Conflict Removal between B-spline Curves for Isobathymetric Line Generalization Using a Snake Model
Authors: Guilbert, E.; Saux, E.; Daniel, M.
Source: Cartography and Geographic Information Science, 1 January 2006, vol. 33, no. 1, pp. 37-52(16)
Abstract:This paper describes a method for suppressing distance conflicts between isobathymetric lines modeled with B-spline curves for cartographic generalization. The initial B-spline curves are obtained by compressing a set of polygonal lines representing the raw data. The conflict removal is realized by respecting strong cartographic constraints, such as the navigation safety and the legibility of the map, and weak constraints, such as the preservation of the submarine relief. A polygonal line representing the minimal displacement that corrects a conflict is first computed. Then, the curve is deformed using a snake model. The constraints are expressed via different energy terms, and the curve is deformed until a valid solution is reached. In order to apply the method without user intervention, the shape parameters of the snake are set automatically. The advantage of the method is that it ensures the respect of strong constraints in every case while taking into account the weaker ones. The method can also be applied to the correction of visual self-intersections. The use of a snake model combined with B-spline curves permits a better control of the deformation than polygonal lines, better preserving of the shape of the curves. Examples of real case studies issued from bathymetric databases are provided, and the benefits and drawbacks of the method are discussed.
Document Type: Research Article
Publication date: January 1, 2006