KR20110102618A - Apparatus and method for modeling curved surface using intersection points in three-dimensional grid structure - Google Patents

Abstract

Disclosed are a surface modeling apparatus and method using intersections in a three-dimensional lattice structure. The intersection generator generates a corner of each cell and an input device for each of a plurality of cells constituting the three-dimensional grid structure generated corresponding 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 point between the movement paths is generated, and a normal vector is calculated according to the direction pointed by the input device at the intersection point. The pattern generator 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. The pattern updater generates a plurality of lower cells by repeatedly dividing a cell including a pattern according to a preset number of divisions, and the direction information of intersection and normal vectors of lower cells generated by splitting an upper cell at each division. Update the generated pattern for the upper cell based on. The curved surface generator generates a three-dimensional curved surface by connecting a plurality of patterns generated by the pattern generator and the pattern updater. According to the present invention, a pattern for each cell is connected by connecting intersections generated for each cell of the three-dimensional lattice structure according to the movement of the input device, rather than generating a three-dimensional curved surface by connecting a pattern of a preset shape. By generating the, it is possible to generate an accurate surface that matches the user's intention.

Description

Apparatus and method for modeling curved surface using intersection points in three-dimensional grid structure}

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 curved surface by generating a polygonal pattern based on an intersection with an edge.

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 inputs different according to directions. Generating a model in this way requires cognitive thinking that can infer a three-dimensional model through two-dimensional output, and requires skill in graphic tools. 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 has been studied in various fields, and in particular, researches on 3D space input interface systems combined with virtual environments that can be intuitively expressed and are relatively space-independent are in progress. . 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.

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

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

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 corresponds to the input space based on the position information and the direction of the input device moving in the three-dimensional input space. For each of a plurality of cells constituting the three-dimensional grid structure generated by the intersection point of the intersection of the edge of each cell and the movement path of the input device is generated, the normal vector in the direction pointed by the input device at the intersection point An intersection generator for calculating; 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 a cell including the pattern according to a preset number of divisions, and based on direction information of intersection points and normal vectors of lower cells generated by splitting an upper cell at each division. A pattern updater for updating a pattern generated for the upper cell with a; And a curved surface generating unit generating a three-dimensional curved surface by connecting the 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, corresponding to the input space based on the position information and the direction of the input device moving in the three-dimensional input space For each of a plurality of cells constituting the three-dimensional grid structure generated by the intersection point of the intersection of the edge of each cell and the movement path of the input device is generated, the normal vector in the direction pointed by the input device at the intersection point An intersection generation step of calculating; 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 plurality of subcells are generated by repeatedly dividing a cell including the pattern according to a preset number of divisions, and based on 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 with a; 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.

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

1 is a block diagram showing the configuration of a preferred embodiment of the curved surface modeling apparatus using the intersection in the three-dimensional lattice structure according to the present invention;
2 is a view showing a 3D mouse and its use example,
3 is a diagram illustrating an example of using a wee moit,
4 shows an example of spatial drawing using a haptic device,
5 shows an infrared tracking system used by the present invention,
FIG. 6 is a diagram illustrating 15 patterns used in a marching cube algorithm and examples of generated surfaces; FIG.
FIG. 7 is a view illustrating a comparison of curved surfaces generated by an existing marching cube algorithm and an expanded marching cube algorithm.
8 is a diagram illustrating an example of intersection 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 is a diagram illustrating examples of various patterns generated for one cell according to the movement of an input device;
11 illustrates an example of a pattern that may be generated according to a generation order of intersection points in one cell;
12 is a view showing an example of a pattern obtained differently according to the direction indicated by the input device,
13A and 13B illustrate a method of connecting intersections when three intersections and a form of a pattern that can be generated;
14A and 14B illustrate a method of connecting intersections when four intersections and a form of a pattern that can be generated;
15A and 15B illustrate a method of connecting intersections in the case of five intersections and a form of a pattern that can be generated;
16A and 16B illustrate a method of connecting intersections and a form of a pattern that can be generated when there are six intersections;
FIG. 17 is a view showing surfaces curved by patterns obtained by the surface modeling apparatus according to the present invention and surfaces generated by a conventional marching cube algorithm;
FIG. 18 is a diagram illustrating a range in which curved surfaces are generated in the present invention and a marching cube algorithm.
19 illustrates a pattern generated by a marching cube algorithm and a pattern generator for an input of an input device passing through one cell;
20 is a view showing a pattern generated by the marching cube algorithm and the pattern generator for a simple input;
21A and 21B show patterns obtained as the speed and direction of an input device passing through a cell changes.
22A and 22B illustrate patterns generated by complex movements of an input device;
23 is a view showing a curved surface obtained according to the size of the cells constituting the three-dimensional lattice structure,
24 is a diagram illustrating an example of dividing a cell according to a change in direction of a normal vector;
FIG. 25 illustrates an example of dividing a cell located at an edge of a movement path of an input device; FIG.
FIG. 26 is a diagram illustrating inconsistencies in patterns occurring when the sizes of adjacent cells are different from each other. FIG.
27 illustrates an example of connecting patterns generated for adjacent cells of different sizes;
28 is a diagram illustrating an example of a three-dimensional curved surface generated by the curved surface generating unit, and
29 is a flowchart illustrating a process of performing a preferred embodiment of the curved surface modeling method using the intersection points in the three-dimensional lattice structure according to the present invention.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the surface modeling apparatus and method using the intersection in the three-dimensional grid structure according to the present invention.

1 is a block diagram showing the configuration of a preferred embodiment of the curved surface modeling apparatus using the intersection point in the three-dimensional lattice structure according to the present invention.

Referring to FIG. 1, the curved surface modeling apparatus according to the present invention 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 an edge of each cell for each of a plurality of cells constituting a three-dimensional grid structure generated corresponding 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 between the path and the movement path of the input device is generated, and a normal vector corresponding to the direction pointed by the input device at the intersection is calculated.

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 that can directly input and output in a three-dimensional virtual space. Such a 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 precise 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 a motor built into the haptic device, and an encoder is attached to the motor to determine the current position and posture 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 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 velocity, and camera tracking with recognition of reflex markers.

One of these is an infrared camera tracking system, which uses a wand 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 because there is no wire connected to the wand, there is no restriction on the user's movement, the position tracking is possible in a wide range, and the data quality is high. However, since a lot of calculations are required to find a feature point in a camera image and calculate three-dimensional coordinates, it is difficult to track in real time. Therefore, a camera 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. FIG. 5 is a view illustrating an infrared tracking system used by the present invention, wherein the wand having the shape as shown in FIG. 5B is moved by two infrared cameras as shown in FIG. To 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.

The intersection generator 110 maps the position information of the input device input from the infrared camera to the three-dimensional coordinate space for actually generating the 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 corresponding to the input space. The three-dimensional grid structure is composed of a plurality of cells, the three-dimensional curved surface is generated by connecting the pattern of the polygon 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 three-dimensional model in various fields. The marching cube algorithm is a method of generating a face by inputting the vertices of a 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.

FIG. 6 is a diagram illustrating 15 patterns used in the marching cube algorithm and examples of generated curved surfaces. Fifteen 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 a 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 of the lattice unit. Extended marching cube (extended marching cube) algorithm is a method to solve the problem that can not 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 expanded marching cube algorithm, (a) is a target model to be drawn by the user, (b) is generated by the basic marching cube algorithm The model, and (c) is a 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 by 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. Therefore, the curved surface modeling apparatus according to the present invention does not generate a surface based on an input value in a grid, and each cell constituting a movement path and a three-dimensional grid structure of the input device based on the position information and the moving direction of the input device; Create a face based on the intersection of.

The intersection generating unit 110 generates an intersection between the edge of each cell constituting the three-dimensional grid 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. When the input device has a shape as shown in (a) of FIG. 8, 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 intersection and normal vectors generated according to a movement path of an input device. FIG. 8 (a) shows the movement of the coordinate axis of the input device, and the movement and rotation of the input device can be tracked through three reflective markers provided in the input device. The intersection generator 110 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 the intersection point and the 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.

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 illustrates an example of intersections that are sequentially generated as the input device passes through one cell. FIG. 9 is a diagram illustrating time points of each of four intersection points generated by the movement of the input 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. Referring to FIG. 11, even when the intersection points are the same, different types of patterns may be generated.

As such, 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. 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. 12 (a) and 12 (b) have the same positions and generation order of four intersections, but the directions of the normal vectors at two intersections below are opposite to each other. 12A illustrates a case where the input device passes through the cell in a straight line without rotating, and generates a pattern by connecting the intersection points in the order of the generated intersection points. However, in FIG. 12B, a twisted pattern is generated as the input device rotates in the cell.

As such, even if the order of generation of the intersection points is the same, a completely different pattern can be generated according to the direction of the normal vector, the pattern generator generates not only the generation order of the intersection points but also the 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. 13A and 13B illustrate a method of connecting intersections when three intersections and a form of a pattern that can be generated. A triangle pattern corresponding to three intersections may be generated in eight forms by changing positions in one cell.

14A and 14B illustrate a method of connecting intersections when four intersections and a form of a pattern that can be generated. Referring to FIGS. 14A and 14B, it can be seen that various patterns are generated according to the generation order of four intersection points and the direction of the normal vector generated when the input device passes one cell once. If there are four intersections, the input and output sides of the input device can be determined for one cell according to the order of intersection. Accordingly, as shown in FIG. 14B, the input is divided into eight cases according to the positional relationship between the input surface IN and the output surface OUT of the input device, and 42 patterns are generated.

15A and 15B illustrate a method of connecting intersections in the case of five intersections and a form of a pattern that can be generated, and this case only occurs when an input enters one side and bends to two sides. First, as shown in (b) of FIG. 15A, 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. 15A. By connecting along, a pattern as shown in (d) of FIG. 15A is generated.

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. 15B are substantially generated by passage of the input device. The remaining patterns occur when the input is interrupted while the input device is passing through the cell.

Next, FIGS. 16A and 16B illustrate a method of connecting intersections and a form of a pattern that can be generated when there are six intersections. Referring to FIG. 16A, when an input device passes through a cell once and six intersections are generated, when an input side is an adjacent line and exits through an adjacent surface to an adjacent line, and when the input surface is an opposite line, the input device is an opposite line. Occurs. The patterns are generated sequentially as shown in (b) to (d) of FIG. 16A according to the generated intersection points and the direction of the normal vector. FIG. 16B illustrates three patterns generated by the passage of the input device substantially from among the patterns that can be generated by the six intersections, and the remaining patterns are entered when the input device passes through the cell and then enters the intersection again. Corresponding.

FIG. 17 is a diagram illustrating curved surfaces obtained by connecting patterns obtained by the curved surface modeling apparatus according to the present invention, and curved surfaces generated by a conventional marching cube algorithm. FIG. 17 (a) is a curved surface obtained by connecting patterns generated for each cell by the pattern generator 120, in which all intersections generated by the movement of the input device by the user are connected to match the intention of the user. The surface is created. FIG. 17B illustrates a curved surface generated by using a marching cube algorithm. Since the input form is simple, a curved surface similar to a user input is generated.

As described above, although the curved surface generated by the present invention and the curved surface generated by the marching cube algorithm are similar, the two methods show a difference in the range for generating the pattern. FIG. 18 is a diagram illustrating a comparison between a range in which curved surfaces are generated in the present invention and a marching cube algorithm. FIG. Figure 18 (a) is a view showing the intersection connection pattern according to the present invention, a curved surface is generated according to the precise range of the wand passed through the cell. However, in the case of using the marching cube algorithm, when a single input is included in a cell, a pattern is formed in the corresponding cell, and thus, a shape generation range widens as shown in FIG.

In addition, the curved surface modeling apparatus according to the present invention can generate an accurate pattern not only for a simple input but also for a complicated input such as a rotation of an input device in a cell. FIG. 19 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. (A) of FIG. 19 illustrates a case in which the input device enters the upper surface of the cell, rotates inside the cell, and exits through the front surface, and (b) illustrates a pattern generated by the marching cube algorithm for the movement of the input device. The figure shown. Since the marching cube algorithm generates a pattern by input points in a cell, when the input is not constant and complicated data, a pattern of a form different from the user's intention is generated. However, when the pattern is generated through the intersection connection as shown in FIG. 19C, a pattern similar to the movement path of the actual input device may be generated regardless of the change in the input due to the rotation of the input device.

20 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. 20, 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.

21A and 21B illustrate patterns obtained as the speed and direction of an input device passing through a cell change. First, FIG. 21A illustrates a case where an input frequency is changed in a specific part of a cell as a user moves an input device. As shown in (a) of FIG. 21A, when the frequency of input increases at the point of change as the direction of movement of the input device changes rapidly in the cell, the pattern of FIG. 21A (b) obtained by the marching cube algorithm is used for each point. By calculating the isovalue of, a pattern is generated that is different from the user's actual intent. However, 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, thereby generating a pattern close to the movement of the actual input device. 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. 21B illustrates a case where 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. 21B has a form irrelevant to the movement of the actual input device, but the pattern by the pattern generating unit 120 shown in (c) of FIG. The user's intention is well reflected by having the shape according to the movement of the input device.

22A and 22B illustrate patterns generated by complex movements of the input device. 22A and 22B both show complex inputs in which 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 with 15 predetermined patterns. However, in the case of such a complicated input, the marching cube algorithm generates a pattern that is not intended by the user as shown in FIGS. 22A and 22B. do. However, in the case of generating a pattern by connecting intersections, a pattern can be generated separately from the complexity of the input, and a pattern similar to the motion of an actual input device as shown in FIGS. 22A and 22B (c). Is generated.

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

The pattern updater 130 generates a plurality of subcells by repeatedly dividing a cell including a 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 cell of a constant size, there is a limit in expressing the details of the model. In addition, as the size of the cell becomes smaller, finer expression is possible, but the computational amount increases, making real-time modeling difficult. Accordingly, the pattern updater 130 selectively divides the cells determined to require detailed expression without dividing all the cells constituting the 3D grid structure to generate a pattern that meets the intention of the user.

An octree is a tree structure in which each node has up to eight child nodes, which is ideal for representing a three-dimensional space composed of cubes. The pattern updater 130 divides the cell including the pattern, that is, the cell passed by the input device, into eight sub-cells among the cells constituting the 3D grid 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 information of the intersection point and the normal vector for each of these upper cells. At this time, the cell having no intersection among the upper cells is excluded in the next partitioning process, and only the upper cell having the updated pattern is divided into lower cells again. The number of repetitive divisions by the pattern updater 130 may be set in advance, and an adaptive criterion may be set for whether or not to divide a specific cell.

FIG. 23 is a diagram showing curved surfaces obtained according to the sizes of cells constituting a three-dimensional lattice structure. FIG. FIG. 23A illustrates a target surface to be drawn by the user. When trying to express this in a three-dimensional lattice structure, if the size of the cells constituting the lattice structure is too large, there is a limit to expressing the shape of a smooth curved surface as shown in Fig. 23 (b). In addition, if the size of the cell is too small, as shown in (c) of FIG. 23, a curved surface having substantially the same shape as the target curved surface may be generated, but the amount of calculation is large, which is inefficient. However, using the adaptive segmentation method as described above, it is possible to quickly generate a curved surface having a similar shape as the user intended as shown in (d) of 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 cells. FIG. 24 is a diagram illustrating an example of dividing a cell according to a change in direction of a normal vector. Referring to the left figure of FIG. 24, 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 generated first when the input device enters the cell and the last generated 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 more than a preset reference angle. Can be divided into cells. As the size of the reference angle decreases, the abrupt change of the input device can be represented well, but the number of divisions increases, and the precision of the detailed expression decreases as the size of the reference angle increases. Therefore, the reference angle may be 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 in order to express in detail the portion corresponding to the edge of the movement path of the input device. FIG. 25 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. 25, when the input device passes through a cell as shown in the left figure, cells corresponding to the edge of the movement path have two intersections, and thus are excluded from the pattern generation. However, except for these cells, creating a pattern creates a surface with a smaller range than the actual input. Therefore, the pattern may be generated by repeatedly dividing a cell located at the edge of the movement path to accurately reflect the actual input.

That is, as shown in the right figure of FIG. 25, 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 a 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 3D curved surface corresponding to the movement of the input device by connecting a plurality of finally generated patterns.

However, when the sizes of adjacent cells including the patterns are different, that is, when cells having different levels in the tree structure are adjacent to each other, the boundary lines of the patterns may not match. FIG. 26 is a diagram illustrating a pattern mismatch that occurs when the sizes of adjacent cells are different. Referring to FIG. 26, the cell on the left is divided into eight subcells while the cell on the right is not divided, and thus adjacent cells have different sizes. In addition, the pattern on the left side represents the curved surface that is generated and bent for each of the lower-sized cells, while the pattern on the right side is generated for one undivided cell and has a flat shape. As a result, when the left and right patterns are connected, spaced points are generated.

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 intersection information of the cell corresponding to the upper cell in the interface between the adjacent cells, and thus, between adjacent cells of different sizes. Make the patterns connect naturally. FIG. 27 is a diagram illustrating an example of connecting patterns generated for adjacent cells of different sizes. Referring to (a) of FIG. 27, a portion spaced between a pattern generated in a lower cell and a pattern generated in an upper cell occurs due to a difference in sizes 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 confirmed that the patterns are naturally connected as shown in FIG. 27 (b).

28 is a diagram illustrating an example of a 3D curved surface generated by the curved surface generating unit 140. Referring to FIG. 28, a three-dimensional curved surface is generated by connecting patterns generated for a plurality of cells to each other. In this case, all cells including the pattern may be divided into sub-cells only for the portion where the curved surface is rapidly changed, and thus the 3D curved surface can be quickly generated while accurately reflecting the user's intention. In addition, even when the input device does not pass through the cell but partially passes, the input path of the input device can be accurately represented by the adaptive division described above.

29 is a flowchart illustrating a process of performing a preferred embodiment of the curved surface modeling method using the intersection points in the three-dimensional lattice structure according to the present invention.

Referring to FIG. 29, the intersection generator 110 may include a plurality of cells constituting a three-dimensional grid structure generated in correspondence 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 corresponding to the direction pointed by the input device is calculated at the intersection (S1110).

Next, the pattern generator 120 generates a polygonal pattern in which the intersections are connected based on the generation order of the intersections and the direction of the normal vector at each intersection for each cell having the 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 points of the lower cells generated by splitting the upper cell at each division and The generated pattern for the upper cell is updated based on the direction information of the normal vector (S1130).

Finally, the curved surface generating unit 140 connects a 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 present invention can also be embodied as computer-readable codes on a computer-readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of the computer-readable recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like, and may be implemented in the form of a carrier wave (for example, transmission via the Internet) . 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 specific preferred embodiments described above, 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.

110-Vertex Generator
120-pattern generator
130-pattern update unit
140-surface generator

Claims (11)

The corners of the cells and the input device of the plurality of cells constituting the three-dimensional lattice structure generated corresponding 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 generator which generates an intersection point between movement paths 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;
A plurality of subcells are generated by repeatedly dividing a cell including the pattern according to a preset number of divisions, and based on direction information of intersection points and normal vectors of lower cells generated by splitting an upper cell at each division. 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. The method of claim 1,
The pattern updating unit generates the sub-cell by dividing a cell having a difference in the direction of a normal vector with respect to the first generated intersection and the last generated intersection among cells including the pattern equal to or greater than a preset reference angle. Surface modeling device. 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. 3. The method according to claim 1 or 2,
If the size of the adjacent cells among the plurality of cells generated by the repetitive division is different from each other, the curved surface generating unit is a cell corresponding to the upper cell with the information of the intersection of the cells corresponding to the lower cells in the interface between the adjacent cells The surface modeling apparatus characterized by matching this branch with information of an intersection. 3. 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. The corners of the cells and the input device of the plurality of cells constituting the three-dimensional lattice structure generated corresponding 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 generation step of generating intersection points between movement paths 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 plurality of subcells are generated by repeatedly dividing a cell including the pattern according to a preset number of divisions, and based on 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 with a; 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. The method of claim 6,
In the pattern updating step, generating a lower cell by dividing a cell having a difference in a direction of a normal vector with respect to a first generated intersection and a last generated intersection among cells including the pattern being equal to or greater than a preset reference angle. Characterized by the surface modeling method. The method according to claim 6 or 7,
In the pattern updating step, a pattern is generated 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 movement path of the input device among the plurality of cells. Surface modeling method. The method according to claim 6 or 7,
In the curved surface generation step, when adjacent cells of the plurality of cells generated by the repetitive division have different sizes, corresponding intersection information of a cell corresponding to a lower cell corresponds to an upper cell at an interface between the adjacent cells. Curved modeling method characterized in that it matches the information of the intersection point of the cell. 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. A computer-readable recording medium having recorded thereon a program for executing the curved surface modeling method according to claim 6 or 7.

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