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Within the Digital Topographic Data, the following datasets are derived datasets:·
Community Facility Points
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Emergency Services Points
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Homesteads
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Shorelines
Feature Structure
In the vector data model, spatial features are represented as discrete geometric objects. These objects include points, lines, and polygons.
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Point Features: Represent singular, discrete geographic locations, or objects, encompassing specific landmarks like population centres, wells, tourist points, helipads, or monitoring stations. Point features are typically defined by a single set of x, y (and optionally, z) coordinates.
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Line Features: Portray linear or one-dimensional geographic elements such as railways, rivers, pipelines, or coastline. These features are characterized by a sequence of interconnected points.
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Polygon Feature: Capture areas or regions on the Earth's surface enclosed by one or more closed boundaries. Examples include land parcels, built-up areas and islands. Polygons are typically defined by a series of interconnected points, forming a closed shape.
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Multi-part Features: Constitute a distinct category capable of representing intricate or multipart geometries. They involve multiple interconnected points, lines, or polygons. For instance, a multi-part polygon might symbolize an island group, where each island serves as a component of the entire feature.
Feature Geometry
All features are defined spatially by their geometry type and vector coordinates. The following geometry types are supported.
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· Multi
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Table 1 - Feature geometry |
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All polygon boundaries must be closed.
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Polygon features may contain an inner set of holes or voids that can be assigned to any feature class. For example, a Lake may have in the middle of it an area of dry land (terrestrial island).