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GIS (Geographic Information System) professionals recognize that imagery is essential for understanding what is happening in the world, learning how the environment is changing, and giving context to other types of data. Image availability, the power of its information content and the number of dissemination methods are rapidly increasing. While digital orthophotography is an essential element in a GIS professional’s geospatial data store, high resolution color and multispectral satellite imagery is also coming into common use. As the spatial and spectral fidelity of these sources improve, so does the ability to extract information important to GIS professionals. One of the most common applications is the use of imagery as a data source to populate, update and assess the quality of GIS databases. Map accurate orthophotos or satellite images are used to collect (digitize) features such as road centerlines, land use areas, building footprints and utility infrastructure. Up-to-date imagery makes it easy to identify areas of development not yet captured in the GIS database. Automated image processing methods tailored for feature extraction can be used to reduce the effort of often tedious digitizing tasks of this type. Other applications exploit the spectral content of the imagery to accomplish land use and land cover mapping; measure, monitor and assess environmental conditions; assess the condition of pavement and other public works assets; and identify building materials. Change detection is also possible when imagery is collected over time. The knowledge gained from these analyses is invaluable as input to land development models and forecasts, environmental impact statements, asset management budgets and reports for communicating important issues to community constituents. A major focus of recent and future ENVI development is providing tools and methods to extract information from images, and to then integrate these results with GIS databases. ENVI currently has many tools for these purposes, including workflows for common image processing tasks for GIS professionals, converting to and editing common vector data formats, and geodatabase support. Moreover, upcoming releases will improve and add to these capabilities. In the most recent version of ENVI, 4.7, there are even more tools to support a variety of GIS image processing tasks, using panchromatic, multispectral, or hyperspectral data. These efficient workflow tools include Change Detection, Image Classification, Orthorectification, Feature Extraction, and the SPEAR Tools, a suite of wizards for performing common image processing tasks. Other GIS functionality in ENVI includes the capability to create maps and reports from existing map templates and the ability to drag and drop layer files between ENVI and ArcGIS.
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