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Introduction
We define 2.5D building topology as a set of
roof features, wall features, and point features; together
with the associations between them. Based on this definition,
we extend 2.5D dual contouring into a 2.5D modeling
method with topology control. Comparing with the previous
method, we put less restrictions on the adaptive simplification
process. We show results under intense geometry
simplifications. Our results preserve significant topology
structures while the number of triangles is comparable to
that of manually created models or primitive-based models.
2.5D Building Topology
The 2.5D building topology can be described as a combination of roof features (denoted as R), wall features (denoted as W), and point features (denoted as P). Their relationships in a building structure can be presented using the projection operator and boundary extraction operator via following formulas:
We demonstrate typical building structures in the following figure
including standing-alone building blocks, vertically attached
blocks, horizontally attached blocks, stair shapes,
and the combinations of these patterns. Nevertheless, our
2.5D building topology representation describes them in a
deterministic and differentiable manner.
Contouring with Topology Control
We propose a novel hyper-point clustering algorithm which allows the existence of multiple building topology
features in one quadtree cell. We adapt the geometry
optimization and polygon generation methods in
2.5D dual contouring to our topology control scheme.
Our contouring method produces 2.5D models with
less triangles while preserving the building topology.
Comparisons
Publications
2.5D Building Modeling with Topology Control
IEEE CVPR 2011, Qian-Yi Zhou and Ulrich Neumann
Links: Paper, Video, Experiment, Poster
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