3D Scan Surface Exclusion for Movable Object Detection
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Solution Overview
Problem
Existing 3D scanning methods struggle to differentiate between movable and rigid objects when generating a virtual 3D model, as movable objects like cheeks, tongue, or instruments obstruct the view and are often captured in multiple sub-scans, making it difficult to distinguish their surfaces from the rigid object's surfaces.
Innovation Solution
The method involves creating excluded volumes in space where no surface can be present for each scan representation, disregarding surface portions located in these excluded volumes, ensuring that only rigid object surfaces contribute to the virtual 3D model by comparing overlapping scan volumes and applying threshold distances to refine the excluded volume definition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple sub-scans are acquired to obtain a complete virtual 3D model, then the completeness of the 3D model is improved, but the difficulty to differentiate between movable and rigid object surfaces increases
Solution Approach 1:
The patent divides the scanning process into multiple sub-scans, each capturing a specific portion of the object. By segmenting the data acquisition into temporal and spatial components, the system can later differentiate between surfaces that appear in only one sub-scan (movable objects) versus surfaces that appear across multiple sub-scans (rigid objects), thus resolving the contradiction between completeness and differentiation difficulty
Solution Approach 2:
The patent performs preliminary actions by acquiring multiple sub-scans before final model generation. This preliminary data collection allows the system to later identify and exclude movable objects by comparing which surfaces appear consistently across the preliminary scans, enabling the differentiation problem to be solved after data acquisition
2Measurement precision
If movable objects obstruct the view of the rigid object during scanning, then the accuracy of the 3D model is worsened, but the complexity of handling movable objects increases
Solution Approach 1:
The patent extracts and removes movable objects from the final 3D model by identifying surfaces that appear in only one sub-scan and excluding them. This extraction approach automatically handles the complexity of movable objects without requiring manual intervention or complex real-time control systems, thus improving measurement precision while avoiding increased device complexity
Solution Approach 2:
The patent discards data from sub-scans where movable objects are detected, while recovering and keeping data from sub-scans where only the rigid object is visible. This selective discarding and recovering process simplifies the handling of movable objects by treating them as removable artifacts rather than requiring complex real-time management
3Productivity
If the scanner speed is increased to reduce scanning time, then the productivity is improved, but the likelihood of capturing movable objects in only one sub-scan increases
Solution Approach 1:
The patent employs periodic action by acquiring multiple sub-scans at different time points during the scanning process. Even when scanning speed is increased, the periodic acquisition of multiple sub-scans ensures that the system can still differentiate between movable and rigid objects by temporal consistency, thus maintaining reliability while improving productivity through faster scanning
Data Source
AI summary
Detecting a movable object in a location includes providing a first 3D representation of at least part of a surface; providing a second 3D representation of at least part of the surface; determining for the first 3D representation a first excluded volume in space where no surface can be present; determining for the second 3D representation a second excluded volume in space where no surface can be present; if a portion of the surface in the first 3D representation is located in space in the second excluded volume, the portion of the surface in the first 3D representation is disregarded in the generation of the virtual 3D model, and/or if a portion of the surface in the second 3D representation is located in space in the first excluded volume, the portion of the surface in the second 3D representation is disregarded in the generation of the virtual 3D model.