3D Scanning Camera-Shake Correction via Common Point Feedback
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Solution Overview
Problem
Existing 3D scanning methods using stripe projection techniques face challenges in accurately capturing the geometry of objects, particularly for dental applications, due to camera-shake-induced errors that result in incorrect merging of images and erroneous surface structures.
Innovation Solution
A method that projects two patterns of parallel stripes with overlapping common points, allowing for immediate data generation and positional correction using binary code or phase shift methods, enabling on-the-fly scanning and compensation for camera-shake errors by rotating the scanning device between exposures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If stripe projection methods are used for 3D scanning, then the three-dimensional geometry of objects can be measured, but camera-shake induced errors occur resulting in incorrect merging of images and erroneous surface structures
Solution Approach 1:
The patent uses feedback by detecting common points (intersection points of light stripes) between overlapping images to determine relative positions, then uses this information to correct image merging errors caused by camera-shake. The system continuously adjusts the merging process based on detected position deviations.
Solution Approach 2:
The patent combines multiple images with overlapping regions into a composite 3D data set. By integrating information from multiple images and using the overlapping common points as reference, it creates a reliable merged result that compensates for camera-shake effects.
2Area of stationary object
If multiple images are merged to form a complete 3D data set, then the entire object surface can be scanned, but camera-shake causes coordinate system misalignment between images
Solution Approach 1:
The system detects common points in overlapping image regions and uses this feedback to calculate relative position deviations. This information is then used to adjust and realign the coordinate systems of merged images, ensuring accurate spatial registration despite camera-shake.
Solution Approach 2:
The patent introduces an additional dimension of correction by using the overlap region information (a spatial dimension) to correct position deviations in the 3D coordinate system. The common points provide reference information that enables dimensional transformation and alignment correction.
3Ease of operation
If a hand-held scanning device is used for dental applications, then ease of operation is improved, but camera-shake errors increase due to device movement between exposures
Solution Approach 1:
The patent implements feedback by continuously detecting common points between overlapping images and using this information to correct position deviations. This allows the system to maintain measurement precision even when the hand-held device moves between exposures, as the feedback mechanism compensates for the movement.
Solution Approach 2:
The patent converts the harmful effect of camera-shake into a beneficial one by using the overlapping common points (which would normally indicate error) as reference markers for determining relative positions and correcting alignment. The shake-induced displacement becomes useful information for spatial calibration.
4Measurement precision
If images are corrected and merged based on common points, then 3D data accuracy is improved, but additional processing steps are required
Solution Approach 1:
The patent performs preliminary action by detecting and recording common points during the image acquisition phase. This preliminary detection simplifies subsequent processing, as the reference points are already identified and can be directly used for position correction and image merging without requiring complex real-time calculations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures accurate 3D data acquisition by correcting for camera-shake-induced defects, allowing for precise reconstruction of object geometry even with hand-held scanning devices, improving resolution and reducing the need for repeated scans.
Implementation Method 1
measuring methods based on the principle of triangulation
Implementation Method 2
Phase-shifting triangulation is disclosed in EP 0 160 797, in which a three dimensional data set is acquired from a sequence of images of a pattern which is displaced from image to image
Data Source
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AI summary
The invention relates to a method for optically scanning the three-dimensional geometry of an object by means of triangulation, in which a pattern (9, 9') is projected onto the object (7) to be scanned in order to obtain a 3D data set, and the projected pattern (9, 9') is recorded in an image (40, 41). In a first step for the production of at least one first image (40), a first pattern (9) is projected and in a second step for the creation of at least one further image (40), a further pattern (9') deviating from the first as regards position or shape is projected onto the object (7) to be scanned and the image (41) is created. The first image (40) and the further image (41) comprise at least one common point (44). The 3D data acquired from the images (40, 41) are merged in a subsequent step on the basis of the 3D data of the at least one common point (44) such that the 3D data acquired from said images (40, 41) agree at least with reference to the 3D data of the common point (44) in the 3D data set.