<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE metadata SYSTEM "http://thor-f5.er.usgs.gov/ngtoc/metadata/fgdc-std-001-1998.dtd">
<metadata>
  <idinfo>
    <citation>
      <citeinfo>
        <origin>U.S. Geological Survey</origin>
        <pubdate>20141010</pubdate>
        <title>NLCD 2001 Percent Developed Imperviousness (2011 Edition, amended 2014) - National Geospatial Data Asset (NGDA) Land Use Land Cover, 3 x 3 Degree: NLCD2001_IMP_N30W102</title>
        <edition>2011</edition>
        <geoform>remote-sensing image</geoform>
        <serinfo>
          <sername>None</sername>
          <issue>None</issue>
        </serinfo>
        <pubinfo>
          <pubplace>Sioux Falls, SD</pubplace>
          <publish>U.S. Geological Survey</publish>
        </pubinfo>
        <othercit>References:
Yang, L, C. Huang, C. Homer, B. Wylie, and M. Coan, 2003. An approach for mapping large-area impervious surfaces:  Synergistic use of Landsat 7 ETM+ and high spatial resolution imagery.  Canadian Journal of Remote Sensing, 29: 2, 230-240.
Homer, C., C. Huang, L. Yang, B. Wylie and M. Coan, 2004. Development of a 2001 national land cover database for the United States.  Photogrammetric Engineering and Remote Sensing.</othercit>
        <onlink>http://gisdata.usgs.gov/tdds/downloadfile.php?TYPE=nlcd2001_imp_3x3&amp;ORIG=META&amp;FNAME=NLCD2001_IMP_N30W102.zip</onlink>
        <onlink>http://tdds.cr.usgs.gov/metadata/nlcd/2001/impervious/conus/NLCD2001_IMP_N30W102.htm</onlink>
        <onlink>http://nationalmap.gov/viewer.html</onlink>
      </citeinfo>
    </citation>
    <descript>
      <abstract>The National Land Cover Database 2001 Percent Developed Imperviousness was produced through a cooperative project conducted by the Multi-Resolution Land Characteristics (MRLC) Consortium.  The MRLC Consortium is a partnership of federal agencies (www.mrlc.gov), consisting of the U.S. Geological Survey (USGS), the National Oceanic and Atmospheric Administration (NOAA), the U.S. Environmental Protection Agency (EPA), the U.S. Department of Agriculture - Forest Service (USDA-FS), the National Park Service (NPS), the U.S. Fish and Wildlife Service (FWS), the Bureau of Land Management (BLM) and the USDA Natural Resources Conservation Service (NRCS).

One of the primary goals of the project is to generate a current, consistent, seamless, and accurate National Land Cover Database (NLCD) circa 2001 for the United States at medium spatial resolution.  For a detailed definition and discussion on MRLC and the NLCD 2001 products, refer to Homer et al. (2003) and http://www.mrlc.gov/mrlc2k.asp.

The NLCD 2001 was created by partitioning the U.S. into mapping zones.  A total of 66 mapping zones were delineated within the conterminous U.S. based on ecoregion and geographical characteristics, edge-matching features and the size requirement of Landsat mosaics.  This update represents a seamless assembly of updated NLCD 2001 Percent Developed Imperviousness for all 66 MRLC mapping zones.  Questions about the NLCD 2001 Percent Developed Imperviousness 2011 Edition can be directed to the NLCD 2001 land cover mapping team at USGS EROS, Sioux Falls, SD (605) 594-6151 or mrlc@usgs.gov.</abstract>
      <purpose>The goal of this project is to provide the Nation with complete, current and consistent public domain information on its land use and land cover.</purpose>
      <supplinf>Corner Coordinates (center of pixel, projection meters)
Upper Left Corner:   -2493045 meters(X),  3310005 meters(Y)
Lower Right Corner:  -177285 meters(X),  2342655 meters(Y)</supplinf>
    </descript>
    <timeperd>
      <timeinfo>
        <rngdates>
          <begdate>19990428</begdate>
          <enddate>20040726</enddate>
        </rngdates>
      </timeinfo>
      <current>ground condition</current>
    </timeperd>
    <status>
      <progress>Complete</progress>
      <update>Every 5 years</update>
    </status>
    <spdom>
      <bounding>
        <westbc>-105</westbc>
        <eastbc>-102</eastbc>
        <northbc>33</northbc>
        <southbc>30</southbc>
      </bounding>
    </spdom>
    <keywords>
      <theme>
        <themekt>NGDA Portfolio Themes</themekt>
        <themekey>NGDA</themekey>
        <themekey>National Geospatial Data Asset</themekey>
        <themekey>Land Use Land Cover Theme</themekey>
      </theme>
      <theme>
        <themekt>None</themekt>
        <themekey>Imperviousness</themekey>
        <themekey>GIS</themekey>
        <themekey>U.S. Geological Survey</themekey>
        <themekey>USGS</themekey>
        <themekey>digital spatial data</themekey>
      </theme>
      <theme>
        <themekt>ISO 19115 Topic Category</themekt>
        <themekey>imageryBaseMapsEarthCover</themekey>
        <themekey>010</themekey>
      </theme>
      <place>
        <placekt>U.S. Department of Commerce, 1995, Countries, dependencies, areas of special sovereignty, and their principal administrative divisions, Federal Information Processing Standard 10-4,): Washington, D.C., National Institute of Standards and Technology</placekt>
        <placekey>United States</placekey>
        <placekey>U.S.</placekey>
        <placekey>US</placekey>
      </place>
    </keywords>
    <accconst>None</accconst>
    <useconst>None</useconst>
    <ptcontac>
      <cntinfo>
        <cntorgp>
          <cntorg>U.S. Geological Survey</cntorg>
        </cntorgp>
        <cntpos>Customer Services Representative</cntpos>
        <cntaddr>
          <addrtype>mailing and physical</addrtype>
          <address>USGS EROS</address>
          <address>47914 252nd Street</address>
          <city>Sioux Falls</city>
          <state>SD</state>
          <postal>57198-0001</postal>
          <country>USA</country>
        </cntaddr>
        <cntvoice>605/594-6151</cntvoice>
        <cnttdd>605/594-6933</cnttdd>
        <cntfax>605/594-6589</cntfax>
        <cntemail>custserv@usgs.gov</cntemail>
        <hours>0800 - 1600 CT, M - F (-6h CST/-5h CDT GMT)</hours>
        <cntinst>The USGS point of contact is for questions relating to the data display and download from this web site.  For questions regarding data content and quality, refer to:
http://www.mrlc.gov/mrlc2k.asp or email:  mrlc@usgs.gov</cntinst>
      </cntinfo>
    </ptcontac>
    <browse>
      <browsen>http://tdds.cr.usgs.gov/browse/nlcd/2001/impervious/conus/NLCD2001_IMP_N30W102.jpg</browsen>
      <browsed>Tiled NLCD Browse Image</browsed>
      <browset>JPEG</browset>
    </browse>
    <datacred>U.S. Geological Survey</datacred>
    <secinfo>
      <secsys>None</secsys>
      <secclass>Unclassified</secclass>
      <sechandl>N/A</sechandl>
    </secinfo>
    <native>Microsoft Windows 7 Version 6.1 (Build 7601) Service Pack 1; ESRI ArcCatalog 9.3.1.4000</native>
  </idinfo>
  <dataqual>
    <attracc>
      <attraccr>The information on data quality for NLCD 2001 Percent Developed Imperviousness 2011 Edition seamless data product was generated by the Regression Tree algorithm that conducts a cross-validation for assessing classification and prediction reliability.  No formal independent accuracy assessment for this product has been made.  The regression tree algorithm employed in NLCD 2001 mapping protocols offers a cross-validation option for assessing classification and prediction reliability.  Cross-validation can provide relatively reliable estimates for imperviousness predictions if the reference data used for cross-validation are collected based on a statistically valid sampling design.  For each mapping zone, a 5-fold cross-validation was conducted by dividing the entire training data set into 5 subsets of equal size.  For each model run, an accuracy estimate was derived using one subset to evaluate the model prediction (with the model developed using the remaining training samples).  This process was repeated 5 times.  After all 5 runs, an average value of all accuracy estimates from the 5 runs was computed.  Users should be cautioned that these cross-validation results provide users with only first-order estimates of data quality, and should not be considered a formal accuracy assessment.</attraccr>
      <qattracc>
        <attraccv>87.6</attraccv>
        <attracce>The above listed value is the mean accuracy obtained for imperviousness data in cross-validation studies for all 66 MRLC Zones.  The table below provides individual zone accuracy values derived from protocols described in the accuracy report above.
MRLC
Zone  Imperviousness Accuracy
1      86.2
2      86.7
3      89
4      90
5      85.8
6      90
7      83
8      86.7
9      85.6
10     86.1
12    85.4
13    89.5
14    93
15    93
16    80
17    87
18    88.1
19    82
20    87.3
21    92.7
22    83.8
23    85
24    87
25    88
26    91
27    90
28    86
29    89
30    88.2
31    85.6
32    91.8
33    90
34    87
35    91
36    88
37a   91
37b   91
38    89
39    88.2
40    86.5
41    85.8
42    86.5
43    85.4
44    92
45    95
46a   86
46b   86
47    81
48    85
49    85
50    90
51    89
52    88
53    71
54    84
55    85
56    90
57    84
58    82
59    86
60    91
61    86.5
62    90.5
63    95
64    93
65    92
66    88</attracce>
      </qattracc>
    </attracc>
    <logic>The method employed to map percent developed imperviousness for NLCD 2001 consists of three key steps: deriving reference data of imperviousness from the high spatial resolution images, calibrating density prediction models using reference data and Landsat spectral bands, and extrapolating the developed models spatially to map per-pixel imperviousness.</logic>
    <complete>This NLCD 2001 Percent Developed Imperviousness data product is the version dated October 10, 2014.</complete>
    <posacc>
      <horizpa>
        <horizpar>N/A</horizpar>
      </horizpa>
      <vertacc>
        <vertaccr>N/A</vertaccr>
      </vertacc>
    </posacc>
    <lineage>
      <procstep>
        <procdesc>The method employed to map percent developed imperviousness for NLCD 2001 consists of three key steps: deriving reference data of imperviousness from the high spatial resolution images, calibrating density prediction models using reference data and Landsat spectral bands, and extrapolating the developed models spatially to map per-pixel imperviousness.  This method is described in detail in Yang et al. (2003).</procdesc>
        <procdate>Unknown</procdate>
      </procstep>
      <procstep>
        <procdesc>To develop adequate training data for impervious estimation, approximately 20 DOQQ's across each mapping zone with a nominal spatial resolution of 1-m were classified into either pervious or non-pervious surfaces, and then summed within each 30 meter Landsat pixel cell to obtain percentage of imperviousness. Training data were selected based on the degree of variance each training data set possesses with regards to Landsat ETM+ imagery used for mapping.  Each added training data set decreased the amount of variance present within the Landsat data as a whole.  The selection process was repeated until the amount of variance explained reached a pre-defined threshold.
By combining the training data with Landsat spectral data and other ancillary data, percent imperviousness prediction models were developed using a regression tree algorithm (named "Cubist").   All data layers used as input for running the Cubist, in order to establish the prediction model for imperviousness are listed in the "Supplemental Information" section.  Three ancillary data sets were used for urban/suburban delineation masking, which is essential to confine the imperviousness mapping within the developed areas.
After the best combination of possible input data layers had been determined and the final percent impervious layer produced, the urban mask created was used to eliminate those pixels from the final percent impervious file that fall outside identified impervious surface areas.  Thus, the impervious pixels identified within the mask were retained, while all non-impervious surface pixels were removed from the final product.  This corrected for any small areas of pixels that may have been included as part of the impervious surface layer because their spectral signature was not covered in the Cubist modeling process.  Finally, visual inspection of imperviousness layer was made with limited manual editing to eliminate non-urban areas based on area of interest delineated by the mapping team.
For Landsat Scene Acquisition dates and identification numbers for imagery used in the NLCD 2001 land, please see:  appendix2_nlcd2001_scene_list_by_zone.txt</procdesc>
        <srcused>Landsat ETM, DEM</srcused>
        <procdate>Unknown</procdate>
        <srcprod>USGS NLCD</srcprod>
      </procstep>
      <procstep>
        <procdesc>NLCD 2001 Impervious (2011 Edition) Processing
To improve NLCD imperviousness the 2011 project included a process to reduce omission and commission error in NLCD 2001, 2006, and 2011 products.  This activity was completed for urban areas in most of the eastern  of the conterminous United States.  High resolution (one-meter ground sample distance) National Aerial Imagery Program (NAIP  http://fsa.usda.gov/FSA/) imagery was used to verify imperviousness.  Using hand-edits imperviousness was removed from areas incorrectly identified as developed and added to areas where developed land cover was missed.  A modeling process was implemented to parse imperviousness changes to the correct era.  These improvements were incorporated with the derived developed classes in all areas of imperviousness and land cover versions released with NLCD 2011 editions.</procdesc>
        <procdate>Unknown</procdate>
      </procstep>
      <procstep>
        <procdesc>Process Step for NLCD 2001 Percent Developed Imperviousness (2011 edition, amended 2014):
The release in 2014 of amended versions of Imperviousness for 2001, 2006, and 2011 was made to correct for unintended differences between the impervious dataset and the four land cover developed classes (Open Space, Low Intensity, Medium Intensity, and High Intensity). NLCD developed classes are tied directly to the impervious product values.  However, the land cover product Minimum Mapping Unit (MMU) is five pixels whereas the impervious product MMU is single pixel.  This MMU difference creates problems when the impervious single pixel MMU product is directly crosswalked into the 5-pixel MMU land cover developed classes.  The smoothing process, which generalizes the land cover product to a 5-pixel MMU, can create small areas which are no longer directly represented in the imperviousness product because they are artifacts of the smoothing.  Since these changes are not real and not present in the impervious layer, the new version removes these artifacts and re-establishes the direct linkage between the imperviousness and land cover products for any developed area.  Combined developed areas (all developed classes combined into a group) in the land cover product must still meet the 5-pixel MMU threshold; however, the four NLCD land cover individual developed classes within the group patch are now represented by a single pixel MMU to retain the direct linkage to the imperviousness product.</procdesc>
        <procdate>Unknown</procdate>
      </procstep>
    </lineage>
  </dataqual>
  <spdoinfo>
    <direct>Raster</direct>
    <rastinfo>
      <rasttype>Pixel</rasttype>
      <rowcount>11842</rowcount>
      <colcount>10312</colcount>
      <vrtcount>1</vrtcount>
    </rastinfo>
  </spdoinfo>
  <spref>
    <horizsys>
      <planar>
        <mapproj>
          <mapprojn>Albers Conical Equal Area</mapprojn>
          <albers>
            <stdparll>29.500000</stdparll>
            <stdparll>45.500000</stdparll>
            <longcm>-96.000000</longcm>
            <latprjo>23.000000</latprjo>
            <feast>0.000000</feast>
            <fnorth>0.000000</fnorth>
          </albers>
        </mapproj>
        <planci>
          <plance>row and column</plance>
          <coordrep>
            <absres>30.000000</absres>
            <ordres>30.000000</ordres>
          </coordrep>
          <plandu>meters</plandu>
        </planci>
      </planar>
      <geodetic>
        <horizdn>North American Datum of 1983</horizdn>
        <ellips>Geodetic Reference System 80</ellips>
        <semiaxis>6378137.0</semiaxis>
        <denflat>298.2572221</denflat>
      </geodetic>
    </horizsys>
  </spref>
  <eainfo>
    <detailed>
      <enttyp>
        <enttypl>nlcd_2001_impervious_2011_edition_2014_10_10.img.vat</enttypl>
        <enttypd>NLCD Imperviousness Layer</enttypd>
        <enttypds>National Land Cover Database 2001</enttypds>
      </enttyp>
      <attr>
        <attrlabl>ObjectID</attrlabl>
        <attrdef>Internal feature number</attrdef>
        <attrdefs>ESRI</attrdefs>
        <attrdomv>
          <udom>Sequential unique whole numbers that are automatically generated.</udom>
        </attrdomv>
      </attr>
      <attr>
        <attrlabl>Value</attrlabl>
        <attrdef>Percent Imperviousness</attrdef>
        <attrdefs>NLCD 2001</attrdefs>
        <attrdomv>
          <rdom>
            <rdommin>0</rdommin>
            <rdommax>100</rdommax>
            <attrunit>percentage</attrunit>
            <attrmres>0.1</attrmres>
          </rdom>
        </attrdomv>
      </attr>
      <attr>
        <attrlabl>Count</attrlabl>
        <attrdef>A nominal integer value that designates the number of pixels that have each value in the file; histogram column in ERDAS Imagine raster attributes table</attrdef>
        <attrdefs>NLCD 2001</attrdefs>
        <attrdomv>
          <udom>Integer</udom>
        </attrdomv>
      </attr>
      <attr>
        <attrlabl>Red</attrlabl>
        <attrdef>Red color code for RGB slice by value for imperviousness image display purposes.  The value is arbitrarily assigned by the display software package, unless defined by user.  Standard user defined ramp for NLCD project is start color light gray, end color red.</attrdef>
        <attrdefs>NLCD 2001</attrdefs>
        <attrdomv>
          <rdom>
            <rdommin>0</rdommin>
            <rdommax>100</rdommax>
            <attrunit>CSS Color Value Percentage</attrunit>
            <attrmres>0.1</attrmres>
          </rdom>
        </attrdomv>
      </attr>
      <attr>
        <attrlabl>Green</attrlabl>
        <attrdef>Green color code for RGB slice by value for imperviousness image display purposes.  The value is arbitrarily assigned by the display software package, unless defined by user.  Standard user defined ramp for NLCD project is start color light gray, end color red.</attrdef>
        <attrdefs>NLCD 2001</attrdefs>
        <attrdomv>
          <rdom>
            <rdommin>0</rdommin>
            <rdommax>100</rdommax>
            <attrunit>CSS Color Value Percentage</attrunit>
            <attrmres>0.1</attrmres>
          </rdom>
        </attrdomv>
      </attr>
      <attr>
        <attrlabl>Blue</attrlabl>
        <attrdef>Blue color code for RGB slice by value for imperviousness image display purposes.  The value is arbitrarily assigned by the display software package, unless defined by user.  Standard user defined ramp for NLCD project is start color light gray, end color red.</attrdef>
        <attrdefs>NLCD 2001</attrdefs>
        <attrdomv>
          <rdom>
            <rdommin>0</rdommin>
            <rdommax>100</rdommax>
            <attrunit>CSS Color Value Percentage</attrunit>
            <attrmres>0.1</attrmres>
          </rdom>
        </attrdomv>
      </attr>
      <attr>
        <attrlabl>Opacity</attrlabl>
        <attrdef>A measure of how opaque, or solid, a color is displayed in a layer.</attrdef>
        <attrdefs>NLCD 2001</attrdefs>
        <attrdomv>
          <rdom>
            <rdommin>0</rdommin>
            <rdommax>100</rdommax>
            <attrunit>Percentage</attrunit>
            <attrmres>0.1</attrmres>
          </rdom>
        </attrdomv>
      </attr>
    </detailed>
    <overview>
      <eaover>Imperviousness Attributes</eaover>
      <eadetcit>Attributes defined by USGS and ESRI.</eadetcit>
    </overview>
  </eainfo>
  <distinfo>
    <distrib>
      <cntinfo>
        <cntorgp>
          <cntorg>U.S. Geological Survey</cntorg>
        </cntorgp>
        <cntpos>Customer Services Representative</cntpos>
        <cntaddr>
          <addrtype>mailing and physical</addrtype>
          <address>USGS National Geospatial Program Office</address>
          <address>12201 Sunrise Valley Drive</address>
          <city>Reston</city>
          <state>VA</state>
          <postal>20192</postal>
          <country>USA</country>
        </cntaddr>
        <cntvoice>1-888-ASK-USGS (1-888-275-8747)</cntvoice>
        <cntemail>tnm_help@usgs.gov</cntemail>
        <hours>Monday through Friday 8:00 AM to 4:00 PM Eastern Time Zone USA</hours>
        <cntinst>Please visit http://www.usgs.gov/ask/ to contact us.</cntinst>
      </cntinfo>
    </distrib>
    <resdesc>Downloadable Data</resdesc>
    <distliab>Although these data have been processed successfully on a computer system at the USGS, no warranty expressed or implied is made by the USGS regarding the use of the data on any other system, nor does the act of distribution constitute any such warranty.  Data may have been compiled from various outside sources.  Spatial information may not meet National Map Accuracy Standards.  This information may be updated without notification. The USGS shall not be liable for any activity involving these data, installation, fitness of the data for a particular purpose, its use, or analyses results.</distliab>
    <stdorder>
      <digform>
        <digtinfo>
          <formname>TIFF</formname>
          <transize>10.244831</transize>
        </digtinfo>
        <digtopt>
          <onlinopt>
            <computer>
              <networka>
                <networkr>http://gisdata.usgs.gov/tdds/downloadfile.php?TYPE=nlcd2001_imp_3x3&amp;ORIG=META&amp;FNAME=NLCD2001_IMP_N30W102.zip</networkr>
              </networka>
            </computer>
            <accinstr>The URL http://nationalmap.gov/viewer.html provides a map interface that allows for viewing and data downloads within a customer defined area of interest. Zoom tools are available that can be used to investigate areas of interest on the map interface. The download tool allows the customer to capture layers from the map, utilizing The National Map process for downloading. The file can be unzipped and imported into various user software applications.</accinstr>
            <oncomp>Not available for dissemination</oncomp>
          </onlinopt>
        </digtopt>
      </digform>
      <fees>None</fees>
      <turnarnd>Variable</turnarnd>
    </stdorder>
    <techpreq>ESRI ArcGIS Suite and/or Arc/Info or other compatible software, and supporting operating systems</techpreq>
    <availabl>
      <timeinfo>
        <rngdates>
          <begdate>2014</begdate>
          <enddate>Unknown</enddate>
        </rngdates>
      </timeinfo>
    </availabl>
  </distinfo>
  <metainfo>
    <metd>20141205</metd>
    <metc>
      <cntinfo>
        <cntorgp>
          <cntorg>U.S. Geological Survey</cntorg>
          <cntper>Customer Services Representative</cntper>
        </cntorgp>
        <cntpos>Customer Services Representative</cntpos>
        <cntaddr>
          <addrtype>mailing and physical</addrtype>
          <address>USGS EROS</address>
          <address>47914 252nd Street</address>
          <city>Sioux Falls</city>
          <state>SD</state>
          <postal>57198-0001</postal>
          <country>USA</country>
        </cntaddr>
        <cntvoice>605/594-6151</cntvoice>
        <cnttdd>605/594-6933</cnttdd>
        <cntfax>605/594-6589</cntfax>
        <cntemail>custserv@usgs.gov</cntemail>
        <hours>0800 - 1600 CT, M - F (-6h CST/-5h CDT GMT)</hours>
      </cntinfo>
    </metc>
    <metstdn>FGDC Content Standard for Digital Geospatial Metadata</metstdn>
    <metstdv>FGDC-STD-001-1998</metstdv>
    <mettc>local time</mettc>
    <metac>None</metac>
    <metuc>None</metuc>
  </metainfo>
</metadata>