WO2011111900A1

WO2011111900A1 - Apparatus and method for modeling curved surface using intersection points in three-dimensional lattice structure

Info

Publication number: WO2011111900A1
Application number: PCT/KR2010/003527
Authority: WO
Inventors: 채영호; 김동택; 남상훈; 김학수
Original assignee: 중앙대학교 산학협력단
Priority date: 2010-03-11
Filing date: 2010-06-01
Publication date: 2011-09-15
Also published as: KR20110102618A; KR101105244B1

Abstract

Disclosed are an apparatus and a method for modeling a curved surface using intersection points in a three-dimensional lattice structure. An intersection point generating member generates intersection points between the movement path of an input device and the corner of each of a plurality of cells, which constitute a three-dimensional lattice structure generated in accordance with the input space, based on the location information and direction of the input device, which moves within the three-dimensional input space, and calculates normal vectors in a direction pointed by the input device at the intersection points. A pattern generating member connects the intersection points of each of the cells having intersection points, based on a generating order of the intersection points and the direction of the normal vectors at each of the intersection points, to generate a polygonal pattern. A pattern regenerating member repeatedly divides the cells, which include a pattern, according to the predetermined number of divisions, to generate a plurality of sub-cells. A curved surface generating member connects the plurality of patterns generated by the pattern generating member and the pattern regenerating member in order to generate a three dimensional curved surface. The present invention generates a pattern for each of the three-dimensional lattice-structured cells by connecting the intersection points generated for each of the cells, in accordance with the movement of the input device, and thus can generate an accurate curved surface that corresponds to the user's intention.

Description

【Specification】

[Name of invention]

Surface Modeling Apparatus and Method Using Intersection in 3D Grid Structure

Technical Field

The present invention relates to an apparatus and method for curved surface modeling using intersections in a three-dimensional grid structure. More particularly, the present invention relates to an input device moving in an input space in the form of a three-dimensional grid structure, and to each cell constituting the grid structure. An apparatus and method for modeling a three-dimensional surface by generating a polygon pattern based on the intersection with the edge.

Background Art

As computer technology advances, three-dimensional models based on computer technology are being used from the design process to actual production. In general, three-dimensional models are produced using computer graphics tools such as Max and Maya through three-dimensional input and output. In order to generate a 3D model through the 2D input and output equipment, the model must be generated based on different inputs according to directions. In order to generate a model in this way, cognitive thinking that can infer a three-dimensional model through two-dimensional output is required, and the skill of graphic tools is required. As 3D models are currently used in various fields, there is a need for a method of generating 3D models more easily, quickly and intuitively. The method of creating 3D models quickly and easily in various fields has been studied in various fields. In particular, the 3D spatial input interface system combined with a virtual environment that can be intuitively expressed and is relatively space-independent is being studied. have. In the design field to create a three-dimensional model, the designer's actual movement must be accurately represented as a model, and accurate position data must be tracked.

Therefore, there is a need for a method that can generate a three-dimensional model that accurately reflects the intention of the user.

[Detailed Description of the Invention]

[Technical problem]

An object of the present invention is to provide a surface modeling apparatus and method using an intersection in a three-dimensional grid structure capable of generating in real time a three-dimensional curved surface accurately expressed the user's intention.

Another technical problem to be solved by the present invention is a computer program for executing a surface modeling method using an intersection in a three-dimensional lattice structure capable of generating in real time a three-dimensional surface accurately expressing a user's intention. in To provide a readable recording medium.

Technical Solution

In order to achieve the above technical problem, the curved surface modeling apparatus using the intersection point in the three-dimensional lattice structure according to the present invention, based on the position information and the direction of the input device moving in the three-dimensional input space in the input space For each of the plurality of cells constituting the three-dimensional lattice structure generated by generating the intersection point between the edge of each cell and the movement path of the input device, the normal in accordance with the direction pointed by the input device at the intersection An intersection generator for calculating a vector; A pattern generation unit generating a polygonal pattern by connecting the intersection points based on a generation order of the intersection points and a direction of the normal vector at each intersection point for each cell having the intersection points; A plurality of subcells are generated by repeatedly dividing the cell including the pattern according to a preset number of divisions, and the direction information of the intersection and normal vectors of the subcells generated by dividing the upper cell by each division is generated. A pattern updating unit updating a pattern generated for the upper cell based on the result; And a curved surface generating unit generating a three-dimensional curved surface by connecting a plurality of patterns generated by the pattern generating unit and the pattern updating unit.

In order to achieve the above technical problem, the curved modeling method using the intersection point in the three-dimensional grid structure according to the present invention, based on the position information and the direction of the input device moving in the three-dimensional input space in the input space Creates an intersection point between the edge of each cell and the movement path of the input device for each of a plurality of cells constituting the three-dimensional lattice structure generated by the cell, and a normal line according to the direction indicated by the input device at the intersection point. An intersection generation step of calculating a vector; A pattern generation step of generating a polygonal pattern by connecting the intersection points based on a generation order of the intersection points and a direction of the normal vector at each intersection point for each cell having the intersection points; Generates a plurality of lower cells by repeatedly dividing a cell including the pattern according to a preset number of divisions, and the direction information of intersection points and normal vectors of lower cells generated by splitting an upper cell at each division. A pattern updating step of updating a pattern generated for the upper cell based on the result; And a surface generation step of generating a three-dimensional curved surface by connecting the plurality of patterns generated in the pattern generation step and the pattern update step.

Advantageous Effects

According to the curved surface modeling apparatus and method using the intersection in the three-dimensional grid structure according to the present invention, the three-dimensional grid structure of the three-dimensional lattice structure according to the movement of the input device is not generated Generated for each cell By connecting the intersections to generate a pattern for each cell, an accurate curved surface that matches the user's intention can be created. In addition, when the pattern is generated for each cell, the pattern reflecting the movement of the input device within the cell can be generated by considering not only the order of intersection but also the direction of the normal vector at each intersection. Furthermore, by dividing the cells by gradual dividing according to the complexity of the movement of the input device, it is possible to generate in real time a curved surface well represented.

[Brief Description of Drawings]

1 is a block diagram showing the configuration of a preferred embodiment of a curved modeling device using intersections in a three-dimensional lattice structure according to the present invention;

2 is a view showing a 3D mouse and an example of using the same;

3 is a diagram showing a weemot and an example of using the same;

4 shows an example of spatial drawing using a haptic device,

FIG. 5 is a diagram showing an infrared tracking system used by the present invention, and FIG. 6 is a diagram showing 15 patterns used in the marching cube algorithm and examples of generated curved surfaces.

7 is a diagram illustrating a comparison of curved surfaces generated by the existing marching cube algorithm and the expanded marching cube algorithm.

8 is a view showing an example of intersections and normal vectors generated according to a movement path of an input device;

9 is a diagram illustrating an example of intersections that are sequentially generated as an input device passes through one cell;

10. A diagram showing examples of various patterns generated for one cell according to the movement of the input device.

11 is a diagram illustrating an example of a pattern that may be generated according to a generation order of intersection points in one cell;

12 illustrates an example of a pattern obtained differently according to a direction indicated by an input device.

FIG. 13 and FIG. 14 are views illustrating a method of connecting intersections when three intersections and a form of a pattern that can be generated.

15 and 16 illustrate a method of connecting intersections when four intersections and a form of a pattern that can be generated;

17 and 18 show a method and a generation method for connecting intersections when there are five intersections. Drawing showing the shape of a possible pattern ，

19 and 20 are diagrams illustrating a method of connecting intersections and a form of a pattern that can be generated when there are six intersections;

FIG. 21 is a view showing curved surfaces connected by patterns obtained by the curved surface modeling apparatus according to the present invention and curved surfaces generated by a conventional marching cube algorithm.

FIG. 22 is a diagram illustrating a range in which curved surfaces are generated in the present invention and a marching cube algorithm.

FIG. 23 is a diagram illustrating a pattern generated by a marching cube algorithm and a pattern generator for an input of an input device passing through one cell; FIG.

24 is a view showing a pattern generated by the marching cube algorithm and the pattern generator for a simple input;

25 and 26 illustrate patterns obtained as the speed and direction of an input device passing through a cell change.

27 and 28 show patterns generated by complex movements of the input device;

29 is a view showing a curved surface obtained according to the size of the sal constituting the three-dimensional lattice structure,

FIG. 30 is a diagram illustrating an example of splitting a cell according to a change in a direction of a normal vector, and FIG. 31 is a diagram illustrating an example of splitting a cell located at an edge of a movement path of an input device.

FIG. 32 is a view illustrating inconsistency of patterns occurring when the sizes of adjacent cells are different from each other. FIG.

33 is a view showing an example of connecting patterns generated for adjacent sals of different sizes;

34 is a view showing an example of a three-dimensional surface generated by the surface generating unit, and

FIG. 35 is a flowchart illustrating a preferred embodiment of a curved surface modeling method using intersections in a three-dimensional lattice structure according to the present invention.

[Form for implementation of invention]

With reference to the accompanying drawings and the ^'will be described in detail a preferred embodiment of a surface modeling device and method using the intersection point of the three-dimensional lattice structure according to the invention. 1 is a block diagram showing the configuration of a preferred embodiment of the curved modeling device using the intersection in the three-dimensional lattice structure according to the present invention.

Referring to FIG. 1, the curved surface modeling apparatus includes an intersection generator 110, a pattern generator 120, a pattern updater 130, and a curved surface generator 140.

The intersection generating unit 110 is a corner of each cell for each of a plurality of cells constituting the three-dimensional grid structure generated by the input space based on the position information and the direction of the input device moving in the three-dimensional input space Create an intersection point between the path and the movement path of the input device, and calculate the normal vector according to the direction that the input device points at the intersection point.

The curved surface modeling apparatus according to the present invention is characterized by generating a three-dimensional curved surface from a three-dimensional input rather than a two-dimensional input. In other words, it uses a system capable of direct input and output in a three-dimensional virtual space. This three-dimensional space input system has the advantage that the user can interact in various ways while maximizing the visual immersion of the user in the virtual space. In the case of using the 3D space input system, researches have been made in various fields recently to alleviate the heterogeneity of the 3D input interface and to enable more accurate input.

The 3D mouse, which is one of the space input devices that can obtain the user's location information in three dimensions, is a device that adds the concept of height to the mouse moving in the x-y plane. 2 is a view showing a 3D mouse and its use example. By using a 3D mouse, movement, rotation and height can be easily adjusted. Although this allows more intuitive input than the conventional two-dimensional input, it only deals with existing graphic tools more efficiently, and has a disadvantage in that it can be used only for a specific task.

Another three-dimensional input device is Wiimote, a game controller made for games. WeMote, or Wii Remote, has a motion detection function as its main function and allows the user to interact with and use objects on the screen. It also uses an optical sensor and accelerometer to track the relative position of the controller. Wemot finds the relative position of the controller through three gyro sensors and infrared sensors, and was originally designed for games, but researches using Wemot's three-dimensional data are being conducted in various fields. 3 is a diagram illustrating a weemot and an example of use thereof. On the other hand, the haptic device is a device that creates an artificial touch to the user by using a tactile sensor. 4 shows an example of spatial drawing using a haptic device. Force is transmitted to the user through the motor built into the haptic device, and the motor has an encoder In this way, the current position and posture are understood in three-dimensional space. The device recognizes the user's hand position as only one point on the tip of the pen. Therefore, when this point collides with another object in the virtual space, the haptic device generates a force to the user and transmits information such as the shape and surface texture of the object. Haptic devices are used in various fields such as mobile phones and game consoles, and research is being conducted in various fields such as design and medical fields.

Tracking systems that track moving objects in space include mechanical tracking with rotation sensors, magnetic tracking with magnetic field generators and magnetic field-specific sensors, ultrasonic tracking with sound speed, and camera tracking with recognition of reflective markers.

One of these is the infrared camera tracking system, which uses wands with two infrared cameras and three infrared reflecting markers to track the wand's position. The camera tracking system is hardly affected by electric and magnetic effects, and there is no restriction on user's operation because there is no wire connected to the wand, it has the advantage of location tracking in a wide range and high quality of data. However, there is a disadvantage in that real-time tracking is difficult because many calculations are required to find a feature point and calculate three-dimensional coordinates in an image of a camera, and a key-mera tracking system using infrared rays can be used to solve this problem.

The above-described three-dimensional input device may be used for the curved modeling device according to the present invention. As an embodiment, a case in which the location information and the moving direction of the input device are tracked using the infrared tracking system will be described. 5 is a view showing an infrared tracking system used by the present invention, the wand having the form as shown in Figure 5 (b) by the two infrared cameras as shown in Figure 5 (a), that is the movement of the input device Will be tracked.

As an infrared camera, you can use NaturalPoint's OptiTrack V100R2 camera, which emits infrared light by 26 infrared LEDs and captures 100 frames per second using an infrared filter. The 3D location information of the input device is calculated from the captured image to find the location in space.

In this way, the intersection generator 110 places the positional information of the input device input from the infrared camera into a three-dimensional coordinate space for actually generating a three-dimensional curved surface. To this end, it is assumed that the three-dimensional input space to which the input device moves has a virtual three-dimensional lattice structure, and creates a three-dimensional lattice structure that surrounds the input space. 3D grid The structure is composed of a plurality of cells, and the three-dimensional curved surface is generated by connecting a polygonal pattern generated in each cell unit. Curve generation algorithm according to the grid unit input has been continuously studied, and various algorithms have been developed.

The marching cube algorithm is an algorithm used to represent a 3D model in various fields. The vertices of the grid are determined by inputting the grid and inverting the values. The marching cube algorithm is used during volume rendering to create an isosurface, a surface whose value is constant in three-dimensional space.

6 is a diagram illustrating 15 patterns used in the marching cube algorithm and examples of generated curved surfaces. 15 patterns as shown in FIG. 6A are determined according to the sign of the input in the grid, and 255 types of faces may be drawn according to the position and direction of the plane. FIG. 6B illustrates a curved surface generated by the marching cube algorithm, and a curved surface model in which patterns in each lattice are naturally connected by connection of isovalues in each lattice.

The existing marching cube algorithm is difficult to express the movement in the lattice because the face is composed by the lattice unit. The extended marching cube algorithm is a solution to the problem that cannot be generated by the 15 patterns of the existing marching cube algorithm. 7 is a view showing a comparison between the curved surface generated by the existing marching cube algorithm and the marching cube algorithm, (a) is a target model to be drawn by the user, (b) is generated by the basic marching cube algorithm And (c) is the model generated by the extended Marching Cube algorithm. Comparing (b) and (c), it can be seen that the angular parts that are difficult to express with the existing marching cube algorithm are accurately represented by the expanded marching cube algorithm.

The marching cube algorithm described above can produce the same face as the actual input if the input is accurate or normal, but if the frequency of input is too small or too large, an unintentional movement different from the actual motion may appear. have. Accordingly, the curved surface modeling apparatus according to the present invention does not generate a surface based on an input value in a grid, but constitutes a movement path and a three-dimensional grid structure of an input device configured based on location information and a moving direction of the input device. Create a face based on the intersection with the cell of.

The intersection generator 110 generates an intersection point between the edge of each cell constituting the three-dimensional lattice structure and the movement path of the input device, and calculates a normal vector according to the direction indicated by the input device for each intersection. The input device has a shape as shown in FIG. 8 (a) In this case, a change in the direction indicated by the input device having a constant moving direction can be seen.

8 is a diagram illustrating an example of intersections and normal vectors generated according to a movement path of an input device. 8 (a) shows the movement of the coordinate axis of the input device, the movement and rotation of the input device can be tracked through the three reflection markers provided in the input device. The intersection generator no generates an intersection at each corner of each cell and calculates a normal vector based on the movement of the input device as shown in FIG. The direction of intersection and normal vector generated for each cell is the basis for generating a pattern that is a unit of three-dimensional curved surface for each cell of each sheet.

The pattern generator 120 generates polygonal patterns by connecting the intersection points based on the generation order of the intersection points and the direction of the normal vector at each intersection point for each cell having the intersection points.

When the input device traverses a cell in one movement, at least three to six intersections are created. The order of intersection is the same as that of input device. FIG. 9 is a diagram illustrating an example of intersections that are sequentially generated as the input device passes through one cell, and temporality is given to each of the four intersections generated according to the movement of the input device. The device can distinguish between incoming and outgoing sides. In addition, the intersections including the information about the generation order are connected according to the generation order to generate a pattern in one cell.

FIG. 10 is a diagram illustrating examples of various patterns generated for one cell according to the movement of an input device. Referring to FIG. 10, the number of intersections generated at the cell edges in the order from the left is three, four, and six, respectively, and the plurality of intersections are connected in the generation order to generate one polygonal pattern. have.

When the number of intersections generated for one cell is three, one triangular pattern is obtained by connecting sequentially generated intersections. However, when there are four or more intersections, patterns may be generated differently according to the moving direction of the input device even in the same order. Therefore, in this case, simply connecting sequentially generated intersections may result in a pattern different from the one intended by the user. FIG. 11 is a diagram illustrating an example of a pattern that may be generated according to a generation order of intersection points in one cell. Degree

Referring to 11, even if the order of the intersection points can be generated different patterns.

Even if the order of the intersection points is the same, the shape of the generated pattern is different when the direction indicated by the input device moving in the constant moving direction is changed. do. In other words, the direction of movement does not change by the rotation of the input device, but the direction of the normal vector at the intersection changes.

12 is a diagram illustrating an example of patterns obtained differently according to a direction indicated by an input device. 12A and 12B, the positions of four intersections and the order of generation are the same, but the directions of the normal vectors at the two intersections below are opposite to each other. 12A illustrates a case where the input device passes a cell in a straight line without rotation, and generates a pattern by connecting intersections in the order of the generated intersections. However, in FIG. 12B, a twisted pattern is generated as the input device rotates in the cell.

In this way, even if the generation order of the intersection points is the same, a completely different pattern can be generated according to the direction of the normal vector. Thus, when generating a pattern for each cell, the pattern generator generates not only the generation order of the intersection points but also normals at each intersection point. Consider the direction of the vector as well. Therefore, it is possible to create a pattern of the correct form to suit the user's intention.

Hereinafter, an example of a pattern that can be generated according to the number of intersection points in one cell will be described.

First, there are three intersections. At least three intersections are required to generate one planar pattern, and a triangle pattern is generated. FIG. 13 and FIG. 14 are views illustrating a method of connecting intersections when three intersections and a form of a pattern that can be generated. A triangular pattern around three intersections may be generated in eight forms by changing positions within one cell as shown in FIG. 14.

15 and 16 are diagrams illustrating a method of connecting intersections when four intersections and a form of a pattern that can be generated. Referring to FIGS. 15 and 16, it can be seen that various types of patterns are generated according to the generation order of the four intersections generated when the input device passes one cell once and the direction of the normal vector. If there are four nodes, you can choose which side the input device enters and exits for a single cell, depending on the order of intersection. Accordingly, as shown in FIG. 16, the input is divided into eight cases according to the positional relationship between the input surface IN and the output surface OUT, and all 42 patterns are generated.

FIG. 17 and FIG. 18 illustrate a method of connecting intersections and a form of a pattern that can be generated when five intersections are formed. In this case, it occurs only when an input is bent to one side and bent to two sides. do. First, as shown in (b) of FIG. 17, a plane is formed by connecting four intersection points according to the generation order of the intersection points and the direction of the normal vector, and the fifth intersection point is directed to the two intersection points as shown in (c) of FIG. In connection with FIG. Produces the same pattern.

In the case of 5 intersections, unlike the case of 4 intersections, the outgoing side is always the opposite line if the input device is adjacent to the input line, and the outgoing side is always the adjacent line if the incoming side is the opposite line. Of the total 12 patterns that can be generated in this way, three patterns as shown in FIG. 18 are substantially generated by passage of the input device. The remaining patterns occur when input is interrupted while the input device passes through the cell.

Next, FIGS. 19 and 20 illustrate a method of connecting intersections and a form of a pattern that can be generated when there are six intersections. Referring to FIG. 19, when an input device passes through a cell once and six intersections are generated, when an input side is an adjacent line, the input device exits through the adjacent surface to an adjacent line, and when the input surface is an opposite line, it is an outgoing opposite line. Occurs. The generated six intersections sequentially generate patterns as shown in FIGS. 19B to 19D according to the generation order and the direction of the normal vector. FIG. 20 illustrates three patterns generated by passage of an input device substantially out of the patterns that can be generated by six intersections, and the remaining patterns enter the intersection after the input device passes through the cell and then generate the intersection points. This is the case.

FIG. 21 is a diagram illustrating a curved surface connected to patterns obtained by the curved modeling device according to the present invention and a curved surface generated by a conventional marching cube algorithm. Of Figure 21 (a) is a pattern generator by 120 a curved surface eojin obtained by connecting the resulting pattern for each cell, as a ^"must connect all the intersection produced by the movement of the input device by the user, user's intention, Surfaces matching C are generated. Figure 21 (b) is a surface generated using the marching cube algorithm, since the form of the input is simple, a surface similar to the user input was generated.

As described above, although the curved surface generated by the present invention and the shape of the curved surface generated by the marching cube algorithm are similar, the two methods show differences in the range of pattern generation. FIG. 22 is a diagram illustrating a range in which curved surfaces are generated in the present invention and the marching cube algorithm. Figure 22 (a) is a view showing the intersection connection pattern according to the present invention, a curved surface is generated according to the range that the wand correctly passed through the cell. However, in the case of using the Marching Cube algorithm, if a single input is included in a cell, a pattern is formed in the corresponding cell, and thus, the surface generation range is widened as shown in FIG. .

In addition, the surface modeling apparatus according to the present invention is not only a simple input but also within a cell. Accurate patterns can be generated even for complex inputs such as the input device rotating. FIG. 23 is a diagram illustrating a pattern generated by a marching cube algorithm and a pattern generator with respect to an input of an input device passing through one cell. FIG. 23 (a) is a view illustrating a case where the input device enters the upper surface of the cell, rotates inside the cell, and exits through the front surface;

(b) shows a pattern generated by the marching cube algorithm for the movement of the input device. Since the marching cube algorithm generates a pattern by input points in a cell, when the input is not constant and complex data, a pattern different from the user's intention is generated. However, when generating a pattern through intersection connection as shown in (c) of FIG. 23, a pattern similar to a movement path of an actual input device may be generated regardless of an input change due to rotation of the input device.

FIG. 24 is a diagram illustrating a pattern generated by the marching cube algorithm and the pattern generator 120 for a simple input. As shown in (a) of FIG. 24, when the input device simply passes through the cell in one direction without rotation, the pattern of (b) and the pattern generating unit 120 of (b) generated by the marching cube algorithm are generated. It can be seen that the shape of the pattern is similarly obtained.

25 and 26 illustrate patterns obtained as the speed and direction of an input device passing through a cell change. First, FIG. 25 illustrates a case in which the frequency of input changes in a specific part of a cell as the user moves the input device. As shown in FIG. 25A, when the frequency of the input increases at a point where the input device changes rapidly as the direction of movement of the input device changes in the cell, the pattern of FIG. 25B obtained by the marching cube algorithm is represented by each point. By calculating the isovalue of, the user's actual intention and argument pattern are generated. However, since the pattern generated by the pattern generating unit 120 of the curved modeling device according to the present invention generates a pattern by connecting the intersections regardless of the frequency of the input as shown in FIG. It can generate a pattern close to the movement of the. The part where the movement of the input device changes rapidly in the cell can be expressed by the division of the cell described later.

In addition, (a) of FIG. 26 illustrates a case in which the movement of the input device stops once in the cell and then proceeds again. In this case, the pattern by the marching cube algorithm shown in (b) of FIG. 26 has a form independent of the movement of the actual input device.

The pattern generated by the pattern generator 120 shown in (c) has a form corresponding to the movement of the input device, and thus reflects the intention of the user.

27 and 28 illustrate patterns generated by complex movements of the input device. 1 drawing. Both Figures 27 and 28 illustrate a complex type of input where the input device is diagonal to the top of the cell and exits sideways past the edges within the cell. The marching cube algorithm generates a surface similar to the actual input in 15 predetermined patterns. However, in the case of such a complicated input, a pattern of a form not intended by the user as shown in FIGS. 27 and 28 (b) is generated. Will be created. However, in the case of generating a pattern by connecting intersections, a pattern can be generated separately from the complexity of the input. As shown in FIGS. 27 and 28 (c), a pattern similar to the motion of an actual input device is shown. Is generated.

As described above, according to the pattern generating unit 120 of the curved modeling device, the pattern corresponding to each cell is generated by connecting the intersections generated at the edges of the cells by the movement path of the input device. Compared to the marching cube algorithm using several patterns defined in Fig. 3, a three-dimensional curved surface that accurately reflects the user's intention can be generated.

The pattern updater 130 generates a plurality of subcells by repeatedly dividing a cell including the pattern according to a preset number of divisions, and generates direction information of intersection points and normal vectors of the subcells generated at each division. Update the pattern on the basis.

In the grid-based algorithm, when the model is represented by a certain size of sal, there is a limit in expressing the details of the model. In addition, the smaller the cell size, the finer the expression becomes, but the computational amount increases, making real-time modeling difficult. Accordingly, the pattern updater 130 selectively divides the cells determined to be necessary for detailed expression without dividing all the cells constituting the 3D grid structure to generate a pattern that meets the user's intention.

The octree is a tree structure in which each node has a maximum of eight child nodes, and is an ideal structure when representing a three-dimensional space composed of cubes. The pattern updater 130 divides a cell including a pattern, that is, a cell passed by the input device, into eight sub-cells among the cells constituting the three-dimensional lattice structure. This division process is repeatedly performed, and the pattern updating process is performed for the lower cells generated for each division. _.

That is, when the uppermost cell is divided and eight upper cells are generated, a new pattern is generated based on the intersection and normal vector information for each of the upper cells. At this time, the cells having no intersection among the upper cells are excluded in the next partitioning process, and only the upper cells having the updated pattern are split into the lower cells again. The number of repetitive divisions by the pattern updater 130 may be set in advance, and whether or not to divide a specific cell. It is also possible to set a red flag.

FIG. 29 is a view showing a curved surface obtained according to the size of a cell constituting the three-dimensional lattice structure. FIG. FIG. 29A illustrates a target surface to be drawn by the user. When trying to express this in the three-dimensional lattice structure, if the size of the cells constituting the lattice structure is too large, there is a limit in expressing the shape of a smooth curved surface as shown in (b) of FIG. In addition, if the size of the sal is too small, as shown in (c) of FIG. 29, a curved surface having a shape substantially the same as that of the target surface may be generated, but the calculation amount is large, which is inefficient. However, as described above, if the dichotomous division method is used, a curved surface having a shape similar to the one intended by the user can be quickly generated as shown in FIG.

On the other hand, instead of dividing all cells including the pattern into lower cells, the pattern updater 130 may divide the corresponding cells only when the input change is large in the sal. 30 is a diagram illustrating an example in which cells are divided according to a change in direction of a normal vector. Referring to the left figure of FIG. 30, when the input device passes through one cell, the direction of the input device changes inside the cell. This can be seen from the direction of the normal vector at the intersection created first when the input device enters the cell and the last created intersection when the input device exits the cell.

Therefore, the pattern updater 130 subordinates the corresponding cell when the direction of the normal vector at the first and the last intersections generated for one cell changes by more than a preset reference angle. The cells may be selectively divided as shown in the right figure of FIG. 30 by dividing into cells. As the size of the reference angle is smaller, the rapid change of the input device can be represented well, but the number of divisions increases, and the accuracy of the detailed expression decreases as the size of the reference angle increases. Therefore, the value of the reference angle is appropriately set, and as an example, the reference angle may be set to 45 ^° .

In addition, the pattern updater 130 may selectively divide the cell located at the edge of the movement path to express in detail the portion corresponding to the edge of the movement path of the input device. FIG. 31 is a diagram illustrating an example of dividing a cell located at an edge of a movement path of an input device. Referring to FIG. 31, when the input device passes through a cell as shown in the figure on the left, celldols corresponding to the edges of the movement path have two intersections and are excluded from pattern generation. However, except for these cells, creating a pattern produces a surface with a smaller range than the actual input. Therefore, the pattern can be divided by repeatedly dividing the cell located at the edge of the movement path to accurately reflect the actual input. Can be generated.

That is, as shown in the right figure of FIG. 31, if the six cells located at the edge of the movement path are divided twice, the lower cells through which the input device passes completely can be obtained. Accordingly, the pattern update unit 130 generates a pattern for the lower cell so that a curved surface matching the movement path of the input device is generated.

The curved surface generating unit 140 connects the plurality of patterns generated by the pattern generating unit 120 and the pattern updating unit 130 to generate a three-dimensional curved surface.

Pattern generation by the pattern generator 120 and the pattern updater 130 is performed in units of cells. The curved surface generating unit 140 may generate a three-dimensional curved surface that is sympathetic to the movement of the input device by connecting a plurality of finally generated patterns.

However, when the sizes of the adjacent sals including the patterns are different, that is, when the cells having different levels in the tree structure are adjacent to each other, the boundary lines of the patterns may not match. FIG. 32 is a diagram illustrating inconsistencies in patterns that occur when sizes of adjacent adjacent cells differ. Referring to FIG. 32, the sal on the left is divided into eight sub-sales, whereas the sal on the right is not divided, and thus the sizes of adjacent sals are different. In addition, the pattern on the left side represents the curved surface generated for each of the small sized sub-cells, while the pattern on the right side is generated for one undivided cell and has a flat shape. Therefore, when the left and right patterns are connected, a spaced point occurs.

In order to solve this problem, the surface generating unit 140 matches the intersection information of the cell corresponding to the lower cell with the information of the intersection of the cell corresponding to the upper cell in the boundary between the adjacent cells. Make the patterns connect naturally. 33 is a diagram illustrating an example of connecting patterns generated for adjacent cells of different sizes. Referring to (a) of FIG. 33, a portion spaced between a pattern generated in a lower cell and a pattern generated in an upper cell occurs due to a change in size of adjacent cells. At this time, by matching the intersection information of the lower cell to the upper cell at the interface between the upper cell and the lower cell, it can be seen that the pattern is naturally connected as shown in FIG. 33 (b).

34 is a diagram illustrating an example of a three-dimensional curved surface generated by the curved surface generating unit 140. Referring to FIG. 34, a three-dimensional curved surface is generated by connecting patterns generated for a plurality of cells to each other. At this time, if all the cells containing the pattern are not divided and only the part where the curved surface is rapidly changed, it is divided into the lower cells to accurately reflect the user's intention. You can also quickly create 3D surfaces. In addition, even when the input device passes through a part of the cell without passing through the cell, the input path of the input device can be accurately represented by the above-described redundancy.

Referring to FIG. 35, the intersection generating unit 110 each includes a plurality of cells constituting a three-dimensional lattice structure generated in response to the input space based on the position information and the direction of the input device moving in the three-dimensional input space. An intersection is generated between the edge of each cell and the movement path of the input device, and a normal vector is calculated according to the direction pointed by the input device at the intersection (S1110).

Next, the pattern generator 120 generates a polygonal pattern in which intersections are connected based on a generation order of intersections and a direction of a normal vector at each intersection for each cell having intersections (S1120). In addition, the pattern updater 130 generates a plurality of lower cells by repeatedly dividing the cell including the pattern according to a preset number of divisions, and the intersection of the lower cells generated by splitting the upper cell at each division. And a pattern generated for the upper cell based on the direction information of the normal vector (S1130).

Finally, the curved surface generating unit 140 connects the plurality of patterns generated by the pattern generating unit 120 and the pattern updating unit 130 to generate a three-dimensional curved surface (S1140).

The invention can also be embodied as computer readable code on a computer readable recording medium. Computer-readable recording media include any type of recording device that stores data that can be read by a computer system. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like, and may also be implemented in the form of a carrier wave (for example, transmission over the Internet). Include. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

Although the preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the above-described specific preferred embodiments, and the present invention belongs to the present invention without departing from the gist of the present invention as claimed in the claims. Various modifications can be made by those skilled in the art, and such changes are within the scope of the claims.

Claims

[Range of request]

[Claim 1]

The edge of each cell and the input of each of the plurality of cells constituting the three-dimensional lattice structure generated by the input space based on the position information and the direction of the input device moving in the three-dimensional input space An intersection generator which generates an intersection point between movement paths of the device and calculates a normal vector according to a direction indicated by the input device at the intersection point;

A pattern generation unit generating a polygonal pattern by connecting the intersection points based on a generation order of the intersection points and a direction of the normal vector at each intersection point for each cell having the intersection points;

The cell including the pattern is repeatedly divided according to a preset number of divisions to generate a plurality of subcells, and the subcells are divided based on the direction information of the intersection points and normal vectors of the subcells generated by dividing the upper cell. A pattern updater for updating a pattern generated for the upper cell with a; And

And a curved surface generator for connecting a plurality of patterns generated by the pattern generator and the pattern updater to generate a three-dimensional curved surface.

[Claim 2]

The method of claim 1,

The pattern updater generates the lower cell by dividing a cell having a difference between a first generated intersection point and a last vector generated intersection point of a normal vector from a cell including the pattern greater than or equal to a preset reference angle. Surface Modeling Apparatus.

[Claim 3]

The method according to claim 1 or 2,

The pattern updating unit generates a pattern based on direction information of intersection points and normal vectors of a lower cell generated by dividing a cell located at an edge of a movement path of the input device among the plurality of cells. Device.

[Claim 4]

The method according to claim 1 or 2,

The curved surface generating unit is lower in the interface between the adjacent cells when the sizes of adjacent cells among the plurality of cells generated by the repetitive division are different. Curved modeling device characterized in that the information of the intersection of the cell corresponding to the cell matching the information of the intersection of the cell corresponding to the upper cell.

[Claim 5]

The method according to claim 1 or 2,

The input device is a wand made of three infrared reflecting markers, and the position information and the moving direction of the input device are obtained by tracking the movement of the wand by two infrared cameras.

[Claim 6]

The edge of each cell and the input of each of a plurality of cells constituting the three-dimensional grid structure generated by the input space based on the position information and the direction of the input device moving in the three-dimensional input space An intersection point generation step of generating an intersection point between movement paths of the device and calculating a normal vector according to a direction indicated by the input device at the intersection point;

A pattern generation step of generating a polygon pattern by connecting the intersection points based on a generation order of the intersection points and a direction of the normal vector at each intersection point for each cell having the intersection points;

A cell including the pattern is repeatedly divided according to a preset number of divisions to generate a plurality of lower cells, and based on the intersection information and normal vector direction information of the lower cells generated by splitting the upper cell at each division. A pattern updating step of updating a pattern generated for the upper cell with; And

And a surface generation step of generating a three-dimensional surface by connecting the plurality of patterns generated in the pattern generation step and the pattern update step.

[Claim 71

In claim 6

In the pattern updating step, the sub-cell is generated by dividing a cell whose difference between the first generated intersection point and the last generated intersection point among the cells including the pattern is greater than or equal to a predetermined reference angle. Surface modeling method characterized in that.

[Claim 8]

The method according to claim 6 or 7,

Moving mirror of the input device among the plurality of cells in the pattern updating step A surface modeling method comprising generating a pattern based on direction information of an intersection point and a normal vector of a lower cell generated by dividing a cell located at an edge of a furnace.

[Claim 9]

The method according to claim 6 or 7,

In the curved surface generating step, when adjacent cells of the plurality of cells generated by the repetitive division have different sizes, information on the intersection points of the cells corresponding to the lower cells is included in the upper cell at the interface between the adjacent cells. Surface modeling method characterized in that the matching of the intersection information of the corresponding cell.

[Claim 10]

The method according to claim 6 or 7,

The input device is a wand made of three infrared reflection markers, and the position information and the moving direction of the input device are obtained by tracking the movement of the wand by two infrared cameras.

[Claim 11]

A computer-readable recording medium having recorded thereon a program for executing the curved modeling method according to claim 6 or 7.