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The USGS Gap Analysis Program maintains four primary data sets: land cover, protected areas, species and aquatic. The GAP Land Cover Data Set is the most complete map ever produced of vegetative associations for the US. Classified into 551 ecological systems, and 32 modified ecological systems (where human impacts have had an effect).
Obtaining an accurate total of all protected land in California and elsewhere is a complex task. Many parcels have inholdings, private lands within the protected areas, which may or may not be accounted for when calculating total area. Also, occasionally one parcel of land is included in two or more inventories.
Shapefile – Esri's proprietary, hybrid vector data format using SHP, SHX and DBF files. Originally invented in the early 1990s, it is still commonly used as a widely supported interchange format. [citation needed] Enterprise Geodatabase – Esri's geodatabase format for use in an relational database system. [citation needed]
The shapefile format is a geospatial vector data format for geographic information system (GIS) software. It is developed and regulated by Esri as a mostly open specification for data interoperability among Esri and other GIS software products . [ 1 ]
TIGER includes both land features such as roads, rivers, and lakes, as well as areas such as counties, census tracts, and census blocks. Some of the geographic areas represented in TIGER are political areas, including state and federally recognized tribal lands, cities, counties, congressional districts, and school districts.
A GIS file format is a standard for encoding geographical information into a computer file, as a specialized type of file format for use in geographic information systems (GIS) and other geospatial applications. Since the 1970s, dozens of formats have been created based on various data models for various purposes
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.
U.S. Bureau of Land Management map showing the principal meridians of California. The San Bernardino meridian, established in 1852, [1] is one of three principal meridians in the state of California. Because of the state's shape, three meridian–baseline sets are required for surveys in all parts of the state.