Aiming at problem that it is difficult to extract line features from topographic maps

and the line features extracted by exsting methods are not accurate

propose a line feature extration method based on Guided Filter. In this method

Guided Filter is introduced

the line features are extracted first by the method based on the energy density and the shear transformation

and the result images are used as the input images of Guided Filter;then use original topographic maps as the Guided images of Guided Filter. The line features are more significant after filtering

and obtain the final line features information by OTSU algorithm. Experimental resuts show that the proposed algorithm can extract line features more accurately

and has better ability of noise inhibition.