Wickham James, Stehman Stephen V, Gass Leila, Dewitz Jon A, Sorenson Daniel G, Granneman Brian J, Poss Richard V, Baer Lori A
Systems Exposure Division, National Exposure Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27111, USA.
College of Environmental Science and Forestry, State University of New York, Syracuse, NY 13210, USA.
Remote Sens Environ. 2017;191:328-341. doi: 10.1016/j.rse.2016.12.026.
Accuracy assessment is a standard protocol of National Land Cover Database (NLCD) mapping. Here we report agreement statistics between map and reference labels for NLCD 2011, which includes land cover for ca. 2001, ca. 2006, and ca. 2011. The two main objectives were assessment of agreement between map and reference labels for the three, single-date NLCD land cover products at Level II and Level I of the classification hierarchy, and agreement for 17 land cover change reporting themes based on Level I classes (e.g., forest loss; forest gain; forest, no change) for three change periods (2001-2006, 2006-2011, and 2001-2011). The single-date overall accuracies were 82%, 83%, and 83% at Level II and 88%, 89%, and 89% at Level I for 2011, 2006, and 2001, respectively. Many class-specific user's accuracies met or exceeded a previously established nominal accuracy benchmark of 85%. Overall accuracies for 2006 and 2001 land cover components of NLCD 2011 were approximately 4% higher (at Level II and Level I) than the overall accuracies for the same components of NLCD 2006. The high Level I overall, user's, and producer's accuracies for the single-date eras in NLCD 2011 did not translate into high class-specific user's and producer's accuracies for many of the 17 change reporting themes. User's accuracies were high for the no change reporting themes, commonly exceeding 85%, but were typically much lower for the reporting themes that represented change. Only forest loss, forest gain, and urban gain had user's accuracies that exceeded 70%. Lower user's accuracies for the other change reporting themes may be attributable to the difficulty in determining the context of grass (e.g., open urban, grassland, agriculture) and between the components of the forest-shrubland-grassland gradient at either the mapping phase, reference label assignment phase, or both. NLCD 2011 user's accuracies for forest loss, forest gain, and urban gain compare favorably with results from other land cover change accuracy assessments.
精度评估是国家土地覆盖数据库（NLCD）制图的标准方案。在此，我们报告了NLCD 2011地图与参考标签之间的一致性统计数据，其中包括约2001年、约2006年和约2011年的土地覆盖情况。两个主要目标是评估分类层次二级和一级的三个单日期NLCD土地覆盖产品的地图与参考标签之间的一致性，以及基于一级类别（如森林损失；森林增加；森林，无变化）的17个土地覆盖变化报告主题在三个变化时期（2001 - 2006年、2006 - 2011年和2001 - 2011年）的一致性。2011年、2006年和2001年单日期的二级总体精度分别为82%、83%和83%，一级总体精度分别为88%、89%和89%。许多特定类别的用户精度达到或超过了先前设定的85%的名义精度基准。NLCD 2011中2006年和2001年土地覆盖成分的总体精度（在二级和一级）比NLCD 2006相同成分的总体精度高出约4%。NLCD 2011单日期时期一级的总体、用户和生产者精度较高，但对于17个变化报告主题中的许多主题，特定类别的用户和生产者精度并不高。无变化报告主题的用户精度较高，通常超过85%，但代表变化的报告主题的精度通常要低得多。只有森林损失、森林增加和城市增加的用户精度超过了70%。其他变化报告主题的用户精度较低可能归因于在制图阶段、参考标签分配阶段或两者中确定草地背景（如开阔城市、草地、农业）以及森林 - 灌木 - 草地梯度成分之间的困难。NLCD 2011中森林损失、森林增加和城市增加的用户精度与其他土地覆盖变化精度评估的结果相比具有优势。
