CN103108125B - A kind of capture Synchronizing Control Devices of multicamera system and method thereof - Google Patents

Abstract

The invention discloses an imaging synchronous control device for a multi-camera system, which includes a synchronous pulse generator, a first and second pulse adjustable module, a beam generator and a beam splitter assembly, wherein the synchronous pulse generator is used to The pulse period and width of the pulse signal are sent out synchronously to all cameras and the first pulse adjustable module; the first and second pulse adjustable modules are respectively used to perform front-edge backward shift and trailing-edge forward shift processing on the pulse signal, and send them to Beam generator: The beam generator emits a collimated beam or a non-diffraction beam according to the pulse signal, and then reaches each camera synchronously after being split by the beam splitter, thereby realizing the synchronous control process of the same beam. The invention also discloses a corresponding image acquisition synchronous control method and its application. Through the present invention, complete synchronous control of multiple cameras' imaging can be realized in a compact and easy-to-operate manner, and is especially suitable for occasions requiring extremely high synchronization such as optical collimation measurement.

Description

A device and method for synchronous image capture control of a multi-camera system

technical field

The invention belongs to the field of optoelectronic technology, and more specifically relates to an imaging synchronization control device and method for a multi-camera system.

Background technique

Multi-camera systems are widely used in stereo vision, three-dimensional imaging, spatial position measurement of multi-point imaging, and large-field parallel imaging, and have broad development prospects. In these applications that use a multi-camera system to perform measurement and monitoring, it is often required that the image acquisition of the multi-cameras be synchronized, so that the projection centers of the multiple cameras coincide and facilitate later image processing.

The method for synchronously capturing images by multiple cameras in the prior art mainly includes: synchronously triggering the shutters of multiple cameras with an external pulse and controlling the exposure time length thereof, so as to realize synchronous image capturing by multiple cameras. For example, the non-patent literature "Implementation of Dual-Camera Synchronization Technology in High-speed Photogrammetry System" (Journal of Surveying and Mapping Science and Technology, 2009, Volume 26, No. 1, Pages 76-78) discloses a multi-camera synchronous imaging system , where the dual camera adopts the mode of synchronizing with the acquisition card, and the clock generator of the acquisition card is used to generate the synchronization source signal, the pixel clock signal of the camera and the HD/VD signal, thus ensuring the synchronization accuracy of the dual camera. As another example, CN200610075401.9 discloses a multi-camera system and its control method, wherein the reset phase information corresponding to the position of the frame is sent to multiple image pickup devices by using a controller equipped with a reset phase sending unit Each of them, and then the image pickup device outputs the captured image pickup frame according to the synchronization reference signal sent from the controller; in this camera system, the synchronization reference signal sent by the controller is used to ensure the synchronization of multi-camera imaging.

However, for some multi-camera systems with extremely high synchronization requirements, such as optical collimation measurement devices, it is necessary to correct the measurement results of optical collimation positioning by measuring the drift of the collimated beam, and the drift of the beam is random In this case, in order to achieve high-precision detection of beam drift, it is necessary to better control the synchronization of the detection camera, and the higher the synchronization accuracy, the higher the high-precision guarantee of beam drift detection. high. In addition, due to the inconsistency of the response time of the external trigger of each camera in the multi-camera system, the length of the shutter including the synchronization of the external trigger and the exposure time (that is, the acquisition time of the image), there will be some inconsistencies, especially when the camera models are different. The difference in trigger response time will be greater and will affect the exposure effect when exposing at high speed. Considering the above situation, the synchronous control method in the prior art will not be able to meet the higher precision synchronous requirements. Correspondingly, there is a technical demand for further improvement in the imaging synchronization control process of the multi-camera system in the related field.

Contents of the invention

In view of the above defects and technical requirements of the prior art, the object of the present invention is to provide a multi-camera system image acquisition synchronization control device and its method, which processes the pulse signal by moving the front edge back and the trailing edge forward and its matching The operation can make the beam generator generate the beam after all the cameras are in the stable exposure state, and end the emission of the beam before all the cameras start to end the exposure state, thereby realizing the complete synchronous control of the imaging of all the cameras, and is especially applicable Multi-camera systems with extremely high synchronization requirements such as optical alignment measurements.

According to one aspect of the present invention, an image acquisition synchronization control device for a multi-camera system is provided, the image acquisition synchronization control device includes a synchronization pulse generator, a first pulse adjustable module, a second pulse adjustable module, a beam generator , and the beam splitter assembly, characterized in that:

The synchronous pulse generator is used to synchronously send pulse signals to all cameras in the multi-camera system and the first pulse adjustable module according to the set pulse period and pulse width, and act on each camera to start exposure, by This controls the imaging period of each camera to be the period of the pulse generated by the synchronous pulse generator, wherein the pulse width is determined to be less than or equal to the exposure time Tw uniformly set by all cameras, and the exposure time Tw is less than or equal to The minimum value of the longest exposure time allowed by each camera, the pulse period is determined to be greater than or equal to the longest imaging period of each camera when it is free to continuously capture images under the Tw exposure time;

The first adjustable pulse module is used to perform front-rear shift processing on the received pulse signal, and then send it to the second adjustable pulse module;

The second pulse adjustable module is used to perform trailing edge forward processing on the received pulse signal, and then send it to the beam generator;

The beam generator emits a collimated beam or a non-diffracting beam according to the received pulse signal, and after being split by the beam splitter assembly, it reaches each camera set in the reflection direction and the transmission direction of the beam splitter synchronously. The process of synchronous control of multiple cameras in the camera system for capturing images of the same light beam.

As further preferably, the number of the beam splitter assemblies is more than 2 and they are distributed on the same optical axis, wherein a camera is respectively arranged correspondingly on the reflection direction of each beam splitter assembly, and at the same time, all the beam splitter assemblies are identical A camera is provided in the transmission direction.

As a further preference, the first adjustable pulse module is a manual adjustable module; the second adjustable pulse module is an electronically controlled adjustable module, and the pulse adjustment is performed under the drive of a control signal source.

As a further preference, the frequency response of the beam generator for emitting and stopping emitting is higher than 1 MHz.

As a further preference, the cameras in the multi-camera system are full-frame cameras or progressive cameras.

As a further preference, all pixels of the cameras in the multi-camera system are exposed at the same time, and are output as a whole block at one time.

As a further preference, the cameras in the multi-camera system are equipped with electronic shutters that allow external triggering, thereby allowing the pulse signal generated by the synchronous pulse generator to control their image acquisition period.

According to another aspect of the present invention, a corresponding image acquisition synchronization control method is also provided, characterized in that the method includes the following steps:

(a) setting a unified exposure time Tw for multiple cameras in the multi-camera system, and the exposure time Tw is determined to be less than or equal to the minimum value among the longest exposure times allowed by all cameras;

(b) Set the pulse period and pulse width for the synchronous pulse generator, the pulse width is less than or equal to the exposure time Tw set uniformly by all cameras, and the pulse period is greater than or equal to the free and continuous acquisition of each camera under the exposure time Tw The longest image acquisition period during the image;

(c) After the above settings are completed, the synchronous pulse generator sends out a pulse signal to act synchronously on multiple cameras to start exposure, and controls the imaging period of each camera to the period of the pulse generated by the synchronous pulse generator ; At the same time, the pulse signal is sequentially processed by the leading edge backward shift and the trailing edge forward shift, and then acts on the beam generator to make it emit light beams according to the processed pulse signal, and the light beams reach each camera, thereby realizing the synchronous control of the same light beam in the multi-camera system.

According to yet another aspect of the present invention, there is also provided the application of the above method in the field of optical collimation measurement or non-diffracting light beams.

Generally speaking, compared with the prior art, the imaging synchronization control device and method thereof according to the present invention mainly have the following technical advantages:

1. Since the pulse signal is used to make multiple cameras perform exposure at the same time, the pulse signal is sequentially processed by the leading edge back and the trailing edge forward before acting on the beam generator, which can make the beam generator stable in all cameras The light beam is generated after the exposure state, and the emission of the light beam is completed before all cameras start to end the exposure state, so that the image capture of all cameras can be completely synchronized;

2. The synchronous control device of the present invention can meet the high degree of synchronization of multiple cameras in a multi-camera system for taking images of the same light beam, and can be easily expanded to add more cameras to take images of the light beam. Just add the beam splitter assembly and its corresponding camera to the axis;

3. The synchronization control method according to the present invention is easy to operate, and can obtain a higher synchronization effect compared with the prior art, so it is especially suitable for providing protection for the detection accuracy of beam drift;

4. In the present invention, the electronic control module adjusts the trailing edge of the pulse signal, controls the width of the pulse, and then controls the beam emission time of the beam generator, thereby achieving the purpose of precisely controlling the sampling time.

Description of drawings

FIG. 1 is a schematic diagram of the overall structure of an imaging synchronization control device according to a preferred embodiment of the present invention;

FIG. 2 is a schematic diagram of the overall structure of an imaging synchronization control device according to another preferred embodiment of the present invention;

Fig. 3 is a timing diagram for displaying free continuous imaging of multiple full-frame cameras in a multi-camera system;

Fig. 4 is a schematic diagram of the continuous imaging sequence of a plurality of full-frame cameras after a unified exposure time Tw is set according to the present invention;

FIG. 5 is a schematic diagram showing the time sequence of controlling the beam generator and multiple full-frame cameras respectively according to the present invention.

Throughout the drawings, the same reference numerals are used to designate the same elements or structures, wherein:

1-beam generator 2-synchronous pulse generator 3-first pulse adjustable module 4-second pulse adjustable module 5-control signal source 6-camera 7-camera 8-camera 9-beam splitter assembly 10-beam splitter Component 11-Camera 12-Beam splitter component

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Fig. 1 is a schematic diagram of the overall structure of an imaging synchronization control system according to a preferred embodiment of the present invention. As shown in Figure 1, according to the image capture synchronization control device of the present invention, it mainly includes a beam generator 1, a synchronous pulse generator 2, a first pulse adjustable module 3, a second pulse adjustable module 4, and a beam splitter assembly 9 and 10.

The synchronous pulse generator 2 is used to send pulse signals synchronously to all cameras 6, 7 and 8 and the first pulse adjustable module 3 in the multi-camera system according to the set pulse period and pulse width, and act on each camera It starts exposure, and controls the imaging period of each camera to be the period of the pulse generated by the synchronous pulse generator. The pulse width is determined to be less than or equal to the exposure time Tw uniformly set by all cameras, the exposure time Tw is less than or equal to the minimum value of the longest exposure time allowed by each camera, and the pulse period is determined to be greater than or equal to It is equal to the longest imaging cycle of each camera when it is free to continuously capture images under Tw exposure time. The first pulse adjustable module 3 is, for example, a manual adjustable module, which performs the front-end shifting process on the pulse signal sent from the synchronous pulse generator 2, and then sends it to the second pulse adjustable module 4; the second pulse The adjustable module is, for example, an electronically controlled adjustable module, and under the drive of the computer or the voltage control signal source 5, the pulse signal sent from the first pulse adjustable module performs trailing edge forward processing, and then sends it to beam generator 1. In the above process, the beam generator 1 can emit light beams after all cameras are in a stable exposure state through the processing of the front edge of the first adjustable pulse module 3, and the trailing edge of the second pulse adjustable module 4 The shifting process can make the beam generator 1 stop the emission of the beam before the moment when all cameras start to end the exposure state, thereby achieving a high degree of consistency in the time of image acquisition by each camera and achieving complete synchronization.

The beam generator 1 is used to emit collimated light or non-diffraction beams and other highly directional beams according to the received pulse signal, and then pass through the beam splitter assemblies 9 and 10 in sequence and then arrive synchronously at the reflection direction and transmission direction of these beam splitters respectively. Each camera in the direction, specifically, a part of the light reaches the cameras 7 and 8 respectively arranged in the reflection direction of the beam splitter, and the other part of the light reaches the camera 6 arranged in the same transmission direction of the beam splitter, thereby realizing the multi-camera system. Synchronous control process of multiple cameras taking images of the same light beam. In addition, the beam images detected by the cameras 7 and 8 can also be synchronously compared, so as to detect the error caused by the beam offset on the beam. The influence error is used to correct the processing result of the image collected by the camera 6 , so that the correction process of the processing result of the image collected by the camera 6 can be realized by using the detection result of beam drift.

Fig. 2 is a schematic diagram of the overall structure of an imaging synchronization control device according to another preferred embodiment of the present invention. Compared with the structure shown in FIG. 1 , the main difference is that a beam splitter assembly 12 is added on the same optical axis of the beam splitter assembly, and a camera 11 is arranged correspondingly in the reflection direction of the beam splitter 12 . This embodiment shows that the present invention can be applied to fully synchronous control of the same beam sampling by various multi-camera systems. If you want to expand the device and add multiple cameras, you only need to add a beam splitter assembly and its corresponding cameras, and expand according to the optical path shown in Figure 2.

The image capture synchronization control process according to the present invention will be explained in detail below with reference to FIGS. 3-5 . Here we take 3 cameras as an example. Since the models of the 3 cameras may be different, the longest exposure time of the 3 cameras is also different. Let the longest exposure time of the 3 cameras be Tw1, Tw2, Tw3, and 3 The free continuous imaging periods of the cameras are T ₁₀ , T ₂₀ , and T ₃₀ respectively, and the timing diagrams of the free continuous imaging of the three cameras can be obtained, as shown in FIG. 3 .

Fig. 4 is a schematic diagram of the continuous image capturing sequence of multiple full-frame cameras after setting a unified exposure time Tw according to the present invention. Here is an explanation in conjunction with the three-camera system shown in Figure 1. The exposure times Tw1, Tw2, and Tw3 in a single imaging cycle of the three cameras are uniformly set as Tw, and Tw should be less than or equal to the maximum allowed by each of the cameras. The minimum value of the long exposure time, as shown in Figure 3, is to take the time equal to or shorter than the exposure time of camera 3 as the common exposure time Tw, at this time, the free and continuous image acquisition periods of the three cameras respectively become 4 shows T1, T2, T3, among which T1 is the longest, and the camera exposure is triggered by the rising edge of the external trigger signal, for example. Then, the synchronous pulse generator sends out a pulse signal with a pulse width W and a pulse period T. The pulse width W is determined to be less than or equal to the exposure time Tw set uniformly by all cameras, and the pulse period is determined to be greater than or equal to The longest image acquisition cycle of each camera when free continuous image acquisition under Tw exposure time. For example, as shown in Figure 4, that is, T=T1, W=Tw. The pulse leading edge of the synchronous pulse generator is TR, and the pulse trailing edge of the synchronous pulse generator is TD. After the rising edge of this pulse is triggered, the camera starts to expose, and the imaging cycle of each camera is controlled to be the cycle of this pulse, which is the The set pulse period.

FIG. 5 is a schematic diagram showing the time sequence of controlling the beam generator and multiple full-frame cameras respectively according to the present invention. Here, it is also described in conjunction with the three-camera system shown in FIG. 1 . First, the three cameras are externally triggered by the synchronous pulse trigger signal determined in Figure 4, so that the three cameras 6, 7 and 8 are all in the exposure state; at the same time, the synchronous pulse trigger signal is manually adjustable through a pulse front Module 3, the trailing edge TD remains unchanged and the leading edge is shifted backwards, changing from TR to TTR, and the shifting time is determined by the longest response time of all cameras responding to the pulse leading edge TR of the synchronous pulse generator. The purpose is to make all cameras The high-frequency beam generator 1 starts to emit light beams only after they are in a stable exposure state. The control signal output by the first pulse adjustable module 3 passes through the second pulse adjustable module 4 with a pulse trailing edge, the front TTR remains unchanged and the trailing edge is moved forward, changing from TD to TTD, so as to control the high frequency response The beam generator 1 emits the end moment of the beam, and makes the high-frequency beam generator end the beam emission before the moment when all cameras start to end the exposure state. Combining the above operations, complete synchronization of beam sampling for all cameras is achieved.

It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (8)

1. A synchronous control device for capturing images of a multi-camera system, the synchronous control device for capturing images comprises a synchronous pulse generator, a first pulse adjustable module, a second pulse adjustable module, a beam generator, and a spectroscopic mirror assembly, wherein Features: The synchronous pulse generator is used to synchronously send pulse signals to all cameras in the multi-camera system and the first pulse adjustable module according to the set pulse period and pulse width, and act on each camera to start exposure, Wherein the pulse width is determined to be less than or equal to the exposure time Tw uniformly set by all cameras, the exposure time Tw is less than or equal to the minimum value in the longest exposure time allowed by each camera, and the pulse period is determined to be greater than Or equal to the longest imaging cycle of each camera when it is free to continuously capture images under the exposure time Tw; The first adjustable pulse module is used to perform leading edge back-shift processing on the received pulse signal, and then send it to the second adjustable pulse module; The second pulse adjustable module is used to perform trailing edge forward processing on the received pulse signal, and then send it to the beam generator; The beam generator emits a collimated beam or a non-diffracting beam according to the received pulse signal, and after being split by the beam splitter assembly, it reaches each of the cameras respectively arranged in the reflection direction and the transmission direction of the beam splitter, each The camera thus realizes the synchronous control process of multiple cameras taking images of the same light beam in the multi-camera system. 2. The image capturing synchronous control device as claimed in claim 1, wherein the quantity of the beam splitter assembly is more than 2 and it is distributed on the same optical axis, wherein on the reflection direction of each beam splitter assembly respectively One said camera is arranged correspondingly, and one said camera is arranged in the same transmission direction of all beam splitter assemblies. 3. The image acquisition synchronization control device according to claim 1 or 2, characterized in that, the first pulse adjustable module is a manual adjustable module; the second pulse adjustable module is an electronically controlled adjustable module module and performs pulse conditioning driven by a control signal source. 4. The image capture synchronization control device according to claim 3, wherein the frequency response of the beam generator for emitting and stopping emitting is higher than 1 MHz. 5. The imaging synchronous control device according to claim 4, wherein the cameras in the multi-camera system are full-frame cameras or progressive cameras, and all pixels of these cameras are exposed at the same time, and one time Sexual block output. 6. The imaging synchronous control device according to claim 5, wherein the cameras in the multi-camera system are equipped with electronic shutters that allow external triggering, thereby allowing the pulse signal generated by the synchronous pulse generator to Control its image acquisition cycle. 7. A method for realizing synchronous image acquisition control by the device according to any one of claims 1-6, characterized in that the method comprises the following steps: (a) setting a uniform exposure time Tw for multiple cameras in the multi-camera system, the exposure time Tw being determined to be less than or equal to the minimum value of the longest exposure time allowed by all cameras; (b) Set its pulse period and pulse width for the synchronous pulse generator, wherein the pulse period is greater than or equal to the longest imaging period when each camera is free to continuously capture images under Tw exposure time, and the pulse width is less than or equal to all The exposure time Tw uniformly set by the camera; (c) After the above settings are completed, the synchronous pulse generator sends out a pulse signal to act synchronously on multiple cameras to start exposure, and controls the imaging cycle of each camera to the cycle of the pulse generated by the synchronous pulse generator ; At the same time, the pulse signal is sequentially processed by the leading edge backward shift and the trailing edge forward shift, and then acts on the beam generator to make it emit light beams according to the processed pulse signal, and the light beams reach each camera, thereby realizing the synchronous control of the same light beam in the multi-camera system. 8. The application of the image acquisition synchronization control method as claimed in claim 7 in the field of optical collimation measurement or non-diffracting light beams.