Please note that 地 is a stem word which means land. The character following 地 will decide on the meaning of the two words (compound word) placed together. In this case, 图 means picture or drawing or chart. Thus 地图 means land drawing or MAP. There are more than two dozen compound words with 地 as the stem word. Some examples are 地 球 (land ball = earth), 地 理 (land logic = geography), 地雷 (land thunder = land mine), 地震(land shaking = earth-quake),地下 (land below = underground).