The following is excerpted from metadata provided by the USGS for the NLCD 2001 (<http://extract.cr.usgs.gov/distmeta/servlet/gov.usgs.edc.MetaBuilder?TYPE=HTML&DATASET=NLCD01CANO&YMAX=39.611501479289956&YMIN=39.611501479289956&XMIN=-76.63165680473374&XMAX=-76.63165680473374>):
"The National Land Cover Database 2001 tree canopy layer for mapping zone 60 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 (USDA) Forest Service (USFS), 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, edgematching features and the size requirement of Landsat mosaics. Mapping zone 60 encompasses whole or portions of several states in the mid-Atlantic region, including the states of New Jersey, Delaware, Maryland, Pennsylvania, Virginia, and the District of Columbia. Questions about the NLCD mapping zone 60 can be directed to the NLCD 2001 land cover mapping team at the USGS EROS Data Center (EDC), Sioux Falls, SD (605) 594-6151 or mrlc@usgs.gov."
This data set was compiled by Indiana University, Indiana Geological Survey, using data believed to be accurate; however, a degree of error is inherent in all data. This product is distributed "AS-IS" without warranties of any kind, either expressed or implied, including but not limited to warranties of suitability to a particular purpose or use. No attempt has been made in either the design or production of these data to define the limits or jurisdiction of any federal, state, or local government. These data are intended for use only at the published scale or smaller and are for reference purposes only. They are not to be construed as a legal document or survey instrument. A detailed on-the-ground survey and historical analysis of a single site may differ from these data.
COPYRIGHT 2007, THE TRUSTEES OF INDIANA UNIVERSITY, INDIANA GEOLOGICAL SURVEY, ALL RIGHTS RESERVED
The information on these media is proprietary to Indiana University, Indiana Geological Survey. Any copying, adaptation, distribution, public performance, or public display of this information without the express written consent of Indiana University, Indiana Geological Survey is discouraged.
CREDIT
It is requested that the Indiana Geological Survey be cited in any products generated from this data. The following source citation should be included: TC2001USGS_IN: Estimated Percentage of Tree Canopy in Indiana in 2001, Derived from the National Land Cover Database (NLCD 2001) (United States Geological Survey, 30-Meter Grid), digital representation by Chris Dintaman, 2007.
LIMITATION OF WARRANTIES AND LIABILITY
This product is provided "AS IS", without any other warranties or conditions, expressed or implied, including, but not limited to, warranties for product quality, or suitability to a particular purpose or use. The risk or liability resulting from the use of this product is assumed by the user. Indiana University, Indiana Geological Survey shares no liability with product users indirect, incidental, special, or consequential damages whatsoever, including, but not limited to, loss of revenue or profit, lost or damaged data or other commercial or economic loss. Indiana University, Indiana Geological Survey is not responsible for claims by a third party. The maximum aggregate liability to the original purchaser shall not exceed the amount paid by you for the product.
"Regression tree algorithms employed in NLCD 2001 mapping offer a cross-validation option for assessing classification and prediction reliability. Cross-validation can provide relatively reliable estimates for tree canopy predictions if the reference data used for cross-validation are collected based on a statistical valid sampling design. For mapping zone 60 tree canopy modeling, 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 and standard error's from the 5 run's were 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."
"This NLCD product of mapping zone 60 Tree Canopy layer is the version 1 dated 09-01-2003.
"The NLCD 2001 database for mapping zone 60 consists of three main data products including: (1) per pixel classified land-cover data (2) sub-pixel percent imperviousness and (3) sub-pixel percent tree canopy density. The land-cover database also includes three additional metadata layers that provide users a spatial node map of the land cover classification, a spatial confidence map of the land cover classification, and a text file of logical statements pertinent to the land cover classification. The three layers are: (1) a spatial node map of the land cover classification, (2) a spatial confidence map of the land cover classification, and, (3) a text file of logical statements related to the land cover classification. These additional metadata layers may be of interest to some data users with specific needs. If you are interested in the detailed metadata information, please refer to <http://www.mrlc.gov> ."
"The method employed to map tree canopy density for NLCD 2001 consists of three key steps: deriving reference data of tree canopy density 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 tree canopy density. This method is described in detail in Huang et al. (2001). This approach was applied to mapping zone 60 by Earth Satellite Corporation (through Greenhorne & O'Mara Inc.) under USGS contract.
"To develop adequate training data for tree canopy density estimation, 21 1-m resolution DOQQ's across mapping zone 60 were classified into either tree canopy or non-tree canopy areas, and then values summed within each 30 meter Landsat pixel cell to obtain the percentage of tree canopy. The training data was selected with a Sample Selection Tool developed by Earthsat Inc. 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 process was repeated until the required number of samples (21) had been allocated."
The "Data Preparation > Mosiac Images" command from the ImageAnalysis extension (version 9.2, build 8.9.1.204) in ESRI ArcGIS 9.2 was used to mosaic the two images into one tiff image for Indiana. The "Data Preparation > Subset Images" command was then used to clip the image to the Indiana boundary. The output image was then saved as an ESRI Grid named "TC2001USGS_IN". TC2001USGS_IN was then projected to Universal Transverse Mercator, Zone 16, NAD 1983.
The information on these media is proprietary to Indiana University, Indiana Geological Survey. Any copying, adaptation, distribution, public performance, or public display of this information without the express written consent of Indiana University, Indiana Geological Survey is discouraged.
CREDIT
It is requested that the Indiana Geological Survey be cited in any products generated from this data. The following source citation should be included: TC2001USGS_IN: Estimated Percentage of Tree Canopy in Indiana in 2001, Derived from the National Land Cover Database (NLCD 2001) (United States Geological Survey, 30-Meter Grid), digital representation by Chris Dintaman, 2007.
LIMITATION OF WARRANTIES AND LIABILITY
This product is provided "AS IS", without any other warranties or conditions, expressed or implied, including, but not limited to, warranties for product quality, or suitability to a particular purpose or use. The risk or liability resulting from the use of this product is assumed by the user. Indiana University, Indiana Geological Survey shares no liability with product users indirect, incidental, special, or consequential damages whatsoever, including, but not limited to, loss of revenue or profit, lost or damaged data or other commercial or economic loss. Indiana University, Indiana Geological Survey is not responsible for claims by a third party. The maximum aggregate liability to the original purchaser shall not exceed the amount paid by you for the product.