![]() Lines are used to represent linear features such as roads, streams, faults, boundaries. Lines are one-dimensional features 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. 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. Points are zero-dimensional objects that contain only a single coordinate pair. Three fundamental vector types exist in geographic information systems (GIS): 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 on a map. The data attributes of these features are then stored in a separate database management system. 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. 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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