Essay Geographical Information System - GIS

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GIS Geographical Information System - GIS What is GIS? GIS is an emerging method of data storage and interpretation. GIS is, simply put a database. It is many tables of data organized by one common denominator, location. The data in a GIS system is organized spatially, or by its physical location on the base map. The information that is stored in the database is the location and attributes that exist in that base map, such as streets, highways, water lines, sewers, manholes, properties, and buildings, etc. each of these items don’t just exist in the database, the attributes associated with the item is also stored. A good example of this would be a specific sewer line, from and arbitrary point A to a point B. Ideally, the…show more content…
This is done using aerial photography (digital orthography). This type of photography is very high definition, and of consistent scale (all photographs are taken from almost exactly the same altitude). The photography that is done is difficult. Times when photographs are able to be taken are few. For instance, time is limited to the winter months due to less foliage, and from 10:00am to 2:00pm to reduce the shadows. STEP 2 - Digital Overlay Once the base maps have been acquired, the time consuming work begins. Each digital map section has to be gone over by a person on a computer. That person outlines each object to be included in the gis system. These objects are the same as the ones stated previously (like sewer lines, water lines, etc.), although they are not limited to those. Along with all of the physical information that is entered into the database, there is a lot of other physical information to be added that is not reflected on the aerials, such as property lines, tax and voting districts, as well as zoning districts. STEP 3 - Data entry Following the design and creation of the basic data skeleton, the actual data need be entered. This includes all of the attribute data for all hydrants, sewer lines, water lines, properties, buildings, streets, highways, creeks, etc. this portion of the process is the most time consuming. The bulk of the data to be entered is on paper, and there is no easy way to convert it to
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