Why are portions of the same road represented by different developed classes?
The developed classes in NLCD 2001 landcover are derived directly from the percent developed impervious layer. As these roads traverse differing landcover, the spectral signature surrounding them can potentially change. For example, the same road traversing rangeland will have a much brighter spectral signature than when it traverses a forested area because of the additional reflectance from the surrounding soil. Since bright spectral signatures are typically used to identify urban areas, the percent developed impervious layer would potentially classify the rangeland areas as more developed than the forest. Hence, despite the best efforts of NLCD to capture the landscape consistently, the spectral context of the road can influence the level of developed class.
