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Software library for spatial-temporal modeling and reasoning
Published in Symeon E. Christodoulou, Raimar Scherer, eWork and eBusiness in Architecture, Engineering and Construction, 2017
V. Semenov, K. Kazakov, K. Petrishchev, V. Zolotov
The following representations are intensively used in the library. Bounding boxes are applied in the operations with spatial decomposition trees and in localization of object collisions. Tessellated boundary representations are used in the measurement functions and in the implementations of the topological and directional operators for solid objects. BVH structures are applied for the optimization of the underlying operators and collision detection methods (Semenov, et al., 2010). Triangle strips, vertex buffers, and other display structures are used for rendering purposes.
Collision detection during planning for sheet metal bending by bounding volume hierarchy approaches
Published in International Journal of Computer Integrated Manufacturing, 2018
D. Raj Prasanth, M. S. Shunmugam
The standard methods adopted in the literature create the sheet metal part and tool models using software developed in-house and use those models in the downstream CAM application. This approach leads to a tight-coupling between the CAD and CAM application which is not always desirable. An alternate approach would be to create the CAD models using standard CAD packages, export them to a neutral format such as STEP, IGES and STL and then use these exported data in the CAM processing. Sivakumar and Dhanalakshmi (2013) have demonstrated the feasibility of such approach by achieving CAD/CAM/CAI integration for cylindrical components. In the present work, such a flexible approach is adopted wherein the part and tool model features are extracted from STL format and used during collision detection phase in the sheet metal planning. Collision detection is then carried out using bounding volume hierarchy approaches. In order to identify the suitable method for collision detection, 10 different sheet metal parts are analysed in terms of number of box–box tests, triangle–triangle tests and time taken for collision detection. The results are presented and discussed.
Interactive CNC simulation using distance fields
Published in International Journal of Computer Integrated Manufacturing, 2018
Allan Yoshio Hasegawa, Roberto Silvio Ubertino Rosso, Marcos de Sales Guerra Tsuzuki
First, a BVH is used to skip intersection tests on most of the surface. The BVH is build using the AABB volumes that surround each leaf-node. This BVH uses a small amount of memory, as it does not need to store any information besides the position of those AABB. This is true because it is possible to access the leaf-node only knowing its position since VDB offers constant time random access, and its volume size is constant (), making it unnecessary to store it for each node. Both the creation and traversal of ray packets on the BVH were performed with an implementation of Embree.