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CN103985121B - An underwater projector cursor given process configuration - Google Patents

An underwater projector cursor given process configuration Download PDF

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CN103985121B
CN103985121B CN 201410200408 CN201410200408A CN103985121B CN 103985121 B CN103985121 B CN 103985121B CN 201410200408 CN201410200408 CN 201410200408 CN 201410200408 A CN201410200408 A CN 201410200408A CN 103985121 B CN103985121 B CN 103985121B
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CN 201410200408
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CN103985121A (en )
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周富强
王晔昕
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北京航空航天大学
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Abstract

本发明属于测量技术领域,将提供一种水下投影仪结构光标定方法。 The present invention belongs to the technical field of measurement, it would provide a projector cursor underwater structures given process. 包括以下步骤:在至少三个位置拍摄位于同一平面的防水靶标和投射靶标的图像对;在摄像机坐标系下,计算平面法向向量和投射靶标三维坐标,采用单视点模型初步标定投影仪及结构参数,将投射靶标三维坐标转换至投影仪坐标系作为参考值;在投影仪坐标系下,建立投射靶标的入射光线以及折射光线模型,计算投射靶标三维坐标;以计算出的投射靶标三维坐标与参考值之间的距离建立目标函数,对所有参数进行递归优化。 Comprising the steps of: located waterproof target and the projected target image of the same plane at least three positions captured; in the camera coordinate system, calculating the surface normal vector and a projection scale three-dimensional coordinates of the target, using a projector and structural preliminary calibration single viewpoint model parameter, the standard three-dimensional coordinates projected target conversion to the projector coordinate system as a reference value; in the projector coordinate system, the establishment of the projection target incident ray and the refracted light model to calculate the projected standard three-dimensional coordinates of the target; standard three-dimensional coordinates of the calculated projection target and the distance between the reference value of objective function, the optimization of all parameters recursively. 本发明考虑投影仪光线从空气介质传播到水介质时发生的折射现象,以及投影仪光轴与防水装置窗口法向向量不平行的情况,能够满足水下投影仪标定需求。 The present invention contemplates propagating light from the projector to the medium of air refraction phenomenon occurring when an aqueous medium, and the optical axis of the projector window waterproof case normal vectors are not parallel, it is possible to meet the requirements of underwater projector calibration.

Description

一种水下投影仪结构光标定方法 An underwater projector cursor given process configuration

技术领域 FIELD

[0001] 本发明涉及一种水下投影仪结构光标定方法,属于测量技术领域。 [0001] The present invention relates to an underwater projector cursor given process configuration, it belongs to the technical field of measurement.

背景技术 Background technique

[0002] 投影仪与摄像机结合的结构光模式,是视觉测量中一种重要的三维测量方法和技术。 [0002] The structured light pattern projector and the camera in combination, is an important measurement of visual three-dimensional measurement methods and techniques. 其原理是采用投影仪结构光传感器,投影仪根据测量需要主动投射特征,如点阵、光栅条纹、编码格网等等,摄像机捕获的图像包含因物体表面形貌变化而产生形变的投射特征, 根据结构光三角测量原理恢复物体表面的三维信息。 The principle is to use structured light sensor of the projector, the projector requires active projection from the measurement, such as lattice, grating strips, coding grid, etc., the image captured by the camera characterized by comprising a projection surface of the object and the topographical variations of deforming, recovery three-dimensional information of the object surface according to the principle of optical triangulation structure. 由于摄像机拍摄的一幅图像可以包含大量特征信息,因此对于近距离的水下三维测量应用,投影仪结构光技术是一种恢复被测物体三维信息的有效手段。 Since a camera image may contain a large number of feature information, and therefore three-dimensional measurement for underwater applications, structured light projector close technology is an effective means to restore the object three-dimensional information.

[0003] 水下投影仪结构光测量环境有别于陆地上的空气介质环境。 [0003] underwater projectors structured light measurement environment different from the environment on land-air medium. 水下环境作业的投影仪需要固定在密封的防水装置内,通过位于投影仪镜头前的透明窗口向位于水中的被测物体投射特征。 Projector underwater environment job needs to be fixed in a waterproof sealed by a transparent window is located in front of the projector lens to the projection from the object located in water. 由于防水装置的使用,使得被测物体与投影仪图像平面分别位于不同介质中, 即被测物体位于水介质中,而投影仪图像平面位于防水装置内的空气介质中,光线从投影仪光心经过窗口平面进入水介质时会产生折射现象。 The use of a waterproof device, such that the object plane and the image projectors are located at different medium, i.e., the object is located in an aqueous medium, the image plane of the projector and the air medium in the waterproof apparatus, the light from the projector optical center when the plane through the window into the aqueous medium will produce refraction. 此时,建立在光线沿直线传播基础上的单视点模型已不再适用。 In this case, light travels in straight lines based on a single viewpoint on the basis of the model is no longer applicable.

[0004] 投影仪的投射过程与摄像机的成像过程相反,可以看做逆向的摄像机。 [0004] projector and the projector during the imaging process the camera contrast, can be seen as a reverse of the camera. 由于折射使光线发生了折弯,用单视点模型描述的投影仪光心位置和实际光心位置不一致。 Refraction of light occurs due to the bending, the optical center of the projector inconsistent position and the actual position of the optical center of the model to describe a single viewpoint. Treibitz等在文章"Flat Refractive Geometry. IEEE Transactions on Pattern Analysis and Machine Intelligence,2012,34(l):51_65"分析指出,折射产生的畸变取决于被测物体与摄像机之间的距离,若采用单视点模型或用径向畸变模型表示这种畸变, 则会产生较大误差,因此单视点模型不能准确描述水下投影仪投射过程。 Treibitz the like in the article "Flat Refractive Geometry IEEE Transactions on Pattern Analysis and Machine Intelligence, 2012,34 (l):. 51_65" analysis pointed out that the refractive distortion generated depends on the distance between the object and the camera, use of a single viewpoint radial distortion model or models represent this distortion, it will produce large errors, so a single viewpoint model can not accurately describe the process of underwater projector projects. 但该文只考虑了光轴与窗口平面法向向量平行时的情况,当光轴与窗口平面法向向量不平行时,基于该文分析建立模型仍会有偏差。 However, this paper only considers the case where the optical axis is parallel to the window plane vector method, when the optical axis of the aperture plane is not parallel to the normal vector, the analysis model based on the paper still biased.

[0005] 从上述分析可知,由于防水装置窗口对光线产生的折射效应,以及投影仪光轴与窗口平面法向向量不平行的影响,传统的投影仪单视点模型已不再适用。 [0005] From the above analysis, due to refraction effect of light generated waterproof window, and the optical axis of the projector window plane is not parallel to the normal vector, the conventional single-view projector model is no longer applicable. 因此,研究一种适用于水下投影仪结构光视觉测量传感器的模型和标定方法具有重要意义。 Thus, calibration models and methods suitable for research underwater projector structured light vision sensor measurements is important.

发明内容 SUMMARY

[0006] 本发明所要解决的技术问题是:提供一种用于水下投影仪结构光传感器的投影仪参数和结构参数的优化标定方法。 [0006] The present invention solves the technical problem are: to provide a method for optimizing the calibration of the projector and structure parameters underwater projector structured light sensor.

[0007] 本发明的技术解决方案为:一种水下投影仪标定方法,其特征在于该方法包含以下步骤: [0007] The technical solutions of the present invention is: A projector calibration method of underwater, characterized in that the method comprises the steps of:

[0008] 1.1、调整位于水下的投影仪结构光传感器,保证摄像机在测量范围内能够拍摄清晰图像且投影仪在测量范围内能够投射清晰图像,在投影仪和已标定摄像机的公共视场范围内,采用一附有防水靶标的平板,同时投影仪对该平板投射另一靶标,称为投射靶标,调整平板位置,直到两个靶标特征点都位于公共视场范围内;自由移动靶标至少三个位置,每移动一个位置,拍摄含有两个靶标的图像对; [0008] 1.1, to adjust the projector is located underwater structured light sensor, to ensure that the camera can shoot in the measurement range and clear image projector capable of projecting in the measuring range a sharp image, the projector and the camera are calibrated in a common field of view inside, using a target plate with water, while the other projector is projected to the target plate, referred to as the projection target, the position adjusting plate, until the standard feature points are two targets located within the common field of view; consisting of at least three standard YiDongBa positions, each shifted by one position, two imaging targets containing images;

[0009] 1.2、提取图像中防水靶标特征点的图像坐标,根据已标定摄像机的参数,求取平板所在平面在摄像机坐标系下的法向向量; [0009] 1.2, extracting image coordinates of the image feature points labeled target water, according to the parameters of a calibrated camera, obtaining the vector plane plate method lies in the camera coordinate system;

[0010] 1.3、提取图像中投射靶标特征点的图像坐标,利用步骤1.2中求得的法向向量,由摄像机参数和特征点的图像坐标,计算投射靶标投射在平板上的对应空间点位于摄像机坐标系下的三维坐标; [0010] 1.3, the extracted image coordinates of the projection target feature point in the image, using a step 1.2 to obtain the normal vector, the image coordinates of the camera parameters and feature points, calculates the corresponding spatial points projected target is projected on a plate located camera three-dimensional coordinates in the coordinate system;

[0011] 1.4、根据投射祀标在图像坐标,以及步骤1.3中求得的其对应空间点的三维坐标, 利用单视点模型初步标定投影仪参数以及投影仪与摄像机之间的结构参数; [0011] 1.4, the three-dimensional coordinates obtained by projecting worship marked in the image coordinates, and step 1.3 the corresponding spatial points, the initial calibration model using a single-view configuration parameters between the projector and the projector and the camera parameters;

[0012] 1.5、使用步骤1.4中得到的结构参数,将步骤1.2中所求的法向向量表示在投影仪坐标系下; [0012] 1.5, using configuration parameters obtained in step 1.4, step 1.2 in the request indicates the normal vector at the projector coordinate system;

[0013] 1.6、在投影仪坐标系下,给定投影仪光心沿光轴方向到防水装置窗口平面的距离初值,建立投影仪图像上每个特征点发出的光线在防水装置中的空气介质传播时光线模型,称为入射光线; [0013] 1.6, in the projector coordinate system, given the projector optical center axis direction from the initial value to the plane of the window waterproof device, establishing the light emitted from each of the feature points on the image projector apparatus in a waterproof air when the light propagating medium model, referred to as the incident light;

[0014] 1.7、建立折射光线的单位向量,根据几何约束求解出尺度因子,确定折射光线长度,求解投影仪坐标系下投影靶标特征点的三维坐标; [0014] 1.7, establishing the light refraction unit vector, according to a geometric constraint solving scale factor, determining the length of refraction of light, solving the three-dimensional coordinates of feature points marked target projection under the projector coordinate system;

[0015] 1.8、将步骤1.3中计算出的三维坐标利用步骤1.4中的结构参数转换至投影仪坐标系下作为参考值; [0015] 1.8, step 1.3 the three-dimensional coordinate is calculated using the structure parameters of step 1.4 to convert the projector coordinate system as a reference value;

[0016] 1.9、给定投影仪光轴相对于窗口平面法向向量之间偏角和转角的初值,以步骤1.7中所述的三维坐标与1.8所述的参考值之间的距离建立目标函数,对投影仪参数和结构参数进行优化,并进行递归优化,即求得的结构参数用于步骤1.5~1.8,直到目标函数值满足设定阈值,阈值根据测量精度要求设定,一般为1〇_ 5至〇• 1mm。 [0016] 1.9, a given initial value with respect to the optical axis of the projector window between the surface normal vector and rotation angle, the distance between the goal of establishing the three-dimensional coordinates of the step with a reference value of 1.7 to 1.8 function, the projector and structure parameters are optimized, and a recursive optimization, i.e., the structural parameters determined for the steps 1.5 to 1.8, until the target function value satisfies the set threshold value, the threshold value is set according to the required measurement accuracy, typically 1 〇_ to 5 billion • 1mm.

[0017] 2、所述的一种水下投影仪标定方法,其特征在于: [0017] 2. An underwater projector calibration method of claim, wherein:

[0018] 2.1、步骤1.1所述的防水靶标为防水材质制成的平面靶标,固定在一平板上,防水靶标厚度与测量距离相比可忽略不计,靶标特征点为平面上的格点,格点之间距离的设计由实际测量距离和摄像机视场等确定,一般为10~100mm;所述的投射靶标,其格点之间的图像坐标距离根据投影仪图像的分辨率确定,一般为10~100像素; [0018] 2.1, planar target according to step 1.1 waterproof target waterproof material made of, immobilized on a plate, waterproof target thickness and the measured distance as compared negligible, the target feature point grid point on a plane, grid design of the distance determined by the distance between the point and the camera field of view of the actual measurement and the like, is generally 10 ~ 100mm; the projection target, the distance between the image coordinates of the grid points is determined according to its resolution of projector image, typically 10 ~ 100 pixels;

[0019] 2.2、步骤1.1所述的防水靶标和投射靶标,在摄像机合理使滤光器件如滤光片的前提下,两靶标在平板上所占区域可重叠;当平板在同一位置时,摄像机不使用滤光器件且投影仪不投射靶标时,摄像机拍摄只得到防水靶标图像,当摄像机使用滤光器件且投影仪投射靶标时,该靶标与防水靶标有重叠区域,摄像机拍摄只得到投射靶标图像; [0019] 2.2, step 1.1 waterproof target and target projection, in that the filter device such as a camera filter reasonable premise, the target area occupied by the two may overlap on the plate; when the tablet at the same position, the camera when not in use the optical device and the projector does not project targets cameras to give only water the target image, when the camera using a filter device and the projector when the projection target, the target and waterproofing target overlap region captured by the camera to obtain only the projected target image ;

[0020] 2.3、步骤1.1所述的拍摄含有两个靶标的图像对,其特征在于,当使用滤光器件时,每一个位置拍摄两幅图像,为分别含有防水靶标和投射靶标的图像对。 Shooting [0020] 2.3, step 1.1 having two target image pair, wherein, when using a filter device, each position of the captured two images, each containing water as a target, and a projection target image pairs.

[0021] 本发明的优点是: [0021] The advantage of the present invention are:

[0022] 第一,考虑投影仪在水下作业时光线从防水装置中的空气介质传播至防水装置外的水介质时产生的折射现象,建立了投影仪光线折射模型; [0022] First, consider the projector light propagates from the air medium waterproof underwater apparatus refraction phenomenon of the water outside the waterproof medium, to establish a model of the projector light refraction;

[0023] 第二,考虑投影仪光轴与防水装置窗口平面法向向量不平行时的情况,以光轴相对于法向向量的偏角和转角描述该现象,并通过优化方法得出两个角度的值; [0023] Second, consider the optical axis of the projector and the plane of the window waterproof case not parallel to the normal vector with respect to the optical axis to the method described in this phenomenon declination and angle of the vector, and a method obtained by optimizing the two the value of the angle;

[0024]第三,合理使用滤光器件,采用了可重叠的防水靶标和投射靶标,让两个靶标能够同时尽量占满视场,提高了标定精度。 [0024] Third, the rational use of filter devices, using a waterproof target may overlap and the projection target, so that two targets can be simultaneously filled field of view as much as possible to improve the calibration accuracy.

附图说明 BRIEF DESCRIPTION

[0025] 图1是本发明建立的水下投影仪光线折射模型示意图。 [0025] FIG. 1 is a schematic model of the present invention to establish underwater projector light refraction.

[0026] 图2是水下投影仪光轴与窗口平面法向向量不平行的示意图。 [0026] FIG. 2 is a schematic view of an underwater optical axis of the projector window plane is not parallel to the normal vector.

[0027] 图3是水下投影仪标定方法流程图。 [0027] FIG. 3 is a flowchart of an underwater projector calibration method.

[0028] 图4是标定水下投影仪使用的靶标位置示意图。 [0028] FIG. 4 is a schematic view of an underwater target location using the calibration of the projector.

具体实施方式 detailed description

[0029] 下面对本发明做进一步详细说明。 [0029] The following further detailed description of the present invention. 本发明建立水下投影仪的光线折射模型,对光轴与防水装置窗口平面法向向量存在旋转角度时的投影仪参数和结构参数进行优化标定, 实现了高精度的水下投影仪标定。 Establish underwater light projector of the present invention, a refractive model, and structural parameters of the projector in the presence of the rotation angle of the optical axis of waterproof window plane normal vector optimize calibration, to achieve a high-precision calibration underwater projector.

[0030] 图1所示为水下投影仪光线折射模型示意图。 [0030] Figure 1 is a schematic view of an underwater projector light refraction model. 以投影仪光心为原点建立投影仪坐标系0P-XPY PZP,原图像坐标系为0U-uv,( UQ,VQ )为主点的坐标。 In the optical center of the projector the projector coordinate origin established 0P-XPY PZP, the original image coordinate system 0U-uv, (UQ, VQ) based coordinate point. 以投景^仪图像上的主点位置为原点建立图像坐标系o-xy,有x = U-UQ,y = V-VQ。 In the principal point on the image analyzer ^ administered view position establishing image coordinate system as the origin o-xy, there are x = U-UQ, y = V-VQ. 定义ox II OpXp,oy II OpYp。 Definition of ox II OpXp, oy II OpYp. x = [ x,y ]T表示投影仪图像平面上的一点的理想图像坐标,Xd=[xd,yd]T为实际受到镜头畸变影响的图像坐标。 x = [x, y] T represents the coordinates of a point over the image on the projector image plane, Xd = [xd, yd] T is the actual image coordinates by lens distortion effects. 从投影仪图像平面上的点Xd=[xd,yd]T投射出的光线,经过防水装置窗口平面时发生折射,记入射光线为Rin,折射光线为Rout。 From the point of the projector image plane Xd = [xd, yd] T of the projected light passes through the plane of the window waterproof device refracted incident light is denoted Rin, as refracted ray Rout. 用n=[Wl -W2 0]T表示投影仪坐标系下窗口平面的单位法向向量,其中W#PW2分别表示投影仪光轴相对于窗口平面法向向量之间的偏角和转角,如图2所示,且满5 With n = [Wl -W2 0] T represents the projector coordinate plane of the window indicate the projector unit normal axis with respect to the vector, wherein the plane of the window W # PW2 and rotation angle between the normal vectors, such as As shown in FIG. 2, and the full 5

Figure CN103985121BD00051

,供表示光轴与法向向量之间的夹角。 For denotes the angle between the optical axis and the normal vector. 窗口平面的法向向量还可以表示为: Window plane normal to the vector can also be expressed as:

[0031] [0031]

Figure CN103985121BD00052

[1] [1]

[0032] 式中d表示从投影仪光心沿光轴方向到窗口平面的距离。 [0032] where d represents the distance from the optical center of the projector window to the plane of the optical axis direction.

[0033] 假设畸变中心和主点重合,考虑二阶的径向和切向畸变,有如下畸变模型: [0033] Suppose the distortion points coincide and the main center, second-order radial and tangential distortion, distortion model are as follows:

[0034] [0034]

Figure CN103985121BD00053

[2] [2]

[0035]式中lu,k2为径向畸变系数,Pl,p2S切向畸变系数,且有: [0035] In the formula lu, k2 is a radial distortion coefficient, Pl, p2S tangential distortion coefficient, and has:

Figure CN103985121BD00054

[0036] [3] [0036] [3]

[0037] 共邪Iy73仅京乂現大焦距在x和y方向上的分量。 [0037] The components were evil Iy73 Beijing qe now only large focal length in x and y directions.

[0038]如图1所示,从投影仪光心至图像平面上的点(Xd,yd)发出入射光线Rin,经过折射后光线沿Rout方向继续传播直到与被测物体表面相交于点? [0038] 1, the incident light ray emitted from the projector Rin optical center to a point on the image plane (Xd, yd), the light is refracted in the direction Rout continues to propagate until it intersects with the surface of the object at a point? (、,4,21〇。用丫表示入射角, Y '表示折射角,根据折射定律有: . (Ah ,, represents the angle of incidence with 4,21〇, Y 'represents a refraction angle in accordance with a law of refraction:

[0039] [0039]

Figure CN103985121BD00061

[4] [4]

[0040] 式中我"表示入射光线方向的单位向量,分表示窗口平面法向向量的单位向量。入射光线Rin可以表示为: [0040] Formula I "indicates a unit vector direction of the incident light, the incident sub-window representing plane method Rin line may represent the vector is a unit vector:

[0041] [0041]

Figure CN103985121BD00062

[5] [5]

[0042] 式中k为一尺度因子。 [0042] wherein k is a scale factor. 入射光线Rin与窗口平面法向向量n满足: Rin incident light plane of the window and n satisfy the vector method:

[0043] Rin.n=i [6] [0043] Rin.n = i [6]

[0044] 将式[1]和[5]代入[6]可以解出尺度因子k。 [0044] Formula [1] and [5] is substituted into [6] can be solved for the scale factor k. 因为防水装置窗口的厚度相比于d可以忽略,则折射光线的单位向量我^可以表示为: Since the thickness of the window compared to a waterproof device d is negligible, the light refraction unit vector I ^ can be expressed as:

[0045] [0045]

Figure CN103985121BD00063

[7] [7]

[0046] 其中mi和m2为: [0046] where mi and m2 as:

[0047] [0047]

Figure CN103985121BD00064

[8] [8]

[0048]其中rfn为水介质的折射率。 [0048] rfn wherein the refractive index of the aqueous medium.

[0049] 折射光线继续传播,与被测物体表面相交于点P,在投影仪坐标系下,点P的坐标可以表示为: [0049] The refracted light continues to propagate, and the object surface at the intersection point P, in the projector coordinate system, the coordinates of the point P can be expressed as:

[0050] [0050]

Figure CN103985121BD00065

[9] [9]

[0051] 上式表示了光线传播的过程,其中0为尺度因子,决定了折射光线的长度,0的值由特征点的折射光线与成像在摄像机图像上像点确定的摄像机光线共同决定。 [0051] The process represented by the formula propagating light, where 0 is a scale factor, determines the length of the light refraction, the refracted ray imaging with a value of 0 by the feature point image light camera points determined jointly decided on the camera image.

[0052] 根据上述模型,水下投影仪的标定包含投影仪参数(焦距、主点坐标、畸变系数、投影仪光心沿光轴方向到窗口平面的距离和投影仪光轴与窗口平面法向向量之间的偏角和转角)以及投影仪与摄像机之间结构参数(旋转和平移关系)的标定,具体步骤如下: [0052] A projector parameters (focal length, principal point, the distortion factor, the projector optical center axis direction from the calibration model described above, the projection distance meter underwater optical axis of the projector and the plane normal to the window plane of the window and rotation angle between the vectors) and the structure of the calibration parameter between the projector and the camera (rotation and translation relation), the following steps:

[0053] 1、利用已经标定好的摄像机,与投影仪组成结构光传感器,即摄像机的焦距、主点坐标和畸变系数已知,摄像机标定方法见Zhang的文章"A Flexible New Technique for Camera Calibration.IEEE Transactions on Pattern Analysis and Machine Intelligence,2000,22(ll):1330-1334" 〇 [0053] 1, using the already-calibrated camera, a structured light projector composed of a sensor, i.e. the camera focal length, principal point, and distortion coefficients are known, camera calibration method, see Zhang article "A Flexible New Technique for Camera Calibration. IEEE Transactions on Pattern Analysis and Machine Intelligence, 2000,22 (ll): 1330-1334 "square

[0054] 2、如图4所示,制作红白相间的防水棋盘格靶标(防水靶标)贴在一平板上,该靶标上的特征点即角点间距已知,角点间距的设定由摄像机视场和工作距离共同决定,一般为10~100mm;投影仪投射红黑相间的棋盘格靶标(投射靶标),该靶标上的角点在投影仪图像坐标系下的坐标已知,记为邱=(邱1,^1),1 = 1一,111,角点间距的设定由投影仪图像的分辨率确定,一般为10~100像素。 [0054] 2, 4, produce red and white checkerboard target water (water target) attached to a plate, characteristic points on the target i.e. the angular spacing is known, the dot pitch is set by the angle the camera field of view and working distance is doubled, is generally 10 ~ 100mm of; projector projects a red and black checkered target (projection target), the corner points on the target coordinates are known in the projector image coordinate system, referred to as Qiu = (1 Qiu, ^ 1), a 1 = 1, 111, the dot pitch angle setting is determined by the resolution of the image projector, generally 10 to 100 pixels. 具体的图像采集步骤为: DETAILED image acquisition steps:

[0055] 1)将防水靶标置于摄像机和投影仪公共视场范围内,并尽量占满摄像机视场。 [0055] 1) The target waterproof camera and projector disposed in a common field of view, and try to fill the camera's field of view. 打开投影仪投射红黑棋盘格靶标,调整平板位置,直到投射靶标和防水靶标都位于公共视场范围内; Open the red and black checkered projector projects the target, adjusting plate position until the projection target and the target are waterproof lie in a common field of view;

[0056] 2)将红色滤光纸放在摄像机前方,由于红色滤光纸能将防水靶标中的红色吸收, 因此该防水靶标在带有红色滤光纸的摄像机中呈现为统一的背景色。 [0056] 2) the red filter paper in front of the camera, since the red filter paper can red absorbing water in the target, thus rendering the water target to a uniform background color camera with a red filter paper. 用摄像机采集图像, 该图像只含有投射靶标的成像,记为?1,(丨=1,2,3,'"8); A camera to capture the projection image contains only the target image, referred to as 1, (Shu = 1,2,3, '' 8)?;

[0057] 3)将投影仪关掉,移开红色滤光纸,并采集红白棋盘格防水靶标图像,该图像只含有防水靶标的成像,记为Cl,(i = l,2,3,'"g); [0057] 3) turn off the projector, remove the red filter paper, and red and white checkered water collecting the target image, the image of the target image contains only water, referred to as Cl, (i = l, 2,3, ' "g);

[0058] 4)重复进行1)~3)步,直到采集足够的图幅数,需至少采集3对图像。 [0058] 4) repeating 1) to 3) step, until a sufficient number of pieces of FIG acquisition, need at least three image capture.

[0059]采用红白棋盘格防水靶标和红黑棋盘格投射靶标为本发明所述合理使用滤光器件的例子之一,任何以类似方式使用滤光器件的标定方式均在保护范围内。 [0059] The red and white checkerboard waterproof red and black checkered target and one target projection optical Examples of the rational use of the standard device of the present invention in any way calibrated in a similar manner using the optical devices within the scope of protection.

[0060] 3、提取图像(^中角点的图像坐标,根据已标定的摄像机,计算图像Cl中平板所在平面在摄像机坐标系下的法向向量^7,计算方法参见此1'1:167 1?.1.,2188 61'11^11所著的"Multiple view geometry in computer vision,Cambridge University Press,2004"。 [0060] 3, extracts the image (in image coordinates ^ corner point, in accordance with a calibrated camera, Cl image is calculated in the plane of plate method under the camera coordinate system to the vector ^ 7, this calculation method, see 1'1: 167 1? .1., 2188 61'11 ^ 11 book "Multiple view geometry in computer vision, Cambridge University Press, 2004".

[0061] 4、提取图像? [0061] 4, extract images? 1中角点的图像坐标,由摄像机参数和角点的图像坐标确定一条射线,利用该射线和步骤3中求得的平面法向向量,可以求得投射在平板上的投射靶标在摄像机坐标系下的三维坐标。 The image coordinates of a corner point determined by the camera parameters and the image coordinates of one corner rays by the radiation obtained in step 3 and the plane normal vector, can be obtained on the projection of the projection target in a camera coordinate system plate under the three-dimensional coordinates.

[0062] 5、根据投射靶标角点的投影仪图像坐标&,以及步骤4中求得的其对应的空间点的三维坐标戈^,利用单视点模型,初步标定投影仪参数以及投影仪到摄像机之间的结构参数,具体方法参见周富强著"《双目立体视觉检测的关键技术研究》,北京航空航天大学博士后研究工作报告,2002"。 [0062] 5, the three-dimensional coordinates of Ge determined in 4 according to the projection target corner projector image coordinates &, and the step of spatial points corresponding ^, using a single-view models, the initial calibration of the projector parameters and a projector to camera between the structural parameters, the specific methods see Zhou Fuqiang the "" key technology research binocular visual inspection ", Beijing University postdoctoral research report on the work of Aeronautics and Astronautics, 2002."

[0063] 6、使用步骤5中得到的结构参数,表示平板所在平面在投影仪坐标系下的法向向量心 [0063] 6, the structural parameters obtained in Step 5, the vector represents the center plane of the plate lies in the method of the projector coordinate system

[0064] [0064]

Figure CN103985121BD00071

[10] [10]

[0065] 式中结构参数R和T分别为摄像机坐标系到投影仪坐标系的旋转矩阵和平移向量。 [0065] wherein R and T are structural parameters of the camera coordinate system to a rotation matrix and translation vector of the projector coordinate system. [0066] 7、给定投影仪光心沿光轴方向到窗口平面的距离d初值,例如当投影仪镜头距离窗口平面很近时,可以令d = 0;设定投影仪光轴相对于窗口平面法向向量之间的偏角奶和转角W2的初值均为0。 [0066] 7, to the optical center of the optical axis direction of the projector window to the initial value planar distance d, for example, when a short distance from the projector lens plane of the window, can make d = 0; set with respect to the optical axis of the projector Initial window plane normal vector and the angle between the rotation angle milk W2 are 0. 利用图像?1中的角点的图像坐标,由式[1]~式[6]建立每个角点发出的光线在防水装置中的空气介质传播时的光线模型,称为入射光线R in。 Using the image? Corner coordinates of the image points in the 1, represented by the formula [1] to the formula [6] model established when the light rays emitted from each corner point in the air propagation medium means water, referred to as incident ray R in.

[0067] 8、根据步骤7中建立的每条入射光线Rin,由式[7 ]和式[8 ]建立对应的折射光线的单位向量先ut,确定了每个角点所对应的光线轨迹,接下来需要确定式[9]中的尺度因子0, 从而确定折射光线在何处与平板相交。 [0067] 8. The Rin of each incident light ray established in step 7, by the formula [7] and the formula [8] to establish a corresponding first refracted ray UT unit vector, determines for each corner the corresponding ray trace, Next, the scale factor needed to determine 0 the formula [9], refraction of light to determine where the plate intersects.

[0068] 9、根据几何约束有: [0068] 9. The geometric constraints are:

[0069] [0069]

Figure CN103985121BD00072

[II] [II]

[0070]将式[9]代入式[11],由下式可以求解出尺度因子扎 [0070] formula [9] into equation [11], the formula bar can be solved by a scale factor

[0071] [0071]

Figure CN103985121BD00081

[12] [12]

[0072] 10、将步骤9中求得的尺度因子0代入[9]式,即可求得投影仪坐标系下投影靶标所投射在平板上所对应的空间点的三维坐标XP。 [0072] 10, in step 9 the obtained scale factor 0 is substituted into equation [9] can be obtained at a projection target projected by the projector in the space coordinate point on the tablet corresponding to the three-dimensional coordinates XP.

[0073] 11、将步骤4中计算出的三维坐标戈,利用步骤6中的结构参数转换至投影仪坐标系下即为 [0073] 11, Step 4 in the three-dimensional coordinates calculated Ge, configuration parameters 6 using the conversion step to the projector coordinate system is the

[0074] 12、将;^作为参考值,用其与步骤10中所得的三维坐标心之间的距离建立目标函数: [0074] 12, the; ^ as a reference value, the distance between the objective function and the three-dimensional coordinates of the center thereof obtained in Step 10:

[0075] [0075]

Figure CN103985121BD00082

[0076] 以步骤5中标定得到的投影仪参数和结构参数作为优化搜索的初值,畸变系数初值均设为〇,其它参数初值参见步骤7。 [0076] projector and structure parameters in Step 5 was calibrated optimization search as the initial value, the initial value of the distortion coefficient are set to square, other initial parameters see Step 7. 利用Levenberg-Marquardt算法对公式[13]进行非线性优化,将优化取得的结构参数R,T应用于步骤6和步骤11的坐标转换,进行递归搜索参数的最优值,直到目标函数值小于设定的距离误差阈值,阈值根据测量精度要求设置,一般为1E-5至0•lmm〇 Using the Levenberg-Marquardt algorithm of equation [13] for the nonlinear optimization, the optimization of structure parameters obtained R, T 6 and applied to the coordinate conversion step of step 11, the value of the optimal parameter search recursively until the objective function value is less than the set given distance error threshold, the threshold value set based on the measurement accuracy, typically 1E-5 to 0 • lmm〇

[0077]实施例 [0077] Example

[0078]采用3500流明的投影仪,分辨率为1024像素X768像素。 [0078] The projector 3500 lumens, a resolution of 1024 pixels X768 pixels. 将投影仪装入防水装置中固定,并与分辨率为1024像素X768像素的光纤摄像机组成结构光传感器。 The projector apparatus in a waterproof fixed, with a resolution of 1024 pixels and a pixel X768 fiber structure composed of the camera photosensor. 投影仪和摄像机相对位置固定。 Fixed position relative to the projector and the camera.

[0079]制作的防水靶标为红白棋盘格靶标,靶标的角点之间距离为34.75mm。 [0079] Production of waterproof targets for red and white checkerboard target, between the target angular distance of the point 34.75mm. 设计的投射靶标为红黑棋盘格靶标,其角点之间的图像距离为64像素。 Projection design targets for red and black checkered target, the distance between the image point of the corners 64 pixels. 利用本发明所述图像采集方法, 将结构光传感器放入实验水池中采集了10组共20张图像。 By the image acquisition method according to the present invention, a structured light sensor to loading the pool collected in 10 groups and 20 images. 利用本发明所述方法进行投影仪和结构参数标定,结果见表1。 Using the method of the present invention and the structural parameters of the projector calibration, the results in Table 1. 表2为参考值三维坐标与利用模型计算得到三维坐标之间的均方根误差。 Table 2 is a three-dimensional coordinates and a reference value calculated using a model RMS error between the three-dimensional coordinates.

[0080]从表1和表2的数据可以看出,采用本发明提出的水下投影仪标定方法,标定得到的投影仪参数和结构参数结果可靠,该方法的标定精度能够满足水下定性监测和定量测量任务。 [0080] From the data in Table 1 and Table 2 can be seen underwater projector calibration method proposed by the present invention, reliable and structural parameters of the projector calibration results obtained, the calibration accuracy of the method can meet the underwater monitored qualitatively and quantitative measurement tasks.

[0081 ]表1投影仪结构光传感器标定结果 [0081] Table 1 projector structured light sensor calibration results

[0082] [0082]

Figure CN103985121BD00083

[0083] [0083]

Figure CN103985121BD00091

[0084] 表2三维坐标的均方根误差 [0084] Table 2 dimensional coordinates RMSE

[0085] [0085]

Figure CN103985121BD00092

[0086] 以上所述为本发明的实施例,并非用于限定本发明的保护范围。 Embodiment [0086] The above embodiment of the present invention, not intended to limit the scope of the present invention.

Claims (2)

  1. 1. 一种水下投影仪标定方法,其特征在于该方法包含以下步骤: 1.1、 调整位于水下的投影仪结构光传感器,保证摄像机在测量范围内能够拍摄清晰图像且投影仪在测量范围内能够投射清晰图像,在投影仪和已标定摄像机的公共视场范围内,采用一附有防水靶标的平板,同时投影仪对该平板投射另一靶标,称为投射靶标,调整平板位置,直到两个靶标特征点都位于公共视场范围内;自由移动靶标至少三个位置,每移动一个位置,拍摄含有两个靶标的图像对; 1.2、 提取图像中防水靶标特征点的图像坐标,根据已标定摄像机的参数,求取平板所在平面在摄像机坐标系下的法向向量; 1.3、 提取图像中投射靶标特征点的图像坐标,利用步骤1.2中求得的法向向量,由摄像机参数和特征点的图像坐标,计算投射靶标投射在平板上的对应空间点位于摄像机坐标 1. An underwater projector calibration method, characterized in that the method comprises the steps of: 1.1, structured light projector sensor adjustment under water, to ensure that within the measuring range and clear image projector camera capable of capturing the measurement range a clear image can be projected, in the projector and the common field of view of the camera has been calibrated using a target plate with water, while the other projector is projected to the target plate, referred to as the projection target, the position adjusting plate, until the two a target feature points are located within a common field of view; free running target mark at least three positions, each shifted by one position, shooting the two target images; 1.2, extracting image coordinates of the image of the standard feature point waterproof target, according calibrated parameters of the camera, obtaining the vector to the plane plate method under the camera coordinate system; 1.3, extracting image coordinates of the projection image of the target feature points, obtained in step 1.2 using the normal vector, the feature points and camera parameters image coordinates, calculating the projection-target projected on the plate corresponding spatial coordinates of points located on the camera 下的三维坐标; 1.4、 根据投射靶标在图像坐标,以及步骤1.3中求得的其对应空间点的三维坐标,利用单视点模型,对投影仪结构光传感器进行初步标定,标定的参数为投影仪参数以及表示投影仪与摄像机之间刚体变换的结构参数; 1.5、 使用步骤1.4中得到的结构参数,将步骤1.2中所求的法向向量表示在投影仪坐标系下; 1.6、 在投影仪坐标系下,给定投影仪光心沿光轴方向到防水装置窗口平面的距离初值,建立投影仪图像上每个特征点发出的光线在防水装置中的空气介质传播时光线模型, 称为入射光线; 1.7、 建立折射光线的单位向量,根据几何约束求解出尺度因子,确定折射光线长度,求解投影仪坐标系下投影靶标特征点的三维坐标; 1.8、 将步骤1.3中计算出的三维坐标利用步骤1.4中的结构参数转换至投影仪坐标系下作为参考值; 1.9、 给定投 Three-dimensional coordinates; and 1.4, the three-dimensional coordinates of the projection target 1.3 obtained in the image coordinates, and a step corresponding spatial points, using a single-view models, the projector structured light sensor initial calibration, the calibration parameters for the projector parameters and structural parameters showing the rigid transformation between the projector and the camera; 1.5, the structure parameters obtained in step 1.4, step 1.2 will be required in the method shown in the projector coordinate system to the vector; 1.6, in the projector coordinate the system, given the projector optical center axis direction from the initial value to the plane of the window waterproof device, establish the light emitted from each of the feature points on the image projector apparatus in an air medium in a waterproof light propagation model, referred to as incident light; 1.7, establishing unit vector of the light refraction according to the geometric constraint solving a scale factor, determined refracted ray length, solving the three-dimensional coordinates of the standard feature points of the projection target at the projector coordinate system; 1.8, calculated in step 1.3 the three-dimensional coordinates using structure parameters in step 1.4 to convert the reference value as the coordinate system of the projector; 1.9, given vote 仪光轴相对于窗口平面法向向量之间偏角和转角的初值,以步骤1.7中所述的三维坐标与1.8所述的参考值之间的距离建立目标函数,对投影仪参数和结构参数进行优化,并进行递归优化,即求得的结构参数用于步骤1.5~1.8,直到目标函数值满足设定阈值,阈值根据测量精度要求设定,其范围为1〇_ 5~0.1mm。 Instrument with respect to an optical axis plane of the window between the normal vector and rotation angle of the initial value, the distance between the three-dimensional coordinates of the step with a reference value of the objective function is 1.8 1.7, parameters and structure of the projector parameters are optimized, and a recursive optimization, i.e., the structural parameters determined for the steps 1.5 to 1.8, until the target function value satisfies the set threshold value, the threshold value is set according to the required measurement accuracy, the range of 1〇_ 5 ~ 0.1mm.
  2. 2. 根据权利要求1所述的一种水下投影仪标定方法,其特征在于: 2.1、 步骤1.1所述的防水靶标为防水材质制成的平面靶标,固定在一平板上,防水靶标厚度与测量距离相比可忽略不计,靶标特征点为平面上的格点,格点之间距离的设计由实际测量距离和摄像机视场确定,其范围为10~100mm;所述的投射靶标,其格点之间的图像坐标距离根据投影仪图像的分辨率确定,其范围为10~100像素; 2.2、 步骤1.1所述的防水靶标和投射靶标,在摄像机合理使用滤光器件的前提下,两靶标在平板上所占区域可重叠;当平板在同一位置时,摄像机不使用滤光器件且投影仪不投射靶标时,摄像机拍摄只得到防水靶标图像,当摄像机使用滤光器件且投影仪投射靶标时, 该靶标与防水靶标有重叠区域,摄像机拍摄只得到投射靶标图像; 2.3、 步骤1.1所述的拍摄含有两个靶标的 2. An underwater projector calibration method according to claim 1, wherein: 2.1, 1.1 of the planar target step waterproof target made of waterproof material, fixed on a plate, the thickness of the target and standard waterproof measuring distance compared negligible, the target feature point of the lattice points on the plane, the design distance between the grid points is determined by the actual measured distance and the camera field of view, the range of 10 ~ 100mm; projection target according to which cell image coordinate distance between the points of the image according to the resolution of the projector is determined, range from 10 to 100 pixels; 2.2, step 1.1 waterproof projection target and target, on the premise of the camera device rational use of filters, two target the area occupied may be superimposed on the plate; when the tablet at the same position, the camera without using a filter device and the projector is not the projection target, cameras only get water the target image, when the camera using a filter device and the projector projects the target the target and target waterproof overlap region captured by the camera is projected only the target image; capturing 2.3, step 1.1 having two targets 像对,其特征在于,当使用滤光器件时,每一个位置拍摄两幅图像,为分别含有防水靶标和投射靶标的图像对。 Like on, wherein, when using a filter device, each of the two position of the captured image, a target containing water and a projection image of the target, respectively.
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