Negative contour extraction method based on original contour

The invention provides a negative contour line extraction method based on an original contour line. The method comprises the following steps: S1) obtaining original data: obtaining original contour line data through mapping equipment; s2) vector depression point extraction: according to the original contour line data, using windowing calculation and simulation to obtain vector defect points in an elevation plane; s3) extracting a depression area in the original contour line data: utilizing the original contour line data to obtain a preliminary vector depression range according to depression filling; s4) optimization of a recess range: obtaining an optimized recess range by using a space attribute fusion and space differentiation method; s5) obtaining a negative contour line; and performing spatial connection on the optimized recess range and the vector defect points to obtain a final recess region, and performing spatial intersection operation on the final recess region and the original contour line data to o