In this paper work, three-dimensional terrain models were reconstructed from twodimensional contour lines. Firstly, spatial curves were generated from contour lines using
parameterized cubic B-spline curve interpolation. Then surfaces were constructed by using
B-spline ruled surface. In the reconstruction process, some issues such as keyholes and
branching may arise. Therefore, we propose a method that handles the branching object to
construct a bilinear patch by following the proposed data point’s extraction algorithm. We
also solved keyholes issues by retaining the same knot vector condition on B-spline ruled
surface. Results are also demonstrated for models with branching and without branching.