Grid data generation from contour images by using Euclid distance transformation

A DEM generation method from a contour map is described, for which implementation is simple and accuracy is sufficient from practical viewpoint. In the proposed method, the Euclidean distance transformation is used to search the points on the contour from which a target point is interpolated. Further, the method does not require complete the closed contour condition. The conversion accuracy evaluated by comparing the result with a human-interpreted DEM is 0.369 m when the elevation interval between contours is 10 m for completely closed contours. Even for the open contours, the accuracy is 0.396 m which is not so much deteriorated from the closed contour case. Both of these figures are supposed to be sufficient for most kind of applications which require contour to DEM conversion