Fundamentals of GIS

Geographic Information System is virtually used in every field. It's comprised of hardware, software, data, humans, and a set of organizational protocols. These components must be well integrated for effective use of GIS to help people reach a common goal. GIS technology applies geographic science with tools for understanding and collaboration. It’s used in every aspect of our daily lives and it is difficult to count its uses as it is used by different institutions and hundreds of thousands of organizations for many different purposes and to make maps that communicate, perform analysis, share information and solve complex problems around the world since it allows the analyzation of environmental, demographic, and topographic data. This is changing the way the world works. GIS is a tool used by individuals and organizations, schools, governments, and businesses seeking innovative ways to solve their problems. It's considered as a decision-making tool which uses spatial information. It supports the study of natural and man-made phenomena. Words can't explain how his tool is so very important in our lives so that the intention of this book is to lay the principle basics foundation of GIS and to define some of the common terminologies which GIS users using.

The Global Positioning System (GPS) is a burgeoning technology, which provides unequalled accuracy and flexibility of positioning for navigation, surveying and GIS data capture. The GPS NAVSTAR (Navigation Satellite timing and Ranging Global Positioning System) is a satellite-based navigation, timing and positioning system. The GPS provides continuous three-dimensional positioning 24 hrs a day throughout the world. The technology seems to be beneficiary to the GPS user community in terms of obtaining accurate data upto about100 meters for navigation, metre-level for mapping, and down to millimetre level for geodetic positioning. The GPS technology has tremendous amount of applications in GIS data collection, surveying, and mapping.

Geophysical Research Letters, 1992

Comparison of Cartesian coordinates determined at collocated sites using two independent space techniques, very lo•ng baseline interferometry (VLBI) and Global Positioning System (GPS), shows remarkable agreement even when the points in question span transcontinental distances. The results corroborate the capabilities of commercial dual-frequency GPS receivers to perform geodetic work at the highest available accuracy. Adjusted geocentric coordinates of a configuration of GPS stations well distributed along the eastern half of the United States were accurately determined (better than 10 '8) in the rigorously defined International Earth Rotation Service •ERS) terrestrial reference frame ITRF 89. Introduction In two significant campaigns, during 1987 and 1990, the National Geodetic Survey (NGS) initiated the formation of a regional A-order high accuracy reference network (HARN) coveting the eastern half of the conterminous United States employing Global Positioning System (GPS) techniques. This network is in the process of being densifted and extended to cover the entire country [Strange and Love, 199 !]. Among the set of points comprising this GPS framework are 10 well-distributed stations previously occupied by mobile very long baseline interferometry (VLB!) instruments or tied by local surveys to other fixed VLBI antennas. Thus, in order to estimate the inherent accuracy of the GPS results, it was logical to compare them against the VLBI-inferred 'ground truth." Although repeatability (i.e., precision) of GPS observables at regional scales is well documented [e.g., Lindqwister et al., 1991; Larson and Agnew, 1991], research to determine "true" accuracy of GPS three-dimensional results is practically non-existent. The obvious explanation is the scarcity, until recently, of results obtained from the comparison of GPS-derived data with other observational techniques collocated at the same geodetic monuments. To this date, the emphasis has been concentrated in comparing individual baseline length and orientation [Larson and Agnew, 1991]. The accuracy study presented here expands in complexity recent attempts [Larson et al., 1991] restricted to a single test

مجلة مرکز البحوث الجغرافیة والکارتوجرافیة, 2020

Cartography and Geographic Information Science, 2002

A new global georeferencing system-the World Geographic Reference System (WGRS)-is proposed. This system has particular advantages for location description and communication with electronic devices, i.e. ., in digital environments that are shared between humans and machines. The new World Geographic Reference System strikes a compromise between the dominant use of numbers in established scientific coordinate systems, such as latitude/longitude, and the colloquial preference for names, particularly names of administrative units and populated places, in everyday life. Specifically, WGRS defines a system of uniform regional grids, each 100x 100 km in extent, anchored on and named by prominent cultural and/or physical features. Subsets of these regional grids, called local grids, which are particularly adapted to smaller places, also may be defined. A location within a regional or local grid is georeferenced by suffixing the grid identifier with a coordinate string of dotted-digit-pairs that represent interleaved Cartesian x-y displacements from the grid origin. A typical WGRS locator, for example, is us.DC.wns.54.18.28, representing a 100x100 m area, the southwest corner of which is 0.512 of the way across (east) and 0.488 of the way up (north) in the Washington, D.C., grid, roughly the lawn surrounding the Washington Monument. This locator, which is easily interpreted by both humans and machines, also may be effectively communicated between them via computer networks using a notation, such as "wgrp://us.DC.wAS.54.18.28" in web code. The similarity of WGRS locators (WGLs) to Uniform Resource Locators (URLs) on the Internet is intentional, facilitating their use in Web and wireless application interfaces, especially those employed in location-based service systems.

Journal of Science and Technology (Ghana), 2008

The concepts of coordinate systems are required in order to identify points in space and to represent them on maps. Position recognition is done by using a mathematical method of assigning numbers, called coordinates to each point in space. There are different coordinate systems the commonest being the system of latitudes, longitudes and ellipsoidal heights.

Geographic Information Systems (GIS) are tools to collect, manage, and present information about our planet. GIS are information systems that deal with spatial or spatially related information. That is, the information is tied to a specific area of the earth. They can be used for public administration, e.g., cartography, property registers, utility routing (electrical, water, serer, cable, telephone lines, etc.). They can be used for environmental studies, both for a local area or the entire earth. For example, biologist might correlate a particular animal population with other plant features, temperatures, elevations, etc., all of which are spatial data.