CN104182969A

CN104182969A - Internal and external parameter calibration method of single-scanline camera

Info

Publication number: CN104182969A
Application number: CN201410387553.7A
Authority: CN
Inventors: 梁灵飞
Original assignee: Henan University of Science and Technology
Current assignee: Henan University of Science and Technology
Priority date: 2014-08-08
Filing date: 2014-08-08
Publication date: 2014-12-03
Anticipated expiration: 2034-08-08
Also published as: CN104182969B

Abstract

A method for calibrating internal and external parameters of a single-line array camera relates to a calculation method for internal and external parameters of a single-line array camera. According to the internal product of the rotation parameter matrix in the external parameter matrix equal to two, the method deduces the relationship between the parameters in the internal parameters and the parameters in the homography matrix, Establish a constraint equation, use the target point coordinates (X, Y, Z) of the calibration board to the imaging point coordinates (u), find out the homography matrix from multiple target points to the output point, substitute into the constraint equation, and then calculate the single line array camera internal and external parameters.

Description

A kind of single line array camera inside and outside parameter scaling method

Technical field

The invention belongs to camera calibration field, relate to a kind of single line array camera inside and outside parameter scaling method.

Background technology

The demarcation of video camera is three-dimensional geometry position and its mutual relationship between corresponding point in image of determining certain point of space object surface.That the image coordinate of being put by known features and world coordinates solve the parameter model of video camera according to the geometric model of the video camera imaging of setting up.Camera calibration is unusual the key link, and the precision of its calibration result and the stability of algorithm are by the accuracy that directly affects video camera work and bear results.Therefore, improving camera calibration precision is the emphasis of camera calibration.

The report that relevant line-scan digital camera is demarcated is less.Can only imaging a line due to the each imaging of single line array camera, single line battle array imaging model is different from traditional area array cameras imaging model, causes the inside and outside parameter computing method that are applicable to area array cameras not to be suitable for single line array camera.Existing single line array camera inside and outside parameter equation of constraint is more complicated, need to ask its a plurality of impact points just can ask for a plurality of unknown parameters in equation of constraint to going out corner homography matrix.Therefore, according to the imaging model of single line array camera, set up simple and effective equation of constraint, be reduced to picture number of times, there is real researching value and actual application value.

Summary of the invention

The object of this invention is to provide a kind of single line array camera inside and outside parameter scaling method, the method equals two according to rotation parameter matrix inner product in outer parameter matrix, derive in intrinsic parameter contacting of parameter in parameter and homography matrix, set up equation of constraint, utilize scaling board coordinate of ground point (X, Y, Z) to imaging point coordinate (u), obtain a plurality of impact points to going out corner homography matrix, substitution equation of constraint, and then calculate the inside and outside parameter of single line array camera.

For achieving the above object, a kind of single line array camera inside and outside parameter scaling method, the step of the method is as follows:

Step 1, according to area array cameras imaging model, derive single line array camera imaging model, obtain homography matrix H model

Step 2, according to single line array camera imaging model, derive Intrinsic Matrix A and the outer parameter matrix of single line array camera ;

Step 3, according to rotation parameter matrix inner product in outer parameter matrix, equal two, derive in intrinsic parameter A contacting of parameter in parameter and homography matrix H ;

Step 4, calculating matrix, and establish B ₁₁, B ₁₂, B ₂₂replace parameter in matrix, substitution , obtain ;

Step 5, choose 3 above scaling board coordinate of ground points (X, Y, Z) to imaging point coordinate (u), calculate 3 above H matrixes, substitution formula, uses least square method to obtain B ₁₁, B ₁₂, B ₂₂value.

Step 6, according to B ₁₁, B ₁₂, B ₂₂calculate Intrinsic Matrix A, then Intrinsic Matrix A, appoint and get a H matrix obtaining, calculate outer parameter matrix ;

In described step (11), the derivation of homography matrix H model is as follows:

Step 1, area array cameras imaging model

Step 2, can only imaging a line due to each imaging of single line array camera, therefore according to area array cameras imaging model, can obtain

Step 3, backstepping again, can obtain

, ,

Therefore .

The invention has the beneficial effects as follows: the computing method of single line array camera inside and outside parameter of the present invention, the inner link in the line-scan digital camera imaging model rotation matrix that employing the present invention releases , and the symmetric matrix forming, forms the equation that transfinites .As long as choose 3 above scaling board coordinate of ground points (X, Y, Z) to imaging point coordinate (u), just can obtain 3 H matrixes above, set up three equations, ask for B parameter 11, B12, B22, and then obtain the inside and outside parameter of single line array camera.This method system is simple, and it is few that unknown parameter is asked for, the significant and practical value of the application of demarcating for single line array camera.

Accompanying drawing explanation

Fig. 1 is the inventive method schematic flow sheet.

Embodiment

In order to understand better technical scheme of the present invention, below in conjunction with accompanying drawing, embodiments of the present invention are described in detail.

As shown in Figure 1, the present invention equals two according to rotation parameter matrix inner product in outer parameter matrix, derive in intrinsic parameter contacting of parameter in parameter and homography matrix, set up equation of constraint, utilize scaling board coordinate of ground point (X, Y, Z) to imaging point coordinate (u), obtain a plurality of impact points to going out corner homography matrix, substitution equation of constraint, and then calculate the inside and outside parameter of single line array camera.

Specific embodiment of the invention is as follows:

1. according to area array cameras imaging model, derive single line array camera imaging model, obtain homography matrix H model

Step 1: area array cameras imaging model

Step 2: can only imaging a line due to each imaging of single line array camera, therefore according to area array cameras imaging model, can obtain

Step 3: backstepping again, can obtain

Step 4: therefore

2. according to single line array camera imaging model, derive Intrinsic Matrix A and the outer parameter matrix of single line array camera ;

Step 1: the imaging model that comprises inside and outside parameter of area array cameras

，

Therefore

，

3. according to rotation parameter matrix inner product in outer parameter matrix, equal two, derive in intrinsic parameter A contacting of parameter in parameter and homography matrix H

Step 1: due to , can obtain

or

Here

Step 2: due to , will , , substitution, can obtain

4. calculate matrix, and establish B ₁₁, B ₁₂, B ₂₂replace parameter in matrix, substitution , obtain ;

Step 1: calculate

Step 2: set B ₁₁, B ₁₂, B ₂₂three parameter replacements parameter in matrix,

Step 3: by B substitution ,

Step 4: due to , , , , and ,

5. choose 3 above scaling board coordinate of ground points (X, Y, Z) to imaging point coordinate (u), calculate 3 above H matrixes, substitution formula, uses least square method to obtain B ₁₁, B ₁₂, B ₂₂value.

6. according to B ₁₁, B ₁₂, B ₂₂calculate Intrinsic Matrix A, then Intrinsic Matrix A, appoint and get a H matrix obtaining, calculate outer parameter matrix ;

Step 1: establish , by ,

Step 2: will , substitution A, obtains Intrinsic Matrix A

Step 3: appoint and get a H matrix obtaining, by A, H substitution , can obtain , further substitution , , , , can obtain outer parameter matrix .

Although embodiment has been described in detail the present invention, those of ordinary skill in the art is to be understood that, technical scheme of the present invention is modified or is equal to replacement, do not depart from the spirit and scope of technical solution of the present invention, it all should be encompassed in the middle of claim scope of the present invention.

Claims

1. a single line array camera inside and outside parameter scaling method, is characterized in that:

Step 4, choose 3 above scaling board coordinate of ground points (X, Y, Z) to imaging point coordinate (u), calculate 3 above H matrixes, substitution formula, uses least square method to obtain B ₁₁, B ₁₂, B ₂₂value;

Step 5, according to B ₁₁, B ₁₂, B ₂₂calculate Intrinsic Matrix A, then according to Intrinsic Matrix A, appoint and get the H matrix that step 4 obtains, calculate outer parameter matrix .

2. a kind of single line array camera inside and outside parameter scaling method according to claim 1, is characterized in that: homography matrix H model-composing method in described step 1,

Step 1, area array cameras imaging model ;

Each imaging a line of step 2, single line array camera, according to area array cameras imaging model, obtains

；

Step 3, to the model backstepping in step 2, can obtain

,

Therefore, .