Layer: 2012 Impervious Surface (ID: 1)

Name: 2012 Impervious Surface

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Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN>The State’s first Impervious Surface (IS) dataset was created as a by-product of the previous vendor’s “change detection” image processing update methodology. The resulting impervious surface data, while not of the highest accuracy, was deemed an acceptable representation of IS in the state. The impervious surface data for the 2012 Update was produced to the same level as the State’s previous datasets, per the project requirements. The work was performed by Aerial Information Systems, Inc. (AIS), located in Redlands, California. The 2012 Impervious Surface data layer was created using a combination of Automated Feature Extraction (AFE) techniques and ArcGIS raster data editing tools. Approximately 2,000 image tiles provided complete coverage of the State. These images were composed of four bands (red, blue, green and IR) at a resolution of 1 foot (0.33 meter). The automated feature extraction involved a number of processing steps and the use of two software products: Genie Pro 2.4, by Obervera, Inc., was used to perform the automated feature extraction and Esri’s ArcGIS was used to perform image cleanup and editing tasks. Using Genie Pro 2.4, training sets and solution files were created and prepared on a representative sample of image tiles. Then the training sets and solution files were combined into one master solution file. Using a python script, all image tiles were processed with the master solution file to create new image tiles. Each of the new image tiles was reviewed to verify that processing step was successfully completed. Where processing problems occurred, the image tiles were re-processed. The analyst revised the original training sets and created new solution files to produce a new result image tile. This process was repeated until the processing errors were corrected. Using ArcMap raster processing tools, four raster catalogs were created which closely matched the extent of the 2007 Impervious Surface raster images. Each of these layers were made up of approximately 500 image tiles. The following series of processing steps were run on each of the four layers: The images were resampled from 0.33 meters to match the 1 meter resolution of the original 2007 IS data. Small mis-identified pixels were removed from each of the four images by running them through the following five processes: Majority Filter, Boundary Clean, Region Group, Set Null, and Nibble. The analyst performed a manual review and edit of each image using ArcMap and the ArcScan extension. The final Impervious Surface geodatabase was created and each of the four regional impervious surface raster data files were imported to the geodatabase.</SPAN></P></DIV></DIV></DIV>

Service Item Id: 3406f2d7ad6e4d00af7f6e65f6311020

Copyright Text: Mapped by Aerial Information Systems, Inc. of Redlands, California for the Delaware Office of State Planning

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