Smartphone Camera Pose Calibration for Medical AR
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Solution Overview
Problem
Commodity smartphones with non-coincident fields of view for their digital cameras face challenges in achieving sub-millimeter accuracy during medical procedures due to unpredictable mounting orientations, which complicates the calibration of intrinsic and extrinsic camera parameters, affecting the precision of augmented reality applications in medical interventions.
Innovation Solution
A method for calibrating the pose transformation data between the front and rear digital cameras of a smartphone by individually calibrating each camera using a calibration pattern and determining their spatial relationship, allowing for accurate alignment and improved precision in surgical procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a smartphone with front-facing and rear-facing cameras is used for augmented reality applications, then the device can provide multiple fields of view, but the mounting orientation of the cameras is unpredictable leading to significant deviation in pose
Solution Approach 1:
The patent applies preliminary action by performing individual calibration of each camera to calibration targets before determining the pose relationship between cameras. This pre-calibration step establishes accurate intrinsic and extrinsic parameters for each camera, which are then used to compute the transformation matrix between the two camera coordinate systems, thereby resolving the pose accuracy issue despite unpredictable mounting orientations
2Measurement precision
If individual camera calibration is performed, then intrinsic and extrinsic parameters can be determined, but the complexity of the calibration process increases
Solution Approach 1:
The patent applies segmentation by dividing the calibration process into separate stages: first, individual calibration of each camera to its respective calibration target to determine intrinsic and extrinsic parameters; second, determination of the pose relationship between the two cameras using the calibrated parameters. This segmentation allows each stage to be optimized independently while maintaining overall accuracy
3Manufacturing precision
If calibration is performed to achieve sub-millimeter accuracy, then surgical precision is improved, but the time required for calibration increases
Solution Approach 1:
The patent applies continuity of useful action by establishing a systematic calibration procedure that can be efficiently repeated. The method uses standardized calibration targets with known patterns and a structured image acquisition sequence, allowing the calibration to be performed consistently and reliably. This systematic approach, combined with the use of transformation matrices that can be pre-computed and stored, reduces the time required for repeated calibration procedures while maintaining sub-millimeter accuracy
Data Source
AI summary
Provided is a method for generating pose transformation data between first and second rigidly mounted digital cameras having non-coincident fields of view. The method includes obtaining a first plurality of images of a first calibration object, obtaining a second plurality of images of the first or a second calibration object, generating first and second object point data, generating first and second calibration data of the first and second digital cameras, determining first pose data between a first frame of reference of the first digital camera and the frame of reference of the first calibration object, determining second pose data between the frame of reference of the second digital camera and the frame of reference of the first or second calibration objects, and calculating the pose transformation data between the pose of the first digital camera and the pose of the second digital camera.