Continuous line laser active three-dimensional scanning system and scanning method

Abstract

The invention provides a continuous line laser active three-dimensional scanning system and a scanning method, which are used for solving the technical problem that high-frame-frequency three-dimensional scanning measurement in an underwater high-resistance environment cannot be realized due to the fact that a rotating part of an existing laser triangulation measurement system is large in length and size and is difficult to integrally, quickly and stably rotate in the underwater high-resistance environment. According to the continuous line laser active three-dimensional scanning system provided by the invention, on the basis of traditional triangular laser measurement, the multi-edge rotating mirror is arranged, and the left camera and the right camera are respectively arranged at specific positions on the left side and the right side of the multi-edge rotating mirror, so that line laser active three-dimensional scanning can be realized only by rotating the multi-edge rotating mirror; the size of a rotating part is reduced, the scanning frame frequency in the high-resistance environment is improved, and the requirement for high-frame-frequency three-dimensional scanning measurement in the underwater high-resistance environment is completely met. Meanwhile, the left camera and the right camera are used for imaging the left area and the right area respectively, so that the scanning range is effectively enlarged.

Description

Technical Field

[0001] The invention relates to a laser three-dimensional scanning device, and in particular to a continuous line laser active three-dimensional scanning system and a scanning method. Background Art

[0002] Laser 3D scanning technology is mainly used for laser radar, which is a general term for laser detection and ranging systems. At present, the principles of laser radar measurement are mainly divided into three types: pulse method, coherence method, and triangulation method. The existing laser triangulation measurement system is generally composed of a continuous line laser, a camera, and a bracket. The laser and the camera are fixed on the bracket at a certain distance and angle, where the emission angle of the laser and the receiving angle of the camera are fixed, and the distance between the two is the baseline length. The laser emits a line laser and irradiates the target to be measured at a certain incident angle. The camera receives the laser echo scattered by the measured object and forms an image on the camera sensor. The incident light of the laser, the reflected light of the target to be measured, and the baseline (the line between the laser and the camera) form a triangle; since the laser echo of the target to be measured at different distances corresponds to different imaging positions on the camera sensor, the distance information of each point of the target to be measured within the range of the line laser illumination can be realized according to the triangular geometric relationship.

[0003] like Figure 1 The figure shows the measurement principle of the existing laser triangulation measurement system. It is known that the angle between the line laser returned from point A on the measured target and the baseline is θ1, the baseline length is L, and the angle between the laser output laser and the baseline is β, then the object distance D1 of point A on the measured target is: D1 = L / (cotβ+cotθ1).

[0004] like Figure 2 The figure shows a schematic diagram of an existing laser triangulation measurement system. Based on laser triangulation ranging, the laser, camera, and bracket are rotated as a whole with a certain point on the bracket as the center, and the scanned three-dimensional space is measured in three dimensions during the rotation. However, the rotating part of this laser triangulation measurement system is long and large in volume, and it is difficult to rotate quickly and stably in an underwater high-resistance environment, and it is impossible to achieve high-frame-rate three-dimensional scanning measurement in an underwater high-resistance environment. Summary of the invention

[0005] The purpose of the present invention is to solve the technical problem that the rotating part of the existing laser triangulation measurement system is too long and has a large volume, and it is difficult to rotate quickly and stably as a whole in a high-resistance underwater environment, resulting in the inability to achieve high-frame-rate three-dimensional scanning measurement in a high-resistance underwater environment, and to provide a continuous line laser active three-dimensional scanning system and scanning method.

[0006] In order to achieve the above object, the technical solution provided by the present invention is as follows:

[0007] A continuous line laser active three-dimensional scanning system, which is special in that it includes a laser, a polygonal rotating mirror, a rotating mirror motor, a left camera, a right camera, a controller and a data processing unit;

[0008] The laser is used to emit continuous line laser;

[0009] The central axis of the multi-prism rotating mirror is arranged perpendicular to the horizontal plane, and the reflecting surface thereof is located on the outgoing light path of the line laser, and is used to reflect the line laser to form line laser reflected light; the rotating mirror motor is used to drive the multi-prism rotating mirror to rotate, and form line laser reflected light at different angles;

[0010] The target area to be scanned is located on the optical path of the line laser reflected light, and the line laser reflected light is reflected at different positions on the surface of the target area to be scanned, forming target reflected light at different positions;

[0011] The left camera and the right camera are respectively located on the optical paths of target reflected light at different positions on the left and right sides of the polygonal rotating mirror, and the focus of the left camera, the focus of the right camera, the intersection of the central axis of the polygonal rotating mirror and the horizontal plane are collinearly arranged in the horizontal direction, and are respectively used to receive and image target reflected light at different positions;

[0012] The polygonal rotating mirror is provided with an absolute angle encoder for measuring the absolute angle of the polygonal rotating mirror in real time;

[0013] The controller is electrically connected to the absolute angle encoder, the left camera and the right camera respectively, and is used to receive the absolute angle of the polygon mirror and the imaging images of the left camera and the right camera in real time, and then record the absolute angle of the polygon mirror when each frame of the image is captured;

[0014] The input end of the data processing unit is connected to the output end of the controller, and is used to calculate the three-dimensional coordinates of the corresponding points in the target area to be scanned based on the pixel coordinates of each point on the line laser center line of the imaging image of the left camera or the right camera during a single line scan, the absolute angle of the corresponding polygonal mirror, the focal length of the left camera or the right camera, the installation angle of the left camera or the right camera, and the corresponding baseline length.

[0015] Furthermore, the absolute angle encoder and the polygonal rotating mirror are both arranged on the rotating shaft of the rotating mirror motor.

[0016] Furthermore, the number of reflective surfaces in the polygonal mirror is greater than or equal to 3.

[0017] Furthermore, the maximum rotation speed V of the polygonal mirror is max for:

[0018] V max ≤(360° / n) / (6 / f)

[0019] Where n is the number of reflective surfaces on the polygon mirror, and f is the camera frame rate.

[0020] Furthermore, the camera frame rates of the left camera or the right camera are the same.

[0021] In addition, the present invention also provides a continuous line laser active three-dimensional scanning method, which uses the above-mentioned continuous line laser active three-dimensional scanning system, and its special feature is that it includes the following steps:

[0022] Step 1: The mirror motor is powered on to drive the polygonal mirror to rotate, and the laser is turned on to emit a continuous line laser. The line laser is reflected by the polygonal mirror to the target area to be scanned, and the target area to be scanned is cyclically scanned;

[0023] Step 2: The controller collects the absolute angle of the polygonal rotating mirror in real time, and determines the emission direction of the line laser according to the absolute angle; when the line laser is on the left side of the polygonal rotating mirror, the controller controls the left camera to continuously receive the target reflected light returned from the left area of ​​the target to be scanned for multiple times to take images; when the line laser is on the right side of the polygonal rotating mirror, the controller controls the right camera to continuously receive the target reflected light returned from the right area of ​​the target to be scanned for multiple times to take images;

[0024] Step 3, the controller collects the images captured by the left camera and the right camera in real time, and records the absolute angle of the polygon mirror when each frame of the image is captured;

[0025] Step 4, the data processing unit calculates the three-dimensional coordinates of each point on the center line of the position illuminated by the current line laser reflected light in the target area to be scanned according to the pixel coordinates of each point on the center line of the line laser of the image of the left camera or the right camera during a single line scan, the absolute angle of the corresponding polygon mirror, the focal length of the left camera or the right camera, the installation angle of the left camera or the right camera, and the corresponding baseline length, in combination with the triangulation method;

[0026] Step 5, each time the polygonal mirror rotates one circle, the three-dimensional coordinates of each point at different positions in the target area to be scanned obtained by multiple line scans are spliced ​​to obtain a frame of three-dimensional scanning image of the target area to be scanned; the continuous line laser active three-dimensional scanning system continuously rotates and reciprocates the target area to be scanned to obtain dynamic results of the target area to be scanned.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. A continuous line laser active three-dimensional scanning system provided by the present invention is provided with a polygonal rotating mirror on the basis of traditional triangulated laser measurement, and a left camera and a right camera are respectively provided at specific positions on the left and right sides of the polygonal rotating mirror. The present invention can realize line laser active three-dimensional scanning only by rotating the polygonal rotating mirror, thereby reducing the volume of the rotating part and improving the scanning frame rate in a high-resistance environment. The system is not only suitable for the traditional laser three-dimensional scanning field, but also suitable for high-frame-rate three-dimensional scanning measurement in an underwater high-resistance environment.

[0029] 2. At the same time, since the present invention uses a left camera and a right camera to image the left and right areas respectively, the scanning range is effectively increased.

[0030] 3. The scanning method based on the continuous line laser active three-dimensional scanning system provided by the present invention is simple and convenient to operate, highly practical, and can be widely used in three-dimensional scanning measurement of various targets. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the measurement principle of the existing laser triangulation measurement system;

[0032] Figure 2 It is a schematic diagram of an existing laser triangulation measurement system;

[0033] Figure 3 A schematic diagram of an embodiment of a continuous line laser active three-dimensional scanning system of the present invention;

[0034] Figure 4 It is a schematic diagram of the left camera receiving the target reflected light returned from the left area of ​​the target to be scanned when the linear laser is on the left side of the polygon mirror in an embodiment of the present invention;

[0035] Figure 5 Schematic diagram of the right camera receiving target reflected light returned from the right area of ​​the target to be scanned when the linear laser is on the right side of the polygonal mirror in an embodiment of the present invention.

[0036] The specific reference numerals are as follows:

[0037] 1. Laser; 2. Polygonal mirror; 3. Left camera; 4. Right camera; 5. Controller. DETAILED DESCRIPTION

[0038] In order to make the advantages and features of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] like Figure 1 As shown, a continuous line laser active three-dimensional scanning system includes a laser 1, a polygonal rotating mirror 2, a rotating mirror motor, a left camera 3, a right camera 4, a controller 5 and a data processing unit.

[0040] The laser 1 is used to emit a continuous line laser; the polygonal rotating mirror 2 is in the shape of a multi-faceted prism, each side of which is a plane reflector, and the plane reflector on each side is the reflective surface of the polygonal rotating mirror 2. In this embodiment, the polygonal rotating mirror 2 has five reflective surfaces. The central axis of the polygonal rotating mirror 2 is arranged perpendicular to the horizontal plane, and its reflective surface is located on the emission light path of the line laser, which is used to reflect the line laser to form a line laser reflected light. The rotating mirror motor is used to drive the polygonal rotating mirror 2 to rotate, forming a line laser reflected light of different angles. At the same time, an absolute angle encoder is arranged on the polygonal rotating mirror 2, which is used to measure the absolute angle of the polygonal rotating mirror 2 in real time. In this embodiment, the absolute angle encoder and the polygonal rotating mirror 2 are both arranged on the rotating shaft of the rotating mirror motor, and the polygonal rotating mirror 2 rotates with the rotating shaft of the rotating mirror motor. The absolute angle encoder is used to record the rotation angle of the rotating mirror motor, and then the absolute angle of the polygonal rotating mirror 2 is obtained according to the rotation angle of the rotating mirror motor.

[0041] The target area to be scanned is located on the optical path of the line laser reflected light, and the line laser reflected light is reflected at different positions on the surface of the target area to be scanned to form target reflected light at different positions.

[0042] Preferably, the left camera 3 and the right camera 4 have the same camera frame rate, and are respectively located on the optical paths of target reflected light at different positions on the left and right sides of the polygonal mirror 2, and the focus of the left camera 3, the focus of the right camera 4, and the intersection of the central axis of the polygonal mirror 2 and the horizontal plane are collinearly arranged in the horizontal direction, and are respectively used to receive and image target reflected light at different positions. The line connecting the focus of the left camera 3 and the center point of the polygonal mirror 2 is the left baseline, and the line connecting the focus of the right camera 4 and the center point of the polygonal mirror 2 is the right baseline. In each imaging image of the left camera 3 and the right camera 4, there is a line laser corresponding to a line laser.

[0043] It is worth noting that the rotation speed of the polygonal rotating mirror 2 cannot be too high. If it is too high, the obtained image density will be low, affecting the final scanning result. Therefore, its maximum rotation speed V max需 Meet the following conditions:

[0044] V max ≤(360° / n) / (6 / f)

[0045] Wherein, n is the number of reflective surfaces on the polygonal mirror 2, and f is the camera frame rate.

[0046] The maximum rotation speed determined by the above formula can ensure that at least six shots are taken in one scan from left to right.

[0047] The controller 5 is electrically connected to the absolute angle encoder, the left camera 3 and the right camera 4 respectively, and is used to receive the absolute angle of the polygon mirror 2 and the imaging images of the left camera 3 and the right camera 4 in real time. The controller 5 is also used to control the imaging time of the left camera 3 and the right camera 4. The controller 5 can record the absolute angle of the polygon mirror 2 when each frame of the image is captured according to the received absolute angle of the polygon mirror 2 and the corresponding imaging images of the left camera 3 and the right camera 4.

[0048] The input end of the data processing unit is connected to the output end of the controller 5, and is used to calculate the three-dimensional coordinates of the corresponding point in the target area to be scanned based on the pixel coordinates of each point on the line laser center line of the image formed by the left camera 3 or the right camera 4 during a single line scan, the corresponding absolute angle of the polygonal mirror 2, the focal length of the left camera 3 or the right camera 4, the installation angle of the left camera 3 or the right camera 4, and the corresponding left baseline length or right baseline length.

[0049] Based on the above continuous line laser active three-dimensional scanning system, the present invention also provides a continuous line laser active three-dimensional scanning method, which specifically includes the following steps:

[0050] Step 1, the mirror motor is powered on to drive the polygonal mirror 2 to rotate, and at the same time, the laser 1 is turned on to emit a continuous line laser, which is reflected by the polygonal mirror 2 to the target area to be scanned, and the target area to be scanned is scanned cyclically.

[0051] Step 2, the controller 5 collects the absolute angle of the polygonal rotating mirror 2 in real time, and determines the emission direction of the line laser according to the absolute angle of the polygonal rotating mirror 2; when the line laser is on the left side of the polygonal rotating mirror 2, the controller 5 controls the left camera 3 to continuously receive the target reflected light returned from the left area of ​​the target to be scanned for multiple times to take pictures and imaging; when the line laser is on the right side of the polygonal rotating mirror 2, the controller 5 controls the right camera 4 to continuously receive the target reflected light returned from the right area of ​​the target to be scanned for multiple times to take pictures and imaging.

[0052] Step 3: The controller 5 collects the images captured by the left camera 3 and the right camera 4 in real time, and records the absolute angle of the polygon mirror 2 when each frame of the image is captured.

[0053] Step 4, the data processing unit calculates the three-dimensional coordinates of each point on the center line of the position illuminated by the current line laser reflected light in the target area to be scanned based on the pixel coordinates of each point on the line laser center line of the image formed by the left camera 3 or the right camera 4 during a single line scan, the corresponding absolute angle of the polygonal mirror 2, the focal length of the left camera 3 or the right camera 4, the installation angle of the left camera 3 or the right camera 4 and the corresponding left baseline length or the right baseline length, using the triangulation method.

[0054] Step 5, the three-dimensional coordinates of each point at different positions in the target area to be scanned obtained by multiple line scans when the polygon mirror 2 rotates one circle are spliced ​​to obtain a frame of three-dimensional scanned image of the target area to be scanned. The continuous line laser active three-dimensional scanning system continuously performs rotational reciprocating scanning on the target area to be scanned, and a dynamic result of the target area to be scanned can be obtained.

[0055] The above description is only used to illustrate the technical solution of the present invention rather than to limit it. For ordinary professional and technical personnel in the field, the specific technical solution recorded in the above embodiment can be modified, or some of the technical features therein can be replaced by equivalents, and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution protected by the present invention.

Claims

1. A continuous line laser active three-dimensional scanning system, characterized in that: It comprises a laser (1), a polygonal rotating mirror (2), a rotating mirror motor, a left camera (3), a right camera (4), a controller (5) and a data processing unit; The laser (1) is used to emit continuous line laser; The central axis of the multi-prism rotating mirror (2) is arranged perpendicular to the horizontal plane, and its reflection surface is located on the emission light path of the line laser, and is used to reflect the line laser to form line laser reflected light; the rotating mirror motor is used to drive the multi-prism rotating mirror (2) to rotate, so as to form line laser reflected light of different angles; The target area to be scanned is located on the optical path of the line laser reflected light, and the line laser reflected light is reflected at different positions on the surface of the target area to be scanned, forming target reflected light at different positions; The left camera (3) and the right camera (4) are respectively located on the optical paths of target reflected light at different positions on the left and right sides of the polygonal rotating mirror (2), and the focus of the left camera (3), the focus of the right camera (4) and the intersection of the central axis of the polygonal rotating mirror (2) and the horizontal plane are arranged in a horizontal direction collinearly, and are respectively used to receive and image target reflected light at different positions; An absolute angle encoder is provided on the polygonal rotating mirror (2) for measuring the absolute angle of the polygonal rotating mirror (2) in real time; The controller (5) is electrically connected to the absolute angle encoder, the left camera (3) and the right camera (4) respectively, and is used to receive the absolute angle of the polygonal mirror (2) and the imaging images of the left camera (3) and the right camera (4) in real time, and then record the absolute angle of the polygonal mirror (2) when each frame of the image is captured; The input end of the data processing unit is connected to the output end of the controller (5) and is used to calculate the three-dimensional coordinates of the corresponding point in the target area to be scanned according to the pixel coordinates of each point on the line laser center line of the image formed by the left camera (3) or the right camera (4) during a single line scan, the absolute angle of the corresponding polygon mirror (2), the focal length of the left camera (3) or the right camera (4), the installation angle of the left camera (3) or the right camera (4) and the corresponding baseline length.

2. The continuous line laser active three-dimensional scanning system according to claim 1, characterized in that: The absolute angle encoder and the polygonal rotating mirror (2) are both arranged on the rotating shaft of the rotating mirror motor.

3. A continuous line laser active three-dimensional scanning system according to claim 1 or 2, characterized in that: The number of reflecting surfaces in the polygonal rotating mirror (2) is greater than or equal to 3.

4. The continuous line laser active three-dimensional scanning method according to claim 3, characterized in that: The maximum rotation speed V of the polygonal rotating mirror (2) max Meet the following conditions: V max ≤(360° / n) / (6 / f) Wherein, n is the number of reflection surfaces on the polygon mirror (2), and f is the camera frame rate.

5. The continuous line laser active three-dimensional scanning method according to claim 1, characterized in that: The camera frame rates of the left camera (3) or the right camera (4) are the same.

6. A continuous line laser active three-dimensional scanning method, using a continuous line laser active three-dimensional scanning system according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1, the mirror motor is powered on to drive the polygonal mirror (2) to rotate, and at the same time, the laser (1) is turned on to emit a continuous line laser, which is reflected by the polygonal mirror (2) to the target area to be scanned, and the target area to be scanned is cyclically scanned; Step 2, the controller (5) collects the absolute angle of the polygonal rotating mirror (2) in real time, and determines the emission direction of the line laser according to the absolute angle; when the line laser is on the left side of the polygonal rotating mirror (2), the controller (5) controls the left camera (3) to continuously receive the target reflected light returned from the left area of ​​the target to be scanned for multiple times to take images; when the line laser is on the right side of the polygonal rotating mirror (2), the controller (5) controls the right camera (4) to continuously receive the target reflected light returned from the right area of ​​the target to be scanned for multiple times to take images; Step 3, the controller (5) collects the images captured by the left camera (3) and the right camera (4) in real time, and records the absolute angle of the polygon mirror (2) when each frame of the image is captured; Step 4, the data processing unit calculates the three-dimensional coordinates of each point on the center line of the position illuminated by the current line laser reflected light in the target area to be scanned according to the pixel coordinates of each point on the center line of the line laser of the image formed by the left camera (3) or the right camera (4) during a single line scan, the absolute angle of the corresponding polygonal mirror (2), the focal length of the left camera (3) or the right camera (4), the installation angle of the left camera (3) or the right camera (4) and the corresponding baseline length, in combination with the triangulation method; Step 5, when the polygon mirror (2) rotates one circle, the three-dimensional coordinates of each point at different positions in the target area to be scanned obtained by multiple line scans are spliced ​​to obtain a frame of three-dimensional scanned image of the target area to be scanned; the continuous line laser active three-dimensional scanning system continuously performs rotational reciprocating scanning on the target area to be scanned to obtain a dynamic result of the target area to be scanned.

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