Overview: Secondary Capture Techniques for Geographical Information Systems Projects

Introduction

Geographic information systems are a computerized system for the collection, storage, manipulation and output of information that is spatially referenced (Obermeyer and Pinto, 1994). Data capture is the process of putting information into the system (Eisntein, 2001). Data used in GIS comes from many sources in many types and it is stored in different ways (Eistein, 2001). Mutluoglu and Ceylan (2009), states that one of the main components of a GIS is the formation of the database. More than 70 % of the time and cost is spent on developing this database. Furthermore, the success of a GIS project depends on the accuracy and current spatial data obtained (Mutluoglu and Ceylan, 2009). Some of the methods adopted for GIS data acquisition are conventional method, RTK-GPS method, photogrammetric method, remote sensing method, scanning and digitizing method, raster and vector data and data transfer. All the above methods are classified under primary and secondary data sources. Primary data capture is direct measurement while secondary data capture is obtained from other sources which can be raster or vector data types (Longely et al, 2005). Primary data sources are those collected in digital format specifically for use in a GIS project. These include raster SPOT and IKONOS Earth Satellite images and vector-survey measurements. Secondary sources are digital and analog datasets that were originally captured for another purpose and need to be converted into a suitable digital format for use in a GIS project (Longley et al, 2005). Geographic data can be either analog or digital. Analog data is a physical product displaying information visually on paper while digital data is information that a computer can read (Ei...

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...ition), McGraw-Hill companies, New York.

Chang, K. T. (2010): Introduction to geographic information system (Sixth edition), McGraw-Hill companies, New York

Longely, P. A., Goodchild, M. F., Maguire, D. J and Rhind, D. W (2001): Geographical information systems and science. John Wiley and sons, INC. New York.

Longely, P. A., Goodchild, M. F., Maguire, D. J and Rhind, D. W (2001): Geographical information systems: principles and technical issues (Second edition). John Wiley and sons, INC. New York.

Mutluoglu, O and Ceylan, A (2009): Accuracy and cost comparison of spatial data-acquisition methods for the development of Geographical Information Systems, “Academic Journals” Vol. 2 (9) pp. 235-242.

Thapa, K and Burtch, R. C (1991): Primary and secondary methods of data collection in GIS/LIS, “Surveys and land Information systems” Vol. 51. pp. 162-170