Apparatus and method for measuring viewing angle

Abstract

The application discloses a kind of methods and devices for measuring viewing angle, it is related to camera or camera lens testing technical field, the system includes: first rotating unit, second rotating unit, translation unit, first shooting target, second shooting target, control unit, second rotating unit is used to drive the translation unit and the camera to be measured around rotation axis X rotation;Second rotating unit is rotationally connected on the first rotating unit, for driving the second rotating unit, the translation unit and the camera to be measured together around rotation axis Y rotation;Control unit is used to prompt or control the first rotating unit, second rotating unit, translation unit carries out the measurement of viewing angle;By adjusting the position of first rotating unit, second rotating unit and translation unit, the angle position of rotating unit is recorded at this time, upper view angle, lower view angle, left view angle, right view angle are obtained, and horizontal view angle and vertical view angle are finally calculated;Accomplish accurate measurement horizontal view angle, vertical view angle.

Description

Technical Field

[0001] This invention relates to the field of camera or video lens testing technology, and in particular to an apparatus and method for measuring angle of view. Background Technology

[0002] Digital imaging products come in many varieties, such as digital cameras, digital camcorders, and video-display systems, and are widely used in production and daily life. Examples include industrial cameras, surveillance cameras, endoscopes, smartphones, in-vehicle CMS (Camera-Monitor-System), and dashcams. FOV (Field of View) is an important indicator for these digital imaging products; it refers to the field of view, angle of view, or field of view. FOV specifically refers to the horizontal field of view. horizontal and vertical FOV vertical The collective term is as follows: Figure 1 As shown.

[0003] In existing technologies, a trigonometric function-based FOV measurement method is generally used: First, a rectangular test chart is selected, with an aspect ratio consistent with that of the camera, such as both being 4:3 or both being 16:9. The four sides of the rectangular test chart have triangular position marks. Then, the width W and height H of the test chart are measured; the camera's optical axis is positioned perpendicular to the test chart, and an image is captured and displayed on a monitor; the distance D between the camera and the test chart is adjusted so that the images of the outer vertices of the four triangular marks on the test chart are exactly at the edge of the monitor; the distance D between the camera and the test chart is measured at this point; finally, the camera's field of view is calculated using trigonometric functions.

[0004] FOV horizontal = 2*arctg[W / (2*D)];

[0005] FOV vertical = 2*arctg[H / (2*D)];

[0006] However, the measurement method based on trigonometric functions to calculate FOV has the following factors that can cause relatively large measurement errors: the optical axis of the camera is only approximately perpendicular to the test card, which will cause measurement errors; the distance between the camera and the test card is used, not the distance from the optical center of the camera to the test card, which will cause measurement errors; if the camera's upper and lower viewing angles are asymmetrical, or the left and right viewing angles are asymmetrical, the measurement error of this method will be even greater. Summary of the Invention

[0007] The purpose of this invention is to provide a device and method for measuring viewing angles, which precisely positions the optical center of the camera under test at the intersection of two rotation axes, and can accurately measure the horizontal and vertical viewing angles.

[0008] To achieve the above objectives, the present invention provides the following solution:

[0009] A device for measuring viewing angle, the device comprising: a first rotation unit, a second rotation unit, a translation unit, a first imaging target, a second imaging target, and a control unit;

[0010] The rotation axis X of the first rotating unit is perpendicular to the rotation axis Y of the second rotating unit, and the extension of the straight line containing the rotation axis Y and the rotation axis X is orthogonal to the optical axis Z of the camera under test at a point O. The rotation axis X, the rotation axis Y and the optical axis Z form an XYZ orthogonal coordinate system, and point O is called the origin of the XYZ orthogonal coordinate system.

[0011] The translation unit is connected to the second rotation unit, and the second rotation unit is used to drive the translation unit and the camera under test to rotate around the rotation axis X; the second rotation unit is rotatably connected to the first rotation unit, and the first rotation unit is used to drive the second rotation unit, the translation unit and the camera under test to rotate together around the rotation axis Y.

[0012] The camera under test is mounted on the translation unit and can move along the optical axis Z; the horizontal edge of the camera under test is parallel to the rotation axis X, and the vertical edge of the camera under test is parallel to the rotation axis Y.

[0013] The first shooting target is composed of at least a square outer frame and crosshairs; the second shooting target is composed of at least a square outer frame and crosshairs; based on the distance from the camera under test, the first shooting target is designated as a near target and the second shooting target as a far target;

[0014] In the default state, the centers of the first and second shooting targets are on the extension line of the optical axis Z and are perpendicular to the optical axis Z; the vertical line of the crosshair is parallel to the rotation axis Y, and the horizontal line of the crosshair is parallel to the rotation axis X.

[0015] The control unit is used to prompt or control the first rotation unit, the second rotation unit, and the translation unit to measure the viewing angle.

[0016] Furthermore, inside the square frame, all areas except the crosshairs are either open or transparent.

[0017] Furthermore, the crosshairs of the second shooting target are thicker than those of the first shooting target.

[0018] Furthermore, the crosshairs of the second shooting target are different colors from those of the second shooting target.

[0019] Furthermore, both the first and second rotation units are equipped with stepper motors and angle start position sensors for rotation via electric drive; the translation unit is equipped with a stepper motor and a line start position sensor for movement via electric drive; the rotation unit calculates the number of steps of the drive motor from the angle start position to calculate the angular position; the translation unit calculates the number of steps of the drive motor from the line start position to calculate the linear position.

[0020] Furthermore, both the first and second rotating units are equipped with attached angle scales for manual rotation; the translation unit is equipped with a linear scale for manual movement, and the angle and linear positions are read by observing the scales; the first and second rotating units and the translation unit are all equipped with locking devices for manual locking or unlocking.

[0021] Furthermore, the device also includes a display unit connected to the camera under test for observing the video images output by the camera under test.

[0022] The present invention also provides a method for measuring viewing angle, applied to the aforementioned device for measuring viewing angle, the method comprising:

[0023] S1. Adjust the first rotation unit and the second rotation unit so that the optical axis Z of the camera under test is perpendicular to the target. The current positions of the first rotation unit and the second rotation unit are their own reference 0°.

[0024] S2. Adjust the position of the translation unit to ensure that the image centers of the two cross targets always coincide during the rotation of the first and second rotation units. At this time, the optical center of the camera under test is located at the origin of the XYZ orthogonal coordinate system.

[0025] S3. Keep the first rotation unit at the reference 0° position, adjust the second rotation unit so that the crosshair of the target in the image is at the top of the full-frame image, and record the angle position of the second rotation unit at this time as the upper field of view (FOV). top ;

[0026] S4. Keep the first rotation unit at the reference 0° position, adjust the second rotation unit so that the crosshair of the target in the image is at the bottom of the full-frame image, and record the angle position of the second rotation unit at this time as the upper field of view (FOV). bottom ;

[0027] S5. Keep the second rotation unit at the reference 0° position, adjust the first rotation unit so that the crossroads of the target in the image are located at the far left of the full-frame image, and record the angle position of the first rotation unit at this time as the left field of view (FOV).left ;

[0028] S6. Keep the second rotation unit at the reference 0° position, adjust the first rotation unit so that the crossroads of the target in the image are located at the far right of the full-frame image, and record the angle position of the first rotation unit at this time as the right field of view (FOV). right ;

[0029] S7. Calculate the vertical and horizontal field of view (FOV). vertical =|FOV top |+|FOV bottom |;

[0030] Calculate the horizontal field of view (FOV) horizontal =|FOV left |+|FOV right The operator |·| represents absolute value.

[0031] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects: The device and method for measuring viewing angles provided by the present invention, by adjusting the positions of the first rotating unit, the second rotating unit and the translation unit, recording the angular position of the rotating unit at this time, obtains the upper viewing angle, lower viewing angle, left viewing angle and right viewing angle, and finally calculates the horizontal viewing angle and vertical viewing angle; thus achieving accurate measurement of viewing angles. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram illustrating the principle of the FOV measurement method based on trigonometric functions in the background art of this invention;

[0034] Figure 2 This is a flowchart of the method for measuring viewing angle in an embodiment of the present invention;

[0035] Figure 3 This is an overall structural diagram of the device for measuring viewing angle in an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram showing the case where the crosshairs of the first target are on the left in an embodiment of the present invention;

[0037] Figure 5 This is a schematic diagram showing the case where the crosshairs of the first target are on top in an embodiment of the present invention;

[0038] Figure 6This is a schematic diagram showing the case where the crosshairs of the first target are at the bottom in an embodiment of the present invention;

[0039] Figure 7 This is a schematic diagram showing the case where the crosshairs of the first target are on the right in an embodiment of the present invention;

[0040] Explanation of reference numerals in the attached diagram: 1. Optical axis; 2. Camera; 3. Rectangular test card; 4. Display; 5. Control unit; 6. First rotation unit; 7. Second rotation unit; 8. Camera under test; 9. Translation unit; 10. First shooting target; 11. Second shooting target; 12. Display unit; 13. Optical center. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] like Figure 1 As shown, in the prior art, the system used in the FOV measurement method based on trigonometric functions generally consists of a camera 2, a rectangular test card 3, and a display 4. The rectangular test card 3 and the display 4 establish a video connection; the optical axis 1 of the camera is perpendicular to the rectangular test card 3, and the image is captured and displayed on the display 4.

[0043] The purpose of this invention is to provide a device and method for measuring viewing angles, which precisely positions the optical center of the camera under test at the intersection of two rotation axes, and can accurately measure the horizontal and vertical viewing angles.

[0044] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] like Figure 3 As shown in the embodiment of the present invention, the device for measuring the viewing angle includes: a first rotation unit 6, a second rotation unit 7, a translation unit 9, a first shooting target 10, a second shooting target 11, and a control unit 5;

[0046] The rotation axis X of the first rotating unit is perpendicular to the rotation axis Y of the second rotating unit, and the extension of the straight line containing the rotation axis Y and the rotation axis X is orthogonal to the optical axis Z of the camera under test 8 at a point O. The rotation axis X, the rotation axis Y and the optical axis Z form an XYZ orthogonal coordinate system, and point O is called the origin of the XYZ orthogonal coordinate system.

[0047] The translation unit 9 is connected to the second rotation unit 7, and the second rotation unit 7 is used to drive the translation unit 9 and the camera under test 8 to rotate around the rotation axis X; the second rotation unit 7 is rotatably connected to the first rotation unit 6, and the first rotation unit 6 is used to drive the second rotation unit 7, the translation unit 9 and the camera under test 8 to rotate together around the rotation axis Y.

[0048] The camera under test 8 is mounted on the translation unit and can move along the optical axis Z; the horizontal edge of the camera under test 8 is parallel to the rotation axis X, and the vertical edge of the camera under test 8 is parallel to the rotation axis Y.

[0049] The first shooting target 10 is composed of at least a square outer frame and cross lines; the second shooting target 11 is composed of at least a square outer frame and cross lines; depending on the distance from the camera 8 under test, the first shooting target 10 is regarded as a near target and the second shooting target 11 is regarded as a far target.

[0050] In the default state, the centers of the first shooting target 10 and the second shooting target 11 are on the extension line of the optical axis Z and are perpendicular to the optical axis Z; the vertical line of the crosshair is parallel to the rotation axis Y, and the horizontal line of the crosshair is parallel to the rotation axis X.

[0051] The control unit 5 is used to prompt or control the first rotation unit 6, the second rotation unit 7, and the translation unit 12 to measure the viewing angle.

[0052] In this embodiment, the area inside the square frame, except for the cross lines, is either hollow or transparent.

[0053] In this embodiment, the crosshairs of the second imaging target 11 are thicker than those of the first imaging target 10; the crosshairs of the second imaging target 11 are different colors from those of the first imaging target 10. Since the crosshairs of the second imaging target 11 (far target image) are thicker than those of the first imaging target 10 (near target), the crosshairs of the second imaging target 11 are not completely obscured when the two crosshairs overlap. The different colors of the crosshairs of the two targets create a sharp contrast in the overlapping image, making it easier to observe whether the two crosshairs are precisely aligned.

[0054] In this embodiment, the electric drive scheme is as follows: both the first rotating unit 10 and the second rotating unit 11 are equipped with stepper motors and angle starting position sensors for rotation via electric drive; the translation unit 9 is equipped with a stepper motor and a linear starting position sensor for movement via electric drive. The rotating unit calculates the number of steps of the drive motor from the angle starting position to determine the angular position, and the translation unit calculates the number of steps of the drive motor from the linear starting position to determine the linear position. The controller directly controls the movement and stopping of the rotating and translation units through control signals. This electric drive scheme has a high degree of automation and is more labor-saving.

[0055] In another embodiment of this aspect, the manual solution is as follows: Both the first rotating unit 6 and the second rotating unit 7 are equipped with attached angle scales for manual rotation, and the angle position is read by observing the angle scales; the translation unit is equipped with a linear scale for manual movement, and the linear position is read by observing the linear scales; the first rotating unit 6, the second rotating unit 7, and the translation unit 9 are all equipped with locking devices for manual locking or unlocking. The controller of the manual solution prompts the operator step-by-step to manually drive the first rotating unit 6, the second rotating unit 7, and the translation unit 9. The manual solution is relatively low-cost and lightweight.

[0056] In a further embodiment, if the camera under test 8 is a digital camera or digital camcorder, a display unit can be added to observe the video images output by the device under test; if the camera under test 8 has a video display function, there is no need to add a display unit, and the video images can be observed using the camera device.

[0057] like Figure 2 As shown, the present invention also provides a method for measuring the viewing angle, applied to the apparatus for measuring the viewing angle, the method comprising:

[0058] S1. Adjust the first rotation unit 6 and the second rotation unit 7 so that the optical axis Z of the camera under test 8 is perpendicular to the target. The current positions of the first rotation unit and the second rotation unit are their own reference 0°.

[0059] S2. Adjust the position of translation unit 9 to ensure that the image centers of the two cross targets always coincide during the rotation of the first rotation unit 6 and the second rotation unit 7. At this time, the optical center of the camera under test 8 is located at the origin of the XYZ orthogonal coordinate system.

[0060] S3. Keep the first rotation unit 6 at the reference 0° position, and adjust the second rotation unit 7 so that the crossroads of the target in the image are located at the top of the full-frame image. Record the angle position of the second rotation unit 7 at this time as the upper field of view (FOV). top ;

[0061] S4. Keep the first rotation unit 6 at the reference 0° position, and adjust the second rotation unit 7 so that the crossroads of the target in the image are located at the bottom of the full-frame image. Record the angle position of the second rotation unit 7 at this time as the upper field of view (FOV). bottom ;

[0062] S5. Keep the second rotation unit at the reference 0° position, adjust the first rotation unit so that the crossroads of the target in the image are located at the far left of the full-frame image, and record the angle position of the first rotation unit at this time as the left field of view (FOV). left ;

[0063] S6. Keep the second rotation unit 7 at the reference 0° position, adjust the first rotation unit 6 so that the crossroads of the target in the image are located at the far right of the full-frame image, and record the angle position of the first rotation unit 6 at this time as the right field of view (FOV). right ;

[0064] S7. Calculate the vertical field of view (FOV) vertical =|FOV top |+|FOV bottom |;

[0065] Calculate the horizontal field of view (FOV) horizontal =|FOV left |+|FOV right The operator |·| represents absolute value.

[0066] like Figure 4-7 The image illustrates a scenario where the centers of two crosshair targets do not coincide: Figure 4 As the target image shifts to the left, the first target's crosshair is on the left; Figure 5 This indicates that during the upward movement of the target image, the first target's crosshair is at the top; Figure 6 This indicates that during the downward movement of the target image, the first target's crosshair is at the bottom; Figure 7 This indicates that during the rightward movement of the target image, the first target crosshair is on the right.

[0067] In summary, the device and method for measuring viewing angles provided by this invention, by adjusting the positions of the first rotating unit, the second rotating unit, and the translation unit, and recording the angular position of the rotating unit at this time, obtains the upper viewing angle, lower viewing angle, left viewing angle, and right viewing angle, and finally calculates the horizontal viewing angle and vertical viewing angle; thus achieving accurate measurement of viewing angles.

[0068] The remaining technical features in this embodiment can be flexibly selected by those skilled in the art to meet different specific practical needs. However, it is obvious to those skilled in the art that these specific details are not necessary to implement the present invention. In other instances, to avoid obscuring the present invention, well-known components, structures, or parts are not specifically described, and all are within the scope of technical protection defined by the claims of the present invention.

[0069] Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this invention should be within the protection scope of the appended claims. In the above description, numerous specific details have been set forth to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other instances, to avoid obscuring the invention, well-known techniques, such as specific construction details, operating conditions, and other technical conditions, have not been specifically described.

[0070] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A device for measuring viewing angle, characterized in that, The device includes: a first rotation unit, a second rotation unit, a translation unit, a first imaging target, a second imaging target, and a control unit; The rotation axis Y of the first rotating unit is perpendicular to the rotation axis X of the second rotating unit, and the extension of the straight line containing the rotation axis Y and the rotation axis X is orthogonal to the optical axis Z of the camera under test at a point O. The rotation axis X, the rotation axis Y and the optical axis Z form an XYZ orthogonal coordinate system, and point O is called the origin of the XYZ orthogonal coordinate system. The translation unit is connected to the second rotation unit, and the second rotation unit is used to drive the translation unit and the camera under test to rotate around the rotation axis X; the second rotation unit is rotatably connected to the first rotation unit, and the first rotation unit is used to drive the second rotation unit, the translation unit and the camera under test to rotate together around the rotation axis Y. The camera under test is mounted on the translation unit and can move along the optical axis Z; the horizontal edge of the camera under test is parallel to the rotation axis X, and the vertical edge of the camera under test is parallel to the rotation axis Y. The first shooting target is composed of at least a square outer frame and crosshairs; the second shooting target is composed of at least a square outer frame and crosshairs; based on the distance from the camera under test, the first shooting target is designated as a near target and the second shooting target as a far target; In the default state, the centers of the first and second shooting targets are on the extension line of the optical axis Z and are perpendicular to the optical axis Z; the vertical line of the crosshair is parallel to the rotation axis Y, and the horizontal line of the crosshair is parallel to the rotation axis X. The control unit is used to prompt or control the first rotation unit, the second rotation unit, and the translation unit to measure the viewing angle.

2. The apparatus for measuring viewing angle according to claim 1, characterized in that, Inside the square frame, all areas except the cross lines are either open or transparent.

3. The apparatus for measuring viewing angle according to claim 1, characterized in that, The crosshairs of the second shooting target are thicker than those of the first shooting target.

4. The apparatus for measuring viewing angle according to claim 1, characterized in that, The crosshairs of the second shooting target are different colors from those of the second shooting target.

5. The apparatus for measuring viewing angle according to claim 1, characterized in that, The first and second rotation units are each equipped with a stepper motor and an angle starting position sensor for rotation via electric drive; the translation unit is equipped with a stepper motor and a line starting position sensor for movement via electric drive; the first and second rotation units calculate the number of steps of the drive motor from the angle starting position to calculate the angle position; the translation unit calculates the number of steps of the drive motor from the line starting position to calculate the line position.

6. The apparatus for measuring viewing angle according to claim 1, characterized in that, The first and second rotating units are each equipped with an attached angle scale for manual rotation; the translation unit is equipped with a linear scale for manual movement, and the angle and linear positions are read by observing the scale; the first and second rotating units and the translation unit are each equipped with a locking device for manual locking or unlocking.

7. The apparatus for measuring viewing angle according to claim 1, characterized in that, The device further includes a display unit, which is connected to the camera under test and is used to observe the video images output by the camera under test.

8. A method for measuring a viewing angle, applied to the apparatus for measuring a viewing angle as described in any one of claims 1-7, characterized in that, The method includes: S1. Adjust the first rotation unit and the second rotation unit so that the optical axis Z of the camera under test is perpendicular to the target. The current positions of the first rotation unit and the second rotation unit are their own reference 0°. S2. Adjust the position of the translation unit to ensure that the image centers of the two cross targets always coincide during the rotation of the first and second rotation units. At this time, the optical center of the camera under test is located at the origin of the XYZ orthogonal coordinate system. S3. Keep the first rotation unit at the reference 0° position, adjust the second rotation unit so that the crosshair of the target in the image is at the top of the full-frame image, and record the angle position of the second rotation unit at this time as the upper field of view (FOV). top ; S4. Keeping the first rotation unit at the reference 0° position, adjust the second rotation unit so that the crossroads of the target in the image are located at the bottom of the full-frame image. Record the angle position of the second rotation unit at this time as the upper field of view (FOV). bottom ; S5. Keep the second rotation unit at the reference 0° position, adjust the first rotation unit so that the crossroads of the target in the image are located at the far left of the full-frame image, and record the angle position of the first rotation unit at this time as the left field of view (FOV). left ; S6. Keep the second rotation unit at the reference 0° position, adjust the first rotation unit so that the crossroads of the target in the image are located at the far right of the full-frame image, and record the angle position of the first rotation unit at this time as the right field of view (FOV). right ; S7. Calculate the vertical field of view (FOV) vertical =| FOV top | + |FOV bottom |; Calculate the horizontal and vertical field of view (FOV) horizontal = | FOV left |+|FOV right |, where| The | operator represents absolute value.

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