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This data layer serves as an Index to help determine the aerial photography source and acquisition date (typically month and year) for air photos of the USDA/NRCS 2015 National Agricultural Imagery Program (NAIP) whcih display in the WI DNR Image Service “EN_Image_Basemap_2015_Leaf_On”. The delineations of air photo coverage provided through this Index are approximate, and may not reflect the precise extent of corresponding aerial photography in the historical aerial photography service. The primary source of the linework in this Index is a statewide 3.75' x 3.75' quarter-quadrangle grid. Quadrangle boundaries were dissolved in areas where the source aerial photography has the same acquisition date. NOTE: Overlapping polygons in the Index often occur along county boundary lines, (which typically do not correspond to the quarter-quadrangle grid), but also inside counties where aerial photography was flown in more than one year. In most cases, seam lines or discontinuities in the air photos along county boundaries can help can users determine which of the overlapping polygons corresponds to the imagery in the historical aerial photography service. |