![]() 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. Other types of point features include the node and the vertex. 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. Points are zero-dimensional objects that contain only a single coordinate pair. ![]() Three fundamental vector types exist in geographic information systems (GISs): points, lines, and polygons (Figure 4.8). 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).Aronoff, S. 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. The objective of this section is to understand how vector data models are implemented in GIS applications.
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