![]() ![]() In the case of polygons, the first coordinate pair (point) on the first line segment is the same as the last coordinate pair on the last line segment. Also called “areas.” are two-dimensional features created by multiple lines that loop back to create a “closed” feature. Polygons have the properties of area and perimeter. Polygons A two-dimensional feature created from multiple lines that loop back to create a “closed” feature. Lines that directly connect two nodes are sometimes referred to as chains, edges, segments, or arcs A one-dimensional object composed of multiple, explicitly connected points. Lines are used to represent linear features such as roads, streams, faults, boundaries, and so forth. Also called an “arc.” are one-dimensional features composed of multiple, explicitly connected points. Lines A one-dimensional object composed of multiple, explicitly connected points. Points can be spatially linked to form more complex features. Vertices are defined as each bend along a line or polygon feature that is not the intersection of lines or polygons. Specifically, a point is a stand-alone feature, while a node is a topological junction representing a common X, Y coordinate pair between intersecting lines and/or polygons. and the vertex A corner or a point where lines meet. Other types of point features include the node The intersection points where two or more arcs meet. Points have only the property of location. ![]() Points are typically used to model singular, discrete features such as buildings, wells, power poles, sample locations, and so forth. are zero-dimensional objects that contain only a single coordinate pair. In a GIS, points have only the property of location. Points A zero-dimensional object containing a single coordinate pair. Three fundamental vector types exist in geographic information systems (GISs): points, lines, and polygons ( Figure 4.8 "Points, Lines, and Polygons"). The spatial information and the attribute information for these models are linked via a simple identification number that is given to each feature in a map. The data attributes of these features are then stored in a separate database management system. Geographic Information Systems: A Management Perspective. Vector data models use points and their associated X, Y coordinate pairs to represent the vertices of spatial features, much as if they were being drawn on a map by hand (Aronoff 1989). In this model, space is not quantized into discrete grid cells like the raster model. In contrast to the raster data model is the vector data model.
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