View-Independent Cut Visualization With Voxelized CSG
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Solution Overview
Problem
Existing methods for visualizing material removal during cut procedures, such as bone resection, are computationally expensive and produce inaccurate, jagged representations due to high computational complexity and sparse temporal sampling of cutting tool positions.
Innovation Solution
The method involves tracking consecutive poses of the cutting tool, applying shape sweeping to smooth these poses, accumulating them in a voxelized constructive solid geometry (CSG) grid, and performing CSG operations using non-polygonal iso-surface ray marching to generate a continuous, high-quality 2D image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If depth peeling procedure with image space CSG methods is used to compute bone resection, then visual representation of cut procedure is provided, but computational cost and complexity increase significantly
Solution Approach 1:
The patent inverts the traditional approach by working in object space rather than image space. Instead of peeling depth information from the camera view and performing CSG operations in 2D image space, the patent accumulates tool poses in a 3D voxel grid and performs CSG operations in object space, then renders the result. This inversion fundamentally reduces computational complexity while maintaining visual accuracy.
Solution Approach 2:
The patent transitions from 2D image space operations to 3D object space operations by introducing a voxel grid representation. The cut trajectory is accumulated in three-dimensional voxel space, allowing CSG operations to be performed on the actual 3D geometry rather than projecting 2D depth images, which reduces the number of rendering passes needed.
2Adaptability or versatility
If virtual camera is moved or rotated to provide different viewing angles, then viewing flexibility is improved, but computation results are invalidated and require re-computation
Solution Approach 1:
The patent performs the computationally intensive CSG operations in object space beforehand, creating a view-independent representation of the resected bone. Once the object space model is computed, any number of viewing angles can be rendered by simply changing the virtual camera position without re-computing the CSG operations, as the 3D voxel grid contains all necessary geometric information.
3Productivity
If consecutive tool poses are sampled sparsely during cutting, then processing speed is maintained, but visual artifacts such as jagged patterns appear in the displayed surface
Solution Approach 1:
The patent creates a continuous 3D voxel representation of the cut trajectory by accumulating tool poses in object space. The voxel grid acts as a continuous medium that fills in the gaps between sparsely sampled tool positions, effectively copying and interpolating the cut path in 3D space. This eliminates jagged artifacts when rendering from any viewing angle while maintaining processing efficiency.
Data Source
AI summary
A method of computer visualization of removal of material from an object by a tool during a procedure includes tracking poses of the tool as the tool removes material from the object, performing a constructive solid geometry (CSG) operation using a model of the object, a plan for the removal of the material from the object, and an accumulation of the tracked poses of the tool, generating a two dimensional image of the object based on a result of the CSG operation, and handling movement of the tool by updating the two dimensional image via an update of only a changed sub-volume of the accumulation of the tracked poses.