GIS DATA FORMATS, DATA SOURCES AND COST
GIS datasets formats
Typical formats of data sets, which allow you to conveniently work with multiple information or map layers, include spatial and attribute data.
Spatial data comes in the forms of raster and vector and is generally organized into so-called
layers or thematic maps.
Raster data is digital image composed by rectangular grids or cells that contain numeric information from a defined range to characterize geographic features. Digital Elevation
Model (DEM) is a form of raster data important in depicting a terrain. It provides crucial information on the topologies of a geographic span.
Vector or shapefile data is constructed as points, lines, and polygons to represent geographical features.
Attribute data is information used to describe characteristics of a locale . The data is organized
in a table containing information linked to a spatial feature by a common identifier. This gives you details or certain types of information associated with each specific feature.
GIS data sources
GIS data is vastly available from many sources,including those in public domains at local, state and federal agencies; international non-governmental organizations or NGOs; and private sector providers.
Each agency supplies relevant datasets pertaining to their line of work. Some of the main providers include: National Oceanic
and Atmospheric Administration (NOAA) for extensive National Weather Service datasets; United States Geological Survey (USGS) for DEMs, administrative boundaries, land cover, soil, and water data; United States Environmental Protection Agency (EPA) for toxic and cleanup
sites; and Census Bureau for demographic and socioeconomic data, which contains a wide range of attributes detailed to the block level. State agencies, have established a central clearing house for state-level datasets.
With increasing demand for GIS in solving various problems, many counties and cities have initiated GIS departments, which oversee and provide relevant geographic data to inquirers.
Cost of the data
Different agencies provide the data at a fee while others give out the data to you freely. Another factor to determine the cost of the data is the type of data that you require, i.e. high resolution satellite images would cost high compared to low resolution images.
Typical formats of data sets, which allow you to conveniently work with multiple information or map layers, include spatial and attribute data.
Spatial data comes in the forms of raster and vector and is generally organized into so-called
layers or thematic maps.
Raster data is digital image composed by rectangular grids or cells that contain numeric information from a defined range to characterize geographic features. Digital Elevation
Model (DEM) is a form of raster data important in depicting a terrain. It provides crucial information on the topologies of a geographic span.
Vector or shapefile data is constructed as points, lines, and polygons to represent geographical features.
Attribute data is information used to describe characteristics of a locale . The data is organized
in a table containing information linked to a spatial feature by a common identifier. This gives you details or certain types of information associated with each specific feature.
GIS data sources
GIS data is vastly available from many sources,including those in public domains at local, state and federal agencies; international non-governmental organizations or NGOs; and private sector providers.
Each agency supplies relevant datasets pertaining to their line of work. Some of the main providers include: National Oceanic
and Atmospheric Administration (NOAA) for extensive National Weather Service datasets; United States Geological Survey (USGS) for DEMs, administrative boundaries, land cover, soil, and water data; United States Environmental Protection Agency (EPA) for toxic and cleanup
sites; and Census Bureau for demographic and socioeconomic data, which contains a wide range of attributes detailed to the block level. State agencies, have established a central clearing house for state-level datasets.
With increasing demand for GIS in solving various problems, many counties and cities have initiated GIS departments, which oversee and provide relevant geographic data to inquirers.
Cost of the data
Different agencies provide the data at a fee while others give out the data to you freely. Another factor to determine the cost of the data is the type of data that you require, i.e. high resolution satellite images would cost high compared to low resolution images.
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