Abstract—Dual Contouring (DC) is a feature-preserving isosurfacing method that extracts crack-free surfaces from both uniform and adaptive octree grids. We present an extension of DC that further guarantees that the mesh generated is a manifold even under adaptive simplification. Our main contribution is an octree-based topology-preserving vertex-clustering algorithm for adaptive contouring. The contoured surface generated by our method contains only manifold vertices and edges, preserves sharp features, and possesses much better adaptivity than those generated by other isosurfacing methods under topologically safe simplification.