|Date(s):||Coverage Availability/Geographic Extent:||Footprint:||Source(s):|
|2008||Texas-Mexico Border||US National Grid||USGS|
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Orthoimagery - Regional
|Available Formats:||GeoTiff, JPEG 2000|
An orthoimage is remotely sensed image data in which displacement of features in the image caused by terrain relief and sensor orientation have been mathematically removed. Orthoimagery combines the image characteristics of a photograph with the geometric qualities of a map. For this dataset, the natural color orthoimages were produced at 0.3-meter pixel resolution (approximately 1-foot). The design accuracy is estimated not to exceed 6 meter horizontal RMSE for locations within the United States.
Each orthoimage provides imagery for a 1500-meter by 1500-meter block on the ground. The projected coordinate system is UTM with a NAD83 datum, spheroid GRS80. There is no image overlap between adjacent files. The naming convention is based on the U.S. National Grid (USNG), taking the coordinates of the SW corner of the orthoimage.
These data have been created as a result of the need for having geospatial data immediately available and easily accessible in order to provide geographic reference for federal, state, and local emergency responders, as well as for homeland security efforts. Orthoimages also serve a variety of purposes, from interim maps to field references for earth science investigations and analysis. The digital orthoimage is useful as a layer of a geographic information system. These data can be used to provide reference information for web browsers and for map applications at a scale of 1:100:000 or smaller.