CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119 or 365 to European Application No. 19306531.5, filed Nov. 28, 2019. The entire contents of the above application(s) are incorporated herein by reference.

FIELD OF THE DISCLOSURE

The disclosure relates to the field of computer programs and systems, and more specifically to methods, systems and programs for civil engineering.

BACKGROUND

A number of systems and programs are offered on the market for the design, the engineering and the manufacturing of objects. CAD is an acronym for Computer-Aided Design, e.g. it relates to software solutions for designing an object. CAE is an acronym for Computer-Aided Engineering, e.g. it relates to software solutions for simulating the physical behavior of a future product. CAM is an acronym for Computer-Aided Manufacturing, e.g. it relates to software solutions for defining manufacturing processes and operations. In such computer-aided design systems, the graphical user interface plays an important role as regards the efficiency of the technique. These techniques may be embedded within Product Lifecycle Management (PLM) systems. PLM refers to a business strategy that helps companies to share product data, apply common processes, and leverage corporate knowledge for the development of products from conception to the end of their life, across the concept of extended enterprise. The PLM solutions provided by Dassault Systèmes (under the trademarks CATIA, ENOVIA and DELMIA) provide an Engineering Hub, which organizes product engineering knowledge, a Manufacturing Hub, which manages manufacturing engineering knowledge, and an Enterprise Hub which enables enterprise integrations and connections into both the Engineering and Manufacturing Hubs. All together the system delivers an open object model linking products, processes, resources to enable dynamic, knowledge-based product creation and decision support that drives optimized product definition, manufacturing preparation, production and service.

Within this context and other contexts, civil engineering is gaining wide importance.

The followings papers and software relate to this field and are referred to hereunder:[1] Attali, D., Glisse, M., Hornus, S., Lazarus, F., & Morozov, D. (2009). Persistence-sensitive simplification of functions on surfaces in linear time.TOPOINVIS,9, 23-24;[2] Autodesk Civil 3D software;[3] Banchoff, T. (1967). Critical points and curvature for embedded polyhedra.Journal of Differential Geometry,1(3-4), 245-256;[4] Bentley Power Civil software;[5] BlueMarble GlobalMapper software;[6] Bremer, P.-T., Hamann, B., Edelsbrunner, H., & Pascucci, V. (2004). A topological hierarchy for functions on triangulated surfaces. Bremer, P-T;Hamann, Bernd; Edelsbrunner, Herbert; Pascucci, Valerio,10(4), 385-396;[7] Čomić, L., De Floriani, L., Magillo, P., & Iuricich, F. (2014).Morphological modeling of terrains and volume data. Springer New York;[8] Danovaro, E., De Floriani, L., Magillo, P., & Mostefa Mesmoudi, M. (2003). Morphology-Driven Simplification and Multiresolution.Proceedings of the11th ACM international symposium on Advances in geographic information systems,63-70;[9] Edelsbrunner, H., Harer, J., & Zomorodian, A. (2003). Hierarchical Morse-Smale Complexes for Piecewise Linear 2-Manifolds.Discrete and Computational Geometry,30(1), 87-107;[10] Forman, R. (1998).Morse theory for cell complexes;[11] Gyulassy, A., Natarajan, V., Pascucci, V., & Hamann, B. (2007). Efficient computation of Morse-Smale complexes for three-dimensional scalar functions.IEEE Transactions on Visualization and Computer Graphics,1440-1447;[12] Kozlov, D. (2008).Combinatorial Algebraic Topology. Springer;[13] Matsumoto, Y. (2001).An introduction to Morse Theory. American Mathematical Society;[14] Meyer, F. (1994). Topographic distance and watershed lines.Signal processing,38(1), 113-125;[15] Takahashi, S., Ikeda, T., Shinagawa, Y., Kunii, T. L., & Ueda, M. (1995). Algorithms for extracting correct critical points and constructing topological graphs from discrete geographical elevation data.Computer Graphics Forum,181-192; and[16] Wolhuter, K. (2015).Geometric Design of Roads Handbook. CRC Press.

All these methods suffer from a lack of accuracy and/or robustness and/or efficiency and/or speed, and/or do not provide satisfactory results.

Therefore, there is a need for an improved method for civil engineering.

SUMMARY

It is therefore provided a computer-implemented method for civil engineering. The method comprises providing a mesh representing a terrain. The method further comprises computing a watershed segmentation of the terrain based on the mesh. The computing of the watershed segmentation includes identifying one or more saddle points on the mesh. The computing of the watershed segmentation further includes, for each identified saddle point, identifying paths each ascending from the saddle point according to a direction of a local maximal slope around the saddle point, and a path descending from the saddle point according to a direction of a steepest slope around the saddle point. The identified ascending paths divide the mesh into connected components. The computing of the watershed segmentation further includes, for each identified saddle point, merging each connected component of which bottom point is the saddle point with a connected component comprising the identified path descending from the saddle point according to a direction of a steepest slope around the saddle point. The merging yields at least a part of a basin.

The method may comprise one or more of the following:the identifying of the paths ascending from the saddle point comprises determining slope local maxima around the saddle point, each respective one of said paths ascending from the saddle point being directed according to a determined slope local maxima;the determined slope local maxima around the saddle point are local maxima of a radial slope around the saddle point;the identifying of the paths ascending from the saddle point comprises projecting mesh elements comprising the saddle point onto a plane, the radial slope around the saddle point being a function of a direction angle around a projection of the saddle point in the plane;the identifying of the paths ascending from the saddle point comprises, for each mesh element comprising the saddle point and comprising at least two local maxima of the radial slope, retrieving, among couples of local maxima of the at least two local maxima of the radial slope, a couple of local maxima of which directions form a maximal angle in the projection of the mesh element, the respective directions of the local maxima of the couple yielding one of said connected components;the retrieving of the couple forming the maximal angle comprises retrieving a first local maxima of the radial slope and a last maxima of the radial slope according to a trigonometric order or to an anti-trigonometric order in the projection of the mesh element;the identifying of the at least one path descending from the saddle point comprises computing a slope global minimum around the saddle point;the slope global minimum is a global minimum of a radial slope around the saddle point;the merging comprises:determining a graph having nodes each representing a connected component and arcs each representing a connection between two connected components; andextracting the connected components of the graph, each connected component of the graph representing a basin of the terrain;each node representing a connected component having a saddle point as a bottom point is connected by an arc in the graph to a node representing a connected component of the mesh that is located below the saddle point and that comprises the identified path descending from the saddle point according to a direction of a steepest slope around the saddle point;at least one of the identified one or more saddle points is a degenerate saddle point; and/orthe terrain is a construction terrain.

It is further provided a computer program comprising instructions for performing the method.

It is further provided a device comprising a data storage medium having recorded thereon the computer program.

The device may form or serve as a non-transitory computer-readable medium, for example on a SaaS (Software as a service) or other server, or a cloud based platform, or the like. The device may alternatively comprise a processor coupled to the data storage medium. The device may thus form a computer system in whole or in part (e.g. the device is a subsystem of the overall system). The system may further comprise a graphical user interface coupled to the processor.

