Interactive cross-section clipping of large 3D geological models in a browser is constrained by client-side memory budgets, JavaScript execution overhead, and the cost of assembling topologically valid section contours. We propose Web3D-CS, a browser-native pipeline for extracting watertight cross-sections from large-scale geological meshes without offline preprocessing. Given a triangle mesh geological model and an interactively controlled clipping plane, we (1) traverse a mesh BVH to collect candidate triangles, (2) compute plane-triangle intersection segments robustly, (3) project segment endpoints to a 2D plane frame and merge near-duplicate endpoints through spatial hashing with tolerance Formula: see text, (4) trace closed contour loops from the resulting degree-constrained adjacency graph, and (5) triangulate outer or inner rings using Earcut before mapping the 2D section back to 3D for rendering. Experiments on models with tens of millions of vertices show that Web3D-CS reduces total clipping time by 57%–83% and the number of cross-section triangles by 80%–88% compared with a browser-native Constructive Solid Geometry (CSG) baseline, while maintaining smooth, topologically consistent boundaries under practical browser memory limits. The results further indicate that clipping latency is driven primarily by loop complexity rather than raw vertex count, highlighting contour tracing as the key optimization target for interactive web-based geological cross-section analysis.
Chen et al. (Fri,) studied this question.