"Geographical objects, instead of individual pixels, are considered the basic unit." (Li et al., 2014)
Li Miao, Zang Shuying, Zhang Bing, Li Shanshan and Wu Changshan. "A Review of Remote Sensing Image Classification Techniques: the Role of Spatio-contextual Information". European Journal of Remote Sensing 47, no. 1 (2014): 389-411.