US Land Grid provides our data in multiple file formats and web mapping streams.
Listing and descriptions for the invidividual field attributes you find in data.
Data and Projection.
Modification and creation dates.
We provide our pre-pocessed data in two datums - Lat/Long NAD27 and Lat/Long NAD83. If you need your data in a different datum and/or a specific projection (eg. NAD27/State Plane) please make your request after placing your order by contacting us at email@example.com. There is no charge for this service.
In a GIS, geographical features are often expressed as vectors, by considering those features as geometrical shapes. Different geographical features are expressed by different types of geometry:
A simple vector map, using each of the vector elements: points for wells, lines for rivers, and a polygon for the lake.
Zero-dimensional points are used for geographical features that can best be expressed by a single point reference—in other words, by simple location. Examples include wells, peaks, features of interest, and trailheads. Points convey the least amount of information of these file types. Points can also be used to represent areas when displayed at a small scale. For example, cities on a map of the world might be represented by points rather than polygons. No measurements are possible with point features.
Lines or polylines
One-dimensional lines or polylines are used for linear features such as rivers, roads, railroads, trails, and topographic lines. Again, as with point features, linear features displayed at a small scale will be represented as linear features rather than as a polygon. Line features can measure distance.
Two-dimensional polygons are used for geographical features that cover a particular area of the earth's surface. Such features may include lakes, park boundaries, buildings, city boundaries, or land uses. Polygons convey the most amount of information of the file types. Polygon features can measure perimeter and area.
Each of these geometries are linked to a row in a database that describes their attributes. For example, a database that describes lakes may contain a lake's depth, water quality, pollution level. This information can be used to make a map to describe a particular attribute of the dataset. For example, lakes could be coloured depending on level of pollution. Different geometries can also be compared. For example, the GIS could be used to identify all wells (point geometry) that are within one kilometre of a lake (polygon geometry) that has a high level of pollution.
Vector features can be made to respect spatial integrity through the application of topology rules such as 'polygons must not overlap'. Vector data can also be used to represent continuously varying phenomena. Contour lines and triangulated irregular networks (TIN) are used to represent elevation or other continuously changing values. TINs record values at point locations, which are connected by lines to form an irregular mesh of triangles. The face of the triangles represent the terrain surface.
AutoCAD DXF - contour elevation plots in AutoCAD DXF format (by Autodesk)
Coverage - Esri's closed, hybrid vector data storage strategy. Legacy ArcGIS Workstation / ArcInfo format with reduced support in ArcGIS Desktop lineup
Digital Line Graph (DLG) - a USGS format for vector data
Enterprise Geodatabase - Esri's geodatabase format for use in an RDBMS
File Geodatabase - Esri's file-based geodatabase format, stored as folders in a file system
Geography Markup Language (GML) - XML based open standard (by OpenGIS) for GIS data exchange
GeoJSON - a lightweight format based on JSON, used by many open source GIS packages
GeoMedia - Intergraph's Microsoft Access based format for spatial vector storage
ISFC - Intergraph's MicroStation based CAD solution attaching vector elements to a relational Microsoft Access database
Keyhole Markup Language (KML) - XML based open standard (by OpenGIS) for GIS data exchange
MapInfo TAB format - MapInfo's vector data format using TAB, DAT, ID and MAP files
Personal Geodatabase - Esri's closed, integrated vector data storage strategy using Microsoft's Access MDB format
Shapefile - Esri's open, hybrid vector data format using SHP, SHX and DBF files
Simple Features - Open Geospatial Consortium specification for vector data
SOSI_Standard - a spatial data format used for all public exchange of spatial data in Norway
Spatial Data File - Autodesk's high-performance geodatabase format, native to MapGuide
TIGER - Topologically Integrated Geographic Encoding and Referencing
ADRG - National Geospatial-Intelligence Agency (NGA)'s ARC Digitized Raster Graphics
BIL - Band Interleaved by Line (image format linked with satellite derived imagery)
CADRG - National Geospatial-Intelligence Agency (NGA)'s Compressed ARC Digitised Raster Graphics (nominal compression of 55:1 over ADRG)
CIB - National Geospatial-Intelligence Agency (NGA)'s Controlled Image Base (type of Raster Product Format)
Digital raster graphic (DRG) - digital scan of a paper USGS topographic map
ECRG - National Geospatial-Intelligence Agency (NGA)'s Enhanced Compressed ARC Raster Graphics (Better resolution than CADRG and no color loss)
ECW - Enhanced Compressed Wavelet (from ERDAS). A compressed wavelet format, often lossy.
Esri grid - proprietary binary and metadataless ASCII raster formats used by Esri
GeoTIFF - TIFF variant enriched with GIS relevant metadata
IMG - ERDAS IMAGINE image file format
JPEG2000 - Open-source raster format. A compressed format, allows both lossy and lossless compression.
MrSID - Multi-Resolution Seamless Image Database (by Lizardtech). A compressed wavelet format, allows both lossy and lossless compression.
netCDF-CF - netCDF file format with CF medata conventions for earth science data. Binary storage in open format with optional compression. Allows for direct web-access of subsets/aggregations of maps through OPeNDAP protocol.