Airborne camera low angle single frame constant velocity scanning imaging start control method and system
By acquiring the starting steady-state time and angle of the aerial camera's depression frame, and combining position servo and speed servo control, the dynamic distortion problem during the start-up of a traditional aerial camera's uniform scanning was solved, achieving high-quality dynamic scanning imaging and efficient image processing.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHANGCHUN INST OF OPTICS FINE MECHANICS & PHYSICS CHINESE ACAD OF SCI
- Filing Date
- 2023-07-21
- Publication Date
- 2026-07-14
AI Technical Summary
Traditional aerial cameras fail to achieve a stable, uniform scanning state when starting imaging at a downward angle, leading to dynamic imaging distortion and difficulties in image processing.
By acquiring the starting and steady-state speed time and the angle traveled by the downward-angled frame, and using position servo and speed servo control, the downward-angled frame is ensured to achieve a uniform scanning state under the shooting command, including uniform scanning from position servo control to starting angle and speed servo control.
This technology enables the downward-facing frame to achieve uniform speed and stability at the start angle of each exposure line during dynamic scanning imaging with an aerial camera, thereby improving image quality and post-processing efficiency.
Smart Images
Figure CN117041732B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of aerial camera imaging control technology, and in particular to an aerial camera single-frame uniform speed scanning imaging start-up control method and system at the downward angle. Background Technology
[0002] Aerial camera imaging is an important technical means of acquiring ground information. It has many advantages such as high mobility, good timeliness, and high resolution, and has wide applications in both military and civilian fields such as intelligence gathering, disaster relief, and agricultural and forestry surveying. Aerial cameras can be roughly divided into several categories according to the type of CCD used and the imaging method, including area array frame type, linear array pushbroom type, and linear array oscillating scan type. Among them, the linear array oscillating scan camera uses a linear array CCD to tilt and scan in a direction perpendicular to the aircraft's heading, ensuring a certain overlap between adjacent images. The complete image of the imaging area is obtained through post-processing image stitching, thereby effectively expanding the camera's field of view.
[0003] In this type of oscillating imaging process, a camera frame perpendicular to the aircraft's heading is typically used to perform a uniform oscillating scan in a zigzag or bow-shaped pattern. The traditional method involves the oscillating frame moving to the starting angle of the scan line using a position servo mechanism upon receiving the pre-capture command. Upon receiving the capture command, the oscillating frame then moves to the ending angle of the line using a speed servo mechanism, following a given angular velocity command. Clearly, during the initial capture phase of each line, the oscillating frame does not achieve a uniform and stable state, which can easily lead to distortion or gaps in the dynamic imaging, and also presents challenges for subsequent image processing.
[0004] Therefore, for linear scan aerial cameras, it is necessary to adopt effective scanning imaging start-up control methods to ensure the dynamic scanning imaging quality of the aerial camera and improve the efficiency of image post-processing. Summary of the Invention
[0005] The purpose of this application is to provide a method and system for starting up single-frame uniform scanning imaging of an aerial camera at a downward angle, in order to solve the above-mentioned problems.
[0006] To achieve the above objectives, this application provides the following technical solution:
[0007] This application provides a method for starting up a single-frame uniform scanning imaging system for an aerial camera at a downward angle, including:
[0008] S1: Obtain the starting steady-speed time Δt of the depression frame;
[0009] S2: Obtain the angle Δθ traveled by the depression frame during the initial steady-speed period;
[0010] S3: Under the command to prepare for taking a picture, the starting angle θ0 of the depression frame is determined, and the depression frame moves to its starting angle θ0 in a position servo control manner.
[0011] S4: Under the command to take a picture, the downward angle frame performs a uniform scanning at a speed servo control mode according to the starting angle θ0 of the downward angle frame.
[0012] Furthermore, step S1 includes the following steps:
[0013] The depression frame is controlled by a speed servo to record the step speed change from zero speed V0 to constant speed V. ref Starting steady-state time Δt 正 And the depression frame jumps from zero speed V0 to uniform speed -V ref Starting steady-state time Δt 负 ;
[0014] Where V0 = 0, V ref >0 represents the angular velocity of the forward scan command for the tilting frame, then -V ref The negative scan angular velocity of the depression frame is the angular velocity of the mission command, Δt. 正 >0 represents the forward scan settling time Δt, where Δt is the fixed-rate time. 负 >0 represents the negative scan stabilization time Δt.
[0015] Furthermore, step S2 includes the following steps:
[0016] The depression frame is controlled by a speed servo to record the step transition from zero speed V0 to uniform speed V. ref Angle Δθ traveled 正 And the angled frame jumps from zero speed V0 to constant speed -V ref Angle Δθ traveled 负 ;
[0017] Where, V0 = 0, V ref >0 represents the angular velocity of the forward scan command for the tilting frame, then -V ref The negative scan mission command angular velocity for the depression frame is Δθ. 正 >0 represents the angle Δθ traveled by the tilting frame during forward scanning at a steady speed. 负 >0 represents the angle Δθ that the downward-facing frame travels during negative scanning at a steady speed.
[0018] Furthermore, step S1 includes the following steps:
[0019] The depression frame starts from zero velocity V0 and gradually increases to a constant velocity V. ref or -V ref In the initial stabilization time, the stabilization index is selected based on the imaging control accuracy. If the 95% speed index is selected, then the stabilization time Δt 正 and Δt 负These are the starting speeds of the frame at the angle of depression, from zero velocity V0 to a constant speed of 95%*V. ref and -95%*V ref The corresponding time for starting and maintaining a steady speed.
[0020] Furthermore, step S3 includes the following steps:
[0021] Step S31: Based on the starting angle θ1 and ending angle θ2 within a single strip of the image captured by the uniform scanning of the tilting frame, determine the starting angle θ0 of the tilting frame. If θ1 < θ2, define the tilting frame as a forward scan, then the starting angle θ0 of the tilting frame = θ1 - Δθ 正 If θ1 > θ2, the depression frame is defined as a negative scan, then the starting angle of the depression frame θ0 = θ1 + Δθ 负 ;
[0022] Step S32: The depression frame moves to the starting angle θ0 using position servo control.
[0023] Furthermore, step S4 includes the following steps:
[0024] Step S41: Delay time Δt 正 or Δt 负 The camera scans here and takes the first photo;
[0025] Step S42: If θ1 < θ2, the depression frame is in a forward scan, and the depression frame starts from zero velocity V0 at the starting angle θ0 and accelerates stepwise to V0. ref Time consumed Δt 正 After Δθ 正 Reaching the initial angle θ1 and achieving a constant velocity V ref The camera took the first photo on this trip, with the frame tilted downwards from the starting angle θ1 at a constant speed V. ref Once the end angle θ2 is reached, the camera takes subsequent photos of this line at continuous intervals based on the overlap rate.
[0026] Step S43: If θ1>θ2, the depression frame performs a negative scan, and the depression frame accelerates from zero speed to -V from the starting angle θ0. ref Time consumed Δt 负 After Δθ 负 Reaching the initial angle θ1 and achieving a constant velocity -V ref The camera took the first photo of this trip, with the frame tilted downwards from the starting angle θ1 at a constant speed of -V. ref Once the scan reaches the end angle θ2, the camera takes subsequent photos of this line at continuous intervals based on the overlap rate.
[0027] Furthermore, the following steps are also included:
[0028] In step S5, steps S3 and S4 are executed alternately in a loop.
[0029] It also provides a single-frame uniform speed scanning imaging start-up control system for aerial cameras with a downward angle, the specific contents of which include:
[0030] Time acquisition module: Acquires the starting and steady-state speed time Δt of the depression frame;
[0031] Angle acquisition module: acquires the angle Δθ traveled by the depression frame during the initial steady-speed period;
[0032] Control module: Under the command to prepare for taking a picture, the starting angle θ0 of the depression frame is determined, and the depression frame moves to its starting angle θ0 by position servo control.
[0033] Scanning module: Under the command of taking a picture, the downward angle frame performs uniform scanning in a speed servo control mode according to the starting angle θ0 of the downward angle frame.
[0034] This application provides a method and system for controlling the start-up of a single-frame uniform speed scanning imaging at the downward angle of an aerial camera, which has the following beneficial effects:
[0035] This application enables aerial cameras to achieve a uniform and stable angular velocity of the downward-angle frame when it reaches the exposure start angle for each line during dynamic scanning imaging operations. This ensures the quality of dynamic scanning imaging and improves the efficiency of post-processing. The method is applicable to dynamic scanning imaging and control of aerial cameras, and is particularly suitable for the start-up control of uniform-velocity single-frame downward scanning imaging in aerial cameras. Attached Figure Description
[0036] Figure 1 This is a flowchart illustrating a single-frame uniform scanning imaging start-up control method for an aerial camera with a downward angle according to an embodiment of this application.
[0037] Figure 2 This is a schematic diagram of the structure of a single-frame uniform speed scanning imaging start-up control system for an aerial camera with a downward angle according to an embodiment of this application;
[0038] Figure 3 This is a schematic diagram of the forward uniform scanning start-up of a single-frame uniform scanning imaging start-up control method for aerial camera depression angle according to an embodiment of this application.
[0039] Figure 4 This is a schematic diagram of the reverse uniform scanning start-up of a single-frame uniform scanning imaging start-up control method for aerial camera depression angle according to an embodiment of this application.
[0040] Figure 5 This is a schematic diagram of the "bow"-shaped scanning mode of the single-frame uniform speed scanning imaging start-up control method for aerial camera depression angle according to an embodiment of this application;
[0041] Figure 6This is a schematic diagram of the zigzag scanning mode of the single-frame uniform speed scanning imaging start-up control method for aerial cameras according to an embodiment of this application. Detailed Implementation
[0042] To enable those skilled in the art to better understand the method of the present invention, the technical solutions in 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 should fall within the scope of protection of the present invention.
[0043] The terms “first,” “second,” “third,” and “fourth,” etc. (if present), in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0044] Example 1
[0045] Reference Appendix Figure 1 This is a flowchart illustrating the single-frame uniform scanning imaging start-up control method for aerial cameras at the downward angle proposed in this application; it specifically includes the following steps:
[0046] S1: Obtain the starting steady-state time Δt of the depression frame.
[0047] In this embodiment, step S1 specifically includes the following steps:
[0048] The depression frame is controlled by a speed servo to record the step speed change from zero speed V0 to constant speed V. ref Starting steady-state time Δt 正 And the depression frame jumps from zero speed V0 to uniform speed -V ref Starting steady-state time Δt 负 ;
[0049] Where V0 = 0, V ref >0 represents the angular velocity of the forward scan command for the tilting frame, then -V ref The negative scan angular velocity of the depression frame is the angular velocity of the mission command, Δt.正 >0 represents the forward scan settling time Δt, where Δt is the fixed-rate time. 负 >0 represents the negative scan stabilization time Δt;
[0050] The depression frame starts from zero velocity V0 and gradually increases to a constant velocity V. ref or -V ref In the initial stabilization time, the stabilization index is selected based on the imaging control accuracy. If the 95% speed index is selected, then the stabilization time Δt 正 and Δt 负 These are the starting speeds of the frame at the angle of depression, from zero velocity V0 to a constant speed of 95%*V. ref and -95%*V ref The corresponding time for starting and maintaining a steady speed.
[0051] S2: Obtain the angle Δθ traveled by the depression frame during the starting steady speed time.
[0052] In this embodiment, step S2 specifically includes the following steps:
[0053] The depression frame is controlled by a speed servo to record the step transition from zero speed V0 to uniform speed V. ref Angle Δθ traveled 正 And the angled frame jumps from zero speed V0 to constant speed -V ref Angle Δθ traveled 负 ;
[0054] Where, V0 = 0, V ref >0 represents the angular velocity of the forward scan command for the tilting frame, then -V ref The negative scan mission command angular velocity for the depression frame is Δθ. 正 >0 represents the angle Δθ traveled by the tilting frame during forward scanning at a steady speed. 负 >0 represents the angle Δθ that the downward-facing frame travels during negative scanning at a steady speed.
[0055] S3: Under the command to prepare for taking a picture, determine the starting angle θ0 of the depression frame, and move the depression frame to its starting angle θ0 by position servo control.
[0056] In this embodiment, step S3 specifically includes the following steps:
[0057] Step S31: Based on the starting angle θ1 and ending angle θ2 within a single strip of the image captured by the uniform scanning of the tilting frame, determine the starting angle θ0 of the tilting frame. If θ1 < θ2, define the tilting frame as a forward scan, then the starting angle θ0 of the tilting frame = θ1 - Δθ 正 If θ1 > θ2, the depression frame is defined as a negative scan, then the starting angle of the depression frame θ0 = θ1 + Δθ 负Please refer to the appendix for details. Figure 5 and appendix Figure 6 .
[0058] Step S32: The depression frame moves to the starting angle θ0 using position servo control.
[0059] S4: Under the command to take a picture, the downward angle frame performs a uniform scanning at a speed servo control mode according to the starting angle θ0 of the downward angle frame.
[0060] In this embodiment, step S4 specifically includes the following steps:
[0061] Step S41: Delay time Δt 正 or Δt 负 The camera scans here and takes the first photo;
[0062] Step S42: Refer to Appendix Figure 6 The zigzag scanning lines shown start from the periphery and move to the apophery. At this point, θ1 < θ2, and the depression frame is scanning in the forward direction. The depression frame starts from zero velocity V0 at the starting angle θ0 and accelerates stepwise to V. ref Time consumed Δt 正 After Δθ 正 Reaching the initial angle θ1 and achieving a constant velocity V ref The camera took the first photo on this trip, with the frame tilted downwards from the starting angle θ1 at a constant speed V. ref Once the end angle θ2 is reached, the camera takes subsequent photos of this line at continuous intervals based on the overlap rate.
[0063] Step S43: Refer to Appendix Figure 5 The even-numbered scan rows of the "bow"-shaped scan shown scan from the far point to the near point. At this time, θ1>θ2, the depression frame is scanning in the negative direction, and the depression frame accelerates stepwise from zero speed to -V from the starting angle θ0. ref Time consumed Δt 负 After Δθ 负 Reaching the initial angle θ1 and achieving a constant velocity -V ref The camera took the first photo of this trip, with the frame tilted downwards from the starting angle θ1 at a constant speed of -V. ref Once the scan reaches the end angle θ2, the camera takes subsequent photos of this line at continuous intervals based on the overlap rate.
[0064] In summary, Embodiment 1 of this application determines the starting angle of the downward-angled frame by obtaining the starting and stabilizing speed time of the downward-angled frame and the corresponding angle traversed by the downward-angled frame, and moves to its starting angle using position servo control; the downward-angled frame performs uniform scanning using speed servo control; during its dynamic scanning imaging operation, when the angle of the downward-angled frame reaches the starting angle position of each line of exposure, it reaches a uniform and stable state, thereby ensuring the dynamic scanning imaging quality of the aerial camera and improving the efficiency of image post-processing.
[0065] Example 2
[0066] Reference Appendix Figure 2 The diagram shown is a structural schematic of a single-frame uniform speed scanning imaging start-up control system for an aerial camera according to an embodiment of this application; the details are as follows:
[0067] Time acquisition module 100: Acquires the starting and steady-state speed time Δt of the depression frame;
[0068] Angle acquisition module 200: acquires the angle Δθ traveled by the depression frame during the starting and steady-speed time;
[0069] Control module 300: Under the command to prepare for taking a picture, the starting angle θ0 of the depression frame is determined, and the depression frame moves to its starting angle θ0 by position servo control.
[0070] Scanning module 400: Under the command of taking a picture, the downward angle frame performs uniform scanning in a speed servo control mode according to the starting angle θ0 of the downward angle frame.
[0071] In summary, Embodiment 2 of this application obtains the starting and steady-state speed time of the depression frame and the corresponding angle traveled by the depression frame through the time acquisition module and the angle acquisition module, respectively. The starting angle of the depression frame is determined by the control module and the frame moves to the starting angle using position servo control. Then, the depression frame performs uniform scanning using speed servo control according to the scanning module. The angular velocity of the depression frame reaches a uniform and stable state, thereby ensuring the dynamic scanning imaging quality of the aerial camera and improving the efficiency of image post-processing.
[0072] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, apparatus, article, or method that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, apparatus, article, or method. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, apparatus, article, or method that includes that element.
[0073] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural changes made based on the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.
[0074] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.
[0075] Of course, the present invention may have many other embodiments. Based on this embodiment, other embodiments obtained by those skilled in the art without any creative effort are all within the scope of protection of the present invention.
Claims
1. A method for controlling the start-up of a single-frame uniform-speed scanning imaging at a downward angle for an aerial camera, characterized in that: include: S1: Obtain the starting steady-speed time of the depression frame ; S2: Obtain the starting steady-speed time The angle traveled by the internal depression frame ; S3: Under the command to prepare for taking photos, determine the starting angle of the downward-facing frame. The depression frame moves to its starting angle using position servo control. ; S4: Under the command to take a picture, based on the starting angle of the aforementioned tilting frame. The depression frame performs uniform scanning using speed servo control. Step S1 includes the following steps: The depression frame is controlled by a speed servo, recording the depression frame's speed from zero. Starting step to constant speed Start-up steady speed time And the depression frame from zero speed Starting step to constant speed Start-up steady speed time ; Where the definition , If the angular velocity of the forward scan command for the tilting frame is given, then... The negative scan angular velocity of the depression frame is the command angular velocity. Forward scan settling time , negative scan settling time ; Step S2 includes the following steps: The depression frame is controlled by a speed servo, recording the depression frame's speed from zero. Starting step to constant speed Angles traveled And the depression frame from zero speed Starting step to constant speed Angles traveled ; The definition is as follows: The angle traveled by the tilting frame during forward scanning at a steady speed. , The angle traveled by the tilting frame during negative scan stabilization. ; Step S3 includes the following steps: Step S31: Scan the starting angle within a single strip at a constant speed according to the downward angle frame. and the ending corner Determine the starting angle of the depression frame. ,like When the downward-facing frame is defined as a forward scan, then the starting angle of the downward-facing frame is... ;like When the downward-angled frame is defined as a negative scan, then the starting angle of the downward-angled frame is... ; Step S32: The depression frame moves to the starting angle using position servo control. ; Step S4 includes the following steps: Delay time or The camera scans here and takes the first photo; like At that time, the downward-facing frame scans in the forward direction, while the downward-facing frame scans from the starting angle. From zero speed Starting step acceleration to ,time consuming Experience Reaching the starting angle And achieve uniform speed The camera took the first photo of the trip, with the frame positioned at a downward angle from the starting angle. at a constant speed Scan to end corner The camera takes subsequent photos of this line at continuous intervals based on the overlap rate; like At that time, the downward-angled frame scans negatively, while the downward-angled frame scans from the starting angle. From zero speed to step acceleration ,time consuming Experience Reaching the starting angle And achieve uniform speed The camera took the first photo of the trip, with the frame positioned at a downward angle from the starting angle. at a constant speed Scan to end corner The camera takes subsequent photos of this line at continuous intervals based on the overlap rate; It also includes the following steps: In step S5, steps S3 and S4 are executed alternately in a loop.
2. The aerial camera single-frame uniform speed scanning imaging start-up control method according to claim 1, characterized in that, Step S1 includes the following steps: The depression frame starts from zero speed Starting step to constant speed or During the initial stabilization time, the stabilization index is selected based on the imaging control accuracy.
3. A single-frame uniform speed scanning imaging start-up control system for an aerial camera with a downward angle, characterized in that, The system is used to perform the aerial camera tilt angle single-frame uniform speed scanning imaging start-up control method according to any one of claims 1 to 2, the system comprising: Time acquisition module: Acquires the starting and steady-speed time of the depression frame. ; Angle acquisition module: acquires the starting steady-speed time. The angle traveled by the internal depression frame ; Control module: Upon receiving the image preparation command, determines the starting angle of the tilting frame. The depression frame moves to its starting angle using position servo control. ; Scanning module: Upon receiving the photo-taking command, it scans the image based on the starting angle of the tilting frame. The depression frame performs uniform scanning using speed servo control.