CN107170239A - A kind of target vehicle follows the trail of grasp shoot method and device - Google Patents

Abstract

The invention discloses a method and device for tracking and capturing a target vehicle. The method includes: after receiving an instruction for tracking and capturing a target vehicle, start to obtain the current frame image from the video shot by the camera device at a preset time interval, and obtain Extract the target vehicle image in the frame image; judge whether the target vehicle image in the frame image meets the preset requirements, if so, save the frame image, if not, adjust the optical parameters of the camera device, so that when the camera device shoots The image of the target vehicle in the video can clearly reflect the information of the target vehicle. The target vehicle tracking and capturing method and device of the present invention capture images from the shooting video at preset time intervals, and adjust the optical parameters of the camera device according to the acquired current frame image after each image acquisition, so that when the camera device shoots a video The image of the target vehicle can clearly reflect the information of the target vehicle, so that an image that can clearly reflect the information of the target vehicle can be obtained from the shooting video.

Description

A method and device for tracking and capturing a target vehicle

technical field

The invention relates to the technical field of intelligent transportation, in particular to a method and device for tracking and capturing a target vehicle.

Background technique

With the full popularity of automobiles, social problems such as urban traffic congestion and frequent highway traffic accidents have become increasingly prominent, and most of these problems occur due to drivers' traffic violations.

At present, the traffic management department monitors and captures traffic violations by installing cameras on road sections, but there are blind spots at some small intersections or roads with fewer vehicles; in addition, based on the advancement of modern technology, the navigation system on general vehicles will Prompt the driver on which road sections will have snapshots, which makes many drivers feel lucky, so running a red light, going the wrong way, reversing at will, changing lanes forcibly, turning around on double solid lines, illegally occupying emergency lanes and turning right to prevent straight pedestrians Such traffic violations often occur, and the existing traffic safety hazards threaten people's property and even life safety.

In order to make up for the lack of camera surveillance set up by the traffic management department, many cities have introduced corresponding policies to encourage citizens to report traffic violations. For reporting citizens, either directly give cash rewards, or give a reward for minor traffic violations without demerit points. The reporting method can be through WeChat, for example, uploading multiple illegal photos or videos, and the reporting system also has corresponding requirements for these illegal photos or videos, for example, the license plate of the illegal vehicle, the appearance of the illegal vehicle and the facts of the violation must be clearly reflected.

However, existing driving recorders can only take fixed and single scene images, and cannot guarantee that the captured images or videos can clearly reflect information such as license plates of illegal vehicles, appearance of illegal vehicles, or illegal facts.

Contents of the invention

In view of this, the object of the present invention is to provide a method and device for tracking and capturing a target vehicle, which can realize the acquisition of an image that can clearly reflect the information of the target vehicle.

To achieve the above object, the present invention provides the following technical solutions:

A method for tracking and capturing a target vehicle, comprising:

After receiving the issued target vehicle tracking and capturing command, start to obtain the current frame image from the video shot by the camera device at a preset time interval, and extract the target vehicle image from the acquired frame image;

Determine whether the target vehicle image in the frame image meets the preset requirements, if so, save the frame image, if not, adjust the optical parameters of the camera device, so that the target vehicle image in the video captured by the camera device can meet the preset requirements. The preset requirement is that the image of the target vehicle in the image can clearly reflect the information of the target vehicle.

Optionally, it also includes: when the preset time interval time point is reached, if the optical parameters of the camera device are being adjusted, immediately after the optical parameters of the camera device are adjusted, an image is acquired from the shooting video, And use the acquisition moment as a starting point to calculate the time point of acquiring the image next time.

Optionally, the preset requirement includes that the ratio of the area of the extracted image of the target vehicle to the entire image is within a preset range;

The adjustment of the optical parameters of the camera device so that the image of the target vehicle in the video captured by the camera device can meet the preset requirements includes:

Adjust the distance between the variable magnification group of the camera device and the front fixed group according to the area ratio, so that the area ratio of the target vehicle image to the entire image in the video captured by the camera device is located at the middle value of the preset range .

Optionally, the adjusting the optical parameters of the camera device so that the image of the target vehicle in the captured video can meet the preset requirements further includes:

Adjusting the distance between the compensation group of the camera device and the zoom group, so that the camera device is focused;

The size of the aperture of the camera device is adjusted so that the exposure of the captured video image is normal.

Optionally, it also includes: if the ratio of the area of the extracted target vehicle image to the entire image is within the preset range, judging that the ratio of the area of the extracted target vehicle image to the entire image is compared with that extracted last time. Whether the change in the area ratio of the target vehicle image to the entire image is greater than the threshold;

If yes, then adjust the distance between the variable magnification group of the camera device and the front fixed group according to the area ratio, so that the area ratio of the target vehicle image to the entire image in the video captured by the camera device is located in the middle of the preset range value.

Optionally, a first stepping motor is connected to the variable magnification group, and the first stepping motor is used to adjust the distance between the variable magnification group and the front fixed group according to the input pulse;

A second stepper motor is connected to the compensation group, and the second stepper motor is used to adjust the distance between the compensation group and the variable magnification group.

Optionally, extracting the target vehicle image from the image includes:

Set a rectangular box in the image that coincides with the edge of the image;

Move the four sides of the rectangular frame in parallel to the opposite direction at the same time, and when the side of the rectangular frame touches the pixel point where the target vehicle is located for the first time, the side stops moving in parallel;

After the four sides of the rectangular frame stop moving in parallel, the obtained image inside the rectangular frame is used as the extracted image of the target vehicle.

Optionally, it also includes: transmitting the saved image to the user's mobile device. After receiving the image, the mobile device reads the location information and time information of the mobile device and records it in a text file, and records the image and the location information and time information text files are stored in the same folder.

A target vehicle tracking and capturing device, comprising:

The obtaining module is used to start obtaining the current frame image from the video shot by the camera at a preset time interval after receiving the issued target vehicle tracking and capturing instruction, and extract the target vehicle image from the obtained frame image;

An adjustment module, used to judge whether the target vehicle image in the frame image meets the preset requirements, if so, save the frame image, if not, adjust the optical parameters of the camera device, so that the target vehicle image in the video captured by the camera device The vehicle image can meet the preset requirement, and the preset requirement is that the image of the target vehicle in the image can clearly reflect the information of the target vehicle.

Optionally, the acquisition module is further configured to, when the preset time interval time point is reached, if the optical parameters of the imaging device are being adjusted, immediately after the adjustment of the optical parameters of the imaging device is completed, immediately from the shooting video The image is acquired in , and the time point of the next image acquisition is calculated using the acquisition moment as the starting point.

Optionally, a control panel is also included, and the control panel is provided with:

The touch display screen is used to display the video image, and sends the target vehicle tracking and capturing instruction when the user touches it;

The image adjustment button is used for manually adjusting to increase or decrease the area ratio of the target vehicle image in the captured image when triggered.

It can be seen from the above technical solution that the target vehicle tracking and capturing method and device provided by the present invention, after receiving the issued target vehicle tracking and capturing command, starts to acquire the current frame image from the video shot by the camera device at a preset time interval, and Extract the target vehicle image from the frame image obtained; for each image obtained, judge whether the target vehicle image in the frame image meets the preset requirements, if so, save the frame image, if not, adjust the camera Optical parameters, so that the image of the target vehicle in the video shot by the camera device can clearly reflect the information of the target vehicle, so that an image that can clearly reflect the information of the target vehicle can be obtained from the video shot.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a flow chart of a method for tracking and capturing a target vehicle provided by an embodiment of the present invention;

Fig. 2 is the flowchart of the method for extracting target vehicle image from acquired image in the embodiment of the present invention;

FIG. 3 is a schematic structural view of an imaging device in an embodiment of the present invention;

Fig. 4 is a flow chart of adjusting according to the extracted target vehicle image in another embodiment of the present invention;

5 is a schematic diagram of a target vehicle tracking and capturing device provided by an embodiment of the present invention;

FIG. 6 is a schematic diagram of a control panel in a tracking and capturing device for a target vehicle provided by an embodiment of the present invention.

detailed description

In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described The embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

Please refer to Fig. 1, a kind of target vehicle tracking capture method provided by the embodiment of the present invention, comprises steps:

S10: Acquire the current frame image from the video shot by the camera device when receiving the issued target vehicle tracking and capturing instruction.

In a specific implementation, the camera device may be a camera device of the user's vehicle (such as a driving recorder). The camera device of the user's vehicle (such as a driving recorder) captures road condition images in real time, and the captured road condition images are displayed to the user through a display screen, such as a touch display screen. When the user observes an illegal vehicle in the road condition image displayed on the touch screen, the user can click the illegal vehicle on the touch screen to select the target vehicle, and trigger the system to issue a target vehicle tracking and capture command.

When the tracking and capturing instruction of the target vehicle is received, the current frame image is acquired from the video shot by the camera device at a preset time interval, and the target vehicle image is extracted from the current frame image.

S11: Determine whether the image of the target vehicle in the image frame meets a preset requirement, the preset requirement being that the image of the target vehicle in the image can clearly reflect the information of the target vehicle.

Wherein, the image of the target vehicle can clearly reflect the information of the target vehicle means that the image of the target vehicle in the image can clearly reflect the appearance of the target vehicle, the vehicle license plate, or the fact that the vehicle violated the law on the spot. Specifically, it can be the extracted image of the target vehicle The ratio of the area to the entire image is within a preset range, and the image is displayed clearly.

If yes, execute step S12;

S12: Save the frame image.

If not, execute step S13;

S13: Adjust the optical parameters of the camera device, so that the image of the target vehicle in the video captured by the camera device can meet the preset requirements.

S14: When the preset time interval time point is reached, the current frame image is acquired from the video shot by the camera device, and the target vehicle image is extracted from the acquired frame image.

In this method, after receiving the target vehicle tracking and capturing instruction, start to capture images from the video shot by the camera device at a preset time interval, specifically, every time the preset time interval time point is reached, the current frame is obtained from the video shot by the camera device image. Specifically, after each preset number of frames of images in the shooting video is captured, one frame of images may be collected, for example, the preset number of frames is 48 frames.

S15: Judging whether the image of the target vehicle in the frame image meets the preset requirement, the preset requirement is that the image of the target vehicle in the image can clearly reflect the information of the target vehicle. The area ratio of the entire image is within a preset range, and the image display is clear.

If so, execute step S16;

S16: Save the frame image.

If not, execute step S17;

S17: Adjust the optical parameters of the camera device, so that the image of the target vehicle in the video captured by the camera device can meet the preset requirements.

Then loop into step S14.

It can be seen that in the target vehicle tracking and capturing method of this embodiment, when the user observes an illegal vehicle through the real-time captured road condition image, the user selects the target vehicle and begins to track and capture the target vehicle; Capture images in the shooting video, adjust the optical parameters of the camera device according to the current frame image obtained after each image acquisition, through adjustment, the target vehicle information can be clearly reflected in the video shot by the camera device, so that it can be obtained from the shooting video The image that can clearly reflect the information of the target vehicle can realize the tracking and capturing of the target vehicle.

In the description of the above embodiments, for example, the following method can be used to extract the target vehicle image from the image, please refer to Figure 2, and the specific steps include:

S100: Set a rectangular frame in the image that coincides with the edge of the image;

S101: Simultaneously move the four sides of the rectangular frame in parallel to opposite sides, and stop the parallel movement when the side of the rectangular frame touches the pixel point where the target vehicle is located for the first time;

S102: After the four sides of the rectangular frame stop moving in parallel, the obtained image inside the rectangular frame is used as the extracted image of the target vehicle.

In one embodiment, it is judged whether the image of the target vehicle in the frame image meets a preset requirement, and the preset requirement includes that the ratio of the extracted area of the image of the target vehicle to the entire image is within a preset range.

In specific implementation, the area ratio of the extracted target vehicle image to the entire image can be calculated by the following method, specifically, after the target vehicle image is extracted from the acquired image using the above method, the acquired image is binarized, specifically It is: set the pixel gray value of the target vehicle image in the image to 0 (that is, black), and the gray value of other pixels to 255 (that is, white), where the number of pixels with a gray value of 0 is divided by Based on the total number of pixels in the image, the obtained value is the area ratio of the extracted target vehicle image to the entire image, and then judge and adjust according to this area ratio.

When the area ratio of the extracted target vehicle image to the entire image exceeds the preset range, the optical parameters of the camera device are adjusted so that the target vehicle image in the captured video can meet the preset requirements, specifically including:

S200: Adjust the distance between the variable magnification group of the camera device and the front fixed group according to the area ratio, so that the area ratio of the image of the target vehicle to the entire image in the video captured by the camera device is at the middle value of the preset range .

In this embodiment, referring to FIG. 3 , the imaging device includes a front fixing group 30 , a variable magnification group 31 , a compensation group 32 , a rear fixing group 33 and an imaging device 34 . In this method, the distance x between the variable magnification group 31 and the fixed group 30 in the imaging device is adjusted specifically according to the area ratio, so that the area ratio of the target vehicle image in the captured video image to the entire image is located at the middle value of the preset range .

For example, the preset range is 47% to 53%. If the area ratio calculated in the acquired current frame image is less than 47%, the focal length of the zoom group of the camera device is controlled to be increased, that is, the increased distance x is adjusted so that subsequent shooting This area ratio in the image is in the range of 47% to 53%; if the calculated area ratio is greater than 53%, then control to reduce the focal length of the zoom group of the camera device, that is, reduce the distance x, so that this area in the subsequent image capture The ratio is in the range of 47% to 53%.

Specifically, a first stepping motor 35 connected to the variable magnification group 31 may be provided for adjusting the distance x from the variable magnification group 31 to the front fixed group 30 in the imaging device. The system calculates the proportion that needs to be adjusted according to the calculated area ratio and the middle value of the preset range, and then calculates the value of x, and then calculates the number of pulses required by the first stepping motor 35 and steps to the first step. The motor 35 outputs pulses to control the first stepper motor 35 to adjust the distance x.

Further, it also includes:

S201: Adjust the distance between the camera compensation group and the zoom group, so as to make the camera focus.

When the distance between the fixed group 30 and the variable magnification group 31 before the camera device is adjusted by the above adjustment steps, it will cause the camera device to shoot blurred, so in this step, the distance between the camera device variable magnification group 31 and the compensation group 32 is adjusted. Adjust to make the camera focus, and the captured image is clear.

Specifically, the distance y between the compensation group 32 and the zoom group 31 in the camera device is adjusted to make the camera device focus. The Laplacian operator may be used as an evaluation function, and the gradient descent algorithm may be used to maximize the evaluation function to adjust the distance y between the compensation group 32 and the variable magnification group 31, so that the camera device can focus clearly.

Specifically, a second stepper motor 36 connected to the compensation group 32 may be provided for adjusting the distance y between the compensation group 32 and the variable magnification group 31 in the imaging device. The system controls the second stepping motor 36 to adjust the position of the compensation group.

S202: Adjust the size of the aperture of the camera device, so that the exposure of the captured video image is normal.

After the zooming in the previous step is completed, according to the video image captured by the camera device in real time, the currently captured frame of image is converted into a grayscale image, and the size of the aperture is adjusted according to the grayscale value of the converted image pixel. Specifically, when the number of pixels with a grayscale value between 0 and 60 accounts for more than 35% of the total number of pixels, it indicates that the current image is underexposed, and the aperture of the camera is increased until the grayscale value is between 0 and 60. The number of pixels between 60 and 35% of the total number of pixels; when the number of pixels with a gray value between 201 and 255 accounts for more than 35% of the total number of pixels, it indicates that the current image is overexposed , at this time, reduce the aperture until the number of pixels with a grayscale value between 201 and 255 accounts for less than 35% of the total number of pixels. In this way, the exposure of the subsequent image taken by the camera device is normal.

In this way, by adjusting the optical parameters of the camera device, the target vehicle information can be clearly reflected in the subsequent video images captured by the camera device.

In another preferred implementation of this method, on the basis of the content of the above-mentioned implementation, please refer to Figure 4, and further include the following steps:

S40: If the ratio of the area of the extracted target vehicle image to the entire image is within the preset range, determine that the ratio of the area of the extracted target vehicle image to the entire image is relative to the target vehicle image extracted last time Whether the change in the area ratio of the entire image is greater than the threshold.

If not, execute step S41.

S41: Save the frame image.

If yes, execute step S42.

S42: Save the frame image, and adjust the distance between the zoom group of the camera device and the front fixed group according to the area ratio, so that the area ratio of the target vehicle image to the entire image in the video captured by the camera device is within the predetermined area ratio. Set the middle value of the range.

For example, the preset range is 47% to 53%, and the threshold is 2.5%. According to the calculation, the area ratio a of the currently extracted target vehicle image to the entire image, and the area ratio b of the target vehicle image extracted last time to the entire image are obtained. , if the change of the area ratio |a-b| is greater than 2.5%, it indicates that the target vehicle has moved a relatively large distance in this time interval relative to the own vehicle (that is, the vehicle where the camera device is located), then adjust the distance between the zoom group of the camera device and the front fixed group The distance x between them makes the ratio of the area of the target vehicle image to the entire image to be 50%, which is the middle value of 47% to 53%.

In this step, after adjusting the distance between the camera device zoom group and the front fixed group according to the area ratio, and further adjusting the distance between the camera device compensation group and the zoom group, so that the camera device is focused, And adjust the aperture size of the camera device, so that the exposure of the captured video image is normal. For specific adjustment methods, refer to steps S201 and S202, which will not be repeated here.

Further preferably, in the target vehicle tracking and capturing method described in each of the above embodiments, it further includes: when the preset time interval time point is reached, if the optical parameters of the camera device are being adjusted, wait for the camera device to After the adjustment of the optical parameters is completed, the image is acquired from the shooting video immediately, and the time point of the next image acquisition is calculated using the acquisition moment as the starting point.

In the process of tracking and capturing the target vehicle, if the optical parameters of the camera device are being adjusted when the preset time interval is reached, wait for the optical parameters of the camera device to be adjusted before acquiring images from the shooting video, thus It can ensure the validity of each captured image and improve the quality of captured images.

After the target vehicle is tracked and captured in the shooting video, the saved image is uploaded. Preferably, the method for tracking and capturing the target vehicle in this embodiment further includes: transmitting the acquired image to the mobile device of the user, and after the mobile device receives the acquired vehicle image that can clearly reflect the information of the target vehicle, read the location of the mobile device Information and time information are recorded in text files, and images of illegal vehicles and text files with location information and time information are stored in the same folder, so that users can easily obtain license plates that clearly reflect illegal vehicles, illegal vehicles Upload or report images of illegal vehicles.

Correspondingly, please refer to FIG. 5, the embodiment of the present invention also provides a target vehicle tracking and capturing device, including:

The obtaining module 50 is used to start obtaining the current frame image from the video shot by the camera at a preset time interval after receiving the issued target vehicle tracking and capturing instruction, and extract the target vehicle image from the obtained frame image;

The adjustment module 51 is used to judge whether the target vehicle image in the frame image meets the preset requirements, if so, save the frame image, and if not, adjust the optical parameters of the camera device so that in the video captured by the camera device The image of the target vehicle can meet the preset requirement, and the preset requirement is that the image of the target vehicle in the image can clearly reflect the information of the target vehicle.

It can be seen that the target vehicle tracking and capturing device provided in this embodiment, after receiving the issued target vehicle tracking and capturing command, starts to acquire the current frame image from the video shot by the camera device at a preset time interval, and from the acquired Extract the target vehicle image in the frame image; for each acquired image, judge whether the target vehicle image in the frame image meets the preset requirements, if so, save the frame image, if not, adjust the optical parameters of the camera to The image of the target vehicle in the video captured by the camera device can clearly reflect the information of the target vehicle, so that an image that can clearly reflect the information of the target vehicle can be obtained from the captured video.

In the target vehicle tracking and capturing device of this embodiment, the acquisition module 50 is configured to start acquiring the current frame image from the video captured by the camera device at a preset time interval after receiving the issued target vehicle tracking and capturing instruction.

For example, a camera device (such as a driving recorder) of the user's vehicle captures a road condition image in real time, and the captured road condition image is displayed to the user through a touch screen. When the user observes an illegal vehicle on the touch screen, the user can click on the illegal vehicle on the touch screen to select the target vehicle, and trigger the sending of the target vehicle tracking and capturing command to the device. When the device receives the target vehicle tracking and capturing instruction, it acquires the current frame image from the video shot by the camera device, extracts the target vehicle image from the frame image, and starts to acquire images from the shot video at preset time intervals.

Therefore, the target vehicle tracking and capturing device of this embodiment, when the user observes an illegal vehicle through the road condition image captured in real time, selects the target vehicle and begins to track and capture the target vehicle; After each image is captured, the optical parameters of the camera device are adjusted according to the current frame image acquired. Through adjustment, the target vehicle information can be clearly reflected in the video shot by the camera device, so that it can be clearly obtained from the shot video. The image reflecting the information of the target vehicle realizes the tracking and capturing of the target vehicle.

In yet another embodiment of the target vehicle tracking and capturing device, on the basis of the content of the above embodiments, the acquisition module 50 is further configured to, if the optical parameters of the camera device are During the adjustment, after the adjustment of the optical parameters of the camera device is completed, an image is acquired from the video shot by the camera device immediately, and the time point of the next image acquisition is calculated using the acquisition time as a starting point. In this way, the validity of each captured image can be guaranteed, and the quality of the captured image can be improved.

In addition, in the target vehicle tracking and capturing device described above in this part, the method involved in extracting the target vehicle image from the image, and adjusting the optical parameters of the camera device according to the captured image, so that the target vehicle image in the captured video can satisfy For the method of preset requirements, all can refer to the description in the previous part about the tracking and capturing method of the target vehicle, and will not be repeated in the embodiments of the device in this part.

Further, on the basis of the contents of the above-mentioned embodiments, the target vehicle tracking and capturing device is provided with a control panel, please refer to FIG. 6, the control panel is provided with: a touch screen for displaying video images, Issue the target vehicle tracking and capturing command at any time; the image adjustment button is used to manually adjust to increase or decrease the area ratio of the target vehicle image in the captured image when triggered.

The road condition image captured by the camera device is displayed on the touch screen. After the user finds an illegal vehicle, he clicks on the illegal vehicle on the display screen to select the target vehicle, which triggers the issuance of the target vehicle tracking and capture command.

When adjusting the area ratio of the target vehicle image in the captured image, the user can manually adjust the image. There are "+" image adjustment button and "-" image adjustment button on the control panel. By triggering the "+" image adjustment button to fine-tune the increase in the area ratio of the target vehicle image, use the "-" image adjustment button to fine-tune Reduce the ratio of the area occupied by the target vehicle image.

The target vehicle tracking and capturing device in this embodiment further includes a communication module, configured to transmit the acquired image to the user's mobile device.

The device transmits the captured images that can clearly reflect illegal vehicle information to the user's mobile device through the communication module. After receiving the vehicle image, the mobile device reads the location information and time information of the mobile device and records them in a text file. Illegal vehicle images and text files with location information and time information are stored in the same folder, so that users can easily obtain images that clearly reflect information such as illegal vehicle license plates, illegal vehicle appearance, and illegal facts. Upload or report images.

During specific implementation, the communication module may be a Bluetooth communication module, which transmits the acquired image to the user's mobile device through Bluetooth communication.

The method and device for tracking and capturing a target vehicle provided by the present invention have been described in detail above. In this paper, specific examples are used to illustrate the principle and implementation of the present invention, and the descriptions of the above embodiments are only used to help understand the method and core idea of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims (10)

1. a kind of target vehicle follows the trail of grasp shoot method, it is characterised in that including：

After the target vehicle issued tracking candid photograph instruction is received, start to shoot video from camera device with prefixed time interval Middle acquisition current frame image, and the extraction target vehicle image from the two field picture of acquisition；

Judge whether target vehicle image meets preset requirement in the two field picture, if so, the two field picture is then preserved, if it is not, then The optical parametric of camera device is adjusted, so that target vehicle image can meet described default in the camera device shoots video It is required that, the preset requirement can clearly reflect target vehicle information for target vehicle image in the picture.

2. target vehicle according to claim 1 follows the trail of grasp shoot method, it is characterised in that also include：When reaching default Between interval time point when, if the optical parametric of the camera device is adjusted, treat the optical parametric of the camera device After the completion of regulation, obtain image from video is shot at once, and calculate by starting point of the acquisition moment acquisition next time image when Between point.

3. target vehicle according to claim 1 or 2 follows the trail of grasp shoot method, it is characterised in that the preset requirement includes The area ratio that the target vehicle image extracted accounts for whole image is located in preset range；

The optical parametric of the regulation camera device, so that target vehicle image can be met in the camera device shoots video The preset requirement includes：

The distance between the camera device zoom group and preceding fixed group are adjusted according to the area ratio, so that in the shooting Device shoots median of the area ratio positioned at the preset range that target vehicle image in video accounts for whole image；

The distance between the camera device compensation group and zoom group are adjusted, so that the camera device is focused；

The aperture size of the camera device is adjusted, so that the video image exposure shot is normal.

4. target vehicle according to claim 3 follows the trail of grasp shoot method, it is characterised in that also include：If the institute extracted State target vehicle image and account for the area ratio of whole image and be located in the preset range, judge the target vehicle that is extracted Image accounts for the area ratio that the area ratio of whole image accounts for whole image relative to the target vehicle image that the last time is extracted Variable quantity whether be more than threshold value；

If so, the distance between the camera device zoom group and preceding fixed group are then adjusted according to the area ratio, so that Camera device shoots median of the area ratio positioned at the preset range that target vehicle image in video accounts for whole image.

5. target vehicle according to claim 3 follows the trail of grasp shoot method, it is characterised in that

The first stepper motor is connected with the zoom group, first stepper motor is used to become according to input pulse regulation is described The distance between times group and described preceding fixed group；

The second stepper motor is connected with the compensation group, second stepper motor is used to adjust the compensation group and the change The distance between organize again.

6. target vehicle according to claim 1 follows the trail of grasp shoot method, it is characterised in that from extracting target from images vehicle Image includes：

The rectangle frame overlapped with image border is set in the picture；

The four edges of rectangle frame are moved in parallel to edge direction simultaneously, in the side first time contact target vehicle of the rectangle frame During the pixel of place, the side stops moving in parallel；

After the four edges of the rectangle frame stop moving in parallel, the mesh extracted is used as using the image in the rectangle frame of acquisition Mark vehicle image.

7. target vehicle according to claim 1 follows the trail of grasp shoot method, it is characterised in that also include：By the image of preservation The mobile device of user is transferred to, mobile device upon receiving the image, reads the location information and time letter of mobile device Cease and recorded with text, and image and record are had into the text files memory of location information and temporal information in identical file In folder.

8. a kind of target vehicle follows the trail of grasp shoot device, it is characterised in that including：

Acquisition module, for receiving after the target vehicle that issues follows the trail of and capture instruction, starts with prefixed time interval from taking the photograph Current frame image is obtained in video as device is shot, and the extraction target vehicle image from the two field picture of acquisition；

Adjustment module, for judging whether target vehicle image meets preset requirement in the two field picture, if so, then preserving the frame Image, if it is not, the optical parametric of camera device is then adjusted, so that the target vehicle image energy in the camera device shoots video The preset requirement is met, the preset requirement can clearly reflect target vehicle information for target vehicle image in the picture.

9. target vehicle according to claim 8 follows the trail of grasp shoot device, it is characterised in that the acquisition module is additionally operable to When reaching prefixed time interval time point, if the optical parametric of the camera device is adjusted, the camera device is treated Optical parametric regulation after the completion of, obtain image from video is shot at once, and calculating is obtained next time by starting point of the acquisition moment Take the time point of image.

10. target vehicle according to claim 8 or claim 9 follows the trail of grasp shoot device, it is characterised in that also including control panel, The control panel is provided with：

Touch display screen, for showing video image, and issues when user touches the target vehicle and follows the trail of and capture instruction；

Image adjustment button, for regulation to increase or reduced target vehicle image in the image of shooting manually when being triggered Area ratio.