Unmanned aerial vehicle monocular tilt-shift visual imaging calibration method

Abstract

The invention relates to the technical field of unmanned aerial vehicle monocular tilt-shift vision imaging, in particular to an unmanned aerial vehicle monocular tilt-shift vision imaging calibration method which comprises the following steps: determining a measurement target, and determining measurement parameters according to the measurement target; establishing a tilt-shift camera imaging model, and obtaining initial tilt-shift camera imaging parameters based on the measurement parameters; establishing a tilt-shift camera imaging optimization model, and determining optimal tilt-shift camera imaging parameters; and configuring the tilt-shift camera based on the optimal tilt-shift camera imaging parameter and determining the take-off position of the unmanned aerial vehicle, and after the unmanned aerial vehicle takes off, adjusting the unmanned aerial vehicle to enable the tilt-shift camera to be aligned with the measurement target, thereby realizing clear imaging of all the measurement targets. According to the method, through the tilt-shift camera imaging model and the tilt-shift camera imaging optimization model, the accurate tilt-shift camera imaging parameters are obtained according to the known measurement parameters, it is ensured that the unmanned aerial vehicle monocular tilt-shift camera achieves clear imaging, and technical support is provided for high-precision multi-point measurement in engineering monitoring.

Description

Technical Field

[0001] The present invention relates to the technical field of unmanned aerial vehicle (UAV) monocular tilt-shift visual imaging, and in particular to a UAV monocular tilt-shift visual imaging calibration method. Background Art

[0002] In recent years, with the rapid development of tilt-shift vision technology, it has been widely applied in various fields. For example, in medicine, this technology is used in corneal measurement, cataract surgery, particle image velocimetry, line structured light, and laser triangulation. In deformation monitoring, tilt-shift vision multi-point bridge measurement technology has achieved full-span displacement monitoring. Furthermore, combined with stereo digital image correlation technology, tilt-shift cameras have also been successfully applied to full-field three-dimensional deformation measurement. Tilt-shift vision technology opens up new possibilities for multi-point displacement measurement of engineering structures, demonstrating significant advantages in monitoring complex engineering structures at great depth.

[0003] However, combining tilt-shift cameras with UAV technology to form a UAV tilt-shift camera monitoring system for high-precision monitoring of multi-point displacements of engineering structures still faces many challenges. Among them, ensuring clear imaging of the airborne tilt-shift camera is one of the key difficulties. Currently, most tilt-shift cameras are mainly used on ground platforms, and their imaging parameters can be optimized through manual adjustment. However, on UAV platforms, the function of automatically adjusting the parameters of tilt-shift cameras is not yet mature, and multiple flight tests are usually required to determine the optimal configuration, which not only reduces operational efficiency but also increases technical complexity. Therefore, studying a UAV monocular tilt-shift vision imaging calibration method to ensure clear imaging of measuring points along the bridge structure by pre-calibrating the imaging parameters of the tilt-shift camera has important research significance and practical application value in solving the above problems. Summary of the Invention

[0004] The purpose of this invention is to provide a method for calibrating monocular tilt-shift vision imaging of an unmanned aerial vehicle (UAV) to solve the technical problems existing in the prior art. The specific technical solutions are as follows:

[0005] The calibration method of monocular tilt-shift vision imaging of UAV includes the following steps:

[0006] S1. Determine the measurement target and determine the measurement parameters according to the measurement target;

[0007] S2. Establishing a tilt-shift camera imaging model and obtaining initial tilt-shift camera imaging parameters based on the measured parameters;

[0008] S3, establishing a tilt-shift camera imaging optimization model and determining the optimal tilt-shift camera imaging parameters;

[0009] S4. Configure the tilt-shift camera based on the optimal imaging parameters and determine the take-off position of the UAV. After the UAV takes off, adjust the UAV so that the tilt-shift camera is aligned with the measurement target, so that clear imaging of all measurement targets can be achieved.

[0010] Furthermore, in S1, the measurement parameters include the measurement range S on the focal plane. t The distance D from the projection point of the optical center of the tilt-shift camera lens on the focal plane to the edge of the measurement range t .

[0011] Furthermore, in S2, the imaging model of the tilt-shift camera is:

[0012] D h =(S+D l )tan(β-θ)=D l tanβ;

[0013] D s =D l / cos(θ+γ)=D h / sin(θ+γ);

[0014]

[0015]

[0016]

[0017] In the above formula, α is the tilt-shift angle, f is the focal length of the tilt-shift camera lens, J is the distance from the optical center of the tilt-shift camera lens to the hinge line, d is the distance from the hinge line to the edge of the field of view, θ is the field of view angle of the tilt-shift camera lens, and D is the distance from the optical center of the tilt-shift camera lens to the hinge line. l and S are the field of view parameters, S is the field of view range on the focal plane, D l D is the distance from the projection point of the optical center of the tilt-shift camera lens on the focal plane to the edge of the field of view. s D is the straight-line distance from the optical center of the tilt-shift camera lens to the edge of the field of view. h is the vertical distance from the optical center of the tilt-shift camera lens to the focal plane, and β and γ are the angles between the line from the optical center of the tilt-shift camera lens to the edge of the field of view and the focal plane. l When and S are known, the imaging parameter D of the tilt-shift camera can be solved h and α.

[0018] Furthermore, the initial tilt-shift camera imaging parameters are obtained based on the measured parameters:

[0019] The measurement parameter D in S1 t With S t As the field of view parameter D land the initial value of S, the initial value of the tilt-shift camera imaging parameter D is obtained through the tilt-shift camera imaging model h and α.

[0020] Furthermore, the imaging optimization model of the tilt-shift camera is specifically as follows:

[0021] τ1=π-(π / 2-(β-θ / 2)+α)-(β-θ);

[0022] τ2=π-(π / 2-(β-θ / 2)+α)-β;

[0023] |ON|=f / sin(τ1);

[0024] |OP|=f / sin(τ2);

[0025]

[0026]

[0027] ∠MON=arcsin(|MN|sinτ1 / |OM|);

[0028] ∠POQ=arcsin(|PQ|sinτ2 / |OQ|);

[0029] β1=β-(θ-∠MON);

[0030] β2=β-∠POQ;

[0031] D t =D h / tan(β2);

[0032] S t =D h / tan(β1)-D t ;

[0033] In the above formula, S t is the measurement range on the focal plane, D t represents the distance from the projection point of the optical center of the tilt-shift camera lens on the focal plane to the edge of the measurement range, β and γ are the angles between the line connecting the optical center of the tilt-shift camera lens to the edge of the field of view and the focal plane, β1 and β2 represent the angles between the line connecting the optical center of the tilt-shift camera lens to the edge of the measurement range and the focal plane, τ1 and τ2 represent the angles between the image plane and the reverse extension line of the line connecting the optical center of the tilt-shift camera lens to the edge of the field of view, and MN and PQ are the pixel areas reserved on the left and right sides of the image plane.

[0034] Furthermore, the specific steps for determining the optimal imaging parameters of the tilt-shift camera include:

[0035] S3.1. Initial value D of the imaging parameter of the tilt-shift camera obtained in S2 h and α and the tilt-shift camera imaging optimization model to calculate the new measurement parameter D t and S t ;

[0036] S3.2. Determine the new measurement parameter D t and S t With the initial measurement parameter D t and S t Is the phase difference less than the set threshold? If it is less than the set threshold, then the corresponding imaging parameter D of the tilt-shift camera is h and α are the optimal imaging parameters of the tilt-shift camera; if they are not less than the set threshold, proceed to step S3.3;

[0037] S3.3. Reduce the field of view parameter D l The initial value of is added, the initial value of the field of view parameter S is added, and the new imaging parameters of the tilt-shift camera are calculated based on the imaging model of the tilt-shift camera;

[0038] S3.4. Calculate new measurement parameters D based on the imaging parameters of the tilt-shift camera obtained in S3.3 and the imaging optimization model of the tilt-shift camera. t and S t ;

[0039] S3.5. Repeat steps S3.2 to S3.4 until the set conditions are met.

[0040] Furthermore, the specific steps of S4 are:

[0041] According to the optimal imaging parameters of the tilt-shift camera obtained in S3, adjust the focus ring of the UAV tilt-shift camera so that it is at a distance D s2 The measurement target is clearly focused, where D s2 is the straight-line distance from the optical center of the tilt-shift camera lens to the edge of the measurement range;

[0042] Adjust the shift angle of the tilt-shift camera to α, according to the vertical distance D from the optical center of the tilt-shift camera lens to the focal plane h The distance D from the projection point of the optical center of the tilt-shift camera lens on the focal plane to the edge of the measurement range t , determine the take-off position of the UAV; after the UAV takes off, adjust the UAV so that the shift camera is aimed at the measurement target, and clear imaging of all measurement targets can be achieved.

[0043] The application of the technical solution of the present invention has the following beneficial effects:

[0044] The UAV monocular tilt-shift visual imaging calibration method proposed in this invention obtains accurate tilt-shift camera imaging parameters based on known measurement parameters through the tilt-shift camera imaging model and the tilt-shift camera imaging optimization model, ensuring clear imaging of the UAV monocular tilt-shift camera and providing technical support for high-precision multi-point measurement in engineering monitoring.

[0045] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0047] Figure 1 This is a flow chart of the calibration method for monocular tilt-shift vision imaging of a UAV according to the present invention;

[0048] Figure 2 is a diagram of a tilt-shift camera imaging model established in an embodiment of the present invention;

[0049] Figure 3 is a diagram of an imaging optimization model of a tilt-shift camera established in an embodiment of the present invention;

[0050] Figure 4 yes Figure 3 Local magnification Figure 1 ;

[0051] Figure 5 yes Figure 3 Local magnification Figure 2 ;

[0052] Figure 6 This is a diagram of the experimental scene of the tilt-shift camera imaging optimization model;

[0053] Figure 7 Figure 1 is the experimental result of the tilt-shift camera imaging optimization model, where (a) is the result without adjusting the tilt-shift angle, and (b) is the result after adjusting the tilt-shift angle.

[0054] Figure 8 This is a diagram of the experimental scene of the UAV monocular tilt-shift visual imaging calibration method of the present invention;

[0055] Figure 9 This is a diagram showing the experimental results of the UAV monocular tilt-shift visual imaging calibration method of the present invention. DETAILED DESCRIPTION

[0056] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered.

[0057] In the description of the present invention, it should be noted that the terms "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", "front", "back", "lateral", "longitudinal", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the present invention.

[0058] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified with "first," "second," etc., may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0059] Example:

[0060] See also Figure 1 The present invention provides a method for calibrating a monocular tilt-shift visual imaging system of an unmanned aerial vehicle, comprising the following steps:

[0061] S1. Determine the measurement target and determine the measurement parameters according to the measurement target;

[0062] S2. Establishing a tilt-shift camera imaging model and obtaining initial tilt-shift camera imaging parameters based on the measured parameters;

[0063] S3, establishing a tilt-shift camera imaging optimization model and determining the optimal tilt-shift camera imaging parameters;

[0064] S4. Configure the tilt-shift camera based on the optimal imaging parameters and determine the take-off position of the UAV. After the UAV takes off, adjust the UAV so that the tilt-shift camera is aligned with the measurement target, so that clear imaging of all measurement targets can be achieved.

[0065] In S1, the measurement parameters are determined based on the determined measurement target and the UAV monocular tilt-shift camera. The measurement parameters include the measurement range S on the focal plane. t The distance D from the projection point of the optical center of the tilt-shift camera lens on the focal plane to the edge of the measurement range t .

[0066] In S2, see Figure 2 , the imaging model of the tilt-shift camera is:

[0067] D h =(S+D l )tan(β-θ)=D l tanβ (Eq. 1);

[0068] D s =D l / cos(θ+γ)=D h / sin(θ+γ) (Eq. 2);

[0069]

[0070]

[0071]

[0072] In the above formula, α is the shift angle, f is the focal length of the tilt-shift camera lens, J is the distance from the optical center of the tilt-shift camera lens to the hinge line, d is the distance from the hinge line to the edge of the field of view, θ is the field of view angle of the tilt-shift camera lens, and D is l and S are the field of view parameters, S is the field of view range on the focal plane, D l D is the distance from the projection point of the optical center of the tilt-shift camera lens on the focal plane to the edge of the field of view. s D is the straight-line distance from the optical center of the tilt-shift camera lens to the edge of the field of view. h is the vertical distance from the optical center of the tilt-shift camera lens to the focal plane, and β and γ are the angles between the line from the optical center of the tilt-shift camera lens to the edge of the field of view and the focal plane. l When and S are known, the imaging parameter D of the tilt-shift camera can be solved h and α.

[0073] The measurement parameter D in S1 t With S t As the field of view parameter D l and the initial value of S, the initial value of the tilt-shift camera imaging parameter D is obtained through the tilt-shift camera imaging model h and α.

[0074] In S3, see Figure 3-Figure 5 In order to ensure that the measurement target does not jump out of the field of view, it is necessary to reserve space on both sides of the image when calculating the imaging parameters of the tilt-shift camera (i.e. Figure 5 The lengths of PQ and MN in the image are calculated and the tilt-shift camera imaging optimization model is established. The tilt-shift camera imaging optimization model is specifically as follows:

[0075] τ1=π-(π / 2-(β-θ / 2)+α)-(β-θ) equation 6);

[0076] τ2=π-(π / 2-(β-θ / 2)+α)-β Formula 7);

[0077] |ON| = f / sin(τ1) (Eq. 8);

[0078] |OP| = f / sin(τ2) (Eq. 9);

[0079]

[0080]

[0081] ∠MON=arcsin(|MN|sinτ1 / |OM|) Equation 12);

[0082] ∠POQ=arcsin(|PQ|sinτ2 / |OQ|) Equation 13);

[0083] β1 = β - (θ - ∠MON) (Eq. 14);

[0084] β2 = β - ∠POQ (Eq. 15);

[0085] D t =D h / tan(β2) (Eq. 16);

[0086] S t =D h / tan(β1)-D t Equation 17);

[0087] In the above formula, S t is the measurement range on the focal plane, D t represents the distance from the projection point of the optical center of the tilt-shift camera lens on the focal plane to the edge of the measurement range. β and γ are the angles between the line connecting the optical center of the tilt-shift camera lens to the edge of the field of view and the focal plane. β1 and β2 represent the angles between the line connecting the optical center of the tilt-shift camera lens to the edge of the measurement range and the focal plane. τ1 and τ2 represent the angles between the image plane and the reverse extension of the line connecting the optical center of the tilt-shift camera lens to the edge of the field of view. MN and PQ are the pixel areas reserved on the left and right sides of the image plane (used to ensure that the measurement target is always within the effective field of view when the measurement target or the camera moves within the allowable range), to prevent the measurement target from being lost in the field of view due to drone shaking.

[0088] The specific steps to determine the optimal tilt-shift camera imaging parameters include:

[0089] S3.1. Initial value D of the imaging parameter of the tilt-shift camera obtained in S2 h and α and the tilt-shift camera imaging optimization model to calculate the new measurement parameter D t and S t ;

[0090] S3.2. Determine the new measurement parameter D t and S t With the initial measurement parameter D t and S tIs the phase difference less than the set threshold? If it is less than the set threshold, then the corresponding imaging parameter D of the tilt-shift camera is h and α are the optimal imaging parameters of the tilt-shift camera; if they are not less than the set threshold, proceed to step S3.3;

[0091] S3.3, in this embodiment, the field of view parameter D is reduced in steps of 10 mm. l The initial value of is added, the initial value of the field of view parameter S is added, and the new imaging parameters of the tilt-shift camera are calculated based on the imaging model of the tilt-shift camera;

[0092] S3.4. Calculate new measurement parameters D based on the imaging parameters of the tilt-shift camera obtained in S3.3 and the imaging optimization model of the tilt-shift camera. t and S t ;

[0093] S3.5. Repeat steps S3.2 to S3.4 until the set conditions are met.

[0094] The specific steps of S4 are:

[0095] According to the optimal imaging parameters of the tilt-shift camera obtained in S3, adjust the focus ring of the UAV tilt-shift camera so that it is at a distance D s2 The measurement target is clearly focused, where D s2 is the straight-line distance from the optical center of the tilt-shift camera lens to the edge of the measurement range;

[0096] Adjust the shift angle of the tilt-shift camera to α, according to the vertical distance D from the optical center of the tilt-shift camera lens to the focal plane h The distance D from the projection point of the optical center of the tilt-shift camera lens on the focal plane to the edge of the measurement range t , determine the take-off position of the UAV; after the UAV takes off, adjust the UAV so that the shift camera is aimed at the measurement target, and clear imaging of all measurement targets can be achieved.

[0097] The UAV monocular tilt-shift visual imaging calibration method proposed in this invention obtains accurate tilt-shift camera imaging parameters based on known measurement parameters through the tilt-shift camera imaging model and the tilt-shift camera imaging optimization model, ensuring clear imaging of the UAV monocular tilt-shift camera and providing technical support for high-precision multi-point measurement in engineering monitoring.

[0098] (1) Tilt-Shift Camera Imaging Optimization Model Verification Experiment

[0099] In order to verify the accuracy of the tilt-shift camera imaging optimization model, a validation experiment of the tilt-shift camera imaging optimization model was carried out. The equipment and parameters used in the experiment are shown in Table 1:

[0100] Table 1 Experimental equipment and parameters for verifying the imaging optimization model of the tilt-shift camera

[0101]

[0102] Set the measuring range S t The distance D from the projection point of the optical center of the tilt-shift camera lens on the focal plane to the edge of the measurement range is 2.4 meters. t is 4.2 meters, such as Figure 6 As shown in the figure, the length of MN and PQ is set to 240 pixels, that is, 240 pixels of space are left on each side of the image. According to equations 1) to 17), the shift angle α is calculated to be 5.6°, and D h is 1.0m; use the angle slide to adjust the shift angle, the result is as follows Figure 7 As shown. Among them, Figure 7 (a) shows the image when the shift angle α is 0°. It can be seen that only the measurement marks 104 and 044 are clear. Figure 7 (b) shows the image when the shift angle is 5.6°. It can be seen that all measurement marks in (b) are clear, which verifies the accuracy of the imaging optimization model of the tilt-shift camera.

[0103] (2) Experimental verification of the calibration method for monocular tilt-shift vision imaging of UAV

[0104] In order to verify the accuracy of the UAV tilt-shift visual imaging calibration method, a verification experiment of the UAV monocular tilt-shift visual imaging calibration method was carried out. The equipment and parameters used in the experiment are shown in Table 2:

[0105] Table 2 Experimental equipment and parameters for verifying the calibration method of monocular tilt-shift vision imaging of UAV

[0106]

[0107]

[0108] Set the measuring range S t The distance D from the projection point of the optical center of the tilt-shift camera lens on the focal plane to the edge of the measurement range is 28 meters. t is 15 meters, such as Figure 8 As shown; set the length of MN and PQ to 320 pixels, that is, leave 320 pixels of space on the left and right sides of the image; according to equations 1)-17), the calculated shift angle is 2.4°, D h 2.1 meters, D s2 15.1 meters Then, the shift angle of the tilt-shift camera is set to 2.4°, and the focus ring of the lens is adjusted to make it focus clearly on the measurement target at a distance of 15.1 meters. t With D h Determine the takeoff location for the drone.

[0109] After the UAV takes off, the images of the measurement marks collected are as follows Figure 9 As shown. Figure 9 It can be seen that the measurement marks T1-T5 can be clearly imaged, which verifies the effectiveness of the UAV monocular tilt-shift vision imaging calibration method.

[0110] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. UAV monocular tilt-shift visual imaging calibration method, characterized by: The steps include: S1. Determine the measurement target and determine the measurement parameters according to the measurement target; S2. Establishing a tilt-shift camera imaging model and obtaining initial tilt-shift camera imaging parameters based on the measured parameters; S3, establishing a tilt-shift camera imaging optimization model and determining the optimal tilt-shift camera imaging parameters; S4. Configure the tilt-shift camera based on the optimal imaging parameters and determine the take-off position of the UAV. After the UAV takes off, adjust the UAV so that the tilt-shift camera is aligned with the measurement target, so that clear imaging of all measurement targets can be achieved.

2. The method for calibrating the monocular tilt-shift vision imaging of a UAV according to claim 1, characterized in that: In S1, the measurement parameters include the measurement range S on the focal plane t The distance D from the projection point of the optical center of the tilt-shift camera lens on the focal plane to the edge of the measurement range t .

3. The method for calibrating the monocular tilt-shift vision imaging of a UAV according to claim 1, characterized in that: In S2, the imaging model of the tilt-shift camera is: <h2 style=";text-align:left;direction:ltr">D<h2 style=";text-align:left;direction:ltr"> h <h2 style=";text-align:left;direction:ltr"> (S+D)<h2 style=";text-align:left;direction:ltr"> l <h2 style=";text-align:left;direction:ltr"> )tan(β-θ) = D<h2 style=";text-align:left;direction:ltr"> l <h2 style=";text-align:left;direction:ltr"> tanβ; D s =D l / cos(θ+γ)=D h / sin(θ+γ); In the above formula, α is the tilt-shift angle, f is the focal length of the tilt-shift camera lens, J is the distance from the optical center of the tilt-shift camera lens to the hinge line, d is the distance from the hinge line to the edge of the field of view, θ is the field of view angle of the tilt-shift camera lens, and D is the distance from the optical center of the tilt-shift camera lens to the hinge line. l and S are the field of view parameters, S is the field of view range on the focal plane, D l D is the distance from the projection point of the optical center of the tilt-shift camera lens on the focal plane to the edge of the field of view. s D is the straight-line distance from the optical center of the tilt-shift camera lens to the edge of the field of view. h is the vertical distance from the optical center of the tilt-shift camera lens to the focal plane, and β and γ are the angles between the line from the optical center of the tilt-shift camera lens to the edge of the field of view and the focal plane.

4. The method for calibrating the monocular tilt-shift vision imaging of a UAV according to claim 3, characterized in that: The initial tilt-shift camera imaging parameters obtained based on the measured parameters are: The measurement parameter D in S1 t With S t As the field of view parameter D l and the initial value of S, the initial value of the tilt-shift camera imaging parameter D is obtained through the tilt-shift camera imaging model h and α.

5. The method for calibrating the monocular tilt-shift vision imaging of a UAV according to claim 4, characterized in that: The specific imaging optimization model of the tilt-shift camera is: τ1=π-(π / 2-(β-θ / 2)+α)-(β-θ); τ2=π-(π / 2-(β-θ / 2)+α)-β; |ON|=f / sin(τ1); |OP|=f / sin(τ2); ∠MON=arcsin(|MN|sinτ1 / |OM|); ∠POQ=arcsin(|PQ|sinτ2 / |OQ|); β1=β-(θ-∠MON); β2=β-∠POQ; <h2 style=";text-align:left;direction:ltr">D<h2 style=";text-align:left;direction:ltr"> t <h2 style=";text-align:left;direction:ltr"> =D<h2 style=";text-align:left;direction:ltr"> h <h2 style=";text-align:left;direction:ltr"> / tan(β2); S t =D h / tan(β1)-D t ; In the above formula, S t is the measurement range on the focal plane, D t represents the distance from the projection point of the optical center of the tilt-shift camera lens on the focal plane to the edge of the measurement range, β and γ are the angles between the line connecting the optical center of the tilt-shift camera lens to the edge of the field of view and the focal plane, β1 and β2 represent the angles between the line connecting the optical center of the tilt-shift camera lens to the edge of the measurement range and the focal plane, τ1 and τ2 represent the angles between the image plane and the reverse extension line of the line connecting the optical center of the tilt-shift camera lens to the edge of the field of view, and MN and PQ are the pixel areas reserved on the left and right sides of the image plane.

6. The method for calibrating the monocular tilt-shift vision imaging of a UAV according to claim 5, characterized in that: The specific steps to determine the optimal tilt-shift camera imaging parameters include: S3.

1. Initial value D of the imaging parameter of the tilt-shift camera obtained in S2 h and α and the tilt-shift camera imaging optimization model to calculate the new measurement parameter D t and S t ; S3.

2. Determine the new measurement parameter D t and S t With the initial measurement parameter D t and S t Is the phase difference less than the set threshold? If it is less than the set threshold, then the corresponding imaging parameter D of the tilt-shift camera is h and α are the optimal imaging parameters of the tilt-shift camera; if they are not less than the set threshold, proceed to step S3.3; S3.

3. Reduce the field of view parameter D l The initial value of is added, the initial value of the field of view parameter S is added, and the new imaging parameters of the tilt-shift camera are calculated based on the imaging model of the tilt-shift camera; S3.

4. Calculate new measurement parameters D based on the imaging parameters of the tilt-shift camera obtained in S3.3 and the imaging optimization model of the tilt-shift camera. t and S t ; S3.

5. Repeat steps S3.2 to S3.4 until the set conditions are met.

7. The method for calibrating monocular tilt-shift vision imaging for a UAV according to claim 6, characterized in that: The specific steps of S4 are: According to the optimal imaging parameters of the tilt-shift camera obtained in S3, adjust the focus ring of the UAV tilt-shift camera so that it is at a distance D s2 The measurement target is clearly focused, where D s2 is the straight-line distance from the optical center of the tilt-shift camera lens to the edge of the measurement range; Adjust the shift angle of the tilt-shift camera to α, according to the vertical distance D from the optical center of the tilt-shift camera lens to the focal plane h The distance D from the projection point of the optical center of the tilt-shift camera lens on the focal plane to the edge of the measurement range t , determine the take-off position of the UAV; after the UAV takes off, adjust the UAV so that the shift camera is aimed at the measurement target, and clear imaging of all measurement targets can be achieved.

Images