Imaging method of rotating object

Abstract

The invention belongs to the technical field of object imaging, and particularly relates to an imaging method of a rotating object. The imaging method comprises the following steps that a rotating picture with the duration T of an imaging target is intercepted, the rotating picture is equally divided into a plurality of equal time periods according to the time interval delta t, and the duration T is larger than the duration of one circle of rotation of the imaging target; imaging the picture in each time period by adopting a plurality of different modulation signals, and acquiring an intensity value of reflected light through a single-pixel detector; calculating a one-dimensional projection curve of the imaging target in each time period according to the intensity value and the modulation signal; arranging the one-dimensional projection curves in different time periods according to time to obtain a projection curve time change diagram of the imaging target; and establishing an angle projection curve according to the time interval delta t, the rotation speed of the imaging target and the projection curve time change diagram, and performing back projection to realize imaging of the rotation target. According to the invention, the rotating object can be effectively imaged.

Description

Technical Field

[0001] The present invention belongs to the technical field of object imaging, and in particular relates to an imaging method for a rotating object. Background Art

[0002] For some rapidly rotating objects, traditional static imaging methods can only capture a momentary image and cannot reflect the dynamic information of the object during rotation, resulting in incomplete information. For example, when traditional optical cameras capture high-speed rotating fan blades, the image may be blurred due to the rapid rotation of the blades.

[0003] When imaging an object from multiple angles, traditional methods can require frequent adjustments to the camera or object position, making the process complex and inefficient. For example, in industrial inspection, performing a full-scale inspection of a complex rotating part using traditional methods can be extremely time-consuming.

[0004] The current technology for imaging rotating objects often requires limiting the object's multiple rotational motion states, which is very cumbersome to operate. Therefore, a fast and effective method for imaging rotating objects is urgently needed. Summary of the Invention

[0005] To address the above problems, the present invention uses only a single-point detector and a spatial modulator to achieve imaging of rotating objects, without the need for traditional complex array imaging devices. The system is flexible and can directly obtain the rotation speed of the rotating object without the need for additional auxiliary devices.

[0006] The present invention discloses a method for imaging a rotating object, the method comprising the following steps:

[0007] Intercepting a rotating image of the imaging target for a duration T, and dividing the rotating image into a plurality of equal time periods at time intervals of Δt, wherein the duration T is greater than the duration of one rotation of the imaging target;

[0008] The images of each time period are imaged using multiple different modulation signals, and the intensity value of the reflected light is obtained through a single-pixel detector;

[0009] Calculating a one-dimensional projection curve of the imaging target in each time period according to the intensity value and the modulation signal;

[0010] Arrange the one-dimensional projection curves in different time periods according to time to obtain a time variation diagram of the projection curve of the imaging target;

[0011] An angle projection curve is established according to the time interval Δt, the rotation speed of the imaging target and the time variation diagram of the projection curve, and back-projection is performed to realize imaging of the rotating target.

[0012] Furthermore, before establishing the angle projection curve according to the time interval Δt, the rotation speed of the imaging target and the projection curve time variation diagram, the method further includes calculating the rotation speed of the imaging target. The method specifically includes the following steps:

[0013] Use the one-dimensional projection curve at time T1 to perform correlation calculation with the one-dimensional projection curves of other time periods to obtain the correlation coefficient curves between them and find the maximum value;

[0014] Obtain the time Ts at which the maximum value is located. The time taken for one rotation can be obtained by calculating Ts-T1;

[0015] The rotation speed of the imaging target is calculated according to the time taken for the imaging target to rotate once.

[0016] Furthermore, the steps of modulating the image of each time period with a plurality of different modulation signals and obtaining the single-pixel detector intensity value specifically include the following steps:

[0017] Generate Hadamard matrix H(i,j) of size N×N;

[0018] Generate multiple modulation signals Pm(x,y), where x and y are corresponding spatial coordinates and m represents the sequence number of the modulation signal;

[0019] The rotating object is modulated using the modulation signal, and an intensity value Sm(t) of the modulated reflected light is acquired using a single-pixel detector.

[0020] Furthermore, the intensity value Sm(t) of the reflected light can be expressed as:

[0021] Sm(t)=∑Pm(x,y)f(x,y;γΔt)

[0022] Where γ represents the speed of the object's rotation.

[0023] Furthermore, the step of calculating the one-dimensional projection curve of the imaging target in each time period according to the intensity value and the modulation signal specifically includes the following steps:

[0024] Obtaining a projection integral curve of the imaging target in the γΔtx direction according to the properties of the modulation signal Pm(x,y);

[0025] The one-dimensional projection curve is obtained through the projection integral curve according to the principle of single-pixel imaging.

[0026] Furthermore, according to the properties of the modulation signal Pm(x,y), Sm(t) is rewritten as:

[0027] Sm(t)=∑H(1)f γΔt (1)

[0028] Among them, f γΔt (l) represents the projection integral curve of the object along the angle γΔtx direction.

[0029] Furthermore, the back-projection to achieve the imaging of the rotating target can be expressed as:

[0030]

[0031] Where S represents the low-pass filter function in the frequency domain. F is the inverse Fourier transform. B is the back projection operation, f / (x,y) represents the edge image of the object, represents the angle projection curve.

[0032] The present invention further discloses a computer-readable storage medium having a computer program stored thereon. When the computer program is run, a method for imaging a rotating object as described in any one of the above embodiments is executed.

[0033] The present invention also discloses a computer device, including a processor and a storage medium, wherein a computer program is stored on the storage medium. The processor reads and runs the computer program from the storage medium to execute a method for imaging a rotating object as described in any one of the above embodiments.

[0034] In the present invention, clear imaging of a rotating object can be achieved without knowing the rotational motion parameters, limiting the multiple rotational motion states of the object, or performing rotational compensation on the synchronous modulation.

[0035] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 A diagram showing the steps of a method for imaging a rotating object according to an embodiment of the present invention is shown;

[0038] Figure 2 A schematic flow chart of a method for imaging a rotating object according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0040] like Figure 1 As shown, the present invention discloses a method for imaging a rotating object, the imaging method comprising the following steps:

[0041] Intercepting a rotating image of the imaging target for a duration T, and dividing the rotating image into a plurality of equal time periods according to a time interval Δt, wherein the duration T is greater than the duration of one rotation of the imaging target;

[0042] The images of each time period are imaged using multiple different modulation signals, and the intensity value of the reflected light is obtained through a single-pixel detector;

[0043] Calculating a one-dimensional projection curve of the imaging target in each time period according to the intensity value and the modulation signal;

[0044] Arrange the one-dimensional projection curves in different time periods according to time to obtain a time variation diagram of the projection curve of the imaging target;

[0045] An angle projection curve is established according to the time interval Δt, the rotation speed of the imaging target and the time variation diagram of the projection curve, and back-projection is performed to realize imaging of the rotating target.

[0046] Specifically, the imaging target is photographed for a period of time, during which the imaging target rotates continuously. During a longer shooting time, a period of shooting data is intercepted to perform imaging analysis of the imaging target. Exemplarily, the intercepted time period is T, and it is worth noting that during the intercepted time period of T, the imaging target rotates at least once. If the intercepted time is less than one rotation, the imaging processing of the rotating imaging target cannot be performed. The intercepted rotating animation is divided into multiple equal time periods according to the time interval Δt. Exemplarily, the rotating animation is divided into multiple different time periods T1, T2, T3...T jIn this embodiment, it is assumed that the imaging target is stationary in each time period. The image in each time period is modulated by a modulation signal, and then the intensity value is detected by a single pixel detector. The one-dimensional projection curve of the imaging target in each time period is calculated by the intensity value and the modulation signal. For example, in time period T1, the projection patterns P1, P2, P3...P i Illuminate the equivalent stationary rotating object and use a single-pixel detector to obtain the detection intensity value, and finally obtain a set of energy intensity detection data I1 with a length of i. Using the energy intensity detection data I1 and the modulation patterns P1, P2, P3...P i Calculate and obtain the one-dimensional projection curve T of the imaging target P1 Similarly, the one-dimensional projection curves of j imaging targets can be obtained, which is expressed as T p1 , T p2 , T p3 ...T pj The one-dimensional projection curve is arranged according to time to obtain a projection curve time variation diagram. An angle projection curve is established according to the time interval Δt, the rotation speed of the imaging target and the projection curve time variation diagram, and back-projection is performed to realize imaging of the rotating target.

[0047] Exemplarily, the angular position corresponding to the imaging target at the initial time T1 is set to 0 degrees, and assuming that the rotation speed of the object is γ, the angular interval of each obtained projection curve is γΔt.

[0048] To realize the imaging of rotating objects, it is only necessary to establish an accurate angle projection curve and perform back-projection transformation to achieve accurate quasi-static imaging of the imaging target.

[0049] This embodiment allows for rapid imaging of rotating objects if the rotational speed of the imaging target is known, without requiring the object's rotational motion to be defined, resulting in a very simple operation. Imaging of the rotating object can be achieved by directly obtaining the angle corresponding to each one-dimensional projection curve and performing a back-projection transformation. However, in most cases, the speed of the rotating object is unknown, requiring the design of a corresponding solution algorithm to obtain the object's rotational speed.

[0050] Furthermore, before establishing the angle projection curve according to the time interval Δt, the rotation speed of the imaging target and the projection curve time variation diagram, the method further includes calculating the rotation speed of the imaging target. The method specifically includes the following steps:

[0051] Use the one-dimensional projection curve at time T1 to perform correlation calculation with the one-dimensional projection curves of other time periods to obtain the correlation coefficient curve between the two and find the maximum value;

[0052] Get the time T of the maximum value s The time it takes to rotate once can be calculated by T s -T1 gets;

[0053] The rotation speed of the imaging target is calculated based on the time taken for the imaging target to rotate once. Specifically, when the imaging target rotates, if the detection sampling time is long enough, the one-dimensional projection curve obtained by inversion will show periodic changes, and the duration of each period corresponds to the duration of the imaging target rotating once. Based on the above theory, the first set of one-dimensional projection curves and the one-dimensional projection curves of other time periods are used for calculation to obtain the correlation coefficient curve between the two and find the maximum value. For example, T p1 Respectively with T p2 , T p3 ...T pj Perform calculations to obtain multiple correlation coefficients. Obtain the time Ts corresponding to the maximum value of the correlation coefficient. Assume that T p1 The corresponding time is 0, and the time length Ts is recorded as the time taken for the imaging target to rotate one circle, and the rotation speed of the imaging target can be further calculated.

[0054] Furthermore, the steps of modulating the image of each time period with a plurality of different modulation signals and obtaining the single-pixel detector intensity value specifically include the following steps:

[0055] Generate Hadamard matrix H(i,j) of size N×N;

[0056] Generate multiple modulation signals P m (x, y), x and y are corresponding spatial coordinates, and m represents the sequence number of the modulation signal;

[0057] The rotating object is modulated using the modulation signal, and an intensity value Sm(t) of the modulated reflected light is acquired using a single-pixel detector.

[0058] Specifically, the picture of each time period is a still picture. Generate a Hadamard matrix H(i,j) of size N×N and multiple modulation signals P m (x, y) modulates the above-mentioned still image, m represents the ordinal number of the modulation signal, and its value is m=1, 2...N, and its pixel size is also N×N.

[0059] The specific representation is:

[0060] P m (x,y)=[H(l)...H(l)]

[0061] Among them, H(l) is the one-dimensional matrix of the lth row of the Hadamard matrix, and its size is 1×N. After the N one-dimensional matrices H(l) are arranged, P m The size of (x,y) is N×N, and the corresponding elements in each row have the same value.

[0062] Use projection patterns P1, P2, P3…P i Illuminate the equivalent still picture of each time period in turn and use a single pixel detector to obtain the intensity value S m (t). Detect i intensity values ​​in each time period, continue for j time periods, and obtain j detection data of length i, using data sets I1, I2, I3...I j It is worth noting that the object needs to rotate more than one circle during the continuous detection time.

[0063] The intensity value S of the emitted light is m (t) can be expressed as:

[0064] S m (t)=∑P m (x,y)f(x,y;γΔt)

[0065] Wherein γ is the rotation speed of the imaging target.

[0066] According to the modulation signal P m The property of (x,y) rewrites Sm(t) as:

[0067] S m (t)=∑H(l)f γΔt (l)

[0068] Among them, f γΔt (l) represents the projection integral curve of the object along the angle γΔtx direction.

[0069] Furthermore, the step of calculating the one-dimensional projection curve of the imaging target in each time period according to the intensity value and the modulation signal specifically includes the following steps:

[0070] According to the modulation signal P m The property of (x, y) obtains the projection integral curve of the imaging target in the γΔtx direction;

[0071] The one-dimensional projection curve is obtained through the projection integral curve according to the principle of single-pixel imaging.

[0072] Specifically, it can be seen that when the object does not rotate, the obtained projection curve is a projection curve at a single angle, which cannot realize the imaging of the object. However, since the object rotates, it is possible to obtain projection curves at different angles, thereby realizing the imaging of the rotating object. After obtaining the projection curves at different angles, we can use the back projection transformation to obtain the image of the rotating object. The formula can be expressed as

[0073]

[0074] Where S represents the low-pass filter function in the frequency domain. F is the inverse Fourier transform. B is the back projection operation, f / (x,y) represents the edge image of the object, represents the angle projection curve.

[0075] Theoretical analysis thus far demonstrates that the proposed method achieves imaging of rotating objects. The rotational velocity is determined by calculating the correlation between the projection integral curves. This method eliminates the need for synchronous rotation of the projection pattern, requiring only a single pattern with a fixed projection angle. This significantly reduces the number of projection patterns required compared to existing methods. The proposed method requires N projection modulation patterns, and the pixel resolution of the acquired image is N×N. This indicates that the proposed method's projection sampling rate is 1 / N. For an image resolution of 128×128, the projection sampling rate is less than 0.8%.

[0076] In another embodiment of the present invention, a computer-readable storage medium is disclosed. A computer program is stored on the medium. When the computer program is run, the method for imaging a rotating object as described in any one of the above embodiments is executed.

[0077] In another embodiment of the present invention, a computer device is disclosed, including a processor and a storage medium, wherein a computer program is stored on the storage medium. The processor reads and runs the computer program from the storage medium to execute a method for imaging a rotating object as described in any one of the above embodiments.

[0078] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for imaging a rotating object, characterized in that: The imaging method comprises the following steps: Intercepting a rotating image of the imaging target for a duration T, and dividing the rotating image into a plurality of equal time periods at time intervals Δt, wherein the duration T is greater than the duration of one rotation of the imaging target; The images of each time period are imaged using multiple different modulation signals, and the intensity value of the reflected light is obtained through a single-pixel detector; Calculating a one-dimensional projection curve of the imaging target in each time period according to the intensity value and the modulation signal; Arrange the one-dimensional projection curves in different time periods according to time to obtain a time variation diagram of the projection curve of the imaging target; An angle projection curve is established according to the time interval Δt, the rotation speed of the imaging target and the time variation diagram of the projection curve, and back-projection is performed to realize imaging of the rotating target.

2. The method for imaging a rotating object according to claim 1, wherein: Before establishing the angle projection curve according to the time interval Δt, the rotation speed of the imaging target and the projection curve time variation diagram, the method further includes calculating the rotation speed of the imaging target. The calculation of the rotation speed of the imaging target specifically includes the following steps: Use the one-dimensional projection curve at time T1 to perform correlation calculation with the one-dimensional projection curves of other time periods to obtain the correlation coefficient curves between them and find the maximum value; Obtain the time Ts at which the maximum value is located. The time taken for one rotation can be obtained by calculating Ts-T1; The rotation speed of the imaging target is calculated according to the time taken for the imaging target to rotate once.

3. The method for imaging a rotating object according to claim 1, wherein: The method of modulating the image of each time period with a plurality of different modulation signals and obtaining the intensity value of a single pixel detector specifically includes the following steps: Generate Hadamard matrix H(i,j) of size N×N; Generate multiple modulation signals Pm(x,y), where x and y are corresponding spatial coordinates and m represents the sequence number of the modulation signal; The rotating object is modulated using the modulation signal, and an intensity value Sm(t) of the modulated reflected light is acquired using a single-pixel detector.

4. The method for imaging a rotating object according to claim 3, wherein: The intensity value of the reflected light Sm(t) can be expressed as: Sm(t)=∑Pm(x,y)f(x,y;γΔt) Where γ represents the speed of the object's rotation.

5. The method for imaging a rotating object according to claim 4, wherein: Calculating the one-dimensional projection curve of the imaging target in each time period according to the intensity value and the modulation signal specifically includes the following steps: Obtaining a projection integral curve of the imaging target in the γΔtx direction according to the properties of the modulation signal Pm(x,y); The one-dimensional projection curve is obtained through the projection integral curve according to the principle of single-pixel imaging.

6. The method for imaging a rotating object according to claim 5, wherein: According to the properties of the modulation signal Pm(x,y), Sm(t) is rewritten as: Sm(t)=∑H(1)f γΔt (l) Among them, f γΔt (l) represents the projection integral curve of the object along the angle γΔtx direction.

7. The method for imaging a rotating object according to claim 1, wherein: The back-projection to achieve the imaging of the rotating target can be expressed as: Where S represents the low-pass filter function in the frequency domain. F is the inverse Fourier transform. B is the back projection operation, f / (x,y) represents the edge image of the object, represents the angle projection curve.

8. A computer-readable storage medium, characterized in that A computer program is stored on the medium, and after the computer program is run, a method for imaging a rotating object according to any one of claims 1 to 7 is executed.

9. A computer device, characterized in that: The method comprises a processor and a storage medium, wherein a computer program is stored in the storage medium, and the processor reads and runs the computer program from the storage medium to execute the imaging method of a rotating object according to any one of claims 1 to 7.

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