GIS - Essay Example

Download file to see previous pages Inherent errors are normally witnessed in source data and documents. Operational errors on the other hand result from GIS manipulation functions and data capture. Possible operational errors sources include; digitizing human error, thematic maps areas mis-labelling, horizontal boundaries misplacement, classified error, human bias and inaccuracies in GIS algorithms. The main of GIS processing is to identify the possible error in data sources as well as minimizing the error amount resulting from the processing. Cost constraints make it easier to avoid errors rather than eliminating them afterwards. A GIS (geographical information system) is a tool that is computerised and is used for both mapping and analysis of existing geographical phenomenon and occurring events on the Earth surface. The technology behind GIS entails the integration of operations of common database like statistical and query analysis with exceptional geographical analysis and visualization benefits provided by maps. It is this ability that makes GIS stand out from the rest of information systems and makes it valuable to most of the private and public enterprises in predicting outcomes and explaining events strategy planning. Data accuracy mostly depends on the original input data quality as well as its precision when the data is being processed. This follows the many states in which inaccuracies and errors may occur within the GIS database. The most common sources of errors include; field measurement inaccuracies, use of equipments that are inaccurate, or in recoding procedures that are not correct. This implies that, higher accuracy calls for higher quality in the initial data and processing that is more precise. However, the two will increase the systems costs. Theoretically, the quality of GIS data is a comprise between the cost involved and the needs. Practically, the choice goes down to what is available at that time or what is acquirable in a reasonable cost or amount of time. The two will determine the quality of working level of a given dataset. DIGITIZING АND SCАNNING OF MАPS Maps are often scanned so as to make use digital data as their bases for other information on vector map as well as to have the scanned data converted to vector data which can be used in vector GIS. For scanning to be successful, the map to be scanned has to have clear defined text, lines and symbols; be of good quality, be free from extraneous strains and have their width lines being greater than 0.1 mm (Bolstad, 2005). The scanning process consists of binary encoding and scanning. In normal cases, scanning results in an 8-bit gray scale regular pixel.Pixels appear in columns and rows and every pixel coordinates are normally identified by the row and column number after which the number is converted to normal coordinates using transformation process. Now that maps that have been scanned do not have any information on the area structures or inner linear (Bolstad, 2005), it is impossible to associate attributes to structures in an effort to define whether the landmark in question is a river or roads. Reclassification involving cells grouping can be conducted on the maps that have already been scanned. Maps that have been ...Download file to see next pagesRead More