JPH09223247A - Simulation method of movement of clothes - Google Patents

Abstract

(57) Abstract: To provide a method for simulating the movement of clothes, which can be applied to many purposes and can cope with a fast movement of the human body. SOLUTION: The shape of a human body 20, the shape and characteristics of clothes,
The initial position of the mass point 24 of the garment is determined based on the sewing information and the information about the garment, and then the correspondence relationship between the mass point 24 and the constituent element 20 of the human body is determined. After adding the vectors, the collision between the mass point 24 and the human body 20 is calculated to obtain the change in the shape of the clothes, and the CG display is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of simulating movements of clothes for designing clothes, designing patterns, and evaluating prototyped clothes in the process of manufacturing clothes. Instead, by using the physical properties of various types of fabrics to calculate and visually display changes in the shape of clothing due to movement of the human body,
It is intended to provide useful information for design and evaluation.

The field of application of the present invention is not only the apparel industry for designing clothes but also clothing fitting simulation in mail-order sales using television and the like, movement of a person in games and animations, and VR (Virtua).
l Reality), the simulation of the clothes of people who appear, and the use for camouflage of clothes in so-called videophone, which is expected to be realized in the near future.

[0003]

2. Description of the Related Art The shape of clothes greatly depends not only on the pattern of the clothes and the sewing conditions, but also on the shape of the human body wearing the clothes.
In order to calculate the situation in which the human body wears clothes, it is necessary to calculate the collision between the human body and clothes. And it is necessary to use an accurate collision model for the calculation.

The collision model consists of two types of collision detection and collision processing.
Divided into two parts. Collision detection is for calculating which part of clothes collides with which part, and collision processing is for calculating how the collided part changes its movement. . Of these, collision detection is of particular interest.

As a conventional clothing shape calculation, there is a method of calculating the static shape and drape of cloth according to a physical law. These use the finite element method, and examples thereof include Textile and Polymer Research Institute Report No. 142 (1984) "Structural analysis of drape phenomenon by computer" and "Method of predicting three-dimensionality of clothes using cotton element", And JP-A-6
No. 3-303106 (the title of the invention is “method of predicting and displaying wearing state of clothes”).

However, this method has a major drawback that the calculation is possible only when the human body is stationary and cannot be calculated when the human body is moving.

As a dynamic model for calculating the deformation state of cloth, Terzopoulos and Fleischer in 1988 "DeDe
formable models ”, The Visual Computer, Vol.4, pp.
306-331, 1988. has been published. This model is a dynamic model that calculates the deformation of the cloth along the time axis.

In the dynamic model by Terzopoulos et al., Assuming a virtual repulsive force, a force for pushing out clothes from a human body is generated, and collision calculation between the human body and clothes is performed. Therefore, the model of Terzopoulos et al. Could not stably calculate the deformation condition of the cloth, and could not actually simulate the deformation condition of clothes when the human body moves.

A study by Thalmann et al. Is well known as a clothing shape calculation when a human body has a motion. P.Volino, M.Courchesne, NM Thalmann:
Versatile and Efficient Techniques for Simulating
Cloth and Other DeformableObjects, Computer Graphi
cs Proceedings, pp. 137-144, 1995.

However, in this research, a method of calculating the portion closest to the point of interest is used as the collision detection method. Although the method of Thalmann et al. Greatly simplifies the shape of the human body in the clothes and reduces the amount of calculation, since it takes a lot of time to perform the calculation, it is not practical to simulate practical clothes. I couldn't make it. In addition, if the shape of the human body is complicated in order to make the simulation more accurate, it takes much more time.

As a study in Japan, "Virtual clothing environment PARTY-Method for calculating collision between clothing and human body in clothing shape calculation-" by Sakaguchi, Mino, and Ikeda, IEICE Transactions, vol.J78-D-II, No.3, pp.483-491 (1995). In this method, the collision detection is limited to the direction and range of the motion prediction vector of the point of interest per unit time. Therefore, with this method, collision detection can be performed relatively efficiently.

However, in the collision detection in which the search is limited to the direction and range of the motion prediction vector per unit time of the target point, the relative speed between the collision objects is large,
When the relative moving distance of the colliding object per unit time interval is large, there is a problem that the missed detection of the collision occurs. In order to avoid this problem, it is necessary to reduce the relative movement distance per unit time interval, and therefore it is necessary to reduce the relative speed between the movement of the human body and the movement of clothes. In actual application, it was necessary to set the unit time interval to be very small or to slow down the movement speed of the human body sufficiently. As a result, even with this method, there is a drawback that the calculation takes too much time when the calculation is performed so as not to miss the detection of the collision, and the movement of the clothes cannot be actually simulated.

[0013]

The problems as described above are
This is caused by the fact that the collision between the clothes and the human body cannot be detected when the human body moves fast. The problem will be described below with reference to the drawings.

In the calculation of the shape of clothes, the cloth forming the clothes is divided and expressed by many minute particles. The human body is composed of triangular patches. After calculating how the mass points that make up the cloth bounce when it collides with the human body, the shape of the clothes is calculated by giving a constraint to hold the self shape of the cloth between the mass points.

At this time, the collision between the cloth model and the human body model is the collision between the point and the surface. With reference to FIG. 7, the detection of this collision is performed by searching the colliding triangular patch surface (collision object) 100 along the search vector 104 from the position of the mass point (collision object) 102 of the cloth model. To do. At this time, as shown in FIG. 7, when the collided object 100 is in the range of the search vector 104, collision detection is possible. However, as shown in FIG.
If the collision object 100 does not exist within the range, the collision cannot be detected.

This problem can be solved to some extent by reducing the unit time interval (Δt) for calculating the movement of clothes. However, such a solution is not an essential solution, and has a problem that the unit time interval (Δt) is made minute and the amount of calculation required for performing a simulation for a predetermined time is enormous. .

If a situation in which a collision is not detected occurs, the mass point of the cloth model gets inside the human body. On the other hand, the mass tends to come out from the inside of the human body due to the self-shape retention of the cloth. Therefore, in this case, the mass point collides with the inner surface of the human body. It is difficult to push this out of the human body, making it impossible to continue calculating the shape of the garment.

Due to these problems, although the conventional clothing simulation method can be used for designing and evaluating clothing, it cannot be applied to real-time simulation of clothing in such fields, and the game mentioned above is also used. Simulation of clothes in animation,
There is a problem that it cannot be applied to many useful applications such as a fitting simulation in a mail order using a television.

Therefore, an object of the present invention as set forth in claim 1 is to ensure that a collision between each element of the human body and each element of the corresponding clothing can be detected in real time.
To provide a method of simulating clothes that is not only useful for designing and evaluating clothes, but also that can be used for more purposes, by making it possible to accurately simulate and display the movement of clothes worn on the human body. Is.

An object of the present invention as set forth in claim 2 is to make it possible to reliably detect a collision between each element of the human body and each element of the corresponding garment, and to achieve high-speed collision between the human body and the garment. By performing calculations, the movement of clothes worn on the human body can be accurately simulated and displayed in real time, which is useful not only for designing and evaluating clothes, but also for more purposes. It is to provide a method for simulating clothes.

An object of the present invention as set forth in claim 3 is to make it possible to reliably detect a collision between each element of the human body and each element of the corresponding clothing by a simple process, so that the collision can be performed in real time. By providing a simulation method of clothing that can be accurately simulated and displayed on the human body, which is useful not only for designing and evaluating clothing but also for more purposes. is there.

[0022]

According to a first aspect of the present invention, there is provided a method for simulating a movement of clothes, including a shape of a human body, a shape of the clothes, physical characteristics of cloth of the clothes, and sewing information of the clothes. Information about the human body, determining the initial shape of the clothing for wearing on the human body, changing the information on the human body shape in response to a predetermined motion of the human body, and the human body corresponding to the motion of the human body. In response to the change in the information about the shape of the clothes, the calculation step for calculating the deformation of the shape of the clothes worn on the human body, the changing step and the calculation step are repeated, and the change in the shape of the clothes is calculated using computer graphics. And animating. The calculation step includes a step of previously obtaining a correspondence relationship between the elements forming the shape of the human body and the elements forming the clothes worn on the human body, and the movement of each element forming the shape of the human body corresponding to the clothes. The steps of transmitting to the constituent elements and the movements of the respective elements constituting the shape of the human body, the collision calculation processing between the respective elements constituting the clothing and the human body are performed, and Determining the position of the element.

Correspondences between the elements forming the shape of the human body and the elements forming the clothes are obtained in advance, and the movements of the elements forming the shape of the human body are transmitted to the corresponding elements forming the clothes. Since the calculation processing of the collision with the human body is performed later, the relative movement between each element that forms the shape of the human body and the element that forms the clothes is as described above. It is smaller than when the movement of the element is not transmitted to the constituent elements of the garment. Even when the movement of the human body is fast, the conventional static method can be used to reliably detect the collision between the clothes and the human body. Therefore, it is less likely that the shape calculation of the clothes cannot be continued due to the situation that the collision is not detected as in the conventional case, and the movement of the clothes can be reliably simulated even when the movement of the human body is fast.
It becomes possible to simulate the movement of clothes in real time, and it is possible to use the clothes for not only the design and evaluation of clothes but also various other applications as described above.

In the method of simulating the movement of clothes according to a second aspect of the present invention, in addition to the configuration of the first aspect of the present invention, the step of obtaining the correspondence in advance is performed from the position of the attention point on the surface of the clothing The present invention is characterized by including a step of establishing a correspondence relationship with an element of a human body that is closest to the point of interest existing in the set search range area as corresponding to the point of interest.

Since the correspondence between each element of the clothing and the human body is determined based on the maximum movement amount of the human body per unit time as described above, the human body and the clothing are not affected by the speed of movement of the human body. Correspondence can be definitely established.

According to a third aspect of the present invention, in addition to the configuration of the first aspect of the invention, the step of transmitting includes a movement vector per unit time of each component of the human body. And a step of vector-adding the obtained movement vector to the corresponding position coordinate vector of the element constituting the clothes.

As described above, since the movement of the human body can be transmitted to the clothes by a simple vector calculation, a practical method for sufficiently reducing the relative speed between the human body and the clothes can be obtained.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION An apparatus for simulating movement of clothes uses a human body and its movement, clothing elements including clothes, and information about the background environment to perform calculations based on physical laws. , To build a virtual clothing environment inside a computer. The calculation content is composed of three types of elements, which are the human body, environment, and clothing.

The human body is three-dimensional shape data in which the three-dimensional shape of the actual human body is represented by a general-purpose triangle patch. This human body is given a sequence of movements to move inside the virtual environment.

The environment is a background in which a human body is placed or surrounding elements (including a chair, a table, etc., and gravity, air resistance, etc.).

The clothing elements are clothes and accessories worn by the human body. For clothes, the mechanical properties of cloth and
The pattern shape and sewing information are given.

In this virtual clothing environment, if the human body moves, the shape of the clothes also changes with the movement. The operator can perform operations on any of the human body, environment, and clothing elements. The effect caused by the operation is calculated by a computer in real time, and the result is presented to the operator by computer graphics (CG).

Such a virtual environment has a conventional CAD (Co
mputer-Aided Design) and will be a tool to bring out human creativity.

In the present invention, the method for simulating the movement of clothes as described above is realized by the following modes. First, in the present invention, in order to perform the calculation without error even when the relative speed between the human body and the clothes is large, the movement of the human body is transmitted to the clothes before the procedure of the collision calculation. I tried to reduce the relative speed. If the relative speed between the human body and clothes is sufficiently small, the conventional static collision calculation method used when the human body is stationary can be applied instead of the conventional dynamic model that calculates the cloth deformation situation. It will be possible. With this method, it is difficult to simulate the movement of clothes when the ball suddenly collides with the clothes at a high speed, but when the human body wearing the clothes moves, it is sufficient to handle it. You can simulate the movement of clothes in real time. In addition, since the processing content is merely to notify the movement of the human body to the clothes, it can be realized by a simple method as will be described later, which is practical.

The processing of the human body motion transmission method for transmitting the movement of the human body to the clothes and reducing the relative speed is performed by (1) calculation of corresponding points between the human body and clothes, and (2) correspondence of clothes by movements of the human body. It is divided into coordinate movement of points and. A method of these will be described below with reference to FIG.

A case of calculating a collision between the human body 20 and the cloth mass points 22, 24 and 26 will be described with reference to FIG. Further, in this case, the human body 20 is assumed to move to a position indicated by a dotted ellipse 30, and a vector (hereinafter, referred to as “movement vector”) 28 representing the amount of movement of the human body in a unit time is defined as v _b Δt. . At this time, for example, from the position of the cloth mass point 24, a search is performed within a range of the maximum movement amount of the human body per unit time plus a margin (3 cm to 9 cm) (32), and the human body corresponding to this mass point 24 is searched. Find the triangular patch 20. In this way, the correspondence between each mass point of the cloth and the triangular patch of the human body is determined.

Next, referring to FIG. 1 (B), the coordinates of the mass point 24 of the clothes are moved by the movement vector v _b Δt 34 of the corresponding triangular patch 20 of the human body in a unit time. Specifically, the coordinate of the mass point 24 is used as a position vector, and the movement vector 34 is vector-added to this coordinate position vector.

By performing this processing, as shown in FIG. 1C, the relative velocity between the human body and the mass point of the clothing corresponding to the triangular patch of the human body is only the deformation of the clothing. . Therefore, this relative velocity becomes sufficiently small, and by applying the static collision calculation method between the human body and clothes, each mass point 22,
It is possible to calculate the movements 36, 38 and 40 of 24 and 26. Of course, when the human body is stationary, it is not necessary to transmit the movement of the human body, but the same result can be obtained by performing the transmission processing of the movement of the human body. Further, the calculation of the corresponding points between the human body and the clothes may be performed only on the moving portion of the human body.

After the relative speed between the human body and the clothes is reduced in this way, the collision between the clothes and the human body and the self-collision between the clothes are calculated. At this time, the influence of the movement of the human body is already reflected in the movement of the cloth by transmitting the movement of the human body to the clothes. Therefore, in the collision calculation between the clothes and the human body at the stage shown in FIG. 1C, it must be handled as if the human body does not move.

The clothes shape calculation method for coping with the movement of the human body will be specifically described below. The clothing shape calculation can be described by the force balance equation shown in the following equation (1).

[0041]

[Equation 1]

Each term in the equation (1) represents a force, and the explanation of each force is shown in Table 1 below.

[0043]

[Table 1]

In the above equation (1) and Table 1, r (hereinafter, underline indicates a vector) indicates a three-dimensional coordinate vector (r _x , r _y , r _z ) of a calculation point of clothes or a human body. .
r'represents a velocity vector and r "represents an acceleration vector. Of the terms in equation (1), the fourth term on the left side represents the mutual constraint between the mass points. The sixth term on the left side represents the human body. Represents the constraint of collision between cloth and cloth.The second term on the right side is
It represents the constraint that the cloth has on the movement of the human body. The fourth and sixth terms on the left side and the second term on the right side of these equations (1) are larger than other forces. Therefore, it is necessary to devise a method for solving the equation (1).

In Table 1, the heading is the 0th row, and the 1st row below.
Specify each line as line, second line, and so on. Also, in Table 1, the “force” column is the first column, the “content” column is the second column, and the “function” is
Will be described below as a third column.

In the first column of Table 1, the function " F " is listed. These are all three-dimensional vectors of [x, y, z]. Each of these elements is a function of time t.
In the formula in the fourth row, third column of Table 1, “Ω” is a region (clothes)
Indicates that the calculations shown in this table are performed for the whole.
In Table 1, a small letter L written in cursive form is a distance between a point and another point at time t, and a small letter L _{0 also} written in cursive form is an initial length between the above two points. Represent each. Ψ is a KES for measuring cloth characteristics.
The measurement value of the tensile property by the (Kawabata Estimate System for fabric) method is shown. Although the KES method is used to measure the characteristics of the cloth in the present embodiment, the measurement method is not limited to the KES method, and other appropriate methods may be applied depending on the purpose. it can.

Similarly, in Table 1, μ represents a mass represented by an arbitrary point. In Table 1, ρ _air in the second row and third column indicates the coefficient of friction of air, and ρ _{clh in} the third row and third column indicates the coefficient of friction of the cloth. In addition, φ represents the measured value of the bending property by the KES method.

As shown in the following formula (2), if the above-mentioned constraint is separated from the formula (1) and the respective constraints are sequentially influenced, this formula can be easily solved.

[0049]

[Equation 2]

In the equation (2), the subscript (N) (N = 0, 1, 2, 3) such as r indicates that the variable has the Nth approximation accuracy. An apparatus and method for simulating the movement of clothes according to the equation (2) will be described below.

FIG. 2 shows an outline of an apparatus 50 for realizing the method for simulating the movement of clothes according to the present invention, and FIG. 3 is a block diagram thereof. Referring to FIGS. 2 and 3, the device 50 includes an operating portion including an input device 60 such as a mouse and a high-speed graphics device 52.
, A computing unit 54 and a parallel computing unit 58 for performing high-speed computation, an external storage unit 56 for storing programs and data, and an unillustrated computing unit 54 and a parallel computing unit 58 in the parallel computing unit 58. And a calculation unit including a communication device that performs high-speed communication between the CPU and the memory.

Referring to FIGS. 2 and 3, arithmetic unit 54
Responds to a command given by the operator via the input device 60 in response to the display content of the display device 52, using the internal memory, the parallel computing device 58, and the external storage device 56. Perform a calculation process such as. In the following calculation processing, a large number of similar vector calculations are performed for a large number of mass points that form the cloth, and therefore, a parallel calculation device 58 is provided for performing these vector calculations in parallel at each point. . The arithmetic unit 54 performs arithmetic operations and controls other than such vector arithmetic operations. Note that, as described above, it is assumed that the initial information such as the human body data and the cloth data required for the calculation is stored in the external storage device 56.

The control flow of the program executed by the arithmetic unit 54 and the parallel computing unit 58 will be described with reference to FIG.

Referring to FIG. 4, first, at step 70, the constraint that the force is large is removed, and as an initial value ( r ₍₀₎ ,
r ' ₍₀₎ ) is set.

Subsequently, at step 72, the equation of motion of the first equation of the equation (2) is solved to obtain r '.

Next, at step 74, using the second equation of the equation (2), ( r ₍₀₎ , r ') is used to obtain r ₍₁₎ satisfying the constraint of the movement of the human body. The process of step 74 is a part for performing the process of transmitting the speed of the human body to the clothes, which is a great feature of the present invention.

Further, in step 76, ( r ₍₁₎ , r ')
Is used to obtain r ′ ₍₂₎ that satisfies the constraint of the cloth shape retention according to the third equation of the equation (2).

In step 78, by using ( r ₍₁₎ , r ' ₍₂₎ ), r ' ₍₃₎ satisfying the constraint of the collision between the cloth and the human body and the cloths is obtained according to the fourth expression of the expression (2). Ask.

Then, in step 80, ( r ₍₁₎ , r '
₍₃₎ ) is used to update the cloth shape, and in step 82, CG display is performed on the display device 52 based on the updated values.

At step 84, it is judged whether the calculation and display for all the frames have been completed, and if so, the process is terminated. If the processing of all the frames is not completed, in step 86, the value calculated by the above calculation ( r
₍₂₎ , r ' ₍₃₎ ) is a new initial value ( r ₍₀₎ , r ' ₍₀₎ )
Then, the control is returned to step 72.

By performing the calculation and CG display in accordance with such a control flow, the movement of the cloth corresponding to the movement of the human body is simulated and displayed as an animation on the display device 52. In this way, a motion such as walking is given to a human body wearing clothes, and specifically, the data representing the shape of the human body is changed in accordance with the motion of the human body, so that the clothing corresponding to the motion is changed. It is possible to see the dynamic deformation visually.

In the following, with the human body wearing clothes,
An experiment simulating the deformation of clothes corresponding to the walking of a human body will be described. After putting the clothes on the human body, a walking motion was given to the human body and an experiment to calculate the deformation of the clothes shape was conducted. The human body model used in the experiment was composed of 1256 triangular patches and was divided into 17 parts. The 17 parts were connected in a tree structure so that they could rotate in three axes. The lower part of the tree structure was naturally affected by the rotation of the upper part.

Next, an actual walking scene of a human body is photographed with a video tape, and the scene for 6 seconds is taken at 2 equal intervals.
I got 0 frames. Key frames were created by manipulating the joint angles of the human body model so that all the extracted frames would overlap the human body in the video image. Furthermore, based on this key frame, an operation at 0.01 second intervals was created by linear interpolation.

As a garment, a women's dress composed of eight patterns was put on an upright human body, and then the human body was given the above-described walking motion. The clothes were given the characteristics of cotton cloth (weight, bending characteristics).

FIG. 5 shows a CG display of the wearing state of the human body before giving a walking motion in this experiment. FIG. 6 shows a CG display of a wearing state of a human body when a walking motion is given to the human body according to the present invention. As shown in FIG. 6, it was found that the present invention can accurately detect a collision and simulate the movement of clothes. In particular, according to the method of the present invention, it is possible to perform accurate collision detection even for the rapid movement of the human body as described above, and it is possible to simulate the movement of clothes in real time.

[Brief description of drawings]

1 is a schematic diagram illustrating the principle of a method according to the present invention.

FIG. 2 is a diagram showing a schematic configuration of an apparatus of the present invention.

FIG. 3 is a block diagram showing a configuration of an apparatus for carrying out the present invention.

FIG. 4 is a flowchart of a program executed by an apparatus that implements the present invention.

FIG. 5 is a diagram showing a CG display of a wearing state of a human body before giving a walking motion.

FIG. 6 is a diagram showing a CG display of a wearing state of a human body when walking, which is simulated according to the present invention.

FIG. 7 is a diagram for explaining a state in which collision detection is possible.

FIG. 8 is a diagram for explaining a case where collision detection is impossible.

[Explanation of symbols]

 20 Triangular patch of human body 22, 24, 26 Material point of cloth 28 Movement vector of human body 34 Vector corresponding to movement vector 50 Clothes simulation device 60 Input device 52 Display device 54 Computing device 56 External storage device 58 Parallel computing device

Claims (3)

[Claims] 1. A human body shape, a clothing shape, a physical characteristic of the cloth of the clothing, and sewing information of the clothing are prepared, and an initial shape of the clothing to be worn on the human body is determined. A step of changing the information about the shape of the human body in response to a predetermined movement of the human body; and a step of changing the shape of the clothing in response to a change in the information about the shape of the human body corresponding to the movement of the human body. A calculation step of calculating, a step of repeating the changing step and the calculation step, and animating the change of the shape of the clothes using computer graphics, wherein the calculating step configures the shape of the human body. And a movement of each element forming the shape of the human body, the step of previously obtaining a correspondence relationship between the element forming the clothes and the element forming the clothes worn on the human body. Correspond to
The step of transmitting to the elements constituting the clothes, the movement of each element constituting the shape of the human body was transmitted,
A method of simulating movement of clothing, comprising: performing a collision calculation process between each element that constitutes the clothing and the human body to determine the position of each element that constitutes the clothing. 2. The step of obtaining the correspondence in advance comprises:
The method according to claim 1, further comprising the step of determining a correspondence relationship between an element of a human body existing within a set search range from the position of the attention point on the surface of the clothing, as being the element corresponding to the attention point. A method for simulating the movement of clothes described. 3. The step of transmitting includes a step of obtaining a movement vector of each constituent element of the human body per unit time, and a vector of the obtained movement vector to a position coordinate vector of a corresponding element constituting the clothes. The method of simulating clothes movement according to claim 1, further comprising the step of adding.