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For example, a data model for a city would include a list of data layers to be included (e.g., roads, buildings, parcels, zoning), with each being specified with the type of generic spatial data model being used (e.g. raster or vector), choices of parameters such as coordinate system, and its attribute columns.
Vector data can be displayed as vector graphics used on traditional maps, whereas raster data will appear as an image that may have a blocky appearance for object boundaries. (depending on the resolution of the raster file). Vector data can be easier to register, scale, and re-project, which can simplify combining vector layers from different ...
A data model in Geographic information systems is a mathematical construct for representing geographic objects or surfaces as data. For example, the vector data model represents geography as points, lines, and polygons; the raster data model represents geography as cell matrixes that store numeric values;
Raster maps of environmental variables including soil pH, potential evapotranspiration, average snow depth, and more. Global 200: Vector data from WWF of "a set of the Earth's terrestrial, freshwater, and marine ecoregions that harbor exceptional biodiversity and are representative of its ecosystems." [7] Global Lakes and Wetlands Database
The fundamental strategy underlying the raster data model is the tessellation of a plane, into a two-dimensional array of squares, each called a cell or pixel (from "picture element"). In digital photography , the plane is the visual field as projected onto the image sensor ; in computer art , the plane is a virtual canvas; in geographic ...
A geodatabase can contain spatially referenced data in vector or raster formats, or non-spatially referenced data in tabular format. [ 27 ] [ 28 ] Each dataset contains information about any number of individual items, but typically all of the items in a dataset are of the same theme (e.g., temperature measurements, roads in a city) and have ...
Data extraction is a GIS process similar to vector overlay, though it can be used in either vector or raster data analysis. Rather than combining the properties and features of both datasets, data extraction involves using a "clip" or "mask" to extract the features of one data set that fall within the spatial extent of another dataset.
There are also many different types of geodata, including vector files, raster files, geographic databases, web files, and multi-temporal data. Spatial data or spatial information is broader class of data whose geometry is relevant but it is not necessarily georeferenced, such as in computer-aided design (CAD), see geometric modeling.