readme.txt

National Land Cover Dataset (NLCD) 2001

Abstract:
This data set is one complete raster coverage of the MRLC 
National Land Cover Data (NLCD) covering the conterminous United 
States. The NLCD is composed of 16-classes, and is derived from 
Landsat 7 Enhanced Thematic Mapper, and Landsat 5 satellite data 
centered around 2001. A complete description of these data can be
found at http://www.mrlc.gov/nlcd.php.

Purpose: 
The NLCD data is distributed by the Multi-Resolution Land 
Characteristics Consortium (MRLC). CDIAC has combined the 
regional files created by the MRLC into one contiguous raster 
data file for the conterminous United States. Smaller, regional 
coverages can be downloaded directly from the 
MRLC: http://www.mrlc.gov/nlcd_multizone_map.php

Metadata:
The NLCD2001 data were downloaded from the MRLC by region 
(regions 1-14 for the conterminous U.S.). Each region (referred to as 
'areas' in the metadata) is composed of several zones. The metadata 
for this dataset corresponds to these regions and zones.  All of the 
metadata files (one for each region) are contained in the file:  
all_regions.zip. These files are compressed and are composed of 
subfolders of relevant metadata for each zone contained within a 
region. For example: area1_metadata.zip contains 
information about zones 1,2,7,8 and 9. Please refer to the graphic 
map (posted at http://cdiac.ornl.gov/datasets/spatial/NLCD2001/meta_2001.html) 
when reviewing the metadata. 

Download NLCD2001 spatial data:
The spatial data is compressed, and is provided in two different 
formats (ArcInfo and ERDAS Imagine).  Winzip 
(http://www.winzip.com) or Stuffit (http://www.stuffit.com) 
may be used to open *zip files.  Due to the size limitation in earlier 
versions of these software packages, only Winzip 9.0, Stuffit 8.5, 
or later versions are recommended to open the zip files distributed here.

1. ESRI ArcInfo Grid. The unzipped files are approximately 2.68GB.
The zipfile contains two directories: info, and nlcd_2001. Please retain the native directory structure of these files after they have been uncompressed. 
ArcInfo Grid file: nlcd2001arc.zip (1.14GB)

2. ERDAS Imagine. The unzipped files are approximately 28GB.
Imagine file: nlcd2001img.zip (1.17GB)

Processing:
Regional files were downloaded individually from the MRLC as Imagine image 
files.  These files were decompressed and read into ArcMap v.9.2.  These 
data are in an Albers Conical Equal Area projection using the Clarke1866 
datum.  Imagine files were converted to ArcInfo Grid files using ArcInfo 
Workstation v9.2. Pixels lying outside of the region/zone of interest 
were coded with a "127".  These values were reclassified as NODATA values 
prior to merging the regions.  The 14 regional files were merged into 3 larger
files using ArcInfo Workstation 9.2.  The final merging was done using the
Mosaic tool in ArcMap Desktop v9.2.  At the time of this processing, the 
Mosaic tool within ArcTools, ArcDesktop v.9 was the only ESRI product 
capable of working with two or more files exceeding a file size of 2GB.


Spatial_Data_Organization_Information:
  Direct_Spatial_Reference_Method: Raster
  Raster_Object_Information:
    Raster_Object_Type: Grid Cell
    Row_Count: 97480
    Column_Count: 154382
    Vertical_Count: 1
- <dataExt>
- <geoEle>
- <GeoBndBox esriExtentType="native">
  <westBL Sync="TRUE">-2364615</westBL> 
  <eastBL Sync="TRUE">2266845</eastBL> 
  <northBL Sync="TRUE">3180435</northBL> 
  <southBL Sync="TRUE">256035</southBL> 
  <exTypeCode Sync="TRUE">1</exTypeCode> 
  </GeoBndBox>
  </geoEle>
  </dataExt>

<rastinfo>
  <rasttype Sync="TRUE">Grid Cell</rasttype> 
  <rowcount Sync="TRUE">97480</rowcount> 
  <colcount Sync="TRUE">154382</colcount> 
  <rastxsz Sync="TRUE">30.000000</rastxsz> 
  <rastysz Sync="TRUE">30.000000</rastysz> 
  <rastbpp Sync="TRUE">8</rastbpp> 
  <vrtcount Sync="TRUE">1</vrtcount> 
  <rastorig Sync="TRUE">Upper Left</rastorig> 
  <rastcmap Sync="TRUE">FALSE</rastcmap> 
  <rastcomp Sync="TRUE">Default</rastcomp> 
  <rastband Sync="TRUE">1</rastband> 
  <rastdtyp Sync="TRUE">matrix values</rastdtyp> 
  <rastplyr Sync="TRUE">FALSE</rastplyr> 
  <rastifor Sync="TRUE" /> 
  </rastinfo>
  </spdoinfo>
- <spref>
- <horizsys>
- <cordsysn>
  <geogcsn Sync="TRUE">GCS_Clarke_1866</geogcsn> 
  <projcsn Sync="TRUE">Clarke_1866_Albers</projcsn> 
  </cordsysn>
- <planar>
- <mapproj>
  <mapprojn Sync="TRUE">Albers Conical Equal Area</mapprojn> 
- <albers>
  <stdparll Sync="TRUE">0.000143</stdparll> 
  <stdparll Sync="TRUE">0.000221</stdparll> 
  <longcm Sync="TRUE">-0.000466</longcm> 
  <latprjo Sync="TRUE">0.000111</latprjo> 
  <feast Sync="TRUE">0.000000</feast> 
  <fnorth Sync="TRUE">0.000000</fnorth> 
  </albers>
  </mapproj>
- <planci>
  <plance Sync="TRUE">row and column</plance> 
  <plandu Sync="TRUE">meters</plandu> 
- <coordrep>
  <absres Sync="TRUE">30.000000</absres> 
  <ordres Sync="TRUE">30.000000</ordres> 
  </coordrep>
  </planci>
  </planar>
- <geodetic>
  <horizdn Sync="TRUE">D_Clarke_1866</horizdn> 
  <ellips Sync="TRUE">Clarke 1866</ellips> 
  <semiaxis Sync="TRUE">6378206.400000</semiaxis> 
  <denflat Sync="TRUE">294.978698</denflat> 
  </geodetic>
  </horizsys>
  </spref>
- <refSysInfo>
- <RefSystem>
- <refSysID>
  <identCode Sync="TRUE">Clarke_1866_Albers</identCode> 
  </refSysID>
  </RefSystem>
  </refSysInfo>
Process_Date: Spring 2008
Process_Contact:
            Contact_Person: Lisa M. Olsen
            Contact_Organization: Carbon Dioxide Information Analysis Center
                                  Oak Ridge National Laboratory
            Address: P.O. Box 2008
            City: Oak Ridge
            State_or_Province: TN
            Postal_Code: 37831-6407
            Country: USA
            Contact_Voice_Telephone: 865-241-5921
            Contact_Electronic_Mail_Address: olsenlm@ornl.gov