Reference and Validation
The Annual NLCD Reference & Validation (R&V) is designed to support the development of consistent land cover and land cover change products and data. The R&V process involves collecting reference data to validate Anderson level II land cover classes and change products across the entire United States. The R&V gathers, organizes, and refines independent reference datasets for the US to generate validation reports for the annual NLCD land cover and land cover change products at the Anderson level II ontology/taxonomy level.
Reference data collected in the annual R&V program is critical for evaluating the accuracy of the NLCD land cover and change products and provides an independent reference dataset for quantifying algorithm performance. Producing an independent reference dataset to evaluate the performance and accuracy of the NLCD land cover and change product range is a critical component of the NLCD R&V program. A key aspect of the NLCD products is the collection of an independent reference dataset to evaluate and validate the NLCD land cover and change products (1).
The NLCD reference data products produced by the R&V program consist of two sample strategies based on 30-meter by 30-meter plots within the continuous United States. A first reference data product includes a dataset of 5,000 randomly distributed plots, which are collected before each year’s land cover map is finalized. A second reference data product contains 5,000 stratified random samples collected from subdivisions within the map extent. The second reference set focuses on rare land cover classes and an annual time series of land cover and change spanning more than 30 years.
Graphic
Point distribution of the simple random sample that was used for the Annual NLCD Collection 1 reference data.
Land use, land cover, and change information for each reference plot is collected annually for the years 1984-2023 using the TimeSync tool, a web-based interface for manually interpreting and recording information from the Landsat dataset. Manual interpretation of Landsat data is further supplemented with fine resolution imagery and other ancillary data. Various quality assurance and quality control (QA/QC) processes are implemented to ensure that the annual NLCD Reference Data Products maintain consistent quality (2).
Product Contents
The annual NLCD Reference Data Product is packaged in a zipped file containing reference data for the initial 10,000 plots in three formats:
Tabular (.xlsx) collection of the annual NLCD reference dataset annual attributes (1984 –2023) for each of the 10,000 plots.
Vector-format shapefile (.shp) for the annual NLCD reference dataset showing individual plot (polygon) location outlines for each of the 10,000 plots.
Tagged image format (.tif) map of stratum class (determined by land cover change type of the pixel).
Data Access
The Reference Data Product is accessible through the USGS Science Data Catalog.
Documentation
Annual NLCD Reference Data Product Guide
Citation Information
There are no restrictions on the use of the annual NLCD Reference Data Products. It is not a requirement of data use, but the following citation may be used in publication or presentation materials to acknowledge the USGS as a data source and to credit the original research.
U.S. Geological Survey (USGS), 2024, Annual NLCD Collection 1 Science Products: U.S. Geological Survey data release, https://doi.org/10.5066/P94UXNTS
Reference
1. J. Wickham, S. V. Stehman, D. G. Sorenson, L. Gass, J. A. Dewitz, Thematic accuracy assessment of the NLCD 2019 land cover for the conterminous United States. GIScience & Remote Sensing 60, (2023).
2. S. V. Stehman, B. W. Pengra, J. A. Horton, D. F. Wellington, Validation of the U.S. Geological Survey's Land Change Monitoring, Assessment and Projection (LCMAP) Collection 1.0 annual land cover products 1985–2017. Remote Sensing of Environment 265, (2021).
Back to the Annual NLCD landing page.
Here are publications associated with Reference and Validation:
Thematic accuracy assessment of the NLCD 2019 land cover for the conterminous United States
Validation of the U.S. Geological Survey’s Land Change Monitoring, Assessment and Projection (LCMAP) collection 1.0 annual land cover products 1985–2017
The U.S. Geological Survey Land Change Monitoring, Assessment and Projection (USGS LCMAP) has released a suite of annual land cover and land cover change products for the conterminous United States (CONUS). The accuracy of these products was assessed using an independently collected land cover reference sample dataset produced by analysts interpreting Landsat data, high-resolution aerial photograp
The Annual NLCD Reference & Validation (R&V) is designed to support the development of consistent land cover and land cover change products and data. The R&V process involves collecting reference data to validate Anderson level II land cover classes and change products across the entire United States. The R&V gathers, organizes, and refines independent reference datasets for the US to generate validation reports for the annual NLCD land cover and land cover change products at the Anderson level II ontology/taxonomy level.
Reference data collected in the annual R&V program is critical for evaluating the accuracy of the NLCD land cover and change products and provides an independent reference dataset for quantifying algorithm performance. Producing an independent reference dataset to evaluate the performance and accuracy of the NLCD land cover and change product range is a critical component of the NLCD R&V program. A key aspect of the NLCD products is the collection of an independent reference dataset to evaluate and validate the NLCD land cover and change products (1).
The NLCD reference data products produced by the R&V program consist of two sample strategies based on 30-meter by 30-meter plots within the continuous United States. A first reference data product includes a dataset of 5,000 randomly distributed plots, which are collected before each year’s land cover map is finalized. A second reference data product contains 5,000 stratified random samples collected from subdivisions within the map extent. The second reference set focuses on rare land cover classes and an annual time series of land cover and change spanning more than 30 years.
Graphic
Point distribution of the simple random sample that was used for the Annual NLCD Collection 1 reference data.
Land use, land cover, and change information for each reference plot is collected annually for the years 1984-2023 using the TimeSync tool, a web-based interface for manually interpreting and recording information from the Landsat dataset. Manual interpretation of Landsat data is further supplemented with fine resolution imagery and other ancillary data. Various quality assurance and quality control (QA/QC) processes are implemented to ensure that the annual NLCD Reference Data Products maintain consistent quality (2).
Product Contents
The annual NLCD Reference Data Product is packaged in a zipped file containing reference data for the initial 10,000 plots in three formats:
Tabular (.xlsx) collection of the annual NLCD reference dataset annual attributes (1984 –2023) for each of the 10,000 plots.
Vector-format shapefile (.shp) for the annual NLCD reference dataset showing individual plot (polygon) location outlines for each of the 10,000 plots.
Tagged image format (.tif) map of stratum class (determined by land cover change type of the pixel).
Data Access
The Reference Data Product is accessible through the USGS Science Data Catalog.
Documentation
Annual NLCD Reference Data Product Guide
Citation Information
There are no restrictions on the use of the annual NLCD Reference Data Products. It is not a requirement of data use, but the following citation may be used in publication or presentation materials to acknowledge the USGS as a data source and to credit the original research.
U.S. Geological Survey (USGS), 2024, Annual NLCD Collection 1 Science Products: U.S. Geological Survey data release, https://doi.org/10.5066/P94UXNTS
Reference
1. J. Wickham, S. V. Stehman, D. G. Sorenson, L. Gass, J. A. Dewitz, Thematic accuracy assessment of the NLCD 2019 land cover for the conterminous United States. GIScience & Remote Sensing 60, (2023).
2. S. V. Stehman, B. W. Pengra, J. A. Horton, D. F. Wellington, Validation of the U.S. Geological Survey's Land Change Monitoring, Assessment and Projection (LCMAP) Collection 1.0 annual land cover products 1985–2017. Remote Sensing of Environment 265, (2021).
Back to the Annual NLCD landing page.
Here are publications associated with Reference and Validation:
Thematic accuracy assessment of the NLCD 2019 land cover for the conterminous United States
Validation of the U.S. Geological Survey’s Land Change Monitoring, Assessment and Projection (LCMAP) collection 1.0 annual land cover products 1985–2017
The U.S. Geological Survey Land Change Monitoring, Assessment and Projection (USGS LCMAP) has released a suite of annual land cover and land cover change products for the conterminous United States (CONUS). The accuracy of these products was assessed using an independently collected land cover reference sample dataset produced by analysts interpreting Landsat data, high-resolution aerial photograp