US 11,854,145 B2
Octree-based three-dimensional building model LOD method
Jun Li, Jiangsu (CN); Jianyong Fan, Jiangsu (CN); Biliang Zhu, Jiangsu (CN); and Zhongjian Xu, Jiangsu (CN)
Assigned to SPEED TECHNOLOGY CO., LTD., Jiangsu (CN)
Appl. No. 17/914,767
Filed by SPEED TECHNOLOGY CO., LTD., Jiangsu (CN)
PCT Filed Mar. 30, 2021, PCT No. PCT/CN2021/084080
§ 371(c)(1), (2) Date Sep. 27, 2022,
PCT Pub. No. WO2021/204025, PCT Pub. Date Oct. 14, 2021.
Claims priority of application No. 202010267603.3 (CN), filed on Apr. 8, 2020.
Prior Publication US 2023/0134338 A1, May 4, 2023
Int. Cl. G06T 17/00 (2006.01); G06T 15/04 (2011.01)
CPC G06T 17/005 (2013.01) [G06T 15/04 (2013.01); G06T 2210/04 (2013.01); G06T 2210/36 (2013.01)] 6 Claims
OG exemplary drawing
 
1. An octree-based three-dimensional building model LOD method, specifically comprising the following steps:
S1, reading three-dimensional building model data, and taking the source model as the most advanced model;
S2, setting a tree depth Depth parameter of the octree, and constructing a sparse octree with a depth of Depth for the components of the building model;
S3, respectively establishing coarse grid blocks for each component by level, the coarse grid block being the outer bounding box of the octree leaf node;
S4, merging the coarse grid blocks of each level to form the components of the building model; setting the minimum neighboring threshold of the bounding box of the leaf node forming the building components, merging the bounding boxes of all leaf nodes according to the Z-axis, X-axis and Y-axis, and forming the coarse grid block of the building component at the current level;
S5, triangularization, i.e., performing triangularization on six faces of each grid block of the coarse grid block generated in step S4, by sequentially dividing each face of the grid cube into two triangular faces in a clockwise direction according to the left-hand coordinate system;
S6, calculating a normal vector of the coarse grid block: calculating a vertex normal vector of each grid block of the coarse grid block generated in step S5; the value of normal vector is one of top, down, front, rear, left and right;
S7, merging the simplified components to form a building model of a coarse grid block: setting the minimum neighboring threshold of each building component, merging the building components according to the Z-axis, X-axis and Y-axis for the coarse grid block of step S6, and taking the merging result as the coarse grid block of the building model at the current level;
S8, deleting internal vertexes: deleting internal points of the coarse grid block in step S7, retaining the surface vertexes of the three-dimensional building model, and deleting internal vertexes by using QEM model simplification algorithm;
S9, setting materials or textures: if the original building model has no textures or materials, using the default material instead; otherwise, the textures and materials of the whole building are calculated, and the whole textures and materials are spliced into a texture; and
S10, outputting the three-dimensional building LOD model.