![]() ![]() ![]() ![]() Some vector formats can store structures such as multi-part polygons (e.g., the State of Hawaii). Polygon (2-dimensional): only the boundary is represented (the software is expected to accurate interpolate all of the interior points) as a line that closes: P =.Some vector formats are able to store more complex linear structures, such as multilines (single features consisting of multiple line segments) and various forms of parametric curves. Line (1-dimensional): represented by an ordered list of points (known in this context as |vertices): l =.In some vector formats, multipoint features are allowed, in which a single feature consists of multiple coordinates three-dimensional points (x,y,z) are another common feature. Point (0-dimensional): represented by a single coordinate: p = (x,y).Traditionally, there are three geometric primitives: points, lines, and polygons. The basic structures ( geometric primitives) available for describing the represented geometry of a feature depend on the Dimension of the feature (or at least, the dimension chosen to represent it). Most Vector data formats use standard relational database technology to store the attributes, but need GIS-specific data structures to store the geometry. Usually, related features (for example, all of the road features in a county) are grouped into a single dataset. The basic framework of the model is to describe each needed feature by its geometry (location and shape) and attributes (also known as properties or characteristics). ![]()
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