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The TIGER files do not contain the census demographic data, but merely the geospatial/map data. GIS can be used to merge census demographics or other data sources with the TIGER files to create maps and conduct analysis. TIGER data is available without cost because U.S. Government publications are required to be released into the public domain.
US Census Bureau US basemaps and US demographic data: U.S. Gazetteer, TIGER/Line shapefiles, census data. National Historical Geographic Information System: NHGIS provides free of charge, aggregate census data and GIS-compatible boundary files for the United States between 1790 and 2012. Atlas of Historical County Boundaries Project (AHCBP)
The origin of the geodatabase was in the mid-1990s during the emergence of the first spatial databases.One early approach to integrating relational databases and GIS was the use of server middleware, a third-party program that stores the spatial data in database tables in a custom format, and translates it dynamically into a logical model that can be understood by the client software.
Esri Enterprise Geodatabase - A proprietary model for storing a geodatabase structure in a variety of commercial and open-source relational database management systems [14] GeoPackage (GPKG) – A standards-based, open format based on the SQLite database format for both vector and raster data, adopted by the Open Geospatial Consortium [ 15 ]
These changes are usually not reflected in the annual TIGER releases. Each ZCTA is constructed by aggregating the Census 2020 blocks whose addresses use a given ZIP code. In assembling census statistical units to create ZCTAs, the Census Bureau took the ZIP code used by the majority of addresses in each census unit at the time the data was ...
Some GIS software, such as ArcGIS Pro, natively supports this model, with functionality including animation. Time-stamped boundaries, using the topological vector data model to decompose polygons into boundary segments, and stamping each segment by the time during which it was valid. This method was pioneered by the Great Britain Historical GIS.
[1] [2] Much of this often happens within a spatial database; however, this is not essential to meet the definition of a GIS. [1] In a broader sense, one may consider such a system also to include human users and support staff, procedures and workflows, the body of knowledge of relevant concepts and methods, and institutional organizations.
The ARC/INFO Coverage data structure (1981), a topological data model based on POLYVRT. Topology was a very early concern for GIS. The earliest vector systems, such as the Canadian Geographic Information System, did not manage topological relationships, and problems such as sliver polygons proliferated, especially in operations such as vector overlay. [9]