CN112353512A - Method and apparatus for preparing tooth model - Google Patents
Method and apparatus for preparing tooth model Download PDFInfo
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- CN112353512A CN112353512A CN202011163381.7A CN202011163381A CN112353512A CN 112353512 A CN112353512 A CN 112353512A CN 202011163381 A CN202011163381 A CN 202011163381A CN 112353512 A CN112353512 A CN 112353512A
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- A61C8/00—Means to be fixed to the jaw-bone for consolidating natural teeth or for fixing dental prostheses thereon; Dental implants; Implanting tools
- A61C8/0089—Implanting tools or instruments
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Abstract
The embodiment of the invention provides a method and equipment for trimming a tooth model, wherein the method comprises the steps of firstly obtaining the tooth model to be trimmed, a preset selection radius and a preset wax pattern height; then obtaining a trimming base point on a visible surface of the tooth model to be trimmed, and constructing a spherical area with the radius equal to a preset selected radius by taking the trimming base point as a spherical center; then identifying visible points on the tooth model to be trimmed which are located within the spherical region; then moving the visible point based on the preset wax pattern height to add or erase the wax pattern in the spherical area to generate a new tooth model; and finally, taking the new tooth model as the tooth model to be trimmed, and repeating the steps until the tooth model meeting the preset requirements is generated. The method can enable a doctor to digitally trim the tooth model according to the self requirement, and then directly manufacture the solid tooth wax model based on the trimmed tooth model, thereby avoiding the complexity of subsequent manual filling.
Description
Technical Field
The invention relates to the technical field of oral implantation, in particular to a method and equipment for trimming a tooth model.
Background
In recent years, with the popularization of oral implant technology in clinic and the improvement of oral health requirements of people, more and more patients choose to implant, repair and treat missing teeth. The oral implant guiding technology can assist a doctor to implant the implant accurately according to the predetermined implant position, and can reduce the risk of accidental injury to adjacent important anatomical structures to the maximum extent. The implant guide technique is one widely used in the oral implant guide technique. Among them, the use of computer aided design manufacturing (also called CAD/CAM) method to design and manufacture an implant guide based on patient medical image data is the direction and trend of development of oral implantology.
In the process of designing and manufacturing the dental implant guide plate, if the dental implant guide plate is directly manufactured by a tooth surface model scanned in the mouth, the guide plate cannot be smoothly put into the teeth of a patient or taken out after being put into the teeth because of the special geometric shape of the teeth (the tooth crown is wider than the tooth root to form a shape with a wide upper part and a narrow lower part). Therefore, before the implant guide plate is manufactured, the tooth model obtained by the intraoral scanning instrument needs to be filled with the undercut. At present, the inverted concave filling treatment is usually to manually fill wax or remove wax on a solid tooth wax pattern, the amount of the filled wax is not easy to control, and meanwhile, the operation is complex, the efficiency is low, and the accuracy is poor.
Disclosure of Invention
The embodiment of the invention provides a method and equipment for trimming a tooth model, which are used for solving the problems of low efficiency and poor accuracy of an artificial filling and recessing method in the prior art and provide a basis for the subsequent design and manufacture of an implantation guide plate.
An embodiment of the present invention provides a method for preparing a tooth model, including:
acquiring a tooth model to be trimmed, a preset selection radius and a preset wax pattern height;
obtaining a trimming base point on a visible surface of the tooth model to be trimmed, and constructing a spherical area with the radius equal to the preset selected radius by taking the trimming base point as a spherical center;
identifying visible points on the tooth model to be trimmed that lie within the spherical region;
moving the visible point based on the preset wax pattern height to add or erase a wax pattern in the spherical area to generate a new tooth model;
and (4) taking the new tooth model as the tooth model to be trimmed, and repeating the steps until the tooth model meeting the preset requirement is generated.
The method of preparing a tooth model according to an embodiment of the present invention, the identifying a visible point on the tooth model to be prepared within the spherical region, further comprising:
acquiring a preset observation direction, setting a first view coordinate system, and defining the Z-axis forward direction of the first view coordinate system as the reverse direction of the preset observation direction;
taking the part of the tooth model to be trimmed, which is positioned in the spherical area, as an operation model, and calculating a Z buffer area corresponding to the operation model in the first view coordinate system based on a Z buffer area algorithm;
traversing all outer contour points P of the operation model1Comparing said outline point P1Z-axis coordinate value p in the first view coordinate systemz1And said outer contour point P1Depth value d in the Z bufferz1(ii) a At pz1≥dz1While marking the outer contour point P1Is a visible point PvWhile the mark contains any visible point PvThe triangular plate is the selected triangular plate.
The method of modifying a tooth model according to an embodiment of the present invention, wherein moving the visible point based on the preset wax pattern height to add or erase a wax pattern in the spherical region, further comprises:
for all visible points PvThe normal of (2) is averaged to obtain a reference normal N;
calculating a visible point P based on the preset wax pattern heightvThe move distance move of (1), in the adding mode, the move is more than or equal to 0; in the erasing mode, move is less than 0;the preset wax pattern height comprises a preset wax pattern adding height and a preset wax pattern erasing height;
moving the point of visibility P along the normal NvMoving distance is move, and moved point P is obtainedmIn the addition mode, PmIs a visible point; in the erasing mode, if move + dist < 0, P ismIs invisible point, otherwise is visible point, wherein dist represents visible point PvA minimum distance from the original tooth model's outer contour surface in the direction of normal N;
traversing all the selected triangular plates on the operation model, if three points P of the moved selected triangular platesmAnd if the points are all visible points, displaying the selected triangular plate after the movement, otherwise hiding the selected triangular plate after the movement.
According to one embodiment of the present invention, the method of modifying a tooth model calculates the visible point P based on the preset wax pattern heightvThe move distance move of (1), in the adding mode, the move is more than or equal to 0; in the erase mode, move < 0, further comprising:
in the addition mode, the movement distance move ═ 1-d2/r2)*h1Wherein h is1Adding a height for presetting the wax pattern, d is a visible point PvThe distance to the center of the sphere of the spherical region, r being the radius of the spherical region;
in the erase mode, the moving distance move-h2Wherein h is2The wax pattern erase height is preset.
According to the method for modifying the tooth model, all the selected triangular plates on the operation model are traversed, if three points P of the selected triangular plates are movedmIf the points are visible points, the selected triangular plate after moving is displayed, otherwise, after the selected triangular plate after moving is hidden, the method further comprises the following steps:
and performing smoothing operation on the selected triangular plate after the movement.
According to the method for modifying the tooth model of the embodiment of the invention, before the obtaining the tooth model to be modified, the preset selection radius and the preset wax pattern height, the method further comprises the following steps:
obtaining an original tooth model, and identifying an inverted concave area of the original tooth model;
after the obtaining of the trimming base point on the visible surface of the tooth model to be trimmed, before the identifying of the visible point on the tooth model to be trimmed, the method further includes:
judging whether the trimming base point is positioned in the inverted concave area, and if the trimming base point is positioned in the inverted concave area, continuing to execute the next step; and if the trimming base point is positioned outside the inverted concave area, reminding a user to confirm.
The method for modifying a tooth model according to an embodiment of the present invention, the obtaining an original tooth model, and identifying an undercut region of the original tooth model, further comprises:
acquiring a preset insertion direction, setting a second view coordinate system, and defining the Z-axis forward direction of the second view coordinate system as the reverse direction of the preset insertion direction;
calculating a Z buffer zone corresponding to the original tooth model in the second view coordinate system based on a Z buffer zone algorithm;
traversing all outer contour points P of the original tooth model2Comparing said outline point P2Z-axis coordinate value p in the second view coordinate systemz2And said outer contour point P2Depth value d in the Z bufferz2(ii) a At pz2<dz2While marking the outer contour point P2Is a reverse concave point Pd；
Based on the undercut point PdCreating a region of undercut.
The method of modifying a tooth model according to an embodiment of the present invention, after identifying the undercut region of the original tooth model, further comprises:
calculating all outer contour points P of the original tooth model2The corresponding depth of the undercut;
and setting the surface of the original tooth model into different colors according to different undercut depths based on the mapping relation between the undercut depths and the colors.
According to the method for modifying the tooth model, all the outer contour points P of the original tooth model are calculated2A corresponding undercut depth, further comprising:
respectively generating radius values r by taking a preset insertion direction as a plane normal and the origin of the second view coordinate system as a circle center1……rn-1、rnN circles of (a), wherein r1～rnAre all less than 1mm, and rn>rn-1(ii) a Get m evenly distributed points b on each circle1……bm-1、bm；
Traversing each undercut point P on the tooth modeldFrom the origin of the coordinates to PdIs added to the origin of coordinates to a radius rnPoint b on the circle ofmForm a new point Pd2Judgment point Pd2Whether the concave area is positioned in the inverted concave area; wherein n and m are increased progressively from 1, and after all points on the previous circle are judged, points on the next circle are judged;
if point Pd2If the position is in the inverted concave area, vector addition calculation is carried out again; if point Pd2Located in the non-undercut region, the undercut point PdThe depth of the undercut is between the radius of the previous circle and the radius of the current circle, and the judgment is stopped at the same time; if the first circle is traversed, a point P is foundd2Located in the non-undercut region, the undercut point PdIs less than r1(ii) a If a point P is not found up to the last circled2Located in the non-undercut region, the undercut point PdIs more than rn。
Embodiments of the present invention further provide an electronic device, comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor executes the program to implement the steps of the method for preparing a tooth model as described in any of the above.
According to the method and the device for trimming the tooth model, provided by the embodiment of the invention, the method for trimming the tooth model can be used for performing the operation of adding or erasing the wax pattern on the spherical area near the trimming base point selected by the user on the tooth model to be trimmed according to the selection radius and the wax pattern height set by the user, so as to obtain a new tooth model. The spherical region can be constructed to adapt to the surface change of the tooth model, so that the three-dimensional model can be operated more naturally. The user can drag the mouse to designate a trimming base point, then freely trimming can be realized according to the requirement, and the user can repeatedly perform the operation of adding or erasing wax patterns to trim the tooth model step by step until the tooth model meeting the requirement is obtained. The method can enable a doctor to digitally trim the tooth model according to the self requirement, and then directly manufacture the solid tooth wax model based on the trimmed tooth model, thereby avoiding the complexity of subsequent manual filling. In addition, the method can be combined with other digital automatic filling methods for the undercut, and after the undercut is automatically filled, personalized detail adjustment can be performed according to requirements.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a schematic flow chart of a method of modifying a tooth model according to an embodiment of the present invention;
FIG. 2 is a schematic illustration of the construction of a spherical region in an embodiment of the present invention;
FIG. 3 is a simplified schematic illustration of moving visible points on an operational model to add or erase wax patterns in an embodiment of the present invention;
FIG. 4 is a schematic illustration of identifying undercut regions in an embodiment of the invention;
FIG. 5 is a simplified schematic illustration of calculating undercut depth in an embodiment of the present invention;
fig. 6 is a schematic structural diagram of an electronic device according to an embodiment of the present invention.
Reference numerals:
1. an original tooth model; 2. Trimming a base point; 3. A spherical region;
4. an added wax pattern; 5. An inverted concave region;
6. an electronic device; 61. A processor; 62. A communication interface;
63. a memory; 64. A communication bus.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the embodiments of the present invention, it should be noted that the terms "first" and "second" are used for the sake of clarity in describing the numbering of the components of the product and do not represent any substantial difference, unless explicitly stated or limited otherwise. "upper", "lower", "left", "right", and the like are used only to indicate relative positional relationships, and when the absolute position of the object to be described is changed, the relative positional relationships may also be changed accordingly. Specific meanings of the above terms in the embodiments of the present invention can be understood by those of ordinary skill in the art according to specific situations.
It is to be understood that, unless otherwise expressly specified or limited, the term "coupled" is used broadly, and may, for example, refer to directly coupled devices or indirectly coupled devices through intervening media. Specific meanings of the above terms in the embodiments of the invention will be understood to those of ordinary skill in the art in specific cases.
As shown in fig. 1 to 3, an embodiment of the present invention provides a method for preparing a tooth model, including:
step S100: obtaining a tooth model to be trimmed, a preset selection radius r and a preset wax pattern height.
Specifically, the original tooth model 1 is copied as the tooth model to be trimmed during initialization, and the original tooth model 1 may be a tooth scanning model of the patient, that is, the original tooth model 1 is obtained by scanning all or part of the oral cavity area of the patient through a three-dimensional digital scanning instrument. If repeated trimming is subsequently required a number of times, the tooth model to be trimmed is based on the tooth model to which the wax pattern has been added or erased the last time.
Step S200: a trimming base point 2 on a visible surface of a tooth model to be trimmed is obtained, and a spherical area 3 with the radius equal to a preset selection radius r is constructed by taking the trimming base point 2 as a spherical center.
Specifically, as shown in fig. 2, the visible surface of the tooth model to be trimmed is the visible surface at the current user viewing angle in the digital three-dimensional software, the trimming base point 2 is the position of the mouse pointer in the digital three-dimensional software, and the user can freely designate the trimming base point 2 by dragging the mouse. Then, a spherical area 3 with a radius equal to a preset selected radius r is constructed with the trimming base point 2 as the center of the sphere. A sphere is constructed by taking the position of a mouse as a sphere center, the sphere is intersected with the tooth model to be trimmed, subsequent operations are all carried out on a visible surface of the operation model within the range of the intersection line, and the selection mode can adapt to the change of the surface of the tooth model, so that the operation on the three-dimensional model is more natural.
Step S300: visible points on the tooth model to be trimmed that lie within the spherical region are identified.
Specifically, as shown in fig. 2, when the preset selection radius r is larger, the spherical region may intersect both the visible surface and the invisible surface of the tooth model to be modified, the solid circular arc in fig. 2 represents the intersection line of the spherical region 3 and the tooth model to be modified (e.g., the original tooth model 1) on the visible surface, the dotted circular arc in fig. 2 represents the intersection line of the spherical region 3 and the tooth model to be modified (e.g., the original tooth model 1) on the invisible surface, and the region that the user desires to be modified is a portion on the visible surface, so it is necessary to identify a visible point on the tooth model to be modified, which is located in the spherical region, and to determine whether the point is located on the visible surface according to the visibility of the point. In some embodiments, the visibility of each point on the tooth model to be modified can be determined based on the Z-buffer of the three-dimensional model display image, and the basic principle is as follows:
when an opaque object in a three-dimensional space is observed, a picture element which is close to a visual point always shields a picture element which is far away, and if the picture element which is visible and invisible is drawn, the vision is ambiguous. The computer therefore has to deal with the problem of blanking (elimination of occluded invisible lines or planes during rendering) when displaying three-dimensional graphics, the blanking being related not only to the object of blanking but also to the position of the observer (viewpoint position). The Z-Buffer (Z-Buffer) algorithm, also known as a depth Buffer algorithm, stores the Z-coordinate value of each visible pixel in image space. All values in the Z-Buffer are initialized to a minimum value before starting to render the three-dimensional scene. And during drawing, checking whether the depth value (namely the Z coordinate value) of the current pixel point is larger than the depth value corresponding to the pixel in the Z-Buffer, if so, indicating that the current pixel point is closer to the observation point and should be displayed on a screen, and simultaneously replacing the corresponding depth value in the Z-Buffer with the Z coordinate value of the current pixel point for updating. Otherwise, the pixel point is invisible and does not need to update the Z-Buffer. The Z-Buffer technology is supported by computer software and hardware related to 3D graphic display.
Step S400: moving the visible point based on the preset wax pattern height to add or erase the wax pattern within the spherical region, generating a new tooth model.
Under the mode of adding the wax pattern, the visible point can move to the outer side of the tooth model to be modified, and then convex outward is formed, and the effect of adding the wax pattern is realized. Under the mode of erasing the wax pattern, the visible point can be moved to the inner side of the tooth model to be modified, so that the inner recess is formed, the effect of erasing the wax pattern is realized, and the limit degree of erasing the wax pattern is that the moved point is positioned on the surface of the original tooth model 1, namely the erasing the wax pattern does not change the shape of the original tooth model 1 and only the added wax pattern is erased.
Step S500: and (5) taking the new tooth model as the tooth model to be trimmed, and repeating the steps S100-S400 until the tooth model meeting the preset requirement is generated. An operator can fill the undercut on the original tooth model 1 by repeatedly adding or erasing wax patterns on the three-dimensional software according to the use requirement of the operator or trim the tooth model generated after the undercut is digitally and automatically filled, the accuracy of adjustment of the tooth model is improved, and after the operator obtains the digital three-dimensional tooth model meeting the requirement, the operator can directly combine a 3D printing technology or other solid wax pattern generation technologies to rapidly manufacture the solid tooth model without manually filling or removing the wax.
According to the method for trimming the tooth model provided by the embodiment, the operation of adding or erasing the wax pattern to the spherical area 3 near the trimming base point 2 selected by the user can be performed on the tooth model to be trimmed according to the selection radius and the wax pattern height set by the user, so that a new tooth model can be obtained. By constructing the spherical region 3, the change of the tooth model surface can be adapted, so that the operation of the three-dimensional model is more natural. The user can drag the mouse to designate the trimming base point 2, and then freely trim according to the requirement, and the user can also repeatedly perform the operation of adding or erasing wax patterns to trim the tooth model step by step until the tooth model meeting the requirement is obtained. The method can enable a doctor to digitally trim the tooth model according to the self requirement, and then directly manufacture the solid tooth wax model based on the trimmed tooth model, thereby avoiding the complexity of subsequent manual filling. In addition, the method can be combined with other digital automatic filling methods for the undercut, and after the undercut is automatically filled, personalized detail adjustment can be performed according to requirements.
Further, step S300 further includes:
step S310: acquiring a preset observation direction, setting a first view coordinate system, and defining the Z-axis forward direction of the first view coordinate system as the reverse direction of the preset observation direction. The preset observation direction is the sight line direction of the current user in the three-dimensional model scene, and the projection mode of the three-dimensional scene is set to be parallel projection (or orthogonal projection), so that the situation that the perspective projection is large and small is avoided.
Step S320: and taking the part of the tooth model to be trimmed, which is positioned in the spherical area 3, as an operation model, and calculating a Z buffer area corresponding to the operation model in the first view coordinate system based on a Z buffer area algorithm. And Z-coordinate values of all visible pixel points in the image space are stored in the Z buffer area.
Specifically, all values in the Z-Buffer are initialized to a minimum value before the three-dimensional scene begins to be rendered. And during drawing, checking whether the depth value (namely the Z coordinate value) of the current pixel point is larger than the depth value corresponding to the pixel in the Z-Buffer, if so, indicating that the current pixel point is closer to the observation point and should be displayed on a screen, and simultaneously replacing the corresponding depth value in the Z-Buffer with the Z coordinate value of the current pixel point for updating. Otherwise, the pixel point is invisible and does not need to update the Z-Buffer.
Step S330: traversing all outer contour points P of the operation model1Comparing the outer contour points P1Z-axis coordinate value p in first view coordinate systemz1And outer contour point P1Depth value d in Z bufferz1(ii) a At pz1≥dz1While marking the outer contour point P1Is a visible point PvWhile the mark contains any visible point PvThe triangular plate is the selected triangular plate.
Furthermore, an allowable error value err may be introduced1The allowable error value err1Indicating tolerable errors occurring during the calculation, at pz1≥dz1+err1Then, mark the outer contour point P1Is a visible point Pv. In a specific embodiment, err1May be 0.001, err1The value of (c) can be determined according to the accuracy of the operation.
Still further, step S400 further includes:
step S410: for all visible points PvThe normal of (a) is averaged to obtain a reference normal N. WhereinVisible point PvIs the average of the normals of all the triangular patches that contain the point. It should be noted that, after each wax pattern is added or erased, the spatial position of the point in the spherical area changes, and the normals to the visible point and the triangular plate need to be recalculated when the operation is performed again.
Step S420: calculating a visible point P based on a preset wax pattern heightvThe move distance move of (1), in the adding mode, the move is more than or equal to 0; in the erasing mode, move is less than 0; the preset wax pattern height comprises a preset wax pattern adding height and a preset wax pattern erasing height.
In the add mode, the movement distance move ═ 1-d2/r2)*h1Wherein h is1Adding a height for presetting the wax pattern, d is a visible point PvThe distance to the center of the sphere of the spherical region, r is the radius of the spherical region; in the erase mode, the moving distance move is-h2Wherein h is2The wax pattern erase height is preset. As shown in fig. 3, in order to make the wax pattern 4 added on the surface of the operation model smoother, not all visible points in the area are directly increased by the same height, but the center of the operation model has the maximum moving height, and the points farther from the center move by a smaller amount and do not move at the boundary, which can be roughly an arc with reference to the shape of the added wax pattern 4 indicated by the dotted line in fig. 3. Set as a visible point P by the above formula of the moving distancevA quadratic function of the distance to the center can make the wax pattern height change smoother.
Step S430: moving the point of visibility P along the normal NvMoving distance is move, and moved point P is obtainedmIn the add mode, PmIs a visible point; in the erase mode, if move + dist < 0, P ismIs invisible point, otherwise is visible point, wherein dist represents visible point PvThe minimum distance from the outer contour surface of the original tooth model in the direction of the normal N.
Specifically, as shown in FIG. 3, from the point of visibility PvGenerating a straight line along the N direction, and obtaining the visible point P from all the intersection points of the straight line and the original tooth model 1vNearest intersection point s, meterCalculating the point s to the point PvVector of (2)
The distance dist, dist along the direction of the normal N is a signed value (if
Positive values along the positive direction of N and negative values otherwise).
When the original tooth model 1 is copied, the scalar quantities of all points and triangular plates on the original tooth model 1 can be set to be 0, and the scalar quantity of the triangular plate is zero to represent that all the triangular plates are hidden currently. Point P moved in the Add modemThe scalar of (1); in the erase mode, the moved point PmIf the point is invisible, the scalar quantity is 0, and if the point is visible, the scalar quantity is 1.
Step S440: traversing all the selected triangular plates on the operation model, if three points P of the moved selected triangular platesmAnd if the points are all visible points, displaying the selected triangular plate after the movement, otherwise hiding the selected triangular plate after the movement.
If three points P of the triangular plate are selectedmIf the scalar quantity of the selected triangular plate is 1, setting the scalar quantity of the selected triangular plate as 1, and displaying the scalar quantity, namely displaying the triangular plate with the increased height after adding the wax pattern; otherwise, the scalar of the selected triangle is set to 0, and the triangle is hidden, namely the completely erased triangle is hidden.
Further, after step S440, the method further includes:
step S450: and performing smoothing operation on the selected triangular plate after the movement. Specifically, the selected triangle is automatically smoothed by using a laplacian smoothing algorithm.
On the basis of the above embodiment, before step S100, that is, before starting to add or erase the wax pattern, the method further includes:
an original tooth model 1 is acquired and the undercut region 5 of the original tooth model 1 is identified.
After obtaining a trimming base point on the visible surface of the tooth model to be trimmed (i.e., step S200), before identifying a visible point on the tooth model to be trimmed within the spherical region (i.e., step S300), the method further includes:
judging whether the trimming base point 2 is positioned in the inverted concave area 5, and if the trimming base point 2 is positioned in the inverted concave area 5, continuing to execute the next step; and if the trimming base point 2 is positioned outside the inverted concave area 5, reminding a user to confirm.
Considering that the most important purpose of the user to trim the tooth model is to fill the undercut, in order to avoid the user from performing a wrong operation, such as mistakenly clicking a non-undercut region while dragging a mouse, it may be determined in advance whether the lower trimming base point is located within the undercut region before performing the wax pattern adding or erasing operation, and if the lower trimming base point is located outside the undercut region, the user may be alerted through a pop-up frame.
Further, the method of identifying the undercut region of the original tooth model 1 may be identical to the method of identifying the visible point, all using the Z-buffer algorithm. As shown in fig. 4, specifically includes:
a) and acquiring a preset insertion direction, setting a second view coordinate system, and defining the Z-axis positive direction of the second view coordinate system as the reverse direction of the preset insertion direction. Wherein, predetermine the direction of insertion and plant the direction of insertion of baffle for the user's installation.
b) And calculating a Z buffer zone corresponding to the original tooth model in the second view coordinate system based on a Z buffer zone algorithm.
c) Traverse all outer contour points P of the original tooth model2Comparing the outer contour points P2Z-axis coordinate value p in second view coordinate systemz2And outer contour point P2Depth value d in Z bufferz2(ii) a At pz2<dz2While marking the outer contour point P2Is a reverse concave point Pd。
Furthermore, an allowable error value err may be introduced2The allowable error value err2Indicating tolerable errors occurring during the calculation, at pz2<dz2+err2Then, mark the outer contour point P2Is a reverse concave point Pd(ii) a At pz2≥dz2+err2Then, mark the outer contour point P2Is a non-inverted pit Pnd. In a specific embodiment, err2May be 0.001, err2The value of (c) can be determined according to the accuracy of the operation.
d) Based on the inverted concave point PdThe undercut region 5 is generated. The undercut region 5 is defined by all undercut points PdA region consisting of a straight line extending downward in the Z-axis direction.
Further, after identifying the undercut region 5 of the original tooth model 1, the undercut region 5 may be further color-distinguished, specifically including:
e) all outer contour points P of the original tooth model 1 are calculated2The corresponding depth of the undercut;
f) the surface of the original tooth model 1 is set to different colors at different undercut depths based on the mapping relationship of the undercut depths and the colors. The mapping may be such that a linear change from a cool tone to a warm tone represents a corresponding increasing undercut depth. By setting the surface of the original tooth model 1 to different colors depending on the undercut depth, the user can be made to observe and understand the undercut structure of the original tooth model 1 more intuitively.
Wherein all outer contour points P of the original tooth model are calculated as shown in FIG. 52The corresponding undercut depth may specifically include:
e1) respectively generating a radius value r by taking the preset insertion direction as a plane normal and the origin of the second view coordinate system as a circle center1……rn-1、rnN circles of (a), wherein r1～rnAre all less than 1mm, and rn>rn-1(ii) a Get m evenly distributed points b on each circle1……bm-1、bm. In a specific embodiment, n is 4, r1＝0.04mm，r2＝0.25mm，r3＝0.5mm，r40.75 mm; and m is 20. In addition, the above numerical values may be other values, and are not limited herein.
e2) Traversing each undercut point P on the tooth modeldFrom the origin of the coordinates to PdIs added to the origin of coordinates to a radius rnPoint b on the circle ofmVector of (2)Form a new point Pd2Judgment point Pd2Whether the concave area is positioned in the inverted concave area; wherein n and m are increased from 1, and after all points on the previous circle are judged, the points on the next circle are judged.
If point Pd2If the position is in the inverted concave area, vector addition calculation is carried out again; if point Pd2Located in the non-undercut region, the undercut point PdThe depth of the undercut is between the radius of the previous circle and the radius of the current circle, and the judgment is stopped at the same time; if the first circle is traversed, a point P is foundd2Located in the non-undercut region, the undercut point PdIs less than r1(ii) a If a point P is not found up to the last circled2Located in the non-undercut region, the undercut point PdIs more than rn。
Wherein the non-inverted concave point PndThe undercut depth of (a) is set to 0; inverted concave point PdSet to the radius of the circle intermediate the current circle and the previous circle, which in a specific embodiment may be 0.02mm, 0.145mm, 0.375mm or 0.625 mm; the depth of the undercut is greater than rnIs a reverse concave point PdThe undercut depth of (2) was set to 1 mm.
As shown in fig. 6, an embodiment of the present invention further provides an electronic device 6, including: a processor (processor)61, a communication Interface (communication Interface)62, a memory (memory)63 and a communication bus 64, wherein the processor 61, the communication Interface 62 and the memory 63 complete communication with each other through the communication bus 64. The processor 61 may invoke logic instructions in the memory 63 to perform the steps of the method of shaping a tooth model as in any of the embodiments described above.
Furthermore, the logic instructions in the memory 63 may be implemented in the form of software functional units and stored in a computer readable storage medium when sold or used as a stand-alone product. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
In another aspect, the present invention also provides a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium, the computer program including program instructions, when the program instructions are executed by a computer, the computer being capable of executing the method for modifying a tooth model provided by the above-mentioned method embodiments.
In yet another aspect, the present invention further provides a non-transitory computer-readable storage medium, on which a computer program is stored, the computer program being implemented by a processor to perform the method for modifying a tooth model provided in the above embodiments.
As can be seen from the above embodiments, the method and apparatus for trimming a tooth model according to the present invention can perform an operation of adding or erasing a wax pattern to the spherical area 3 near the trimming base point 2 selected by the user on the tooth model to be trimmed according to the selection radius and the wax pattern height set by the user, so as to obtain a new tooth model. By constructing the spherical region 3, the change of the tooth model surface can be adapted, so that the operation of the three-dimensional model is more natural. The user can drag the mouse to designate the trimming base point 2, and then freely trim according to the requirement, and the user can also repeatedly perform the operation of adding or erasing wax patterns to trim the tooth model step by step until the tooth model meeting the requirement is obtained. The method can enable a doctor to digitally trim the tooth model according to the self requirement, and then directly manufacture the solid tooth wax model based on the trimmed tooth model, thereby avoiding the complexity of subsequent manual filling. In addition, the method can be combined with other digital automatic filling methods for the undercut, and after the undercut is automatically filled, personalized detail adjustment can be performed according to requirements.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A method of preparing a tooth model, comprising:
acquiring a tooth model to be trimmed, a preset selection radius and a preset wax pattern height;
obtaining a trimming base point on a visible surface of the tooth model to be trimmed, and constructing a spherical area with the radius equal to the preset selected radius by taking the trimming base point as a spherical center;
identifying visible points on the tooth model to be trimmed that lie within the spherical region;
moving the visible point based on the preset wax pattern height to add or erase a wax pattern in the spherical area to generate a new tooth model;
and (4) taking the new tooth model as the tooth model to be trimmed, and repeating the steps until the tooth model meeting the preset requirement is generated.
2. The method of preparing a tooth model according to claim 1, wherein said identifying a visible point on said tooth model to be prepared that is within said spherical region further comprises:
acquiring a preset observation direction, setting a first view coordinate system, and defining the Z-axis forward direction of the first view coordinate system as the reverse direction of the preset observation direction;
taking the part of the tooth model to be trimmed, which is positioned in the spherical area, as an operation model, and calculating a Z buffer area corresponding to the operation model in the first view coordinate system based on a Z buffer area algorithm;
traversing all outer contour points P of the operation model1Comparing said outline point P1Z-axis coordinate value p in the first view coordinate systemz1And said outer contour point P1Depth value d in the Z bufferz1(ii) a At pz1≥dz1While marking the outer contour point P1Is a visible point PvWhile the mark contains any visible point PvThe triangular plate is the selected triangular plate.
3. The method of modifying a tooth model according to claim 2, wherein said moving the visible point based on the preset wax pattern height to add or erase a wax pattern within the spherical region further comprises:
for all visible points PvThe normal of (2) is averaged to obtain a reference normal N;
calculating a visible point P based on the preset wax pattern heightvThe move distance move of (1), in the adding mode, the move is more than or equal to 0; in the erasing mode, move is less than 0; the preset wax pattern height comprises a preset wax pattern adding height and a preset wax pattern erasing height;
moving the point of visibility P along the normal NvMoving distance is move, and moved point P is obtainedmIn the addition mode, PmIs a visible point; in the erasing mode, if move + dist < 0, P ismIs invisible point, otherwise is visible point, wherein dist represents visible point PvA minimum distance from the original tooth model's outer contour surface in the direction of normal N;
traversing all the selected triangular plates on the operation model, if three points P of the moved selected triangular platesmAnd if the points are all visible points, displaying the selected triangular plate after the movement, otherwise hiding the selected triangular plate after the movement.
4. The method of preparing a tooth model according to claim 3, wherein said calculating a visible point P based on said preset wax pattern heightvThe move distance move of (1), in the adding mode, the move is more than or equal to 0; in the erase mode, move < 0, further comprising:
in the addition mode, the movement distance move ═ 1-d2/r2)*h1Wherein h is1Adding a height for presetting the wax pattern, d is a visible point PvThe distance to the center of the sphere of the spherical region, r being the radius of the spherical region;
in the erase mode, the moving distance move-h2Wherein h is2The wax pattern erase height is preset.
5. The method of claim 4, wherein, in said traversing all of said selected triangular plates on said operational model, if three points P of said selected triangular plates after the movementmIf the points are visible points, the selected triangular plate after moving is displayed, otherwise, after the selected triangular plate after moving is hidden, the method further comprises the following steps:
and performing smoothing operation on the selected triangular plate after the movement.
6. The method of preparing a tooth model according to any one of claims 1 to 5, further comprising, prior to said obtaining the tooth model to be prepared, a preset selection radius and a preset wax pattern height:
obtaining an original tooth model, and identifying an inverted concave area of the original tooth model;
after the obtaining of the trimming base point on the visible surface of the tooth model to be trimmed, before the identifying of the visible point on the tooth model to be trimmed, the method further includes:
judging whether the trimming base point is positioned in the inverted concave area, and if the trimming base point is positioned in the inverted concave area, continuing to execute the next step; and if the trimming base point is positioned outside the inverted concave area, reminding a user to confirm.
7. The method of preparing a dental model as defined in claim 6, wherein the obtaining an original dental model, identifying undercut regions of the original dental model, further comprises:
acquiring a preset insertion direction, setting a second view coordinate system, and defining the Z-axis forward direction of the second view coordinate system as the reverse direction of the preset insertion direction;
calculating a Z buffer zone corresponding to the original tooth model in the second view coordinate system based on a Z buffer zone algorithm;
traversing all outer contour points P of the original tooth model2Comparing said outline point P2Z-axis coordinate value p in the second view coordinate systemz2And said outer contour point P2Depth value d in the Z bufferz2(ii) a At pz2<dz2While marking the outer contour point P2Is a reverse concave point Pd；
Based on the undercut point PdCreating a region of undercut.
8. The method of fitting a tooth model according to claim 7, further comprising, after identifying the undercut region of the original tooth model:
calculating all outer contour points P of the original tooth model2The corresponding depth of the undercut;
and setting the surface of the original tooth model into different colors according to different undercut depths based on the mapping relation between the undercut depths and the colors.
9. The method of claim 8, wherein said calculating all outer contour points P of said original tooth model2A corresponding undercut depth, further comprising:
respectively generating by taking a preset insertion direction as a plane normal and the origin of the second view coordinate system as a circle centerRadius value r1……rn-1、rnN circles of (a), wherein r1～rnAre all less than 1mm, and rn>rn-1(ii) a Get m evenly distributed points b on each circle1……bm-1、bm；
Traversing each undercut point P on the tooth modeldFrom the origin of the coordinates to PdIs added to the origin of coordinates to a radius rnPoint b on the circle ofmForm a new point Pd2Judgment point Pd2Whether the concave area is positioned in the inverted concave area; wherein n and m are increased progressively from 1, and after all points on the previous circle are judged, points on the next circle are judged;
if point Pd2If the position is in the inverted concave area, vector addition calculation is carried out again; if point Pd2Located in the non-undercut region, the undercut point PdThe depth of the undercut is between the radius of the previous circle and the radius of the current circle, and the judgment is stopped at the same time; if the first circle is traversed, a point P is foundd2Located in the non-undercut region, the undercut point PdIs less than r1(ii) a If a point P is not found up to the last circled2Located in the non-undercut region, the undercut point PdIs more than rn。
10. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor, when executing the program, carries out the steps of the method of shaping a tooth model according to any one of claims 1 to 9.
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