Abstract: The present invention relates to a method and an apparatus which reproduce a digital terrain model (DTM) from contour data with geomorphological consistency and natural features including fine folds. An initial DTM ho is produced (step 101), and set ho as an initial value (step 102). Then the operator T which smooths the elevational values along flowing water lines or the neighborhood of the lines is operated on the DTM h (step 103), further the operator B which sets the boundary values by substituting the contour data is operated on the DTM h (step 104). The number n of operating times of the steps 103 and 104 is checked (step 105). If n is less than preset number nmax, return to the step 103 and if n reaches nmax, go to the step 106 and the DTM h is output.