DESIGN AND IMPLEMENTATION OF GEOGRAPHICAL INFORMATION SYSTEM
CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
This chapter gives an overview about the aim, objectives, background and operation environment of the system. There are several definitions of GIS in existence. However, none of such definitions is universally accepted. It is difficult to agree on a single definition for GIS for the simple reason that various kinds of GIS exist, each made for different purposes and for different types of decision making. As we will see shortly in the range of definitions presented below, people offer definitions of GIS with different emphasis on various aspects of GIS.
Man has always used geographical information. Geographical features and data gathering form part of our everyday lives. Indeed, most of the decisions we make on a daily basis are influenced by some aspects of geography. Hence, one would be right to say that, generally speaking, geographical information system is as old as man himself. However, in this unit our focus is on modern geographical information system. We will briefly look at the emergence and growth of GIS as well as the underlying factors.
1.2 STATEMENT OF THE PROBLEMS
“As transportation, communication, and utility networks continue to grow in complexity and size, the likelihood of two or more networks occupying a common right-of-way or intersecting each other also continues to increase. Conflicts arise when one network or another decides to perform construction or maintenance on their facilities.” (Ellis, 2003, p. 5). Mulaku phrases this issue in other words by stating “there will be intense completion for the finite space that utility facilities must occupy on road and other reserves and hence precise location will become even more important” (Mulaku, 2004, p. 30). Each year departments of transpiration spend millions of dollars to deal with problems that arise due to utility conflicts. As these conflicts arise, it is vital that the owners of the various utilities be able to accurately locate their facilities in three-dimensional space. Accurate location is the beginning of conflict detection, avoidance, and resolution.
Mulaku documents that over 80 percent of all utility operations are spatial in nature (Mulaku, 2004). This information was collaborated by Hemakumara in a paper entitled Geographic Information Systems in Utilities and Utility Management. Hemakumara determined that 80 to 85 percent of a utility’s information needs is location or spatially based (Hemakumara, 2003). Utilities, needs are dependent upon spatial information for their operations, engineering, and management. The information must not only be available, it must be precise (Mulaku, 2004).
In 2003, Ellis completed a study for the Florida Department of Transportation (FDOT) entitled Development of Improved Strategies for Avoiding Utility Related Delay During FDOT Highway Construction Projects. Ellis determined that utility relocation delays were one of the top five causes of construction delays on FDOT projects. These delays in turn caused project time delays and additional project costs. Ellis further determined that one of the major factors accounting for the delays was the fact that actual locations and types of utilities shown on the plans did accurately portray actual field conditions (Ellis, 2003). Ellis accurately describes the fundamental problem by stating “one of the fundamental problems is that there is usually no accurate data on the exact location, or sometimes even the existence of these buried features (2003, p. 7). Allred substantiated this view, in a paper entitled Underground Facilities: The Need for Accurate Records in an Expanding Society. Allred documents that there is a need for accurate as-built mapping of all underground facilities (Allred, 2004).
All types of utilities contribute to the complexity of locating underground utilities. Kelly and Nawarynsky assert that “Excavation is one the most dangerous activities in the construction industry (Kelly, Nawarynsky, 1996, p.1). Excavation is the single largest cause of gas and hazardous liquid pipeline accidents in the United States. During the 1988 to 1993 time period, 33 percent of all gas pipeline incidents were cause by excavation damage by persons other than the facilities owner or owner’s contractors. In addition, 35 deaths and 151 injuries were attributed to theses incidents as well as $42.5 million in property damage (Kelly, Nawarynsky, 1996).
Given the extent of the problem, the construction industry can gain substantial benefit from the accurate mapping of underground utilities. A Geographic Information System (GIS) is especially well adapted to provide information on utility location (Hemakumara, 2003). This view is shared by NETTWORK, 2002. They state that GIS provides the necessary computational, graphical, and information handling technology needed to record all necessary information on all buried utilities in a user friendly, accurate, three dimensional manner. While the accurate mapping of new installations is well defined in the literature, this paper is intended to investigate methods and procedures that can be used to capture the legacy utility location information in a modern GIS format.
1.3 OBJECTIVES OF THE STUDY
To introduce students to the concepts and the techniques of handling geographical data through a particular form of information system – GIS;
To introduce students to the skills and techniques to input, manage, analyse and display spatial information; and
To introduce students to the concepts and techniques for spatial data analysis and modelling.
Geographical Information System (GIS) is an information system that is specially designed handling spatial (or geographical) data. It combines a set of interrelated sub-systems that create, edit, manipulate, analyse and display data both in text and graphic forms. GIS supports spatial analysis and modelling for the discipline of geography (e.g. location, proximity, and spatial distribution), so that it becomes a vital tool for modern geography. With the rapid progress of computing and Internet technology, GIS technology allows easy and fast access to important geographical information on the region, environment and society.
1.4 SIGNIFICANCE OF THE STUDY
The significance of this study was to help and give a benefit to the student, business marketers, geologists, methodologists, school management, companies, and other places that need this system. The system would improve the monitoring capacities of those who maintain the system.
1.5 LIMITATION OF THE STUDY
Unavailability of academic materials.
Transport problem
Lack of financial support
Lack of Time
Unavailability of programming software such as Visual Basic.Net.
1.6 SCOPE OF THE STUDY
This research work will concentrate on the implementation of the system to see how it works and how it can be used.
1.7 ASSUMPTION OF THE STUDY
During the process of data collection, information relating to Geographical Information System was developed by me and written project was obtained from the internet and the Library. Hence, it is assumed that all the data collected are correct and contains no false information.
1.8 DEFINITION OF TERMS
Attribute – A characteristic of a geographic feature, typically stored in tabular format and linked to the feature in a relational database. The attributes of a well-represented point might include an identification number, address, and type.
Base Layer – A primary layer for spatial reference, upon which other layers are built. Examples of a base layer typically used are either the parcels, or street centerlines.
Buffer – A zone of a specified distance around a feature.
Computer Aided Design (CAD) – An automated system for the design, drafting and display of graphically oriented information.
Coordinate – An x,y location in a Cartesian coordinate system or an x,y,z coordinate in a three dimensional system. Coordinates represent locations on the Earth’s surface relative to other locations.
Database – A logical collection of interrelated information, managed and stored as a unit. A GIS database includes data about the spatial location and shape of geographic features recorded as points, lines, and polygons as well as their attributes.
Digital Elevation Model (DEM) – Terrain elevation data provided in digital form.
Digitize – To encode map features as x,y coordinates in digital form. Lines are traced to define their shapes. This can be accomplished either manually or by use of a scanner.
Geocode – The process of identifying a location by one or more attributes from a base layer.
Geographic Information System (GIS) – An organized collection of computer hardware, software, geographic data, and personnel designed to efficiently capture, store, update, manipulate, analyze, and display all forms of geographically referenced information.
Global Positioning System (GPS) – A satellite based device that records x,y,z coordinates and other data. Ground locations are calculated by signals from satellites orbiting the Earth. GPS devices can be taken into the field to record data while walking, driving, or flying.
Layer – A logical set of thematic data described and stored in a map library. Layers act as digital transparencies that can be laid atop one another for viewing or spatial analysis.
Line – Lines represent geographic features too narrow to be displayed as an area at a given scale, such as contours, street centerlines, or streams.
Metadata – Information about a data set. It may include the source of the data; its creation date and format; its projection, scale, resolution, and accuracy; and its reliability with regard to some standard.
Ortho Imagery – Aerial photographs that have been rectified to produce an accurate image of the Earth by removing tilt and relief displacements, which occurred when the photo was taken.
Point – A single x,y coordinate that represents a geographic feature too small to be displayed as a line or area at that scale.
Polygon – A multisided figure that represents area on a map. Polygons have attributes that describe the geographic feature they represent.
Scale – The ratio or relationship between a distance or area on a map and the corresponding distance or area on the ground.
Spatial Analysis – The process of modeling, examining, and interpreting model results. Spatial analysis is useful for evaluating suitability and capability, for estimating and predicting, and for interpreting and understanding.
Structured Query Language (SQL) – A syntax for defining and manipulating data from a relational database. Developed by IBM in the 1970s, it has become an industry standard for query languages in most relational database management systems.
Theme – An ArcView theme stores map features as primary features (such as arcs, nodes, polygons, and points) and secondary features such as tics, map extent, links, and annotation. A theme usually represents a single geographic layer, such as soils, roads, or land use.
Attribute – A characteristic of a geographic feature, typically stored in tabular format and linked to the feature in a relational database. The attributes of a well-represented point might include an identification number, address, and type.
Base Layer – A primary layer for spatial reference, upon which other layers are built. Examples of a base layer typically used are either the parcels, or street centerlines.
Buffer – A zone of a specified distance around a feature.
Computer Aided Design (CAD) – An automated system for the design, drafting and display of graphically oriented information.
Coordinate – An x,y location in a Cartesian coordinate system or an x,y,z coordinate in a three dimensional system. Coordinates represent locations on the Earth’s surface relative to other locations.
Database – A logical collection of interrelated information, managed and stored as a unit. A GIS database includes data about the spatial location and shape of geographic features recorded as points, lines, and polygons as well as their attributes.
Digital Elevation Model (DEM) – Terrain elevation data provided in digital form.
Digitize – To encode map features as x,y coordinates in digital form. Lines are traced to define their shapes. This can be accomplished either manually or by use of a scanner.
Geocode – The process of identifying a location by one or more attributes from a base layer.
Geographic Information System (GIS) – An organized collection of computer hardware, software, geographic data, and personnel designed to efficiently capture, store, update, manipulate, analyze, and display all forms of geographically referenced information.
Global Positioning System (GPS) – A satellite based device that records x,y,z coordinates and other data. Ground locations are calculated by signals from satellites orbiting the Earth. GPS devices can be taken into the field to record data while walking, driving, or flying.
Layer – A logical set of thematic data described and stored in a map library. Layers act as digital transparencies that can be laid atop one another for viewing or spatial analysis.
Line – Lines represent geographic features too narrow to be displayed as an area at a given scale, such as contours, street centerlines, or streams.
Metadata – Information about a data set. It may include the source of the data; its creation date and format; its projection, scale, resolution, and accuracy; and its reliability with regard to some standard.
Ortho Imagery – Aerial photographs that have been rectified to produce an accurate image of the Earth by removing tilt and relief displacements, which occurred when the photo was taken.
Point – A single x,y coordinate that represents a geographic feature too small to be displayed as a line or area at that scale.
Polygon – A multisided figure that represents area on a map. Polygons have attributes that describe the geographic feature they represent.
Scale – The ratio or relationship between a distance or area on a map and the corresponding distance or area on the ground.
Spatial Analysis – The process of modeling, examining, and interpreting model results. Spatial analysis is useful for evaluating suitability and capability, for estimating and predicting, and for interpreting and understanding.
Structured Query Language (SQL) – A syntax for defining and manipulating data from a relational database. Developed by IBM in the 1970s, it has become an industry standard for query languages in most relational database management systems.
Theme – An ArcView theme stores map features as primary features (such as arcs, nodes, polygons, and points) and secondary features such as tics, map extent, links, and annotation. A theme usually represents a single geographic layer, such as soils, roads, or land use.
