CN113298886A - Calibration method of projector - Google Patents
Calibration method of projector Download PDFInfo
- Publication number
- CN113298886A CN113298886A CN202110847573.8A CN202110847573A CN113298886A CN 113298886 A CN113298886 A CN 113298886A CN 202110847573 A CN202110847573 A CN 202110847573A CN 113298886 A CN113298886 A CN 113298886A
- Authority
- CN
- China
- Prior art keywords
- projector
- calibration
- matrix
- coordinate system
- parameter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/80—Analysis of captured images to determine intrinsic or extrinsic camera parameters, i.e. camera calibration
Landscapes
- Engineering & Computer Science (AREA)
- Computer Vision & Pattern Recognition (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Projection Apparatus (AREA)
- Transforming Electric Information Into Light Information (AREA)
Abstract
The invention discloses a calibration method of a projector, which comprises the steps of placing a calibration object in a view field of the projector according to the field condition and adjusting a lens to focus on the calibration object; interactively controlling the projector to project light rays onto the mark points on the calibration object; estimating an intrinsic parameter K and an extrinsic parameter R, t of the projector using the 3D-2D matching coordinates; and (4) iteratively optimizing the projector parameters according to the principle of minimum re-projection error to obtain the optimal internal parameter K and distortion coefficient d. According to the invention, a camera or a sensor of a third party is not needed, and only the projector is required to be guided to project an image onto a space object with a known size interactively, so that correct 3D-2D matching coordinates can be directly obtained, and a calibration task of the projector in a large range is completed.
Description
Technical Field
The invention relates to the technical field of projector calibration, in particular to a projector calibration method.
Background
The projector is widely applied to the fields of data visualization, space augmented reality, interactive field teaching, structured light three-dimensional reconstruction and the like. In these application scenarios, it is generally necessary to precisely control the projector to project the image onto a predetermined spatial position, so that the projector needs to be calibrated in actual operation. Although the optical path of the projector is completely opposite to that of the camera, the two structures are quite similar, so that the model of the projector is completely the same as that of the camera and is also an intrinsic parameter model based on perspective projection. Therefore, the calibration of the projector is similar to the calibration of the camera, and a spatial three-dimensional coordinate and a two-dimensional pixel coordinate corresponding to the spatial three-dimensional coordinate on an image plane need to be acquired and recorded as a 3D-2D matching coordinate.
The projector and the camera have different functions, and only have a projection function, and do not have the ability of sensing the surrounding environment, so all current calibration methods for projectors need to complete the calibration task by using a third-party camera or sensor, for example, a projector calibration method and device (CN 201710122971.7) and a monocular camera and projector combined calibration method (CN 202011104456.4) are disclosed. In order to obtain 3D-2D matching coordinates, the existing methods are mainly respectively of two types, the first type is that 3D coordinates are known, and the key point is that a structural light fixed object image which is shot by a camera or received by a sensor and is covered with a projector for projection is used for determining 2D coordinates of an imaging point on a projector image plane corresponding to a space point; another is that the 2D coordinates are known, the features are projected onto a calibration object by a projector, and then the 3D coordinates of the features are measured using binocular vision. To accomplish the calibration task, either method must rely on the sensing capabilities of third party cameras or sensors to obtain the 3D-2D matching coordinates. Calibrating a projector using a third party camera or sensor also presents a number of problems: (1) on the hardware level, a camera, a sensor or a binocular system must be added for calibrating the projector, so that the complexity of the system is improved, and the use cost is also improved; (2) when the device is used by a user, the projector is generally required to be controlled to project a structured light 2 image or other mode images, meanwhile, the camera is required to shoot in sequence, and the sensor is also required to receive corresponding information, so that the requirement on the user is high; (3) both the camera and the projector have limitations of field of view and focal length, and the camera needs to capture a projected image, so that how to select a proper configuration (such as resolution of the camera, distance between the camera and the projector, and angle) to obtain a high-precision calibration result is also a problem to be considered; (4) in the calibration process, the physical quantity required for calibration can be obtained by a camera and a sensor of a third party, and additional errors such as image noise, camera lens distortion and the like may be introduced. (5) The calibration of the projector, whether by means of a third-party camera or a sensor, can only be carried out to a small extent.
Disclosure of Invention
The invention aims to provide a projector calibration method. According to the invention, a camera or a sensor of a third party is not needed, and only the projector is required to be guided to project an image onto a space object with a known size interactively, so that correct 3D-2D matching coordinates can be directly obtained, and a calibration task of the projector in a large range is completed.
The technical scheme of the invention is as follows: a calibration method of a projector, wherein a device participating in calibration comprises the projector and a host computer, wherein the host computer can control the projector to project any type of images, and the calibration method comprises the following calibration steps:
firstly, taking a calibration object which is calibrated with N marking points in advance, adjusting a lens of a projector according to the required working space of the projector, and focusing the lens on the calibration object;
secondly, marking the coordinates of N marked points on the marker in a world coordinate system as
Interactively controlling the pixel coordinates of the projector, and recording the pixel coordinates corresponding to the N marking points
；
Thirdly, recording an internal parameter matrix of the projector as K, a rotation matrix of the world coordinate system relative to the projector coordinate system as R and a translation vector of the world coordinate system relative to the projector coordinate system as t, and establishing an equation set according to perspective projection
；
Step four, solving the equation set in step three, and solving the equation set in step two
And
written in homogeneous form and comprising K, R, t in matrix
In the method, a matrix M is obtained through solving;
separating an internal parameter K and an external parameter R, t of the projector from the matrix M in sequence;
step six, distortion coefficient vector
Incorporated into the projector model, denoted pri (), the objective function is constructed
And performing iterative optimization on each parameter to further obtain an optimized projector internal parameter K, d, and completing the calibration of the projector.
Compared with the prior art, the invention has the beneficial effects that: according to the method, only one calibration object is needed to complete the calibration task, the projector is controlled to project light beams to the marks of the calibration object through a manual interactive method, so that the corresponding 3D-2D matching coordinates are directly obtained, and the model parameters of the projector can be directly obtained by using the calibration method provided by the invention. The method for projecting the light beam by the projector directly does not need a third-party camera or a sensor, does not need the projector to project a complex structured light image, is flexible and simple to operate, and can be suitable for field calibration of different fields of view.
Because a third-party camera or a sensor is not needed, the hardware cost is low, the algorithm complexity during calibration is low, the pixel coordinates of the projector can be recorded directly according to the interactive light beam, and extra calculation cost is not needed.
Because a third-party camera or a sensor is not needed, the calibration method does not introduce additional error factors such as image noise, camera lens distortion and the like, so that the accumulated error of the calibration result is low, and in addition, the reprojection error is minimized through iterative optimization of all parameters, so that the optimal calibration result is obtained.
In the foregoing calibration method for a projector, the size of the calibration object is known, and the number N of the marker points on the calibration object is greater than 6.
In the aforementioned calibration method for a projector, in the second step, when the coordinates of the pixels of the projector are interactively controlled, the projected light beam reaches the center of each mark point.
In the foregoing calibration method for a projector, the internal parameter matrix K of the projector includes
Four variables.
In the calibration method for the projector, when the matrix M is solved in the fourth step, the equation in the third step is rewritten into the equation
And solving by a least square method to obtain a matrix M.
In the aforementioned calibration method for a projector, the coordinates of N pixels obtained in step two are used in step six
Using K, R, t and 0 distortion coefficients obtained in step five as initial values, and using gradient descent method to make objective function
The minimum is obtained and the optimized projector intrinsic parameters K, d are obtained.
Drawings
FIG. 1 is a schematic diagram of hardware components used in a calibration method of a projector according to the present invention;
FIG. 2 is a schematic flow chart of a calibration method for a projector according to the present invention;
FIG. 3 is a schematic illustration of a calibration object used in an embodiment of the present invention;
FIG. 4 is a graph of the results of a calibration test experiment using the calibration material of FIG. 3.
Detailed Description
The invention is further illustrated by the following figures and examples, which are not to be construed as limiting the invention.
Example (b): a calibration method of a projector, the device involved in calibration comprises a projector, a computer host and a calibration object, as shown in figure 1, wherein the computer host can control the projector to project any type of image, the specific calibration method comprises the following steps (the flow is shown in figure 2), in this embodiment, the object to be calibrated is a commercial projector, the model is DELL M115HD, and the resolution is 1024 x 768.
Firstly, a prepared self-made calibration object is taken, N (N is more than 6) marking points are arranged on the calibration object, the spatial position relation among all the marking points is accurately measured in advance, preferably, 13 marking points are taken on the calibration object in the embodiment, the calibration object is placed in a projection operation space according to the projection range of a projector, the projector projects a cross pattern on the calibration object, and the lens of the projector is adjusted, so that the projected cross pattern can be imaged on the calibration object most clearly (as shown in fig. 3).
Step two, recording the coordinates of 13 mark points on the calibration object in the world coordinate system when the image projected in the step one is imaged on the calibration object most clearly
(ii) a The effect of projecting a bright spot can be achieved by setting the gray value of a certain pixel in a projection picture to be 255 and the gray values of the rest pixels to be 0, the projection position of the bright spot in the space can be moved by changing the position of the pixel in the image, the bright spot can be interactively moved to the center of a certain mark point by means of observation of human eyes, the movement of the bright spot is repeated, the bright spot is respectively moved to the centers of all mark points on a calibration object, and when the bright spot is recorded to move to the center of the mark point, the bright spot in the projection image can be recordedThe coordinates of the 13 pixels are recorded as
Thereby obtaining 13 pairs of 3D-2D matching coordinates.
Thirdly, recording an internal parameter matrix of the projector as K, a rotation matrix of the world coordinate system relative to the coordinate system of the projector as R, and a translation vector of the world coordinate system relative to the coordinate system of the projector as t, wherein the internal parameter matrix of the projector K comprises
Four variables, based on perspective projection, to establish a system of equations
And solving an equation by using the 13 pairs of matched coordinates obtained in the step two.
Step four, in order to solve the equation set in step three, the equation set in step two is solved
And
written in homogeneous form and including the quantities to be solved K, R, t in the matrix
In step three, therefore, the equation in step three needs to be rewritten into
And then the matrix M can be obtained by solving through a least square method.
And step five, separating the internal parameter K and the external parameter R, t of the projector from the matrix M in sequence.
Step six, considering the distortion effect of the lens, and transforming the distortion coefficient vector
Incorporated into the model of the projector is,and (5) constructing an objective function, which is marked as pri ()
Using the coordinates of 13 pixels obtained in step two
Using K, R, t and 0 distortion coefficients obtained in step five as initial values, and using gradient descent method to make objective function
Get the minimum and thus optimized projector intrinsic parameters K, d, and in particular, the best projector intrinsic parameters
Coefficient of distortion
And finally completing the calibration of the projector.
In order to verify the validity of the calibration parameters, in this embodiment, all the mark points on the calibration object are projected as target points, that is, the pixel coordinates of the bright point in the projected image corresponding to the bright point projected to the center position of each mark point are calculated by using the calibrated projector and the spatial coordinates of the mark points, so that the center positions of all the mark points are lit, and the effect is as shown in fig. 4.
The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-mentioned examples, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.
Claims (6)
1. A calibration method of a projector, the device involved in calibration comprises a projector and a host computer, wherein the host computer can control the projector to project any type of images, and the method is characterized in that: the method comprises the following calibration steps:
firstly, taking a calibration object which is calibrated with N marking points in advance, adjusting a lens of a projector according to the required working space of the projector, and focusing the lens on the calibration object;
secondly, marking the coordinates of N marked points on the marker in a world coordinate system as
Interactively controlling the pixel coordinates of the projector, and recording the pixel coordinates corresponding to the N marking points
；
Thirdly, recording an internal parameter matrix of the projector as K, a rotation matrix of the world coordinate system relative to the projector coordinate system as R and a translation vector of the world coordinate system relative to the projector coordinate system as t, and establishing an equation set according to perspective projection
；
Step four, solving the equation set in step three, and solving the equation set in step two
And
written in homogeneous form and comprising K, R, t in matrix
In the method, a matrix M is obtained through solving;
separating an internal parameter K and an external parameter R, t of the projector from the matrix M in sequence;
step six, distortion coefficient vector
Incorporated into the projector model, denoted pri (), the objective function is constructed
And performing iterative optimization on each parameter to further obtain an optimized projector internal parameter K, d, and completing the calibration of the projector.
2. A calibration method for a projector according to claim 1, wherein: the size of the calibration object is known, and the number N of the marking points on the calibration object is more than 6.
3. A calibration method for a projector according to claim 1, wherein: in the second step, when the pixel coordinates of the projector are interactively controlled, the projected light beams reach the centers of the mark points.
4. A calibration method for a projector according to claim 1, wherein: the intrinsic parameter matrix K of the projector comprises
Four variables.
5. A calibration method for a projector according to claim 1, wherein: when the matrix M is solved in the fourth step, the equation in the third step is rewritten into
And solving by a least square method to obtain a matrix M.
6. A calibration method for a projector according to claim 1, wherein: in the sixth step, the N pixel coordinates obtained in the second step are utilized
Step (b), step (b)Using K, R, t and 0 distortion coefficient obtained in the fifth step as initial values, and using gradient descent method to make objective function
The minimum is obtained and the optimized projector intrinsic parameters K, d are obtained.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110847573.8A CN113298886B (en) | 2021-07-27 | 2021-07-27 | Calibration method of projector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110847573.8A CN113298886B (en) | 2021-07-27 | 2021-07-27 | Calibration method of projector |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113298886A true CN113298886A (en) | 2021-08-24 |
| CN113298886B CN113298886B (en) | 2021-10-08 |
Family
ID=77331088
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110847573.8A Active CN113298886B (en) | 2021-07-27 | 2021-07-27 | Calibration method of projector |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113298886B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113793390A (en) * | 2021-08-26 | 2021-12-14 | 光量信息科技(宁波)有限公司 | Interactive three-dimensional marking method of projector |
| CN115546311A (en) * | 2022-09-28 | 2022-12-30 | 中国传媒大学 | Projector calibration method based on scene information |
| CN117593378A (en) * | 2023-11-01 | 2024-02-23 | 誉昊光电科技(珠海)有限公司 | Device and method for calibrating internal parameters of vehicle-mounted camera module |
Citations (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1570553A (en) * | 2004-05-13 | 2005-01-26 | 上海交通大学 | Composite calibration method of mold surface optical measurement system |
| CN106707526A (en) * | 2016-12-14 | 2017-05-24 | 深圳奥比中光科技有限公司 | Automatic focusing method and system for light source projector |
| CN106991702A (en) * | 2017-03-03 | 2017-07-28 | 浙江华睿科技有限公司 | A kind of projector calibrating method and device |
| CN107462184A (en) * | 2017-08-15 | 2017-12-12 | 东南大学 | The parameter recalibration method and its equipment of a kind of structured light three-dimensional measurement system |
| CN108076333A (en) * | 2016-11-11 | 2018-05-25 | 美国科视数字系统公司 | The system and method being fitted for the advanced lens geometry structure of imaging device |
| CN108230399A (en) * | 2017-12-22 | 2018-06-29 | 清华大学 | A kind of projector calibrating method based on structured light technique |
| CN108475103A (en) * | 2015-09-30 | 2018-08-31 | 惠普发展公司，有限责任合伙企业 | Interactive display |
| US20190313070A1 (en) * | 2016-11-23 | 2019-10-10 | Réalisations Inc. Montreal | Automatic calibration projection system and method |
| US20200036949A1 (en) * | 2018-07-30 | 2020-01-30 | Coretronic Corporation | Projection system and projection method |
| CN112284296A (en) * | 2020-11-05 | 2021-01-29 | 中国烟草总公司郑州烟草研究院 | Measuring device and method for projector workbench movement precision calibration |
| CN112614075A (en) * | 2020-12-29 | 2021-04-06 | 凌云光技术股份有限公司 | Distortion correction method and equipment for surface structured light 3D system |
| CN112991467A (en) * | 2021-05-08 | 2021-06-18 | 光量信息科技(宁波)有限公司 | Camera-based laser projection identification automatic guiding positioning and real-time correction method |
| CN113160339A (en) * | 2021-05-19 | 2021-07-23 | 中国科学院自动化研究所苏州研究院 | Projector calibration method based on Samm's law |
| CN113191963A (en) * | 2021-04-02 | 2021-07-30 | 华中科技大学 | Projector residual distortion full-field calibration method and device without additional operation |
-
2021
- 2021-07-27 CN CN202110847573.8A patent/CN113298886B/en active Active
Patent Citations (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1570553A (en) * | 2004-05-13 | 2005-01-26 | 上海交通大学 | Composite calibration method of mold surface optical measurement system |
| CN108475103A (en) * | 2015-09-30 | 2018-08-31 | 惠普发展公司，有限责任合伙企业 | Interactive display |
| CN108076333A (en) * | 2016-11-11 | 2018-05-25 | 美国科视数字系统公司 | The system and method being fitted for the advanced lens geometry structure of imaging device |
| US20190313070A1 (en) * | 2016-11-23 | 2019-10-10 | Réalisations Inc. Montreal | Automatic calibration projection system and method |
| CN106707526A (en) * | 2016-12-14 | 2017-05-24 | 深圳奥比中光科技有限公司 | Automatic focusing method and system for light source projector |
| CN106991702A (en) * | 2017-03-03 | 2017-07-28 | 浙江华睿科技有限公司 | A kind of projector calibrating method and device |
| CN107462184A (en) * | 2017-08-15 | 2017-12-12 | 东南大学 | The parameter recalibration method and its equipment of a kind of structured light three-dimensional measurement system |
| CN108230399A (en) * | 2017-12-22 | 2018-06-29 | 清华大学 | A kind of projector calibrating method based on structured light technique |
| US20200036949A1 (en) * | 2018-07-30 | 2020-01-30 | Coretronic Corporation | Projection system and projection method |
| CN112284296A (en) * | 2020-11-05 | 2021-01-29 | 中国烟草总公司郑州烟草研究院 | Measuring device and method for projector workbench movement precision calibration |
| CN112614075A (en) * | 2020-12-29 | 2021-04-06 | 凌云光技术股份有限公司 | Distortion correction method and equipment for surface structured light 3D system |
| CN113191963A (en) * | 2021-04-02 | 2021-07-30 | 华中科技大学 | Projector residual distortion full-field calibration method and device without additional operation |
| CN112991467A (en) * | 2021-05-08 | 2021-06-18 | 光量信息科技(宁波)有限公司 | Camera-based laser projection identification automatic guiding positioning and real-time correction method |
| CN113160339A (en) * | 2021-05-19 | 2021-07-23 | 中国科学院自动化研究所苏州研究院 | Projector calibration method based on Samm's law |
Non-Patent Citations (3)
| Title |
|---|
| 冀红彬等: "单周期条纹双四步相移投影仪的标定方法", 《光子学报》 * |
| 金施群等: "单幅图像的三维重构视觉系统误差修正", 《应用科学学报》 * |
| 龚春园等: "投影仪全参数平面线性估计的高精度标定方法", 《西安交通大学学报》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113793390A (en) * | 2021-08-26 | 2021-12-14 | 光量信息科技(宁波)有限公司 | Interactive three-dimensional marking method of projector |
| CN115546311A (en) * | 2022-09-28 | 2022-12-30 | 中国传媒大学 | Projector calibration method based on scene information |
| CN117593378A (en) * | 2023-11-01 | 2024-02-23 | 誉昊光电科技(珠海)有限公司 | Device and method for calibrating internal parameters of vehicle-mounted camera module |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113298886B (en) | 2021-10-08 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN113298886B (en) | Calibration method of projector | |
| CN110809786B (en) | Calibration device, calibration chart, chart pattern generation device, and calibration method | |
| US20170243374A1 (en) | Calibration device, calibration method, optical device, image-capturing device, projection device, measuring system, and measuring method | |
| CN106887023A (en) | For scaling board and its scaling method and calibration system that binocular camera is demarcated | |
| US8223208B2 (en) | Device and method for calibrating an imaging device for generating three dimensional surface models of moving objects | |
| JP2015128242A (en) | Image projection device and calibration method of the same | |
| WO2018029950A1 (en) | Calibration device, calibration method, optical device, imaging device and projection device | |
| JP7218435B2 (en) | CALIBRATION DEVICE, CALIBRATION CHART AND CALIBRATION METHOD | |
| CN108020175A (en) | A kind of more optical grating projection binocular vision tongue body surface three dimension entirety imaging methods | |
| CN109727290A (en) | Zoom camera dynamic calibrating method based on monocular vision triangle telemetry | |
| CN110648274B (en) | Method and device for generating fisheye image | |
| CN210322247U (en) | Optical module assembly and debugging testing device | |
| CN107610183A (en) | New striped projected phase height conversion mapping model and its scaling method | |
| CN113255643A (en) | Machine vision recognition algorithm applied to displacement monitoring | |
| CN111009030A (en) | Multi-view high-resolution texture image and binocular three-dimensional point cloud mapping method | |
| EP3144894B1 (en) | Method and system for calibrating an image acquisition device and corresponding computer program product | |
| CN115830103A (en) | Monocular color-based transparent object positioning method and device and storage medium | |
| CN114283203A (en) | Calibration method and system of multi-camera system | |
| CN114792345B (en) | Calibration method based on monocular structured light system | |
| CN115187612A (en) | Plane area measuring method, device and system based on machine vision | |
| US20220006989A1 (en) | Method for Automatically Restoring a Calibrated State of a Projection System | |
| CN111429531A (en) | Calibration method, calibration device and non-volatile computer-readable storage medium | |
| CN113330487A (en) | Parameter calibration method and device | |
| WO2023028939A1 (en) | Information acquisition system, calibration method and apparatus therefor, and computer-readable storage medium | |
| CN113865514B (en) | Calibration method of line structured light three-dimensional measurement system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |