finding out how long they are.are.

Two points, a beginning and an ending Two points, a beginning and an ending point.point.

The more complex the line, the more The more complex the line, the more points we will need to indicate exactly points we will need to indicate exactly where it is located.where it is located.

AREASAREAS

Objects observed closely enough to be Objects observed closely enough to be clearly seen to occupy both length and clearly seen to occupy both length and width are called areas.width are called areas.

Two-dimensional objects include the area Two-dimensional objects include the area occupied by a yard, the areal extent of a occupied by a yard, the areal extent of a city, and an area as large as a continentcity, and an area as large as a continent..

SURFACESSURFACES

Adding the dimension of height to our Adding the dimension of height to our area features allows us to observe and area features allows us to observe and record the existence of surfaces.record the existence of surfaces.

Surfaces occur all around us as natural Surfaces occur all around us as natural features. Hills, valleys, ridges, cliffs.features. Hills, valleys, ridges, cliffs.

Continuous dataContinuous data

SPATIAL MEASUREMENT LEVELSSPATIAL MEASUREMENT LEVELS

Objects themselves are called entities Objects themselves are called entities (coordinates)(coordinates)

Spatial features or entities also have Spatial features or entities also have additional information besides spatial additional information besides spatial informationinformation

The additional non-spatial information The additional non-spatial information that helps us describe the objects we that helps us describe the objects we observe in space comprises the feature’s observe in space comprises the feature’s attributes attributes

GEOGRAPHIC DATA GEOGRAPHIC DATA MEASUREMENTSMEASUREMENTS

Range from simply naming objects, to give Range from simply naming objects, to give ourselves something to call them, to ourselves something to call them, to precise measurements that allow us to precise measurements that allow us to directly compare the qualities of different directly compare the qualities of different objects.objects.

Nominal Scale: Named data, no Nominal Scale: Named data, no comparisoncomparison

GEOGRAPHIC DATA GEOGRAPHIC DATA MEASUREMENTSMEASUREMENTS

Ordinal Scale: From best to worst. The Ordinal Scale: From best to worst. The spectrum is based entirely on what we spectrum is based entirely on what we intended to use the information for.intended to use the information for.

Interval scale: Numbers are assigned to Interval scale: Numbers are assigned to the items measured.the items measured.

Ratio scale: Most useful, level of data Ratio scale: Most useful, level of data measurement. Allows us to make a direct measurement. Allows us to make a direct comparison between two spatial comparison between two spatial variablesvariables..

SPATIAL LOCATION AND SPATIAL LOCATION AND REFERENCESREFERENCES

Absolute location: It will give us definitive, Absolute location: It will give us definitive, measurable, fixed point in space.But we measurable, fixed point in space.But we must have a reference system against must have a reference system against which to evaluate such a location.which to evaluate such a location.

Spherical grid system, places two sets of Spherical grid system, places two sets of imaginary lines around the earthimaginary lines around the earth

SPATIAL LOCATION AND SPATIAL LOCATION AND REFERENCESREFERENCES

Parallels Parallels

The angular distance-The angular distance-llatitudeatitude

Meridians Meridians

TThe angular distance-he angular distance-longitudelongitude

GRAPHIC DATAGRAPHIC DATA

RASTERRASTER rasterraster grid cellsgrid cells resolutionresolution dots or pixeldots or pixel coveragecoverage grid, grid, compact storing of compact storing of

raster dataraster data

VECTORVECTOR X and Y coordinatesX and Y coordinates representative of representative of

dimensionalitydimensionality simple networksimple network topologytopology PolygonPolygon direct translation of direct translation of

the graphicthe graphic topologically coded topologically coded

network and polygonnetwork and polygon

NON GRAPHIC DATANON GRAPHIC DATA

SIMPLE LISTSIMPLE LIST Simplest file structure is called simple Simplest file structure is called simple

list.list. Our names, addresses like creating a Our names, addresses like creating a

separate index card for each name separate index card for each name (unordered)(unordered)

Searching is very inefficient (Suppose Searching is very inefficient (Suppose your database contains 200000 records)your database contains 200000 records)

ORDERED SEQUENTIAL FILESORDERED SEQUENTIAL FILES

The sequence of alphabetical characters.The sequence of alphabetical characters. Names and addresses in ordered files.Names and addresses in ordered files.

INDEXED FILESINDEXED FILES

It can be developed as direct files or It can be developed as direct files or inverted filesinverted files

Key attribute say a number sequence or Key attribute say a number sequence or alphabetic sequence. Search was based alphabetic sequence. Search was based on the key attributes ‘yellow pages’on the key attributes ‘yellow pages’

Attributes are the primary search criteria Attributes are the primary search criteria and the entities rely on them for selection. and the entities rely on them for selection. We call this an indexed inverted file We call this an indexed inverted file structurestructure

DATABASEDATABASE

A collection of multiple files is called A collection of multiple files is called database. The complexity of working with database. The complexity of working with database system requires a more database system requires a more elaborate structure for management elaborate structure for management called data base management system.called data base management system.

Hierarchical data structuresHierarchical data structures network systemnetwork system relational database structurerelational database structure

HIERARCHICAL DATA HIERARCHICAL DATA STRUCTURESTRUCTURE

Parent-to child branchingParent-to child branching classifying plants and animalsclassifying plants and animals A major advantages of this system is that A major advantages of this system is that

it is easy to search because the structure it is easy to search because the structure is so well defined and easy to expandis so well defined and easy to expand

NETWORK SYSTEMSNETWORK SYSTEMS

This structure allows users to move from This structure allows users to move from data item to data item through a series of data item to data item through a series of pointerspointers

network systems are generally considered network systems are generally considered to be an improvement over hierarchical to be an improvement over hierarchical structures for GIS work because they are structures for GIS work because they are less rigid and can handle many to many less rigid and can handle many to many reletionshipsreletionships

RELATIONAL DATABASE RELATIONAL DATABASE MANAGEMENT SYSTEMMANAGEMENT SYSTEM

The data are stored as ordered records or The data are stored as ordered records or rows of attribute values called tuplesrows of attribute values called tuples

Tubles are grouped with data rows in Tubles are grouped with data rows in aform collectively called relationsaform collectively called relations

primary keyprimary key relational joinrelational join graphic representation of entities and graphic representation of entities and

attributesattributes