“…For example, common algorithmic strategies include region growing (Amo et al, 2006;Bicego et al, 2003;Hu et al, 2007;Mena and Malpica, 2005;Tesser and Pavlidis, 2000), segmentation and clustering (Ferchichi and Wang, 2005;Wan et al, 2007), machine learning (Butenuth et al, 2003;Yager and Sowmya, 2003), multi-scale extraction and refinement (Baumgartner and Hinz, 2000;Heipke et al, 1995;Mayer et al, 1998;Steger, 1998), and active contours (Laptev et al, 2000;Peng et al, 2008). These methods tend to work well in rural environments, where color and intensity is relatively distinctive and consistent within roads, and in urban environments when assumptions can be made about the structure of roads (e.g., a semi-regular grid pattern (e.g., Hu et al, 2004;Youn and Bethel, 2004)) and/or a knowledge base and carefully tuned parameters can be provided (e.g., Hinz, 2004).…”