In this paper, a novel method is proposed to extract rocks from Martian surface images by using 8 data field. It models the interaction between two pixels of an image in the context of imagery 9 characteristics. First, foreground rocks are differed from background information by binarizing 10 image on roughly partitioned images. Second, foreground rocks are grouped into clusters by 11 locating the centers and edges of clusters in data field via hierarchical grids. Third, the target 12 rocks are discovered for the Mars Exploration Rover (MER) to keep healthy paths. The 13 experiment with images taken by MER shows the proposed method is practical and potential.