CN-121999137-A - Weightless fault transient three-dimensional imaging method and weightless fault transient three-dimensional imaging system thereof

CN121999137ACN 121999137 ACN121999137 ACN 121999137ACN-121999137-A

Abstract

The three-dimensional imaging method loads the tested object on the loading body and takes the tested object as a test whole, so that the test whole is in a free motion state, and finally, a three-dimensional reconstruction result of the tested object is obtained through 5 steps. Under the condition that the space positions of the ray source and the detector are kept fixed, the object to be measured passes through the imaging view field under the condition of no fixed support, the invention introduces stable space geometric constraint, and combines time sequence projection data to realize joint estimation of the pose of the object to be measured and the geometric parameters of the system, thereby realizing stable three-dimensional reconstruction of the object to be measured under the condition of limited projection quantity and insufficient geometric consistency.

Inventors

XU YUAN
Lin Hangji
PAN ZENGXIANG
DUAN XIAOMAN
ZHOU LINGHONG

Assignees

南方医科大学

Dates

Publication Date: 20260508
Application Date: 20260206

Claims (10)

1. The weightless fault transient three-dimensional imaging method is characterized by comprising the following steps of: S1, loading an object to be tested on a loading body and taking the object to be tested as a test whole, enabling the test whole to be in a free motion state, continuously collecting X-ray projection data of the test whole at a plurality of projection moments under the condition that a ray source and a detector are fixed, and forming time sequence projection data; S2, preprocessing each frame of projection data in the time sequence projection data obtained in the S1, extracting two-dimensional projection features related to the spatial pose of the detected object and the geometric calibration structure unit in the carrier from the preprocessed projection data, and performing cross-frame correlation on the two-dimensional projection features between adjacent projection moments to obtain projection feature information, wherein the projection feature information is the contour features of the detected object, the edge features of the detected object and the projection positions of the three-dimensional feature marks; s3, deducing an initial space pose parameter sequence of the measured object relative to a system reference coordinate system at each moment based on projection characteristic information corresponding to the time sequence projection data of the S2; s4, obtaining an initial space pose parameter sequence according to the S3, and estimating the initial space pose parameter sequence in a joint constraint mode to obtain refined space pose parameters and corrected system geometric parameters; S5, the refined space pose parameters and corrected system geometric parameters are obtained in the S4, an imaging geometric relation corresponding to the projection moment is constructed, and tomographic reconstruction processing is carried out on time sequence projection data under the imaging geometric relation, so that a three-dimensional reconstruction result of the measured object is obtained.
2. The weightless fault transient three-dimensional imaging method according to claim 1, wherein the step S3 is performed by: S3.1, defining a space pose transformation table, and determining the space pose transformation of the measured object relative to a system reference coordinate system at the j-th projection moment according to the formula (1) ; ... Formula (1); Wherein, the For the rotation matrix of the object to be measured, For the translation vector of the object under test, And Forming a spatial pose parameter of the measured object at the j-th projection moment together; s3.2, calculating the theoretical projection position of a preset three-dimensional characteristic mark X i in the loading body at the j-th projection moment according to the formula (2) : ... Formula (2); Wherein K is a system internal geometric parameter matrix, and M is a system external geometric parameter matrix; The projection mapping relation is jointly determined by the internal geometric parameter matrix K of the system, the external geometric parameter matrix M of the system and the space pose of the measured object; the system geometric parameters consist of a system internal geometric parameter matrix K and a system external geometric parameter matrix M; S3.3, theoretical projection position through S3.2 Projection characteristic information obtained by S2 By comparison, a re-projection error can be constructed and a constrained optimization function can be constructed, the constrained optimization function being represented by equation (3): ... Formula (3); Wherein the method comprises the steps of For ensuring the consistency between the space pose parameters and the projection observation data, For constraining the continuity of pose changes at adjacent moments, As the amount of change between adjacent poses, For the weight parameters used to balance the effects of both, K O is the system internal geometry matrix of the coarse estimate, M O is the system external geometry matrix of the coarse estimate; And S3.4, obtaining an initial space pose parameter sequence of the measured object at each projection moment by minimizing the constraint optimization function.
3. The method for three-dimensional imaging of a weight loss fault transient according to claim 2, wherein the system internal geometric parameter matrix K is represented by formula (4): ....formula (4); wherein SAD is the orthographic projection distance from the ray source to the whole reference center of the test, SID is the orthographic projection distance from the ray source to the detector, and c x and c y are the main point coordinates of the detector.
4. The method for three-dimensional imaging of a weight loss fault transient of claim 3, wherein the system external geometric parameter matrix M is represented by formula (5): ... Formula (5); Wherein, the For the translational offset of the detector, Is a rotation matrix of the detector relative to the system reference frame.
5. The method of three-dimensional imaging of a weight loss fault transient of claim 4, wherein the objective function of the joint constraint mode is represented by formula (6): ... Formula (6).
6. The method of claim 5, wherein the tomographic reconstruction algorithm is an analytical tomographic reconstruction algorithm or an iterative tomographic reconstruction algorithm.
7. The method for transient three-dimensional imaging of a weightless fault of any one of claims 1 to 6, wherein the free motion state is free-falling motion, parabolic motion or supported spatial motion driven by an initial velocity without external force; The three-dimensional characteristic mark is steel balls and steel wires; the preprocessing operation is at least one of a denoising operation or an enhancing operation.
8. The method for three-dimensional imaging of weight loss fault transient according to any one of claims 1 to 6, wherein the carrier is divided into three layers from top to bottom, which are respectively defined as an upper layer, a middle layer and a lower layer; the measured object is fixed in the middle layer, and three-dimensional characteristic marks are fixedly loaded in the upper layer and the lower layer respectively.
9. A weightless fault transient three-dimensional imaging system, which is characterized in that the weightless fault transient three-dimensional imaging method according to any one of claims 1 to 8 is carried out.
10. The weightless fault transient three-dimensional imaging system according to claim 9, wherein there is provided: The projection data acquisition module is used for continuously acquiring X-ray projection data of the test whole at a plurality of projection moments, and introducing a geometric calibration prior of a known space structure through the loading body; The projection feature extraction module is used for preprocessing a projection image and extracting two-dimensional projection of the geometric calibration feature of the loading body, and establishing consistent corresponding relations of the same geometric calibration feature under different projection moments through cross-frame correlation to obtain projection feature information; the space pose deducing module deduces an initial space pose parameter sequence of the measured object relative to a system reference coordinate system at each moment based on the projection characteristic information; The geometric parameter estimation module is used for carrying out cooperative estimation and correction on the system geometric parameters and the space pose parameters of the measured object by jointly utilizing projection observation results at multiple projection moments under the spatial structure constraint of the loading body to obtain refined space pose parameters and corrected system geometric parameters; and the fault reconstruction module is used for obtaining the refined space pose parameters and the corrected system geometric parameters, constructing an imaging geometric relationship corresponding to the projection moment and completing three-dimensional fault reconstruction.

Description

Weightless fault transient three-dimensional imaging method and weightless fault transient three-dimensional imaging system thereof Technical Field The invention relates to the technical field of X-ray computed tomography imaging under aerospace medicine, biological experiments, material science or extreme environment imaging, in particular to a weightless fault transient three-dimensional imaging method and a weightless fault transient three-dimensional imaging system. Background The computed tomography technology acquires projection data of a measured object at different angles and performs tomographic reconstruction based on known and stable system geometric parameters, so as to obtain three-dimensional structure information of the measured object. Existing CT imaging systems generally assume that the object under test remains stationary during scanning or that the source and detector are controllably rotated relative to the object under test by rotating the scanning mechanism. Under the condition, the geometric consistency assumption is satisfied among projection data at each moment, so that the three-dimensional structure information of the measured object can be obtained by directly adopting a traditional tomographic reconstruction algorithm. However, in a weightless environment or under a condition of no fixed support, the object to be measured cannot be fixed or controlled to rotate through a mechanical structure during scanning, and the motion state of the object to be measured is usually represented as free falling, parabolic motion or spatial motion driven by an initial speed without external force. Under the condition, the spatial position and the gesture of the measured object in the imaging view field continuously change along with time and are difficult to acquire or accurately control in advance, so that the problems that 1, the spatial gesture of the measured object corresponding to single-frame projection is unknown, 2, the projection data at different moments does not meet the geometric consistency assumption of the traditional CT imaging, 3, the stay time of the measured object in the imaging view field is limited, and the number of the acquired projections is limited are caused. Therefore, in order to solve the defects in the prior art, it is particularly necessary to provide a weight loss fault transient three-dimensional imaging method and a weight loss fault transient three-dimensional imaging system. Disclosure of Invention The first object of the invention is to provide a weightless fault transient three-dimensional imaging method which aims at overcoming the defects of the prior art. The weightless fault transient three-dimensional imaging method can realize stable three-dimensional reconstruction of the measured object under the conditions of limited projection quantity and insufficient geometric consistency. The above object of the present invention is achieved by the following technical measures: The weightless fault transient three-dimensional imaging method is provided, and is carried out by the following steps: S1, loading an object to be tested on a loading body and taking the object to be tested as a test whole, enabling the test whole to be in a free motion state, continuously collecting X-ray projection data of the test whole at a plurality of projection moments under the condition that a ray source and a detector are fixed, and forming time sequence projection data; S2, preprocessing each frame of projection data in the time sequence projection data obtained in the S1, extracting two-dimensional projection features related to the spatial pose of the detected object and the geometric calibration structure unit in the carrier from the preprocessed projection data, and performing cross-frame correlation on the two-dimensional projection features between adjacent projection moments to obtain projection feature information, wherein the projection feature information is the contour features of the detected object, the edge features of the detected object and the projection positions of the three-dimensional feature marks; s3, deducing an initial space pose parameter sequence of the measured object relative to a system reference coordinate system at each moment based on projection characteristic information corresponding to the time sequence projection data of the S2; s4, obtaining an initial space pose parameter sequence according to the S3, and estimating the initial space pose parameter sequence in a joint constraint mode to obtain refined space pose parameters and corrected system geometric parameters; S5, the refined space pose parameters and corrected system geometric parameters are obtained in the S4, an imaging geometric relation corresponding to the projection moment is constructed, and tomographic reconstruction processing is carried out on time sequence projection data under the imaging geometric relation, so that a three-dimensional reconstruction result of the mea