CN104537659A - Automatic two-camera calibration method and system - Google Patents

Abstract

The invention provides an automatic two-camera calibration method and system. The method comprises the steps of controlling PTZ cameras for shooting a monitored region according to the preset movement step length in the horizontal direction and the movement step length in the perpendicular direction to obtain PTZ images, and recording shooting parameters needed when each PTZ image is shot, wherein the overlapping region of the previous and later PTZ images shot by the PTZ cameras is larger than the preset overlapping range, and the shooting parameters of the PTZ cameras include the current shooting multiples of the PTZ cameras, movement values of the PTZ cameras in the horizontal direction and movement values of the PTZ cameras in the perpendicular direction; extracting feature points of each PTZ image and feature points of a wide-angle image; matching the feature points of each PTZ image with the feature points of the wide-angle image to obtain a matched pair of each PTZ image and the wide-angle image; according to pixel coordinates of the feature points of the PTZ images and the wide-angle image in the matched pairs, obtaining a mapping relation between the coordinates of the pixel points in the wide-angle image and the shooting parameters of the PTZ cameras. According to the automatic two-camera calibration method and system, the calibration process is simple, and the calibration result is high in accuracy.

Description

The automatic calibration method of twin camera and system

Technical field

The present invention relates to camera calibration technical field, particularly relate to a kind of automatic calibration method of twin camera, and a kind of automatic calibration system of twin camera.

Background technology

Current protection and monitor field to obtain clear monitor video image as monitoring and law enforcement evidence obtaining foundation demand improve constantly; tradition single camera supervisory system directly can not obtain the picture rich in detail of continuous moving target at a distance in large scene; but by manually carrying out feature amplification to the manually zoom of object; this monitor mode can cause the waste of huge manpower, and often can produce the situation that monitor staff fails to report because of fatigue.Therefore the application project cost of existing pair of camera monitoring system is higher, is only applied to special important place, can not be widely used in present city security protection and field of traffic.

Extensively adopt dual camera supervisory system in conventional art, this system has two camera heads, comprises wide angle cameras, i.e. gunlock, and Pan/Tilt/Zoom camera, i.e. ball machine; Wide angle cameras guides ball machine video camera to rotate the position navigating to monitoring target, makes target be placed in the center of PTZ ball machine video camera.PTZ is writing a Chinese character in simplified form of Pan/Tilt/Zoom in safety monitoring application, represents The Cloud Terrace comprehensive (up and down, left and right) and moves and camera lens zoom, Zoom control.The spatial mappings relation of the location of pixels of a fixed cameras and the camera motion of ball machine PTZ is the key that both link.When comparatively large for outdoor large scene engineering calibration difficulty, existing scaling method is more loaded down with trivial details, so the universality of the monitoring of dual camera is low, equipment cost is higher.

In prior art, the method for camera calibration is divided three classes:

One class is calibrated manually, to choose in wide angle picture a pixel as target, write down image coordinate, then control marble forming machine, make the impact point of gunlock be positioned at the center of ball machine picture, pixel each in wide angle picture is calibrated, the gunlock pixel and the ball machine movement position that define supervisory system put mapping table one to one, but more loaded down with trivial details in the process of practical application, particularly under large scene, the process of calibrating one by one is very huge.

One class is geometric maps modelling, it needs enough accurate camera imaging model and environment geometric model, adopt the conversion of multiple reference points zoom and focus parameter model parameter, the accuracy that calibration maps depends on this model parameter accuracy, parametric solution process more complicated, easy generation solves parameter and does not restrain, and cannot ensure the accuracy of calibrating.

Another kind of is data fitting method, by gathering information between the picture element position information of wide-angle and camera motion, employing polynomial approximation solves or least square method carries out obtaining mapping relations, three are adopted to solve Mapping and Converting matrix to the level of above wide-angle gunlock image pixel coordinates and ball machine and vertical height to some least square method in conventional art, the internal reference of video camera is wherein obtained by distortion correction method, wherein three to above be obtained by the employing sift/surf Feature Correspondence Algorithm of image to point, but the maximum problem of the method is produce very large deviation in the texture of the scene that outdoor large scene and texture are more single and a large amount of repeatability, the precision of parametric solution parameter can have influence on the accuracy of calibration, if there is the scene of a lot of similar square and repeated texture to each security protection in whole city and traffic zone guarded region, implement difficulty larger.In addition a kind of is exactly adopt a large amount of off-line datas to carry out calibration process, needs to adopt mass data collection to carry out matching, and calculated amount is larger.

Summary of the invention

Based on this, the invention provides a kind of automatic calibration method and system of twin camera, its calibration process is simple, and the calibration results degree of accuracy is high.

An automatic calibration method for twin camera, comprises the steps:

Control Pan/Tilt/Zoom camera to take described guarded region by the horizontal motion step-length preset and movement in vertical direction step-length, obtain PTZ image, and the acquisition parameters of described Pan/Tilt/Zoom camera when records photographing often opens described PTZ image; Wherein, before and after during Pan/Tilt/Zoom camera shooting, the overlapping region of two PTZ images is greater than default overlapping range; The acquisition parameters of described Pan/Tilt/Zoom camera comprises the current shooting multiple of described Pan/Tilt/Zoom camera, movement value in the horizontal direction and movement value in vertical direction;

Extract the unique point of often opening PTZ image, and extract the unique point of being taken the wide angle picture that described guarded region obtains by wide angle cameras; Wherein, the described unique point of PTZ image and the unique point of wide angle picture are binary features point;

Mate the unique point of described PTZ image and the unique point of described wide angle picture, obtain described PTZ image right with mating of described wide angle picture;

According to described coupling to described in the pixel coordinate of the unique point of PTZ image and the unique point of described wide angle picture, obtain the mapping relations of the coordinate of pixel in described wide angle picture and the acquisition parameters of described Pan/Tilt/Zoom camera.

A kind of automatic calibration system of twin camera, described twin camera comprises wide angle cameras and Pan/Tilt/Zoom camera, and described wide angle cameras shooting guarded region obtains wide angle picture, the acquisition PTZ image of described Pan/Tilt/Zoom camera shooting guarded region, wherein, described system comprises:

Control module, described guarded region is taken by the horizontal motion step-length preset and movement in vertical direction step-length for controlling described Pan/Tilt/Zoom camera, obtain described PTZ image, and the acquisition parameters of described Pan/Tilt/Zoom camera when records photographing often opens described PTZ image; Wherein, before and after during Pan/Tilt/Zoom camera shooting, the overlapping region of two PTZ images is greater than default overlapping range; The acquisition parameters of described Pan/Tilt/Zoom camera comprises the current shooting multiple of described Pan/Tilt/Zoom camera, movement value in the horizontal direction and movement value in vertical direction;

Extraction module, for extracting the unique point of unique point and the described wide angle picture often opening PTZ image; Wherein, the described unique point of PTZ image and the unique point of wide angle picture are binary features point;

Matching module, for the unique point of the unique point and described wide angle picture of mating described PTZ image, obtains described PTZ image right with mating of described wide angle picture;

Mapping relations acquisition module, for according to described coupling to described in the pixel coordinate of the unique point of PTZ image and the unique point of described wide angle picture, obtain the mapping relations of the coordinate of pixel in described wide angle picture and the acquisition parameters of described Pan/Tilt/Zoom camera.

The automatic calibration method of above-mentioned twin camera and system, taking described guarded region by the horizontal motion step-length preset and movement in vertical direction step-length by controlling Pan/Tilt/Zoom camera, obtaining described PTZ image, and recording the acquisition parameters of Pan/Tilt/Zoom camera; Extracting and matching feature points is carried out to described PTZ image and wide angle picture, the Feature Points Matching pair of both acquisitions; According to Feature Points Matching to described in the Feature point correspondence relation of PTZ image and wide angle picture, determine the mapping relations of the coordinate of pixel in described wide angle picture and the acquisition parameters of described Pan/Tilt/Zoom camera; Calibration process of the present invention is simple, Engineering operation is convenient, is extracted and coupling achieves automatic Calibration by image characteristic point, decreases time and the complexity of demarcation; The present invention does not relate to non-geometric parameter model, can ensure the degree of accuracy of calibration result.

Accompanying drawing explanation

Fig. 1 is the automatic calibration method schematic flow sheet in one embodiment of twin camera of the present invention.

Fig. 2 is the automatic calibration system structural representation in one embodiment of twin camera of the present invention.

Embodiment

Below in conjunction with embodiment and accompanying drawing, the present invention is described in further detail, but embodiments of the present invention are not limited thereto.

As shown in Figure 1, be the automatic calibration method schematic flow sheet in the first embodiment of twin camera of the present invention, comprise the steps:

S11, control Pan/Tilt/Zoom camera and by the horizontal motion step-length preset and movement in vertical direction step-length, described guarded region is taken, obtain PTZ image, and the acquisition parameters of described Pan/Tilt/Zoom camera when records photographing often opens described PTZ image; Wherein, before and after during Pan/Tilt/Zoom camera shooting, the overlapping region of two PTZ images is greater than default overlapping range; The acquisition parameters of described Pan/Tilt/Zoom camera comprises the current shooting multiple of described Pan/Tilt/Zoom camera, movement value in the horizontal direction and movement value in vertical direction;

S12, extract and often open the unique point of PTZ image, and extract the unique point of being taken the wide angle picture that described guarded region obtains by wide angle cameras; Wherein, the described unique point of PTZ image and the unique point of wide angle picture are binary features point;

S13, mate the unique point of described PTZ image and the unique point of described wide angle picture, obtain described PTZ image right with mating of described wide angle picture;

S14, according to described coupling to described in the pixel coordinate of the unique point of PTZ image and the unique point of described wide angle picture, obtain the mapping relations of the coordinate of pixel in described wide angle picture and the acquisition parameters of described Pan/Tilt/Zoom camera;

The automatic calibration method of the twin camera of the present embodiment, taking described guarded region by the horizontal motion step-length preset and movement in vertical direction step-length by controlling Pan/Tilt/Zoom camera, obtaining described PTZ image, and recording the acquisition parameters of Pan/Tilt/Zoom camera; Extracting and matching feature points is carried out to described PTZ image and wide angle picture, the Feature Points Matching pair of both acquisitions; According to Feature Points Matching to described in the Feature point correspondence relation of PTZ image and wide angle picture, determine the mapping relations of the coordinate of pixel in described wide angle picture and the acquisition parameters of described Pan/Tilt/Zoom camera; The method calibration process of the present embodiment is simple, Engineering operation is convenient, is extracted and coupling achieves automatic Calibration by image characteristic point, decreases time and the complexity of demarcation; The method of the present embodiment does not relate to non-geometric parameter model, can ensure the degree of accuracy of calibration result.

For S11, control Pan/Tilt/Zoom camera and by the horizontal motion step-length preset and movement in vertical direction step-length, described guarded region is taken, obtain PTZ image, and the acquisition parameters of described Pan/Tilt/Zoom camera when records photographing often opens described PTZ image; Wherein, before and after during Pan/Tilt/Zoom camera shooting, the overlapping region of two PTZ images is greater than default overlapping range; The acquisition parameters of described Pan/Tilt/Zoom camera comprises the current shooting multiple of described Pan/Tilt/Zoom camera, movement value in the horizontal direction and movement value in vertical direction;

In the present embodiment, wide-angle imaging function photographs the wide angle picture of whole guarded region, and Pan/Tilt/Zoom camera then can photograph the partial enlargement image in guarded region; First, horizontal direction and the movement in vertical direction step delta P and Δ T of PTZ can be preset, control Pan/Tilt/Zoom camera samsara shooting on wide angle picture and obtain multiple PTZ images, ensure that last PTZ image and a rear PTZ image ensure to have certain region at least overlapping simultaneously; Such as can be set to the region overlap of rare 1/2, or the region of 2/3 is overlapping, this horizontal motion step-length, movement in vertical direction step-length and overlapping range size preset specifically can set according to actual needs, and the present embodiment does not limit this;

Pan/Tilt/Zoom camera is when taking guarded region, to the acquisition parameters often opening the Pan/Tilt/Zoom camera of its correspondence of PTZ image record generated, described acquisition parameters comprises the current shooting multiple z of described Pan/Tilt/Zoom camera, movement value p in the horizontal direction and movement value t in vertical direction; In the present embodiment, shooting multiple can be fixed value, and movement value p in the horizontal direction and movement value t in vertical direction, the shooting zero-bit of Pan/Tilt/Zoom camera can be preset, position when taking according to Pan/Tilt/Zoom camera and the difference of zero-bit, determine movement value p in the horizontal direction and movement value t in vertical direction.

S12, extract and often open the unique point of PTZ image, and extract the unique point of being taken the wide angle picture that described guarded region obtains by wide angle cameras; Wherein, the described unique point of PTZ image and the unique point of wide angle picture are binary features point;

In the present embodiment, to often opening PTZ image and described wide angle picture carries out feature extraction; The unique point that the present embodiment extracts, available two enter value tag descriptor, but do not limit ORB, BRISK, FREAK etc.; Binary-coded method is adopted to extract descriptor to unique point peripheral region block (patch), Gaussian smoothing can be carried out to patch before extraction feature, can reduce the interference of noise, scale-of-two descriptor is simpler, and storage space calculates also less than SIFT, SURF faster.Such as, ORB feature is utilized to carry out wide angle picture and PTZ image extract minutiae respectively.

S13, mate the unique point of described PTZ image and the unique point of described wide angle picture, obtain described PTZ image right with mating of described wide angle picture;

In the present embodiment, characteristic matching is carried out to the unique point extracted from two width images; Feature interpretation is carried out according to scale-of-two, hamming distance can be adopted, search method (Nearest Neighbor recently, AN) as, FLANN, or approximate KNN is searched (Approximate Nearest Neighbor, ANN), such as K-d tree with BBF, Randomized Kd-trees, Hierarchical K-means Tree, LSH (Locality-Sensitive Hashing) scheduling algorithm carries out preliminary characteristic matching, is not limited to this class methods.Again the point matched is screened, retain correct match point.Conventional method comprises Ransac, obtains mating { (x of wide angle picture and PTZ image ₁, y ₁) _wide..., (x _n, y _n) _wide} _wide{ (x ₁, y ₁) _ptz..., (x _n, y _n) _ptz} _pTZ.

S14, according to described coupling to described in the pixel coordinate of the unique point of PTZ image and the unique point of described wide angle picture, obtain the mapping relations of the coordinate of pixel in described wide angle picture and the acquisition parameters of described Pan/Tilt/Zoom camera;

In the present embodiment, PTZ image includes the unique point of described PTZ image and the unique point of described wide angle picture with the centering of mating of wide angle picture, according to the pixel coordinate of the unique point of two width images, the mapping relations of the coordinate of pixel in described wide angle picture and the acquisition parameters of described Pan/Tilt/Zoom camera can be obtained.

PTZ image is opened to N and repeats above-mentioned calibration process, n can be obtained and tie up mapping relations, when the pixel coordinate of Input Monitor Connector object, then according to the acquisition parameters of Pan/Tilt/Zoom camera corresponding to mapping relationship searching, the partial enlargement image of monitoring target can be obtained.

It is below the second embodiment of the automatic calibration method of twin camera of the present invention, the difference of present embodiment and the first embodiment is, the described Pan/Tilt/Zoom camera of described control is taken described guarded region by the horizontal motion step-length preset and movement in vertical direction step-length, obtain described PTZ image, and when records photographing often opens described PTZ image, the step of the acquisition parameters of described Pan/Tilt/Zoom camera can comprise:

According to the zero-bit of the Pan/Tilt/Zoom camera shooting preset, make four of described wide angle picture vertex positions be positioned at the central point of described Pan/Tilt/Zoom camera shooting, obtain horizontal direction moving range and the vertical direction moving range of described Pan/Tilt/Zoom camera; Wherein, described zero-bit is one of them summit of described wide angle picture;

Control described Pan/Tilt/Zoom camera by the horizontal motion step-length preset and movement in vertical direction step-length, in described horizontal direction moving range and vertical direction moving range, described guarded region is taken, obtain described PTZ image, and the acquisition parameters of described Pan/Tilt/Zoom camera when records photographing often opens described PTZ image; Wherein, described movement value be in the horizontal direction described Pan/Tilt/Zoom camera in the horizontal direction with the difference of described zero-bit, described movement value be in vertical direction described Pan/Tilt/Zoom camera in vertical direction with the difference of described zero-bit;

In the present embodiment, using one of them summit of wide angle picture as zero-bit, such as, can be the left upper apex of wide angle picture, then in image, the value of upper left is minimum, and the value of bottom right is maximum; Concrete, the position of zero-bit can select arbitrary summit of wide angle picture according to actual needs, and the present embodiment does not limit this; Shake Pan/Tilt/Zoom camera, the summit of wide angle picture is made to be positioned at the center of Pan/Tilt/Zoom camera shooting, record Pan/Tilt/Zoom camera when four summits are positioned at the center of Pan/Tilt/Zoom camera shooting and, from zero-bit to the rotation distance of this camera site, obtain horizontal direction frontier point and vertical direction frontier point: P _min, P _max, T _minand T _max, P is herein level shake Pan, T is vertical movement Tilt, obtains horizontal direction moving range and the vertical direction moving range of Pan/Tilt/Zoom camera according to horizontal direction frontier point and vertical direction frontier point;

Then, control described Pan/Tilt/Zoom camera and move in the horizontal direction samsara follow shot guarded region in scope and vertical direction moving range, obtain multiple PTZ images, can take by the horizontal motion step delta P preset and movement in vertical direction step delta T time mobile, the acquisition parameters of described Pan/Tilt/Zoom camera when records photographing often opens described PTZ image; Described movement value be in the horizontal direction described Pan/Tilt/Zoom camera in the horizontal direction with the difference of described zero-bit, described movement value be in vertical direction described Pan/Tilt/Zoom camera in vertical direction with the difference of described zero-bit.

In a preferred embodiment, outdoor scene is existed to the situation of single scene and repeated texture scene, often there will be the situation that characteristic matching centering matched position has relatively large deviation, therefore need to check that coupling is right, it is comparatively large or occur the unique point of matching error to delete error; In the present embodiment, in the unique point of described coupling described PTZ image and the unique point of described wide angle picture, obtain described PTZ image and described wide angle picture mate right step after, also can comprise step:

Described wide angle picture is divided into multiple image block, determines the coordinate range that each image block is corresponding;

According to the movement value in the horizontal direction that described PTZ image is corresponding and the movement value in vertical direction, determine the coordinate range of the image block corresponding with described PTZ image;

Judge that whether the pixel coordinate of the unique point of described coupling centering wide angle picture is corresponding with described coordinate range;

If not corresponding, then judge that described coupling is to wrong and deleted;

In the present embodiment, positional information is introduced to unique point: N number of little image block is divided into wide angle picture, and according to the pixel coordinate of wide angle picture, determine the coordinate range of each little image block; Such as, be 6 little image blocks that the wide angle picture of 300*200 is divided into 3*2 by resolution, then the coordinate range of first image block is: row (0,100) (0 is arranged, 100), the coordinate range of second image block is: row (100,200) row (0,100), by that analogy;

Owing to setting the zero-bit of Pan/Tilt/Zoom camera, then wide angle picture position (x, y) with the motion (p of the horizontal vertical of ball machine, t) be substantially consistent, therefore corresponding according to PTZ image acquisition parameters: the movement value in horizontal direction and the movement value in vertical direction, and the step-length preset, then can determine that PTZ image is corresponding with which image block; Such as, if the acquisition parameters that PTZ image is corresponding is: Pan/Tilt/Zoom camera is mobile 5 steps in the horizontal direction, step-length is 30 pixels, mobile 6 steps in vertical direction, step-length is 10 pixels, therefore can determine that the image block that PTZ image is corresponding should be second image block, and corresponding coordinate range is row (100,200) (0,100) are arranged;

Therefore, the pixel coordinate of the unique point of coupling centering wide angle picture and PTZ image characteristic point, both corresponding relations, the coordinate range of image block that should be corresponding with the above-mentioned PTZ image determined is consistent; Such as, find coupling centering if check, the pixel coordinate of the unique point of the wide angle picture corresponding with PTZ image characteristic point is in the coordinate range of the 3rd image block, then can judge that this coupling is to wrong, should be deleted at once.Wherein, the size and shape of above-mentioned image block can set according to the size of the wide angle picture of reality, and the present embodiment does not limit this, can be preferably the palace lattice that ranks number is equal, is more conducive to improving detection speed.

The present embodiment to wide angle picture partitioned image block, and checks the right process of coupling by above-mentioned, can find out the unique point of matching error rapidly, and then improve the accuracy of demarcating.

In a preferred embodiment, described according to described coupling to described in the pixel coordinate of the unique point of PTZ image and the unique point of described wide angle picture, the step obtaining the mapping relations of the coordinate of pixel in described wide angle picture and the acquisition parameters of described Pan/Tilt/Zoom camera comprises:

To the { (x of described coupling centering ₁, y ₁) _ptz..., (x _n, y _n) _ptz} _pTZ{ (x ₁, y ₁) _wide..., (x _n, y _n) _wide} _wide, calculate the unique point (x nearest apart from the central point of described PTZ image _r, y _r) _ptz, calculate the central point (x apart from described wide angle picture _r, y _r) _widenearest unique point; Wherein, described { (x ₁, y ₁) _ptz..., (x _n, y _n) _ptz} _pTZfor the unique point of described coupling centering PTZ image; Described { (x ₁, y ₁) _wide..., (x _n, y _n) _wide} _widefor the unique point of described coupling centering wide angle picture, (x _n, y _n) be pixel coordinate;

According to (x _r, y _r) _ptzthe acquisition parameters of corresponding Pan/Tilt/Zoom camera, obtains described mapping relations (x _r, y _r, p, t, z); Wherein, p, t, z are the acquisition parameters of described Pan/Tilt/Zoom camera;

In the present embodiment, for often opening PTZ image and wide angle picture, there is corresponding coupling to (comprising the unique point of described PTZ image and the unique point of described wide angle picture); In the present embodiment, the unique point (x nearest apart from the central point of described PTZ image can be calculated _r, y _r) _ptz, calculate the central point (x apart from described wide angle picture _r, y _r) _widenearest unique point, this distance can adopt Euclidean distance method to calculate; Afterwards according to the (x in PTZ image _r, y _r) _ptz, (the x in wide angle picture _r, y _r) _wide, these mapping relations (x can be obtained _r, y _r, p, t, z), i.e. the corresponding relation of the coordinate of pixel and the acquisition parameters of described Pan/Tilt/Zoom camera in described wide angle picture.

Taken by the samsara of Pan/Tilt/Zoom camera, constantly obtain PTZ image, and automatically can obtain mapping relations; To the mapping relations obtained, also after running up to some, statistical analysis technique can be adopted, such as, adopt the average in calculating mapping relations and variance, mapping relations larger for variance are deleted, thus reduce error, improve the degree of accuracy of demarcating.

In a preferred embodiment, for the monitoring point do not comprised in mapping relations, linear interpolation method can be adopted to obtain the corresponding PTZ value of this point; Can comprise the steps:

Obtain pixel to be monitored;

When not comprising pixel to be monitored in described mapping relations, calculate the acquisition parameters of Pan/Tilt/Zoom camera corresponding to described pixel to be monitored according to following formula:

$\left\{\begin{array}{cc}{p}_0=p_{\mathrm{nl}}+\frac{x_0-x_{\mathrm{nl}}}{x_{\mathrm{nr}}-x_{\mathrm{nl}}}*(p_{\mathrm{nr}}-p_{\mathrm{nl}}),& x_{\mathrm{nl}}<x_0<x_{\mathrm{nr}},\\ t_0=t_{\mathrm{nl}}+\frac{y_0-y_{\mathrm{nl}}}{y_{\mathrm{nr}}-y_{\mathrm{nl}}}*(t_{\mathrm{nr}}-t_{\mathrm{nl}}),& y_{\mathrm{nl}}<y_0<y_{\mathrm{nr}},\end{array}\right.$

Wherein, (x ₀, y ₀) _widefor described pixel to be monitored, (x _nr, y _nr) _wide(x _nl, y _nl) _widefor two pixels that pixel to be monitored described in described mapping relations middle distance is nearest.

As shown in Figure 2, it is the automatic calibration system structural representation in the first embodiment of a kind of twin camera of the present invention, described twin camera comprises wide angle cameras and Pan/Tilt/Zoom camera, described wide angle cameras shooting guarded region obtains wide angle picture, described Pan/Tilt/Zoom camera shooting guarded region obtains PTZ image, and described system comprises:

Control module 21, described guarded region is taken by the horizontal motion step-length preset and movement in vertical direction step-length for controlling described Pan/Tilt/Zoom camera, obtain described PTZ image, and the acquisition parameters of described Pan/Tilt/Zoom camera when records photographing often opens described PTZ image; Wherein, before and after during Pan/Tilt/Zoom camera shooting, the overlapping region of two PTZ images is greater than default overlapping range; The acquisition parameters of described Pan/Tilt/Zoom camera comprises the current shooting multiple of described Pan/Tilt/Zoom camera, movement value in the horizontal direction and movement value in vertical direction;

Extraction module 22, for extracting the unique point of unique point and the described wide angle picture often opening PTZ image; Wherein, the described unique point of PTZ image and the unique point of wide angle picture are binary features point;

Matching module 23, for the unique point of the unique point and described wide angle picture of mating described PTZ image, obtains described PTZ image right with mating of described wide angle picture;

Mapping relations acquisition module 24, for according to described coupling to described in the pixel coordinate of the unique point of PTZ image and the unique point of described wide angle picture, obtain the mapping relations of the coordinate of pixel in described wide angle picture and the acquisition parameters of described Pan/Tilt/Zoom camera;

The automatic calibration system of the twin camera of the present embodiment, taking described guarded region by the horizontal motion step-length preset and movement in vertical direction step-length by controlling Pan/Tilt/Zoom camera, obtaining described PTZ image, and recording the acquisition parameters of Pan/Tilt/Zoom camera; Extracting and matching feature points is carried out to described PTZ image and wide angle picture, the Feature Points Matching pair of both acquisitions; According to Feature Points Matching to described in the Feature point correspondence relation of PTZ image and wide angle picture, determine the mapping relations of the coordinate of pixel in described wide angle picture and the acquisition parameters of described Pan/Tilt/Zoom camera; The present embodiment calibration process is simple, Engineering operation is convenient, is extracted and coupling achieves automatic Calibration by image characteristic point, decreases time and the complexity of demarcation; The present embodiment does not relate to non-geometric parameter model, can ensure the degree of accuracy of calibration result.

For control module 21, described guarded region is taken by the horizontal motion step-length preset and movement in vertical direction step-length for controlling described Pan/Tilt/Zoom camera, obtain described PTZ image, and the acquisition parameters of described Pan/Tilt/Zoom camera when records photographing often opens described PTZ image; Wherein, before and after during Pan/Tilt/Zoom camera shooting, the overlapping region of two PTZ images is greater than default overlapping range; The acquisition parameters of described Pan/Tilt/Zoom camera comprises the current shooting multiple of described Pan/Tilt/Zoom camera, movement value in the horizontal direction and movement value in vertical direction;

In the present embodiment, wide-angle imaging function photographs the wide angle picture of whole guarded region, and Pan/Tilt/Zoom camera then can photograph the partial enlargement image in guarded region; First, horizontal direction and the movement in vertical direction step delta P and Δ T of PTZ can be preset, control Pan/Tilt/Zoom camera samsara shooting on wide angle picture and obtain multiple PTZ images, ensure that last PTZ image and a rear PTZ image ensure to have certain region at least overlapping simultaneously; Such as can be set to the region overlap of rare 1/2, or the region of 1/3 is overlapping, this horizontal motion step-length, movement in vertical direction step-length and overlapping range size preset specifically can set according to actual needs, and the present embodiment does not limit this;

Pan/Tilt/Zoom camera is when taking guarded region, to the acquisition parameters often opening the Pan/Tilt/Zoom camera of its correspondence of PTZ image record generated, described acquisition parameters comprises the current shooting multiple z of described Pan/Tilt/Zoom camera, movement value p in the horizontal direction and movement value t in vertical direction; In the present embodiment, shooting multiple can be fixed value, and movement value p in the horizontal direction and movement value t in vertical direction, the shooting zero-bit of Pan/Tilt/Zoom camera can be preset, position when taking according to Pan/Tilt/Zoom camera and the difference of zero-bit, determine movement value p in the horizontal direction and movement value t in vertical direction.

For extraction module 22, for extracting the unique point of unique point and the described wide angle picture often opening PTZ image; Wherein, the described unique point of PTZ image and the unique point of wide angle picture are binary features point;

In the present embodiment, to often opening PTZ image and described wide angle picture carries out feature extraction; The unique point that the present embodiment extracts, available two enter value tag descriptor, but do not limit ORB, BRISK, FREAK etc.; Binary-coded method is adopted to extract descriptor to unique point peripheral region block (patch), Gaussian smoothing can be carried out to patch before extraction feature, can reduce the interference of noise, scale-of-two descriptor is simpler, and storage space calculates also less than SIFT, SURF faster.Such as, ORB feature is utilized to carry out wide angle picture and PTZ image extract minutiae respectively.

For matching module 23, for the unique point of the unique point and described wide angle picture of mating described PTZ image, obtain described PTZ image right with mating of described wide angle picture;

In the present embodiment, characteristic matching is carried out to the unique point extracted from two width images; Feature interpretation is carried out according to scale-of-two, hamming distance can be adopted, search method (Nearest Neighbor recently, AN) as FLann, or approximate KNN is searched (Approximate Nearest Neighbor, ANN), such as K-dtree with BBF, Randomized Kd-trees, Hierarchical K-means Tree, LSH (Locality-Sensitive Hashing) scheduling algorithm carries out preliminary characteristic matching, is not limited to this class methods.Again the point matched is screened, retain correct match point.Conventional method comprises Ransac, obtains mating { (x of wide angle picture and PTZ image ₁, y ₁) _wide..., (x _n, y _n) _wide} _wide{ (x ₁, y ₁) _ptz..., (x _n, y _n) _ptz} _pTZ.

For mapping relations acquisition module 24, for according to described coupling to described in the pixel coordinate of the unique point of PTZ image and the unique point of described wide angle picture, obtain the mapping relations of the coordinate of pixel in described wide angle picture and the acquisition parameters of described Pan/Tilt/Zoom camera;

In the present embodiment, PTZ image includes the unique point of described PTZ image and the unique point of described wide angle picture with the centering of mating of wide angle picture, according to the pixel coordinate of the unique point of two width images, the mapping relations of the coordinate of pixel in described wide angle picture and the acquisition parameters of described Pan/Tilt/Zoom camera can be obtained.

PTZ image is opened to N and repeats above-mentioned calibration process, n can be obtained and tie up mapping relations, when the pixel coordinate of Input Monitor Connector object, then according to the acquisition parameters of Pan/Tilt/Zoom camera corresponding to mapping relationship searching, the partial enlargement image of monitoring target can be obtained.

Be below the second embodiment of the automatic calibration system of twin camera of the present invention, the difference of present embodiment and the first embodiment is, described control module 21 also comprises:

Moving range acquisition module, for the zero-bit according to the Pan/Tilt/Zoom camera shooting preset, make four of described wide angle picture vertex positions be positioned at the central point of described Pan/Tilt/Zoom camera shooting, obtain horizontal direction moving range and the vertical direction moving range of described Pan/Tilt/Zoom camera; Wherein, described zero-bit is one of them summit of described wide angle picture;

Shooting control module, for controlling described Pan/Tilt/Zoom camera by the horizontal motion step-length preset and movement in vertical direction step-length, in described horizontal direction moving range and vertical direction moving range, described guarded region is taken, obtain described PTZ image, and the acquisition parameters of described Pan/Tilt/Zoom camera when records photographing often opens described PTZ image; Wherein, described movement value be in the horizontal direction described Pan/Tilt/Zoom camera in the horizontal direction with the difference of described zero-bit, described movement value be in vertical direction described Pan/Tilt/Zoom camera in vertical direction with the difference of described zero-bit;

In the present embodiment, using one of them summit of wide angle picture as zero-bit, such as, can be the left upper apex of wide angle picture, then in image, the value of upper left is minimum, and the value of bottom right is maximum; Shake Pan/Tilt/Zoom camera, the summit of wide angle picture is made to be positioned at the center of Pan/Tilt/Zoom camera shooting, record Pan/Tilt/Zoom camera when four summits are positioned at the center of Pan/Tilt/Zoom camera shooting and, from zero-bit to the rotation distance of this camera site, obtain horizontal direction frontier point and vertical direction frontier point: P _min, P _max, T _minand T _max, P is herein level shake Pan, T is vertical movement Tilt, obtains horizontal direction moving range and the vertical direction moving range of Pan/Tilt/Zoom camera according to horizontal direction frontier point and vertical direction frontier point;

Then, control described Pan/Tilt/Zoom camera and move in the horizontal direction samsara follow shot guarded region in scope and vertical direction moving range, obtain multiple PTZ images, can take by the horizontal motion step delta P preset and movement in vertical direction step delta T time mobile, the acquisition parameters of described Pan/Tilt/Zoom camera when records photographing often opens described PTZ image; Described movement value be in the horizontal direction described Pan/Tilt/Zoom camera in the horizontal direction with the difference of described zero-bit, described movement value be in vertical direction described Pan/Tilt/Zoom camera in vertical direction with the difference of described zero-bit.

In a preferred embodiment, outdoor scene is existed to the situation of single scene and repeated texture scene, often there will be the situation that characteristic matching centering matched position has relatively large deviation, therefore need to check that coupling is right, it is comparatively large or occur the unique point of matching error to delete error; Therefore, the system of the present embodiment also can comprise:

Divide module, for described wide angle picture is divided into multiple image block, determine the coordinate range that each image block is corresponding;

Coordinate range determination module, the movement value in the horizontal direction corresponding according to described PTZ image and the movement value in vertical direction, determine the coordinate range of the image block corresponding with described PTZ image;

Judge module, whether the pixel coordinate for the unique point judging described coupling centering wide angle picture is corresponding with described coordinate range;

Removing module, if for not corresponding, then judges that described coupling is to wrong and deleted;

In the present embodiment, positional information is introduced to unique point: N number of little image block is divided into wide angle picture, and according to the pixel coordinate of wide angle picture, determine the coordinate range of each little image block; Such as, be 6 little image blocks that the wide angle picture of 300*200 is divided into 3*2 by resolution, then the coordinate range of first image block is: row (0,100) (0 is arranged, 100), the coordinate range of second image block is: row (100,200) row (0,100), by that analogy;

Owing to setting the zero-bit of Pan/Tilt/Zoom camera, then wide angle picture position (x, y) with the motion (p of the horizontal vertical of ball machine, t) be substantially consistent, therefore corresponding according to PTZ image acquisition parameters: the movement value in horizontal direction and the movement value in vertical direction, and the step-length preset, then can determine that PTZ image is corresponding with which image block; Such as, if the acquisition parameters that PTZ image is corresponding is: Pan/Tilt/Zoom camera is mobile 5 steps in the horizontal direction, step-length is 30 pixels, mobile 6 steps in vertical direction, step-length is 10 pixels, therefore can determine that the image block that PTZ image is corresponding should be second image block, and corresponding coordinate range is row (100,200) (0,100) are arranged;

Therefore, the pixel coordinate of the unique point of coupling centering wide angle picture and PTZ image characteristic point, both corresponding relations, the coordinate range of image block that should be corresponding with the above-mentioned PTZ image determined is consistent; Such as, find coupling centering if check, the pixel coordinate of the unique point of the wide angle picture corresponding with PTZ image characteristic point is in the coordinate range of the 3rd image block, then can judge that this coupling is to wrong, should be deleted at once.Wherein, the size and shape of above-mentioned image block can set according to the size of the wide angle picture of reality, and the present embodiment does not limit this, can be preferably the palace lattice that ranks number is equal, is more conducive to improving detection speed.

The present embodiment to wide angle picture partitioned image block, and checks the right process of coupling by above-mentioned, can find out the unique point of matching error rapidly, and then improve the accuracy of demarcating.

In a preferred embodiment, described mapping relations acquisition module 24 also can be used for: to the { (x of described coupling centering ₁, y ₁) _ptz..., (x _n, y _n) _ptz} _pTZ{ (x ₁, y ₁) _wide..., (x _n, y _n) _wide} _wide, calculate the unique point (x nearest apart from the central point of described PTZ image _r, y _r) _ptz, calculate the central point (x apart from described wide angle picture _r, y _r) _widenearest unique point; Wherein, described { (x ₁, y ₁) _ptz..., (x _n, y _n) _ptz} _pTZfor the unique point of described coupling centering PTZ image; Described { (x ₁, y ₁) _wide..., (x _n, y _n) _wide} _widefor the unique point of described coupling centering wide angle picture, (x _n, y _n) be pixel coordinate; According to (x _r, y _r) _ptzthe acquisition parameters of corresponding Pan/Tilt/Zoom camera, obtains described mapping relations (x _r, y _r, p, t, z); Wherein, p, t, z are the acquisition parameters of described Pan/Tilt/Zoom camera;

In the present embodiment, for often opening PTZ image and wide angle picture, there is corresponding coupling to (comprising the unique point of described PTZ image and the unique point of described wide angle picture); In the present embodiment, the unique point (x nearest apart from the central point of described PTZ image can be calculated _r, y _r) _ptz, calculate the central point (x apart from described wide angle picture _r, y _r) _widenearest unique point, this distance can adopt Euclidean distance method to calculate; Afterwards according to the (x in PTZ image _r, y _r) _ptz, (the x in wide angle picture _r, y _r) _wide, these mapping relations (x can be obtained _r, y _r, p, t, z), i.e. the mapping relations of the coordinate of pixel and the acquisition parameters of described Pan/Tilt/Zoom camera in described wide angle picture.

Taken by the samsara of Pan/Tilt/Zoom camera, constantly obtain PTZ image, and automatically can obtain mapping relations; To the mapping relations obtained, also after running up to some, statistical analysis technique can be adopted, such as, adopt the average in calculating mapping relations and variance, mapping relations larger for variance are deleted, thus reduce error, improve the degree of accuracy of demarcating.

In a preferred embodiment, for the monitoring point do not comprised in mapping relations, linear interpolation method can be adopted to obtain the corresponding PTZ value of this point; The system of the present embodiment also can comprise:

Acquisition module, for obtaining pixel to be monitored;

Parameter calculating module, for when not comprising pixel to be monitored in described mapping relations, calculates the acquisition parameters of Pan/Tilt/Zoom camera corresponding to described pixel to be monitored according to following formula:

$\left\{\begin{array}{cc}{p}_0=p_{\mathrm{nl}}+\frac{x_0-x_{\mathrm{nl}}}{x_{\mathrm{nr}}-x_{\mathrm{nl}}}*(p_{\mathrm{nr}}-p_{\mathrm{nl}}),& x_{\mathrm{nl}}<x_0<x_{\mathrm{nr}},\\ t_0=t_{\mathrm{nl}}+\frac{y_0-y_{\mathrm{nl}}}{y_{\mathrm{nr}}-y_{\mathrm{nl}}}*(t_{\mathrm{nr}}-t_{\mathrm{nl}}),& y_{\mathrm{nl}}<y_0<y_{\mathrm{nr}},\end{array}\right.$

Wherein, (x ₀, y ₀) _widefor described pixel to be monitored, (x _nr, y _nr) _wide(x _nl, y _nl) _widefor two pixels that pixel to be monitored described in described mapping relations middle distance is nearest.

The automatic calibration method of twin camera of the present invention and system, described guarded region is taken by the horizontal motion step-length preset and movement in vertical direction step-length by controlling Pan/Tilt/Zoom camera, obtain described PTZ image, and record the acquisition parameters of Pan/Tilt/Zoom camera; Extracting and matching feature points is carried out to described PTZ image and wide angle picture, the Feature Points Matching pair of both acquisitions; According to Feature Points Matching to described in the Feature point correspondence relation of PTZ image and wide angle picture, determine the mapping relations of the coordinate of pixel in described wide angle picture and the acquisition parameters of described Pan/Tilt/Zoom camera; The present embodiment calibration process is simple, Engineering operation is convenient, is extracted and coupling achieves automatic Calibration by image characteristic point, decreases time and the complexity of demarcation; The present embodiment does not relate to non-geometric parameter model, can ensure the degree of accuracy of calibration result.

The above embodiment only have expressed several embodiment of the present invention, and it describes comparatively concrete and detailed, but therefore can not be interpreted as the restriction to the scope of the claims of the present invention.It should be pointed out that for the person of ordinary skill of the art, without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection domain of patent of the present invention should be as the criterion with claims.

Claims (10)

1. an automatic calibration method for twin camera, is characterized in that, comprises the steps:

Control Pan/Tilt/Zoom camera to take described guarded region by the horizontal motion step-length preset and movement in vertical direction step-length, obtain PTZ image, and the acquisition parameters of described Pan/Tilt/Zoom camera when records photographing often opens described PTZ image; Wherein, before and after during Pan/Tilt/Zoom camera shooting, the overlapping region of two PTZ images is greater than default overlapping range; The acquisition parameters of described Pan/Tilt/Zoom camera comprises the current shooting multiple of described Pan/Tilt/Zoom camera, movement value in the horizontal direction and movement value in vertical direction;

Extract the unique point of often opening PTZ image, and extract the unique point of being taken the wide angle picture that described guarded region obtains by wide angle cameras; Wherein, the described unique point of PTZ image and the unique point of wide angle picture are binary features point;

Mate the unique point of described PTZ image and the unique point of described wide angle picture, obtain described PTZ image right with mating of described wide angle picture;

According to described coupling to described in the pixel coordinate of the unique point of PTZ image and the unique point of described wide angle picture, obtain the mapping relations of the coordinate of pixel in described wide angle picture and the acquisition parameters of described Pan/Tilt/Zoom camera.

2. the automatic calibration method of twin camera according to claim 1, it is characterized in that, the described Pan/Tilt/Zoom camera of described control is taken described guarded region by the horizontal motion step-length preset and movement in vertical direction step-length, obtain described PTZ image, and when records photographing often opens described PTZ image, the step of the acquisition parameters of described Pan/Tilt/Zoom camera comprises:

According to the zero-bit of the Pan/Tilt/Zoom camera shooting preset, make four of described wide angle picture vertex positions be positioned at the central point of described Pan/Tilt/Zoom camera shooting, obtain horizontal direction moving range and the vertical direction moving range of described Pan/Tilt/Zoom camera; Wherein, described zero-bit is one of them summit of described wide angle picture;

Control described Pan/Tilt/Zoom camera by the horizontal motion step-length preset and movement in vertical direction step-length, in described horizontal direction moving range and vertical direction moving range, described guarded region is taken, obtain described PTZ image, and the acquisition parameters of described Pan/Tilt/Zoom camera when records photographing often opens described PTZ image; Wherein, described movement value be in the horizontal direction described Pan/Tilt/Zoom camera in the horizontal direction with the difference of described zero-bit, described movement value be in vertical direction described Pan/Tilt/Zoom camera in vertical direction with the difference of described zero-bit.

3. the automatic calibration method of twin camera according to claim 2, it is characterized in that, in the unique point of described coupling described PTZ image and the unique point of described wide angle picture, obtain described PTZ image and described wide angle picture mate right step after, also comprise step:

Described wide angle picture is divided into multiple image block, determines the coordinate range that each image block is corresponding;

According to the movement value in the horizontal direction that described PTZ image is corresponding and the movement value in vertical direction, determine the coordinate range of the image block corresponding with described PTZ image;

Judge that whether the pixel coordinate of the unique point of described coupling centering wide angle picture is corresponding with described coordinate range;

If not corresponding, then judge that described coupling is to wrong and deleted.

4. the automatic calibration method of the twin camera according to Claims 2 or 3, it is characterized in that, described according to described coupling to described in the pixel coordinate of the unique point of PTZ image and the unique point of described wide angle picture, the step obtaining the mapping relations of the coordinate of pixel in described wide angle picture and the acquisition parameters of described Pan/Tilt/Zoom camera comprises:

To the { (x of described coupling centering ₁, y ₁) _ptz..., (x _n, y _n) _ptz} _pTZ{ (x ₁, y ₁) _wide..., (x _n, y _n) _wide} _wide, calculate the unique point (x nearest apart from the central point of described PTZ image _r, y _r) _ptz, calculate the central point (x apart from described wide angle picture _r, y _r) _widenearest unique point; Wherein, described { (x ₁, y ₁) _ptz..., (x _n, y _n) _ptz} _pTZfor the unique point of described coupling centering PTZ image; Described { (x ₁, y ₁) _wide..., (x _n, y _n) _wide} _widefor the unique point of described coupling centering wide angle picture, (x _n, y _n) be pixel coordinate;

According to (x _r, y _r) _ptzthe acquisition parameters of corresponding Pan/Tilt/Zoom camera, obtains described mapping relations (x _r, y _r, p, t, z); Wherein, p, t, z are the acquisition parameters of described Pan/Tilt/Zoom camera.

5. the automatic calibration method of twin camera according to claim 4, is characterized in that, also comprises step:

Obtain pixel to be monitored;

When not comprising pixel to be monitored in described mapping relations, calculate the acquisition parameters of Pan/Tilt/Zoom camera corresponding to described pixel to be monitored according to following formula:

$\left\{\begin{array}{cc}{p}_0=p_{\mathrm{nl}}+\frac{x_0-x_{\mathrm{nl}}}{x_{\mathrm{nr}}-x_{\mathrm{nl}}}*(p_{\mathrm{nr}}-p_{\mathrm{nl}}),& x_{\mathrm{nl}}<x_0<x_{\mathrm{nr}},\\ t_0=t_{\mathrm{nl}}+\frac{y_0-y_{\mathrm{nl}}}{y_{\mathrm{nr}}-y_{\mathrm{nl}}}*(t_{\mathrm{nr}}-t_{\mathrm{nl}}),& y_{\mathrm{nl}}<y_0<y_{\mathrm{nr}},\end{array}\right.$

Wherein, (x ₀, y ₀) _widefor described pixel to be monitored, (x _nr, y _nr) _wide(x _nl, y _nl) _widefor two pixels that pixel to be monitored described in described mapping relations middle distance is nearest.

6. the automatic calibration system of a twin camera, described twin camera comprises wide angle cameras and Pan/Tilt/Zoom camera, and described wide angle cameras shooting guarded region obtains wide angle picture, and described Pan/Tilt/Zoom camera shooting guarded region obtains PTZ image, it is characterized in that, described system comprises:

Control module, described guarded region is taken by the horizontal motion step-length preset and movement in vertical direction step-length for controlling described Pan/Tilt/Zoom camera, obtain described PTZ image, and the acquisition parameters of described Pan/Tilt/Zoom camera when records photographing often opens described PTZ image; Wherein, before and after during Pan/Tilt/Zoom camera shooting, the overlapping region of two PTZ images is greater than default overlapping range; The acquisition parameters of described Pan/Tilt/Zoom camera comprises the current shooting multiple of described Pan/Tilt/Zoom camera, movement value in the horizontal direction and movement value in vertical direction;

Extraction module, for extracting the unique point of unique point and the described wide angle picture often opening PTZ image; Wherein, the described unique point of PTZ image and the unique point of wide angle picture are binary features point;

Matching module, for the unique point of the unique point and described wide angle picture of mating described PTZ image, obtains described PTZ image right with mating of described wide angle picture;

Mapping relations acquisition module, for according to described coupling to described in the pixel coordinate of the unique point of PTZ image and the unique point of described wide angle picture, obtain the mapping relations of the coordinate of pixel in described wide angle picture and the acquisition parameters of described Pan/Tilt/Zoom camera.

7. the automatic calibration system of twin camera according to claim 6, is characterized in that, described control module also comprises:

Moving range acquisition module, for the zero-bit according to the Pan/Tilt/Zoom camera shooting preset, make four of described wide angle picture vertex positions be positioned at the central point of described Pan/Tilt/Zoom camera shooting, obtain horizontal direction moving range and the vertical direction moving range of described Pan/Tilt/Zoom camera; Wherein, described zero-bit is one of them summit of described wide angle picture;

Shooting control module, for controlling described Pan/Tilt/Zoom camera by the horizontal motion step-length preset and movement in vertical direction step-length, in described horizontal direction moving range and vertical direction moving range, described guarded region is taken, obtain described PTZ image, and the acquisition parameters of described Pan/Tilt/Zoom camera when records photographing often opens described PTZ image; Wherein, described movement value be in the horizontal direction described Pan/Tilt/Zoom camera in the horizontal direction with the difference of described zero-bit, described movement value be in vertical direction described Pan/Tilt/Zoom camera in vertical direction with the difference of described zero-bit.

8. the automatic calibration system of twin camera according to claim 7, is characterized in that, also comprises:

Divide module, for described wide angle picture is divided into multiple image block, determine the coordinate range that each image block is corresponding;

Coordinate range determination module, the movement value in the horizontal direction corresponding according to described PTZ image and the movement value in vertical direction, determine the coordinate range of the image block corresponding with described PTZ image;

Judge module, whether the pixel coordinate for the unique point judging described coupling centering wide angle picture is corresponding with described coordinate range;

Removing module, if for not corresponding, then judges that described coupling is to wrong and deleted.

9. the automatic calibration system of the twin camera according to claim 7 or 8, is characterized in that, described mapping relations acquisition module also for: to described coupling centering { (x ₁, y ₁) _ptz..., (x _n, y _n) _ptz} _pTZ{ (x ₁, y ₁) _wide..., (x _n, y _n) _wide} _wide, calculate the unique point (x nearest apart from the central point of described PTZ image _r, y _r) _ptz, calculate the central point (x apart from described wide angle picture _r, y _r) _widenearest unique point; Wherein, described { (x ₁, y ₁) _ptz..., (x _n, y _n) _ptz} _pTZfor the unique point of described coupling centering PTZ image; Described { (x ₁, y ₁) _wide..., (x _n, y _n) _wide} _widefor the unique point of described coupling centering wide angle picture, (x _n, y _n) be pixel coordinate; According to (x _r, y _r) _ptzthe acquisition parameters of corresponding Pan/Tilt/Zoom camera, obtains described mapping relations (x _r, y _r, p, t, z); Wherein, p, t, z are the acquisition parameters of described Pan/Tilt/Zoom camera.

10. the automatic calibration system of twin camera according to claim 9, is characterized in that, also comprises:

Acquisition module, for obtaining pixel to be monitored;

Parameter calculating module, for when not comprising pixel to be monitored in described mapping relations, calculates the acquisition parameters of Pan/Tilt/Zoom camera corresponding to described pixel to be monitored according to following formula:

$\left\{\begin{array}{cc}{p}_0=p_{\mathrm{nl}}+\frac{x_0-x_{\mathrm{nl}}}{x_{\mathrm{nr}}-x_{\mathrm{nl}}}*(p_{\mathrm{nr}}-p_{\mathrm{nl}}),& x_{\mathrm{nl}}<x_0<x_{\mathrm{nr}},\\ t_0=t_{\mathrm{nl}}+\frac{y_0-y_{\mathrm{nl}}}{y_{\mathrm{nr}}-y_{\mathrm{nl}}}*(t_{\mathrm{nr}}-t_{\mathrm{nl}}),& y_{\mathrm{nl}}<y_0<y_{\mathrm{nr}},\end{array}\right.$

Wherein, (x ₀, y ₀) _widefor described pixel to be monitored, (x _nr, y _nr) _wide(x _nl, y _nl) _widefor two pixels that pixel to be monitored described in described mapping relations middle distance is nearest.