JPH04304574A - Device for generating animation - Google Patents

Abstract

PURPOSE:To obtain an animation video which does specially converge to a specified shape and has a large sense of realilty. CONSTITUTION:A body to be a display object is expressed by a model formed by the aggregation of particles, activating force decided based on the curvature of the position is given to the particle concerned so as to permit the position of the particle to successively change by activating force concerned so that the animation work of an animator is more simplified and, at the same time, the animation video which has the more large sense of reality is easily generated.

Description

[Detailed description of the invention]

0001

[Table of Contents] The present invention will be explained in the following order. Industrial field of application Conventional technology (Figure 9) Problems to be solved by the invention (
Figures 10 and 11) Means for solving the problem (Figure 8) Effects (Figure 8) Examples (Figures 1 to 8) Effects of the invention

0002
]

[Industrial Field of Application] The present invention relates to an animation creation device, and particularly to a three-dimensional special effects device for broadcasting.
For example, it is suitable for application to an animation creation device that uses a computer's calculation function to draw an animation image of how a soft object such as cloth moves in an environment such as gravity, wind, and obstacles. It is something.

0003

2. Description of the Related Art Conventionally, when creating an animation video using an animation creation device, an animator has to
A graphic input method is used that involves drawing small pictures or defining the shape of a graphic and its changes on the screen. When creating an animation of a "flag" As shown in FIG. 9, the animation creation device 1 includes an image conversion device 2.

The image conversion device 2 maps and displays television images on a curved surface, and uses the original image data PC1 (in this case, a "flag" pattern and After deforming the image data (image data) based on the animation data D1 obtained from the animation data memory 4, output image data PC2 obtained by deforming the image of the "flag" is sent to the output image memory 5.

[0005] Animation data D1 is "
It is a coordinate value representing the shape of a flag, and includes one or more frame data as necessary. This animation data is created in advance by hand by an animator, or generated by calculation by combining simple functions.

[0006]

[Problem to be Solved by the Invention] However, when trying to create an animation video using the conventional method shown in FIG. There is a problem in that experienced animators have to perform complicated graphic input work.

Particularly, when attempting to animate the movement of figures that are not artificial, such as natural phenomena, a great deal of time and effort is required to input the figures, resulting in poor productivity.

[0008] As one method to solve this problem, a method has been proposed in which movements that imitate natural phenomena are defined in a model by combining simple functions, but this method is ``too regular and unnatural.'' The drawback was that it was unable to respond to changes in the environment. One way to solve this problem has traditionally been to create an animated video in which a soft, two-dimensional object like cloth is flapping around due to the force of a fluid like wind. In this case, the following calculation method has been proposed to determine the display position on the display screen.

Firstly, the curved surface of the "cloth" to be displayed is considered as a collection of minute quadrilaterals, and secondly, the force exerted by the fluid on the minute quadrilaterals is expressed as a vector representing the direction of the fluid and a minute Thirdly, the sum of the fluid forces acting on all the tiny quadrilaterals is:
Think of it as adding to the "cloth" as a force that moves the entire "cloth".

However, in reality, such force changes continuously depending on the shape and position of the object, so if the speed and direction of the fluid are uniform in time and space, It has the disadvantage that it converges to a certain position or shape as time passes. Furthermore, even if the speed and direction of the fluid were changed temporally and spatially, the shape of the object changed slowly and unnaturally. For example, as shown in Figure 10(A), a "cloth"-like object fixed to a pole at two points, the upper left end and the lower left end, like a "flag," is Consider an animation video that expresses the behavior of an object when placed inside.

FIG. 10(A) shows the initial state of the "flag",
In this case, the wind is blowing from a direction parallel to the flag (to the left).

In the state shown in FIG. 10(A), for each minute quadrilateral constituting the "flag," the vector representing the direction of the fluid, that is, the wind, and the shape and orientation of the minute quadrilateral are used. The force exerted on each minute quadrilateral is calculated, and the direction and amount of movement of each part of the "flag" is changed by the force exerted on each minute quadrilateral. As a result, each tiny quadrilateral of the animation's "flag" has a different force based on local conditions, and each of these different forces moves the corresponding tiny quadrilateral to a different position. By doing so,
The animation video of the “flag” after conversion is shown in Figure 10 (B) ~
As shown in FIG. 10(D), it changes in a fluttering manner.

However, when we calculate the force exerted on such minute quadrilaterals over time, we find that the environment for each minute quadrilateral, in this case, changes in the direction of the wind and the relationship between the shapes and orientations of the quadrilaterals. Since there is a relatively small limit to the shape of the flag, as the result of the transformation calculation of the flag is repeated, the shape of the flag converges.

For example, from the state shown in FIG.
As the transformation operations shown in (B) to Figure 10 (D) are repeated, the "flag" eventually converges without any noticeable change from the slightly drooping state shown in Figure 10 (E). become a state. In reality, this state of convergence does not change much after the gravity of the flag and the buoyancy of the wind are balanced.

Next, in the convergence state shown in FIG. 10(E), when the direction of the wind is rotated by 45 degrees, the shape of the "flag" after conversion is as shown in FIG. 10(E) due to the change in the direction of the wind. It starts moving from the state and sequentially moves to Figs. 11 (A), (B), (C) and (
The state changes to the state shown in FIG. 11(E) through the state D). In this way, the way the "flag" flutters after conversion is that the wind direction is 45 degrees.
It changes in response to the rotation, but the speed of change is actually slow, so there is a problem that the sense of reality is not sufficient.

After such a change, the shape of the "flag" becomes converged again and does not change significantly. In this way, with conventional methods, the image of an object converges to an equilibrium state in a constant fluid, and the shape of the object does not change slowly even if the speed or direction of the fluid changes temporally or spatially. There is a problem that it becomes unnatural.

The present invention has been made in consideration of the above points, and is based not only on the conventional force that is determined continuously based on the velocity of the fluid and the local direction of the object, but also on the curvature of the object. This paper attempts to propose an animation creation device that can create animations that do not fall into an equilibrium state by applying a determined force.

[0018]

[Means for Solving the Problem] In order to solve this problem, the present invention provides an animation display target FLG.
A conversion target model is formed by setting a large number of material points MP on the figure, and the curvature K0 corresponding to the material point MP is calculated based on vectors h0 to h3 in the direction connecting the material points MP.
Find K1, find the acting forces F0 and F1 that act on the mass point MP based on the curvatures K0 and K1, and apply these acting forces F0 and F1 to the mass point MP to change the display position of the mass point MP on the conversion animation figure. to change.

[0019]

[Operation] Vectors h0 and h2 in the direction connecting the mass points MP
, h1 and h3 to find the curvatures K0 and K1 corresponding to the position of the mass point MP, use these curvatures K0 and K1 to find the acting forces F0 and F1 acting on the mass point MP, and calculate the acting forces F0 and F1. The position of the mass point MP is changed by . As a result, the position of the material point after conversion changes continuously, thereby making it possible to further accelerate the rate of change of the animation image without causing the animation image to converge.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

Animation creation device 11 according to the present invention
As shown in FIG. 1 with the same reference numerals assigned to corresponding parts to those in FIG. 9, created animation data D2 created in the animation data creation device 12 is supplied to the animation data memory 4 as animation data D1.

The animation data creation device 12 creates three-dimensional coordinate value data representing the shape of the "flag" at successive times of the "flag" to be created as an animation video.Animation data D2 occurs as. As shown in FIGS. 2 and 3, the animation data creation device 12 determines information such as "strength of gravity,""strength of wind,""shape and position of obstacles," etc. for the animation display target FLG. Environmental data D11 consisting of data indicating what kind of environment the "flag" that is about to be moved is placed is provided from the environmental data memory 21 to the equation of motion calculation device 22.

The equation of motion calculation device 22 executes calculations such as creating and solving equations of motion corresponding to the environmental data D11 for the model representing the "flag", and converts the calculation results into three-dimensional coordinate array data D12. It is given to the format conversion device 23 as a file format.

The format conversion device 23 converts the three-dimensional coordinates into animation data in a format that can be used by the image conversion device 2 (FIG. 1), and supplies this to the animation data memory 4 as created animation data D2.

As shown in FIG. 2, the equation of motion calculation device 22 calculates the position of each point on the surface of the "flag" using a three-dimensional system that represents the position of each point on the surface of the "flag" by connecting mass points MP three-dimensionally in a lattice shape by means of springs SP. Expressed by a model.

That is, each grid point (white circle) represents a mass point MP, and all line segments between the grid points represent springs SP. Therefore, in the case of this three-dimensional model, a maximum of six springs SP can be connected to one mass point MP of the three-dimensional object. On the other hand, in the case of a flat object such as a "flag", as shown in FIG. 3, four springs SP are connected to one mass point MP.
It is possible to express a model of a "flag", and it can also be expressed by connecting less than four springs SP to the mass points MP at the corners and ends.

In the three-dimensional model shown in FIG. 3, mass point MP is a collection of masses at one point, and moves according to Newton's equation of motion. The spring SP has a length in its natural state and generates a force according to the displacement according to Hook's law. In addition, there is a resilient hinge between adjacent springs that attempts to maintain the adjacent springs at a 90° angle. Thus, a force acts between the diagonal hinges to keep the springs at 180 degrees.

In the three-dimensional model of FIG. 4, each mass point MP
moves according to the following equation of motion.

[Math 1]

Here, M is the mass of the mass point MP, Г is the attenuation coefficient, x is the three-dimensional coordinate of the mass point MP, t is time, and F is the mass point M
This is the acting force acting on P. In equation (1), the mass M is a constant, the damping coefficient Γ is added to converge the motion and is a constant, and the acting force F acting on the mass point MP is a quantity that changes with time and is a constant for the entire mass point MP. Determined by placement and environment.

The differential equation expressed by equation (1) is:
By quantizing by time t in the equation of motion calculation device 22 of FIG. 2, the following equation

After being converted into a difference equation as shown in [Equation 2], by performing calculations to solve for x(t+dt), the following equation is obtained.

[Math 3] get.

In equations (2) and (3), x(t)
is the current coordinate, x(t-dt) is the coordinate before the unit processing time, and x(t+dt) is the coordinate after the unit processing time. In this way, the equation of motion calculation device 22 can determine the position to which the mass point MP will move at the time point after the next processing time from equation (3) by determining the force F that the mass point receives in the current state.

By the way, the acting force F that mass point MP receives is expressed by the following formula:

[Math 4] Represented by

In equation (4), K is the curvature at the position of the mass point MP, W is the velocity vector of the fluid, A is the viscosity of the fluid, n is the normal vector at the position of the mass point MP, (,) is the inner product, and f is the is a conversion function that represents the change in force due to curvature,
Thereby, the acting force F of the mass point MP can be determined based on the curvature of the object at the position of the mass point MP. In equation (4), (|W|−|(W, n)|) is a value determined by the direction of the wind and the direction of the curved surface, and becomes larger as the wind and the curved surface become parallel.

The acting force F expressed by equation (4) at this mass point MP can be simply determined as follows. First, as shown in FIG. 4, unit vectors directed from a mass point MP to an adjacent mass point MP are h0, h1, h2
and h3, unit vectors n0 and n1, which are normalized sums of opposing unit vectors, are expressed by the following equations in the directions of the two sets of opposing springs SP.

[Math 5]

[Equation 6] On the other hand, the unit vectors d0 and d1, which are the normalized differences between opposing unit vectors, are expressed as follows:

[Math 7]

[Math. 8] It can be expressed as

Next, for a pair of opposing unit vectors, for example h0 and h2, the sum vector h0+h
2 and the difference vector h0-h2, as shown in FIG. 5, means that two vectors oriented in substantially orthogonal directions can be easily obtained at a position near the mass point MP. Another pair of opposing unit vectors h1 and h3
The same applies to Therefore, the sum of unit vectors h0+
The direction of h2 and the direction of the sum of unit vectors h1+h3 have directions that intersect with each other, and their curvatures K0 and K1 are expressed by the following formula

[Math. 9]

It can be determined by the following equation. Then, in the same manner as described above for equation (4), using the curvatures K0 and K1, the following equation

[Math. 11]

Two acting forces F0 and F1 acting on the mass point MP can be found in the directions of the unit vector sums h0+h2 and h1+h3 (directions that intersect with each other) using Equation 12.

Thus, the acting force F acting on the mass point MP is the sum of these two acting forces,

[Math. 13] becomes.

In equations (11) and (12), a function as shown in FIG. 6 is used as the conversion function f. That is, the transformation functions f(K0) and f(K1) are the curvatures K0 and K1
The function is selected such that it is 0 when 0, increases as the curvatures K0 and K1 increase, and begins to decrease when a predetermined curvature is reached. In this example, the curvatures K0 and K
Since 1 is calculated based on equations (9) and (10), its variation range is from 0 to 2,
When K0, K1=1, that is, when unit vectors h0 and h2, h1 and h3 are orthogonal to each other, the decrease starts from this point.

[0038] Thus, the curvatures K0 and K1 are K0, K1=
in the range 0 to 1, so the unit vectors h0 and h2
, h1 and h2 are bent in orthogonal directions from a state where they face in opposite directions, the acting force F applied to the mass point increases. Also, the curvature K0, K1 is K0,
K1 is in the range of 1 to 2, therefore, when the unit vectors h0 and h2, h1 and h2 bend further from the perpendicular direction, the acting force F applied to the mass point is It's getting smaller.

When the acting force F determined as described above is applied to each mass point MP, the output image data PC2 obtained from the image conversion device 2 converts the display target FLG (FIG. 3) into the image shown in FIG.
As shown in A) to (E), continuous fluttering animation images can be displayed.

[0040] Even if the wind strength and direction are constant, the animation image of this "flag" changes according to the change in curvature at the relevant position with respect to the material point MP that constitutes each part of the "flag". By being able to cause the same positional movement as when the acting force F is applied, it is possible to cause the flag as a whole to fluttering naturally in a continuous manner. If the conversion function f can be adjusted here, the intensity of the fluttering can be adjusted.

The equation of motion calculation device 22 repeatedly executes the mass point position conversion processing procedure shown in FIG. 8 during one unit processing time, thereby calculating all the mass points MP on the "flag" (FIG. 3).
As a result, the "flag", which is a soft object, is affected by gravity,
Create animation videos that move softly in response to environmental conditions such as wind power.

In other words, the equation of motion calculation device 22 is shown in FIG.
After starting the processing of the material point position conversion processing procedure in step SP0, one sample point on the "flag" shape on the original image is selected in step SP1, and the sample point adjacent to the material point MP is selected in step SP2. The unit vectors h0, h1, h2, and h3 directed toward the matching mass points are found, and in the subsequent step SP3, equations (5) and (6) are calculated.
Opposing unit vectors h0 and h2, h based on the formula
Unit vectors n0, n formed by normalizing the sum of 1 and h3
1, in step SP4, equation (7) and (
8) Opposing unit vectors h0 and h2 based on formula
, unit vector d0 obtained by normalizing the difference between h1 and h3
, d1 is determined.

In step SP5, the equation of motion calculation device 22 calculates the curvatures K0 and K1 of the mass point MP using simple calculation formulas based on formulas (9) and (10).
is calculated, and in step SP6, equations (11) and (12) are calculated.
) Based on the formula, the mass point MP for the curvatures K0 and K1 is
Find the acting forces F0 and F1 acting on the
Then, calculate the total acting force F acting on the mass point based on equation (13), add this to other acting forces, and use the total acting force to calculate the new value after conversion of the sample point based on equation (3). Find the coordinates.

In this way, the equation of motion calculation device 22 completes calculation of the coordinate position after transformation for the sample point, and
The calculation result is stored in the animation data memory 4 as created animation data D2. Thereafter, the equation of motion calculation device 22 determines whether processing of all sample points has been completed in step SP8, and when a negative result is obtained, returns to step SP1 described above to determine the coordinate position of a new sample point. Enter calculation.

After completing the calculation of the coordinate positions after transformation for all the sample points on the "flag" figure on the original image in the same manner, the equation of motion calculation device 22 proceeds to step SP.
If a positive result is obtained in step 8, step SP
9, the mass point position conversion processing procedure ends.

In this way, the equation of motion calculation device 22 completes the conversion process for one "flag" during one unit of processing time, and thereafter performs the same conversion process every time a new unit of processing time starts. Repeat. As a result, Fig. 7 (A), (B), (
As shown in C), (D), and (E), the position of each mass point of the "flag" changes depending on environmental conditions such as gravity and wind power as well as the curvature of the "flag" at the position of each mass point during the sequential processing time. By changing based on changes in the wind, it is possible to realize an animation image in which a soft "flag" continuously flutters in the wind, and the figure moves so that the change occurs immediately when the direction of the wind changes.

According to the above configuration, when creating an animation of a figure, the object is represented by a model that combines mass points MP and springs SP, and the position of each point on the object is determined by "gravity", " Mass point MP for environment such as “wind wind”
When trying to determine the motion of an object by calculating it according to the laws of physics, by adding an acting force that acts on each point based on the change in curvature on the object, it is possible to control the animation figure to a predetermined shape. By being able to continuously change the shape without converging, it is possible to create even more realistic animations.

First, by adding a force determined by simple calculation, realistic motion can be expressed. Second, there is no need to input temporal and spatial changes in the fluid. Third, the dynamics of movement can be controlled by using a force intermediate between catastrophic force and continuous force. As a result, when creating an animation, when the animator automatically creates the video without manually drawing or determining the shape of the figure, unnatural convergence of the animation video does not occur. You can do it like this.

[0049]

[Effects of the Invention] As described above, according to the present invention, an object to be displayed is represented by a model consisting of a set of mass points,
When creating an animation transformation figure by calculating the position of the mass point when it moves according to the laws of physics under environmental conditions such as gravity, wind power, and obstacles, the position of the mass point or its vicinity By applying the acting force determined by simple calculations based on the curvature of To easily create an animation video with a greater sense of reality without causing a delay in response action.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an animation data creation device according to the present invention.

FIG. 2 is a block diagram showing the detailed configuration of the animation data creation device shown in FIG. 1;

FIG. 3 is a schematic diagram showing a model to be displayed.

FIG. 4 is a schematic diagram showing unit vectors between mass points.

FIG. 5 is a schematic diagram showing the sum and difference of unit vectors.

FIG. 6 is a curve diagram showing a conversion function of acting force to curvature.

FIG. 7 is a schematic diagram showing continuous changes in an animation video.

FIG. 8 is a flowchart showing a mass point position conversion processing procedure.

FIG. 9 is a block diagram showing a conventional animation creation device.

FIG. 10 is a schematic diagram showing a conventional animation video.

FIG. 11 is a schematic diagram showing a conventional animation video.

[Explanation of symbols]

1, 11...Animation creation device, 2...Image conversion device, 3...Original image memory, 4...Animation data memory, 12...Animation data creation device, 2
1...Environmental data memory, 22...Equation of motion calculation device, 23...Format conversion device.

Claims (1)

[Claims] Claim 1: Forming a conversion target model by setting a large number of material points on a figure to be displayed as an animation, and determining the curvature corresponding to the material point based on a vector in a direction connecting the material points, An animation creation device characterized in that the acting force acting on the mass point is determined based on the curvature, and the display position of the mass point on the converted animation figure is changed by applying the acting force to the mass point.