From the course: Foundations of Geographic Information Systems (GIS)

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Evaluating spatial relationships

Evaluating spatial relationships - GIS Tutorial

From the course: Foundations of Geographic Information Systems (GIS)

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Evaluating spatial relationships

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If you want to know how many six-inch water lines are in your city, query a database. If you want to know where the six-inch water lines are that are in danger of corroding from running through highly acidic soils, ask a GIS. Because location is a part of every GIS data set, your GIS knows what things are near each other, what things intersect, and even which polygons contain which points on the ground. So in the case of water lines, what you'd really be doing is giving your GIS a water line and a soils layer and asking the GIS to find all the water lines that intersect the acidic soil polygons. Intersects are one of the many spatial relationships that GIS is able to understand, such as within a distance of, contains, are contained by, and shares a boundary with. Let me show you a map of Louisville, Kentucky. It's got fire district polygons on it. And when you zoom in, you can see there are address points. Suppose the fire chief wants to know how many homes and businesses the…

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