CN105125303B - Dental Stereoscopic Image Construction Method - Google Patents
Dental Stereoscopic Image Construction Method Download PDFInfo
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- CN105125303B CN105125303B CN201410238874.0A CN201410238874A CN105125303B CN 105125303 B CN105125303 B CN 105125303B CN 201410238874 A CN201410238874 A CN 201410238874A CN 105125303 B CN105125303 B CN 105125303B
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- 238000010276 construction Methods 0.000 title 1
- 210000002455 dental arch Anatomy 0.000 claims abstract description 64
- 238000000034 method Methods 0.000 claims abstract description 20
- 239000000523 sample Substances 0.000 claims abstract description 16
- 238000005070 sampling Methods 0.000 claims description 5
- 238000004364 calculation method Methods 0.000 abstract description 23
- 238000012545 processing Methods 0.000 abstract description 13
- 238000012216 screening Methods 0.000 abstract description 2
- 230000001225 therapeutic effect Effects 0.000 abstract 1
- 230000005484 gravity Effects 0.000 description 14
- 238000010586 diagram Methods 0.000 description 13
- 238000006073 displacement reaction Methods 0.000 description 8
- 239000013598 vector Substances 0.000 description 8
- 239000007787 solid Substances 0.000 description 3
- 238000013519 translation Methods 0.000 description 3
- 238000012937 correction Methods 0.000 description 2
- 241000282465 Canis Species 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 210000001847 jaw Anatomy 0.000 description 1
- 210000000214 mouth Anatomy 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 210000001519 tissue Anatomy 0.000 description 1
- 238000003325 tomography Methods 0.000 description 1
Abstract
Description
技术领域technical field
本发明是关于一种牙体立体影像建立方法，通过初步坐标位移与牙弓曲线校正而得出精确的牙体模型。The invention relates to a method for establishing a three-dimensional image of a tooth body, which obtains an accurate tooth body model through preliminary coordinate displacement and dental arch curve correction.
背景技术Background technique
请参考中国台湾专利公开第201302166号案，其公开一种齿模位置方法，实施该方法需使用多种硬件装置，包含有咬合器、设有标记元件与参考物件的标记模组与感测装置。该前案是应用于电脑断层(CT)影像的重建与定位，患者必须操作在咬合器并咬着该标记模组，才可以进行位置标记，造成患者在临床治疗上的不舒适感。再者，该前案的治具结构复杂，容易造成位置感测的误差。Please refer to China Taiwan Patent Publication No. 201302166, which discloses a tooth mold positioning method. The implementation of this method requires the use of various hardware devices, including an articulator, a marking module with a marking element and a reference object, and a sensing device. . The previous proposal was applied to the reconstruction and positioning of computerized tomography (CT) images. The patient must operate the articulator and bite the marking module before the position marking can be performed, which causes discomfort for the patient in clinical treatment. Furthermore, the jig structure of this prior art is complicated, which easily causes errors in position sensing.
发明内容Contents of the invention
本发明的目的是提供一种颚牙体立体影像模型建立方法，以解决现有技术中因复杂结构容易产生误差的缺陷。The purpose of the present invention is to provide a method for establishing a three-dimensional image model of jaws and teeth, so as to solve the defect that errors are easily generated due to complex structures in the prior art.
本发明的技术方案是提供一种牙体立体影像建立方法，包含：The technical solution of the present invention is to provide a method for establishing a three-dimensional image of a tooth, comprising:
利用一探头拍摄多个牙齿以产生多个牙齿第一点云数据与第二点云数据，该第一点云数据与第二点云数据分别具有对应的X轴、Y轴与Z轴旋转索引值；Using a probe to photograph a plurality of teeth to generate a plurality of tooth first point cloud data and second point cloud data, the first point cloud data and the second point cloud data have corresponding X-axis, Y-axis and Z-axis rotation indexes respectively value;
由一影像处理装置接收该第一点云数据、第二点云数据与旋转索引值，并根据一影像位移对照表与该旋转索引值叠合多个牙齿的第一点云数据与第二点云数据以形成一临床牙体立体影像；The first point cloud data, the second point cloud data and the rotation index value are received by an image processing device, and the first point cloud data and the second point cloud data of a plurality of teeth are superimposed according to an image displacement comparison table and the rotation index value Cloud data to form a clinical three-dimensional image of teeth;
筛选该临床牙体立体影像上的顶点，使筛选出的顶点仅对应分布在牙齿的咬合面上；Screening vertices on the clinical tooth stereoscopic image, so that the selected vertices are only correspondingly distributed on the occlusal surface of the teeth;
对筛选出的顶点进行多项式拟合计算以取得一初步牙弓曲线；Perform polynomial fitting calculation on the screened vertices to obtain a preliminary dental arch curve;
对该初步牙弓曲线进行等分后，产生多个真子集，各真子集包含有至少一顶点；After equally dividing the preliminary dental arch curve, multiple proper subsets are generated, and each proper subset contains at least one vertex;
于每组真子集中定义出一拟合参照点；defining a fitting reference point in each proper subset;
以多项式拟合这些拟合参照点以得到一临床牙弓曲线；fitting these fitting reference points with a polynomial to obtain a clinical dental arch curve;
根据该临床牙弓曲线的任一重心点与一标准牙弓曲线上所有的数据点进行第K个邻近取样法(k-th nearest neighbor method,KNN method)，以得出最接近各重心点的一数据点；According to any center of gravity point of the clinical dental arch curve and all data points on a standard dental arch curve, the Kth nearest neighbor sampling method (k-th nearest neighbor method, KNN method) is performed to obtain the closest neighbor to each center of gravity point. a data point;
根据各重心点与其对应数据点的偏移量对该临床牙体立体影像进行校正。The clinical tooth stereoscopic image is corrected according to the offset between each center of gravity point and its corresponding data point.
本发明仅利用探头拍摄患者的牙齿影像，并利用影像处理方式进行牙体模型的建立，自然不会有现有技术所述使用复杂硬件设备导致患者不舒适感的缺点；也因本发明没有使用复杂的硬件结构，本发明主要通过演算法进行牙体模型的建立，自然避免现有技术所述结构因素导致感测误差的缺失。The present invention only uses the probe to take images of the patient's teeth, and utilizes the image processing method to establish the dental model. Naturally, there is no disadvantage of using complex hardware equipment in the prior art to cause discomfort to the patient; also because the present invention does not use Due to the complex hardware structure, the present invention mainly establishes the tooth model through algorithms, which naturally avoids the lack of sensing errors caused by the structural factors described in the prior art.
附图说明Description of drawings
图1：本发明立体牙齿建模系统的电路方块示意图。Fig. 1: A schematic circuit block diagram of the three-dimensional tooth modeling system of the present invention.
图2：本发明中建立标准牙体立体影像与标准牙弓曲线的流程示意图。Fig. 2: A schematic flow chart of establishing a standard tooth stereoscopic image and a standard dental arch curve in the present invention.
图3：本发明拍摄牙齿舌侧面示意图。Fig. 3: Schematic diagram of photographing the lingual side of a tooth in the present invention.
图4：本发明拍摄牙齿颊侧面示意图。Figure 4: Schematic diagram of photographing the buccal side of teeth in the present invention.
图5：本发明第一标准影像与第二标准影像叠合示意图Figure 5: Schematic diagram of superposition of the first standard image and the second standard image in the present invention
图6：本发明产生咬合平面YOCC的示意图。Figure 6: Schematic representation of the invention producing an occlusal plane Y OCC .
图7：本发明顶点分布在牙齿咬合面与牙龈处的示意图。Fig. 7: A schematic diagram of distribution of vertices in the occlusal surface and gums of the present invention.
图8：本发明顶点仅分布在牙齿咬合面的示意图。Fig. 8: A schematic diagram of the vertices of the present invention distributed only on the occlusal surface of the teeth.
图9：本发明根据图7的顶点拟合出的初步牙弓曲线的示意图。Fig. 9: A schematic diagram of the preliminary dental arch curve fitted according to the vertices in Fig. 7 according to the present invention.
图10：本发明在真子集找出拟合参照点的示意图。Fig. 10: A schematic diagram of the present invention finding fitting reference points in proper subsets.
图11：本发明拟合图10的拟合参照点得到临床牙弓曲线的示意图。Fig. 11: A schematic diagram of the present invention fitting the fitting reference points in Fig. 10 to obtain a clinical dental arch curve.
图12：本发明中建立临床牙体立体影像与临床牙弓曲线的流程示意图。Fig. 12: Schematic flow chart of establishing clinical dental stereoscopic images and clinical dental arch curves in the present invention.
图13：本发明标准牙弓曲线与临床牙弓曲线的示意图。Fig. 13: A schematic diagram of the standard dental arch curve and the clinical dental arch curve of the present invention.
图14：本发明标准牙弓曲线与临床牙弓曲线部分线段的示意图。Fig. 14: Schematic diagram of the standard dental arch curve and partial line segments of the clinical dental arch curve in the present invention.
主要元件符号说明Description of main component symbols
10 探头 11 姿态感测器10 Probe 11 Attitude Sensor
12 点云数据取样单元 100 牙齿12 point cloud data sampling units 100 teeth
101 牙齿舌侧面 102 牙齿颊侧面101 Teeth lingual 102 Teeth buccal
20 影像处理装置 21 坐标数值回授比对单元20 Image processing device 21 Coordinate value feedback comparison unit
22 标准牙模对位坐标数据库 23 牙体点云数据处理单元22 Standard dental model alignment coordinate database 23 Dental point cloud data processing unit
24 第一阶段贴合计算单元 25 比对计算单元24 The first stage fitting computing unit 25 Comparing computing unit
26 第二阶段贴合计算单元 31 标准牙弓曲线26 Second stage fitting calculation unit 31 Standard dental arch curve
310 数据点 32 临床牙弓曲线310 data points 32 clinical arch curves
320 重心点 40 标准牙体立体影像320 center of gravity 40 standard dental stereo images
401 咬合面 402 牙龈401 Occlusion 402 Gum
41 顶点 42 拟合参照点41 Vertices 42 Fitting reference points
50 初步牙弓曲线 51 标准牙弓曲线50 Preliminary Arch Curve 51 Standard Arch Curve
500 等分线500 bisector
具体实施方式detailed description
请参考图1所示，本发明立体牙齿建模系统包含有一探头10与一影像处理装置20。该探头10具有拍照功能并设有一姿态感测器11与一点云数据取样单元12，其中该姿态感测器11可为陀螺仪。该影像处理装置20可为设于该探头10外的电脑，且该影像处理装置20连线到该探头10以进行数据传输，并负责牙齿立体影像模型的建立与校正。该影像处理装置20包含有一坐标数值回授比对单元21、一标准牙模对位坐标数据库22、一牙体点云数据处理单元23、一第一阶段贴合计算单元24、一比对计算单元25与一第二阶段贴合计算单元26。Please refer to FIG. 1 , the three-dimensional dental modeling system of the present invention includes a probe 10 and an image processing device 20 . The probe 10 has a camera function and is provided with an attitude sensor 11 and a point cloud data sampling unit 12, wherein the attitude sensor 11 can be a gyroscope. The image processing device 20 can be a computer installed outside the probe 10, and the image processing device 20 is connected to the probe 10 for data transmission, and is responsible for establishing and correcting the three-dimensional image model of teeth. The image processing device 20 includes a coordinate value feedback comparison unit 21, a standard dental mold alignment coordinate database 22, a dental point cloud data processing unit 23, a first-stage fit calculation unit 24, and a comparison calculation unit. The unit 25 is attached to a second stage calculation unit 26 .
本发明是对标准牙齿实体模型与患者口腔内的牙齿分别建构出一标准牙体立体影像与一临床牙体立体影像，并分别计算出一标准牙弓曲线与一临床牙弓曲线，以在判断出该临床牙弓曲线与标准牙弓曲线的误差后，对该临床牙体立体影像进行校正。以下请配合图2所示，先以该标准牙弓曲线的建立为例说明。The present invention constructs a standard tooth body stereoscopic image and a clinical tooth body stereoscopic image respectively for the standard tooth solid model and the teeth in the patient's oral cavity, and calculates a standard dental arch curve and a clinical dental arch curve respectively to judge After finding out the error between the clinical dental arch curve and the standard dental arch curve, the clinical dental stereoscopic image is corrected. Please take the establishment of the standard dental arch curve as an example to illustrate as shown in Figure 2 below.
使用者可持该探头10拍摄该标准牙齿实体模型，本实施例仅以拍摄下颚牙齿为例说明，但本发明同样可应用于上颚牙齿。对于单颗牙齿100而言，主要是对该牙齿100拍摄一第一标准影像与一第二标准影像，第一与第二标准影像为点云(point cloud)数据，其中点云数据是指由点构成的图案，请参考图3所示，该第一标准影像可为朝该牙齿舌侧面101所拍摄的影像，且拍摄角度为相对一水平面呈45度角，请参考图4所示，该第二标准影像可为朝该牙齿颊侧面102所拍摄的影像，且拍摄角度为相对一水平面呈45度角。于拍摄时，该姿态感测器11是根据拍摄当时该探头10的空间位置产生空间坐标参数，在直角坐标系统下，空间坐标参数包含有x轴旋转索引值(yaw)、y轴旋转索引值(pitch)、z轴旋转索引值(roll)、x坐标(dx)、y坐标(dy)、z坐标(dz)(步骤101)。因此，每张拍摄的标准影像都有对应的空间坐标参数。The user can hold the probe 10 to take pictures of the standard tooth solid model. The present embodiment only takes pictures of the mandibular teeth as an example, but the present invention can also be applied to the mandibular teeth. For a single tooth 100, it is mainly to shoot a first standard image and a second standard image for the tooth 100, the first and second standard images are point cloud (point cloud) data, wherein the point cloud data refers to the For the pattern formed by the dots, please refer to FIG. 3. The first standard image can be an image taken towards the lingual side of the tooth 101, and the shooting angle is 45 degrees relative to a horizontal plane. Please refer to FIG. 4. The The second standard image can be an image taken toward the buccal side 102 of the tooth, and the shooting angle is 45 degrees relative to a horizontal plane. When shooting, the attitude sensor 11 generates space coordinate parameters according to the spatial position of the probe 10 at the time of shooting. Under the Cartesian coordinate system, the space coordinate parameters include x-axis rotation index value (yaw) and y-axis rotation index value (pitch), z-axis rotation index value (roll), x coordinate (dx), y coordinate (dy), z coordinate (dz) (step 101). Therefore, each captured standard image has corresponding spatial coordinate parameters.
取得第一与第二标准影像后，使用者可操作该影像处理装置20以将该第一标准影像与第二标准影像中的牙齿部分相互对位与叠合，如图5所示，为第一标准影像A与第二标准影像B叠合后的示意图，并记录该第一标准影像与第二标准影像的在x轴方向、y轴方向与z轴方向上的平移量。因此，当拍摄完该标准牙齿实体模型的所有牙齿并完成叠合动作后，形成一标准牙体立体影像，并取得一系列牙齿的旋转索引值及对应的平移量，则这些旋转索引值与平移量可在该标准牙模对位坐标数据库22中建立一影像位移对照表(步骤102)。After obtaining the first and second standard images, the user can operate the image processing device 20 to align and superimpose the tooth parts in the first standard image and the second standard image, as shown in FIG. A schematic diagram of superimposing a standard image A and a second standard image B, and recording the translation amounts of the first standard image and the second standard image in the x-axis direction, the y-axis direction and the z-axis direction. Therefore, after shooting all the teeth of the standard tooth solid model and completing the superposition action, a standard tooth body stereoscopic image is formed, and a series of tooth rotation index values and corresponding translation values are obtained, then these rotation index values and translation An image displacement comparison table can be established in the standard dental model alignment coordinate database 22 (step 102).
建立出该标准牙体立体影像后，由该比对计算单元25接收该标准牙体立体影像以进行其标准牙弓曲线的计算，以下根据胡颂玉等人所著《牙弓拥挤度分析技术研究》<http://www.zclw.net/article/sort040/sort046/info-7554.html>说明牙弓曲线的计算，如附件。After the standard dental stereoscopic image is established, the comparison calculation unit 25 receives the standard dental stereoscopic image to calculate the standard dental arch curve. <http://www.zclw.net/article/sort040/sort046/info-7554.html> explains the calculation of the dental arch curve, as attached.
请参考图6所示，该比对计算单元25首先在该标准牙体立体影像40定义出四个特征点B1、B2、B3、B4，该四个特征点B1、B2、B3、B4分别为左、右恒牙的颊侧尖点与左、右尖牙的颊侧尖点，本发明是以平均标准差方法计算出一咬合平面YOCC，前述特征点B1～B4为最接近咬合平面YOCC的四个点。Please refer to FIG. 6 , the comparison calculation unit 25 first defines four feature points B1, B2, B3, and B4 on the standard tooth stereoscopic image 40, and the four feature points B1, B2, B3, and B4 are respectively For the buccal cusps of the left and right permanent teeth and the buccal cusps of the left and right canines, the present invention calculates an occlusal plane Y OCC with the method of average standard deviation, and the aforementioned feature points B1-B4 are the closest to the occlusal plane Y Four points of OCC .
于计算出咬合平面YOCC后，是在该标准牙体立体影像40的点云数据中筛选出特征点，以根据筛选出的特征点进行后续标准牙弓曲线的计算。该标准牙体立体影像40的点云数据中，任三点可建构出一个三角网格，因此多个点可建构出多个三角网格，由这些三角网格近似牙齿与周边组织的曲面。由于多个三角网格构成的近似曲面为分片线性曲面(piecewise linear approximation)，本发明采用面积加权法计算三角网格顶点点云数据的特征向量，顶点的特征向量可表示如下：After the occlusal plane Y OCC is calculated, feature points are selected from the point cloud data of the standard dental stereoscopic image 40 , so as to perform subsequent calculation of the standard dental arch curve based on the selected feature points. In the point cloud data of the standard dental stereoscopic image 40, any three points can construct a triangular mesh, so multiple points can construct multiple triangular meshes, and these triangular meshes approximate the curved surface of the tooth and surrounding tissues. Since the approximate surface formed by a plurality of triangular meshes is a piecewise linear approximation, the present invention uses the area weighting method to calculate the eigenvectors of the point cloud data of the vertices of the triangular meshes, and the eigenvectors of the vertices can be expressed as follows:
Ai,j与分别表示第j个三角网格的面积与单位向量。若以xi、yi与zi代表三角网格的顶点坐标，则所有三角网格顶点的集合定义如下：A i,j and represent the area and unit vector of the jth triangular mesh, respectively. If x i , y i and z i represent the vertex coordinates of the triangular mesh, the set of all vertices of the triangular mesh is defined as follows:
接近在该咬合平面YOCC上的顶点可作为建立一初步牙弓曲线的参照点，咬合平面YOCC可以近似作为各顶点的切平面，因此在顶点处咬合平面YOCC的向量和三角网格顶点向量的方向近似一致，故以一集合Sφ表示顶点向量与咬合面向量(即咬合平面YOCC的法向量)的夹角小于一预设角度φ的定点集合，Sφ定义如下，其中预设角度φ＝10°由实验模拟的较佳结果。The vertices close to the occlusal plane Y OCC can be used as a reference point for establishing a preliminary dental arch curve, and the occlusal plane Y OCC can be approximated as the tangent plane of each vertex, so the vector of the occlusal plane Y OCC and the vertices of the triangular mesh at the vertex The directions of the vectors are approximately the same, so a set S φ represents the vertex vector with occlusal plane vector (That is, the normal vector of the occlusal plane Y OCC ) is a set of fixed points whose included angle is smaller than a preset angle φ, S φ is defined as follows, wherein the preset angle φ=10° is a better result of experimental simulation.
请参考图7所示的对照图，由Sφ筛选出的三角网格顶点41分布在牙齿咬合面401与牙龈402。本发明使用一真子集S* φτ以排除位于牙龈402处的顶点41，真子集S* φτ定义如下：Please refer to the comparison diagram shown in FIG. 7 , the triangular mesh vertices 41 selected by S φ are distributed on the occlusal surface 401 and the gum 402 . The present invention uses a proper subset S * φτ to exclude the vertex 41 located at the gum 402, and the proper subset S * φτ is defined as follows:
其中dis(Vi,YOCC)表示顶点41至咬合平面YOCC之间的距离，τ为常数，本较佳实施例是以τ＝3(mm)，τ的值是预设在影像处理装置20中，真子集S* φτ筛选出的顶点请参考图8所示，可见顶点41仅分布在咬合面401上，没有分布在牙龈处，留下的顶点41即作为建立初步牙弓曲线的参照点(步骤103)。Where dis(V i , Y OCC ) represents the distance between the vertex 41 and the occlusal plane Y OCC , τ is a constant, and in this preferred embodiment, τ=3 (mm), the value of τ is preset in the image processing device In 20, the vertices selected by the proper subset S * φτ are shown in Fig. 8. It can be seen that the vertices 41 are only distributed on the occlusal surface 401, and are not distributed on the gums. The remaining vertices 41 are used as a reference for establishing the preliminary dental arch curve point (step 103).
请参考图8所示，接着根据真子集S* φτ筛选出的顶点41进行多项式拟合计算以取得初步牙弓曲线，本发明是以四次多项式拟合出该初步牙弓曲线方程式f(x,y)＝ax4+bx3+cx2+dx+e-y，其中多项式系数a～e是由带权的最小平方法求出(步骤104)。Please refer to FIG. 8 , and then perform polynomial fitting calculation on vertices 41 screened out according to the proper subset S * φτ to obtain the preliminary dental arch curve. The present invention uses a quartic polynomial to fit the preliminary dental arch curve equation f(x ,y)=ax 4 +bx 3 +cx 2 +dx+ey, wherein the polynomial coefficients a~e are obtained by the weighted least square method (step 104).
请参考图9所示，揭露筛选后的顶点41在XOY坐标平面的投影点，以及根据这些投影点拟合出的初步牙弓曲线50。Please refer to FIG. 9 , which discloses the projected points of the screened vertices 41 on the XOY coordinate plane, and the preliminary dental arch curve 50 fitted according to these projected points.
接着，将该初步牙弓曲线50由多个等分线500等分为n个区段，并在每个等分点插入一法平面以对S* φτ的集合进行划分，即得到S* φτ的多个组真子集S*1 φτ、S*2 φτ…S*n φτ(步骤105)。假设初步牙弓曲线50在第i个等分点处的切向量(即等分面的法向量)为在X轴上的分量为沿X轴增加的方向，S*i φτ定义如下：Next, the preliminary dental arch curve 50 is equally divided into n segments by a plurality of bisectors 500, and a normal plane is inserted at each bisector point to divide the set of S * φτ , that is, S * φτ Multiple groups of proper subsets S *1 φτ , S *2 φτ ... S *n φτ (step 105 ). Assume that the tangent vector (i.e. the normal vector of the bisecting surface) of the preliminary dental arch curve 50 at the i-th bisecting point is The component on the X-axis is the direction that increases along the X-axis, and S *i φτ is defined as follows:
请参考图10所示，接着计算在每组真子集S*1 φτ、S*2 φτ…S*n φτ中的顶点41到该咬合平面YOCC的距离，以将距离该咬合平面YOCC最长的顶点作为拟合参照点42，并过滤其他顶点而仅保留拟合参照点42(步骤106)。请参考图11所示，以四次多项式拟合这些拟合参照点42以得到标准牙弓曲线51(步骤107)。Please refer to FIG. 10 , and then calculate the distance from the vertex 41 in each group of proper subsets S *1 φτ , S *2 φτ ... S *n φτ to the occlusal plane Y OCC , so as to maximize the distance from the occlusal plane Y OCC The longer vertex is used as the fitting reference point 42, and other vertices are filtered to keep only the fitting reference point 42 (step 106). Referring to FIG. 11 , these fitted reference points 42 are fitted with a quartic polynomial to obtain a standard dental arch curve 51 (step 107 ).
前述是说明标准牙弓曲线的计算，请参考图12所示的流程图，以下说明临床牙体立体影像与其临床牙弓曲线的计算。使用者可持该探头10拍摄患者的实际牙齿影像，本实施例仅以拍摄下颚牙齿为例说明。对于患者的单颗牙齿而言，如同前述第101步骤，是对患者牙齿拍摄一第一影像与一第二影像，该第一影像可为朝牙齿舌侧面所拍摄的影像，且拍摄角度为相对一水平面呈度角，而该第二影像可为朝牙齿颊侧面所拍摄的影像，且拍摄角度为相对一水平面呈45度角，该探头10亦产生对应的旋转索引值。当该探头10拍摄完第一影像与第二影像后，该点云数据取样单元12分别将该第一影像与第二影像对应产生一第一点云数据与一第二点云数据(步骤101’)。The foregoing describes the calculation of the standard dental arch curve. Please refer to the flow chart shown in FIG. The user can hold the probe 10 to take pictures of the actual teeth of the patient. This embodiment only uses the pictures of mandibular teeth as an example for illustration. For a patient's single tooth, as in the aforementioned 101st step, a first image and a second image are taken of the patient's tooth. The first image can be taken towards the lingual side of the tooth, and the shooting angle is relative to A horizontal plane is at an angle of 40 degrees, and the second image can be taken toward the buccal side of the tooth, and the shooting angle is 45 degrees relative to the horizontal plane, and the probe 10 also generates a corresponding rotation index value. After the first image and the second image are taken by the probe 10, the point cloud data sampling unit 12 respectively generates a first point cloud data and a second point cloud data corresponding to the first image and the second image (step 101 ').
在探头10产生单颗牙齿的第一点云数据、第二点云数据与对应的旋转索引值后，该影像处理装置20从该探头10接收该第一点云数据、第二点云数据与旋转索引值。该坐标数值回授比对单元21接收该第一点云数据与第二点云数据的旋转索引值，以根据这些旋转索引值从该标准牙模对位坐标数据库22的影像位移对照表读取对应的位移量，并将旋转索引值与对应的位移量传送到该第一阶段贴合计算单元24。该牙体点云数据处理单元23则将该第一点云数据与一第二点云数据传送给该第一阶段贴合计算单元24。After the probe 10 generates the first point cloud data, the second point cloud data and the corresponding rotation index value of a single tooth, the image processing device 20 receives the first point cloud data, the second point cloud data and the corresponding rotation index value from the probe 10. The rotation index value. The coordinate value feedback comparison unit 21 receives the rotation index values of the first point cloud data and the second point cloud data, so as to read from the image displacement comparison table of the standard dental mold alignment coordinate database 22 according to these rotation index values The corresponding displacement amount, and transmit the rotation index value and the corresponding displacement amount to the first-stage fitting calculation unit 24 . The dental point cloud data processing unit 23 transmits the first point cloud data and a second point cloud data to the first-stage fitting calculation unit 24 .
该第一阶段贴合计算单元24接收到该第一点云数据、第二点云数据与对应的位移量后，该第一阶段贴合计算单元24即自动根据位移量将该第一点云数据与第二点云数据相互叠合，形成单颗牙齿的一初步叠合影像。重复前述步骤，对多个颗牙齿分别建立初步叠合影像，由于两个相临的初步叠合影像包含有共同的影像特征，例如拍摄到相同的牙齿，该第一阶段贴合计算单元24将该多个初步叠合影像根据共同的影像特征彼此接合后，形成一临床牙体立体影像(步骤102’)。该第一阶段贴合计算单元24完成该临床牙体立体影像后，由该比对计算单元25接收该临床牙体立体影像，以对该临床牙体立体影像计算其临床牙弓曲线，该临床牙弓曲线的计算方法与该标准牙弓曲线的计算方法相同，简言之，即筛选出该临床牙体立体影像中各牙齿咬合面上的顶点(步骤103’)、根据筛选后的顶点形成一初步牙弓曲线(步骤104’)、产生多个真子集(步骤105’)、定义拟合参照点(步骤106’)以及根据拟合参照点拟合出该临床牙弓曲线(步骤107’)，在此不再详细赘述。After the first-stage fitting calculation unit 24 receives the first point cloud data, the second point cloud data and the corresponding displacement, the first-stage fitting calculation unit 24 automatically converts the first point cloud according to the displacement. The data and the second point cloud data are superimposed on each other to form a preliminary superimposed image of a single tooth. Repeat the above steps to create preliminary superimposed images for multiple teeth respectively. Since two adjacent preliminary superimposed images contain common image features, for example, the same teeth are photographed, the first-stage fitting calculation unit 24 will After the multiple preliminary superimposed images are joined together according to common image features, a clinical three-dimensional image of teeth is formed (step 102 ′). After the first-stage fitting calculation unit 24 completes the clinical dental stereoscopic image, the comparison calculation unit 25 receives the clinical dental stereoscopic image to calculate the clinical dental arch curve for the clinical dental stereoscopic image. The calculation method of the dental arch curve is the same as the calculation method of the standard dental arch curve. In short, the vertices on the occlusal surface of each tooth in the clinical dental stereoscopic image are screened out (step 103'), and formed according to the screened vertices. A preliminary dental arch curve (step 104'), generate a plurality of proper subsets (step 105'), define fitting reference points (step 106'), and fit the clinical dental arch curve according to fitting reference points (step 107' ), which will not be described in detail here.
根据前述步骤获得临床牙弓曲线后，计算该临床牙弓曲线相对于该标准牙弓曲线的偏移数据，以根据偏移数据对该对该临床牙体立体影像进行校正(步骤108’)，请参考图13所示，揭露标准牙弓曲线31与临床牙弓曲线32，该第二阶段贴合计算单元26将计算出临床牙弓曲线32的偏移量以近似该标准牙弓曲线31。如图14所示标准牙弓曲线31与临床牙弓曲线32的部分线段，首先对该临床牙弓曲线32定义出多个重心点320，这些重心点320为该第二牙弓曲曲线32的等分点(如图10所示等分线与牙弓曲线的交点)，其坐标分别为(xa,ya)、(xb,yb)、…、(xf,yf)、…，该标准牙弓曲线31亦定义有多个数据点310，这些数据点310为该标准牙弓曲线31的等分点，且这些数据点310的坐标分别为(x1,y1)、(x2,y2)、…、(x6,y6)、…。本发明根据该临床牙弓曲线32的任一重心点310与该标准牙弓曲线31上所有的数据点310进行第K个邻近取样法(k-th nearest neighbor method,KNN method)，以找出最接近该重心点320的一数据点310，举例而言，最邻近重心点310(xa,ya)的数据点为(x1,y1)。当取得两个最接近的数据点310与重心点320后，计算重心点320的偏移数值(Xi,Yi)，Xi＝xa-x1，Yi＝ya-y1。After obtaining the clinical dental arch curve according to the aforementioned steps, calculate the offset data of the clinical dental arch curve relative to the standard dental arch curve, so as to correct the clinical tooth stereoscopic image according to the offset data (step 108'), Please refer to FIG. 13 , which discloses the standard dental arch curve 31 and the clinical dental arch curve 32 , and the second-stage fitting calculation unit 26 will calculate the offset of the clinical dental arch curve 32 to approximate the standard dental arch curve 31 . As shown in Figure 14, the standard dental arch curve 31 and the partial line segment of the clinical dental arch curve 32, first define a plurality of center of gravity points 320 for the clinical dental arch curve 32, these center of gravity points 320 are the second dental arch curve 32 The bisector point (the intersection point of the bisector line and the dental arch curve as shown in Figure 10), its coordinates are (xa, ya), (xb, yb), ..., (xf, yf), ..., the standard dental arch The curve 31 also defines a plurality of data points 310, these data points 310 are the bisection points of the standard dental arch curve 31, and the coordinates of these data points 310 are (x1, y1), (x2, y2), . . . (x6, y6), .... The present invention performs the K-th nearest neighbor method (KNN method) according to any center of gravity point 310 of the clinical dental arch curve 32 and all data points 310 on the standard dental arch curve 31 to find out A data point 310 closest to the center of gravity point 320 , for example, a data point closest to the center of gravity point 310 (xa, ya) is (x1, y1). After obtaining the two closest data points 310 and the center of gravity point 320 , calculate the offset value (Xi, Yi) of the center of gravity point 320 , Xi=xa−x1, Yi=ya−y1.
因此，该第二阶段贴合计算单元26中以(Xi,Yi)数据作为该临床牙体立体影像偏移校正的依据，亦即该临床牙体立体影像的点云数据中包含有图13所示的重心点320，该临床牙体立体影像中，于重心点320周围包含有对应的点数据群，这些点数据群根据其重心点320的偏移数据进行在x轴与y轴上的偏移，整体而言是使该临床牙体立体影像根据标准牙弓曲线进行偏移(可参考欧洲专利第EP2026279号“Methodand system for aligning three-dimensional surfaces”)，借此产生更精确的牙齿立体影像。Therefore, in the second-stage fitting calculation unit 26, the (Xi, Yi) data is used as the basis for offset correction of the clinical dental stereoscopic image, that is, the point cloud data of the clinical dental stereoscopic image includes the data shown in FIG. 13 The center of gravity point 320 shown in the clinical dental stereoscopic image contains corresponding point data groups around the center of gravity point 320, and these point data groups are offset on the x-axis and y-axis according to the offset data of the center of gravity point 320 Generally speaking, the three-dimensional image of the clinical tooth is shifted according to the standard dental arch curve (refer to European Patent No. EP2026279 "Method and system for aligning three-dimensional surfaces"), thereby generating a more accurate three-dimensional image of the tooth .
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