JPH10124702A - Device for manufacturing flame picture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily manufacture a real flame picture. SOLUTION: A flame picture manufacturing device 18 manufactures a flame picture by generating plural particles from a prescribed generating source prepared by a projection processor 14 from the shape of a candle or the like inputted from a shape inputting device 10 in each calculation step. That is, the flame picture manufacturing device 18 generates particles having particle information such as a center position coordinate, radius, and center color by using a designated and inputted parameter, moves the pertinent particles according to a rule of motion, changes the radius, defines the center of each particle as a common vertex, replaces it with plural polygons inscribed to a circle with the radius, decides each polygon color by interpolating a color inside the polygon based on the center color set at the common vertex of each polygon and a color differently set at an inscribed vertex, and synthesizes the colors decided for all the particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is applied to the production of computer graphics (CG) images, for example, the production of CG calendars, CG holograms, CG animations, CG commercials, CG posters, high-vision CG still picture programs, and the like. The present invention relates to a suitable flame image production apparatus.

[0002]

2. Description of the Related Art Technologies for producing a flame image by CG include, for example, N.I. CHIBA et al, THE JOURN
AL OF VIZUALIZATION AND C
OMPUTER ANIMATION, VOL. 5: 3
7-53 (1994). This technology is
A virtual flame image is created by generating a plurality of particles that are the source of a flame from a predetermined source at each calculation step, moving each particle according to a predetermined motion rule, and finally extinguishing it. It is.

In this technique, the trajectory of each particle is assumed for each calculation step, and the color of the flame is calculated based on the trajectory. This will be described for one particle. As shown in FIG. 15, assuming a trajectory consisting of a line segment connecting the position of the same particle in an arbitrary step and the next step, and from this trajectory, a perpendicular to the angle of θ Consider a mountain that consists of two quadrangular polygons that spread and half-cones located at both ends.

[0004] The highest temperature of each particle is assigned to the starting point and the ending point of the mountain ridge corresponding to the particle position in each calculation step, and the other points are interpolated according to the height of the mountain. Create a streamline of flame particles by assigning colors. By executing this calculation process for each particle for each calculation step, an animation image expressing the fluctuation of the flame as a whole is produced.

[0005]

However, according to the technique introduced in the above-mentioned document, as in the past, an operator manually draws a slightly different shape of a flame every frame by a pictorial technique, and as a whole, Although the work efficiency is remarkably improved as compared with the method of using an animation image of a flame expressing fluctuation, it is not always enough to easily produce a realistic flame image.

The present invention has been made to solve the above-mentioned conventional problems, and has as its object to provide a flame image producing apparatus capable of easily creating a realistic flame image.

[0007]

According to the present invention, there is provided a flame image producing apparatus for producing a virtual flame image by generating a plurality of particles which are a source of a flame from a predetermined source for each calculation step. For, at least the center position coordinates, means for setting particle information consisting of a radius and a center color, means for moving the particles according to a preset motion rule, means for changing the radius of the particles, Means for replacing a particle with a plurality of polygons whose center position coordinates are a common vertex and which is inscribed in a circle of that radius; and for each polygon, a center color set at the common vertex is separately set. A means for determining the color of each polygon by interpolating and calculating the color inside the polygon based on the color of the inscribed vertex, and producing a flame image by combining the color of each polygon determined for all particles Nisato be configured to include a means, it is obtained by solving the above problems.

That is, in the present invention, the radius of each particle is changed while moving each of the generated particles in accordance with the motion rule in each calculation step, and the center of each particle is set to a common vertex. In addition, the image is replaced with a plurality of polygons inscribed in a circle of that radius, and the colors (= flame particles) serving as a unit of the flame are determined using the polygons, and a flame image is produced by synthesizing them. Since the flame particles can be moved and the size can be changed at each calculation step, it is possible to easily produce a more realistic flame image.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of an image production system including a flame image production apparatus according to an embodiment of the present invention.

The above image production system is a shape input device comprising a memory or the like in which a shape serving as a source of fire, for example, "candle" or "bird" in the case of producing an animation of a firebird is stored in advance. 10, a light used to create a projection image for the input shape, a light for inputting information about the camera, and a camera information input device 12
And a projection processing device 14 for performing two-dimensional projection processing of the shape based on the shape, light and camera information input from each of the devices 10 and 12, and various parameters used when producing a flame image. Flame parameter specifying device 16
Flame image production for generating a plurality of particles that are the source of a flame by using a part or the whole of the projected shape as a generation source, and generating a virtual flame image by changing the particles according to various parameters. A device 18.

The light and camera information input device 1
Numeral 2 is for inputting information generally used when creating a projection image in the CG. The light information input here includes a position of a light illuminating the shape input from the shape input device 10. , The color of the light, and the type of light (point light source, surface light source, parallel light source), and the camera information includes information such as the position coordinates (three-dimensional) of the viewpoint, the angle of view, and the gazing point.

Further, in the above flame parameter designating device 16,
Flame parameters such as those shown in Table 1 below can be specified.

[0014]

[Table 1]

In Table 1 above, No. The image size of No. 1 is the size in the XY direction of the image of one frame produced for each calculation step, The total number of frames of No. 2 is the total number of image frames required to produce a flame image. 3 is the number of frames to be produced per second, The center color of 7 is (red: 1.0, grn: 1.0, blue:
1.0) is white, No. The alpha of 6 will be described later (1
3) A constant applied to the equation.

In addition, No. Nos. 7 and 8 are parameters used for calculating the ascending movement vector. Nos. 9 to 12 are parameters used for calculating the vortex field movement vector. The polygon size of 13 is the scale value of the polygon set to the particle.
0 is the initial radius of the particle. The shape of No. 14 is a polygon constituting the generation source. The fifteen filter constants are the numbers in the vertical and horizontal directions of the filter shown in FIG.

The flame image producing apparatus 18 of the present embodiment has a CG
At the time of production, the apparatus reads data from the shape input device 10, the light, and the camera information input device 12, and automatically produces an image expressing the fluctuation of the flame.

The flame image producing apparatus 18 sets (A) means for setting particle information including a center position coordinate, a radius, a pseudo energy, and a center color for each of the calculation steps; (C) means for changing at least the former of the particle radius, pseudo energy and center color,
(D) means for eliminating particles, (E) means for replacing the particles with a plurality of polygons whose center position coordinates are a common vertex and which is inscribed in a circle of the radius, and (F) for each polygon, Means for determining the color of each polygon by interpolation calculation of the color inside the polygon based on the center color set to the common vertex and the color of the inscribed vertex set separately,
(G) means for creating a flame image by combining the colors of the polygons determined for all particles, and (H) means for performing pixel value smoothing processing on the image for which the synthesis of each polygon color has been completed. And are each built with software. Hereinafter, each of these means (A) to (H) will be described in detail.

(A) Means for setting particle information including a center position coordinate, a radius, a pseudo energy, and a center color for an arbitrary particle i. Specifically, since the flame is composed of a group of particles, each particle i is defined by a time (calculation time) t corresponding to a calculation step. (1) Three-dimensional center position coordinates: Pi (t) = (px, py, pz), (2) radius: Ri (t), (3) pseudo energy: Ei (t), (4) center color: Ci (t) = (red, grn, blu, alpha) and a function to set the initial value of each particle information.

(1) Initial position of three-dimensional center position coordinates:
Pi (t = 0) can be automatically set by designating the position on the plane (polygon) shown in FIG. 2 which constitutes the object shape corresponding to the source input from the shape input device 10, for example, by the user. The number of particles N generated at that time can be set by the following equation (1), which is proportional to the area area of the designated surface, for example. In this equation, the user designates const (constant) in advance.

N = area × const (1)

Each initial value of other particle information, that is, (2)
Radius: Ri (t = 0), (3) Pseudo energy: Ei (t = 0),
(4) Center color: Ci (t = 0) is also set by the user in advance.

(B) means for moving the plurality of generated particles i according to a preset motion rule. This means that, for each particle, the three-dimensional center position coordinate at time t: Pi (t) = (px, py, pz) and the center position coordinate at time t−1 one time earlier: Pi (t) The function has a function of changing the position of each particle in units of calculation time by changing from -1) by the following equation (2).

Pi (t) = Pi (t-1) + Masc (t) + Mvor (t) + Mstr (t) (2)

In the equation (2), the center position of each particle is represented by an ascending movement vector due to the rise of the airflow: Masc (t), a vortex field movement vector due to the rotation of the airflow: Mvor (t), the attraction or repulsion between the particles. The motion vector is changed according to three motion rules consisting of Mstr (t).

Hereinafter, the respective motion vectors, which are the motion rules included in the above equation (2), will be sequentially described.

(1) Ascending movement vector: Masc (t) This ascending movement vector: Masc (t) is, for example, assuming that the rising direction at time t is Dasc (t) and the magnitude of the rising is const, It is expressed by equation (3). This const is specified by the user in advance.

Masc (t) = const · Dasc (t) (3)

(2) Vortex field movement vector: Mvor (t) This vortex field movement vector can be generated by synthesizing virtual vortex velocity fields of various sizes, as a rotating effect of airflow. Individual vortices are shown in (0) to (iii) below.
Shall be generated in the step.

Step (0): Definition of Vortex Rotation Speed (FIG. 3) The vortex rotation speed v (d) is determined as follows.

V (d) = (v _max / const) · d (0.0 ≦ d ≦ const) (4A) v (d) = v _max · (1.0−sin θ) (const <d ≦ Rv) (( 4B) d: distance from the center of the vortex Rv: radius of the vortex v _max : maximum rotation speed of the vortex const: arbitrary constant (0.0 ≦ d ≦ Rv) θ: (π / 2.0) · (Rv−d) / Rv

Step (i): Generation of Vortex The generation of a vortex is performed by initially giving the center position, radius, rotation speed, rotation direction, and number of vortices arbitrarily.

Step (ii): Vortex Growth (FIG. 4) After the vortex growth occurs, it is considered that the radius of the vortex increases at a constant rate at each calculation step.

Rv (t) = Rv (0) · (1.0 + t / Tv) (5) Rv (0): Initial radius of vortex Tv: Lifetime of vortex t: Arbitrary time

Step (iii): Vortex Decay (FIG. 5) After the vortex decline occurs, it is assumed that the rotation speed of the vortex decreases at a constant rate at each calculation step.

V (t) = v (0) · (1.0−t / Tv) (6) v (0): initial rotation speed of vortex Tv: life time of vortex t: arbitrary time

(3) Movement vector due to attraction (repulsion) between particles: Mstr (t) This is a movement vector due to attraction or repulsion between particles at an arbitrary time t, and the movement vector of particle i: M
str _i (t) is given by the following equation (7).

[0038]

(Equation 1) const: Arbitrary constant N: Total number of particles Pi (t): Coordinates of center position of particle i Pj (t): Coordinates of center position of particle j

(C) Means for changing at least the former of the radius, pseudo energy and center color of each generated particle i. When the total time to be calculated is T, the radius of the particle i in the calculation step of the time t: Ri (t) is calculated by the following equation (8) based on the initial radius of the particle: Ri (0). It has a function to calculate.

Ri (t) = (1.0−t / T) · Ri (0) (8)

This means has a function of setting the pseudo energy: Ei (t) for each calculation step.
That is, the pseudo energy E set for the particle i at time t
i (t) is, for example, the following (9), where T is the total time for calculation.
It can be calculated by the formula.

Ei (t) = exp (−t / T) (9)

Further, this means has a function of setting a center color: Ci (t) for each step. However, in this embodiment, the center color of the particle i: Ci (t) is always constant.

(D) Means for eliminating generated particles.
This has a function of extinguishing the generated particles under predetermined conditions. As a specific method of annihilation of particles,
For example, there is a method of extinguishing when the pseudo energy Ei (t) becomes equal to or less than a predetermined threshold value, and a method of extinguishing when a predetermined time (lifetime) has elapsed from the generation time.

FIG. 6 conceptually exaggerates FIG. 6 by moving particles at each calculation step using each of the means (A) to (D) of the flame image producing apparatus 16 described in detail above. A flame composed of such a collection of particles will be generated. The polygon which is the source of the flame shown in FIG. 2 is located at the lower end of the flame as shown by the broken line in FIG.

(E) Means for replacing the generated particles with a plurality of polygons whose center position coordinates are set to a common vertex and which is inscribed in a circle having that radius. FIG. 7 specifically shows a polygon replacement function by this means. In this embodiment, a particle represented by a circle having a center position coordinate: Pi (t) and a radius: Ri (t) is represented by a center. Is a common vertex, and the other vertices are each replaced by four triangular polygons inscribed in the circle.

(F) For each of the replaced polygons, the color inside each polygon is calculated by interpolation based on the center color set at the common vertex and the color of the inscribed vertex set separately. Means to determine. In this embodiment, for each of the triangular polygons shown in FIG. 7, the central color corresponding to the highest temperature at the common vertex located at the center of the particle is represented by:
The colors corresponding to the lowest temperature (for example, black) are assigned to the two vertices inscribed in the circle, and based on the colors of these vertices,
So-called Gouraud shading
Is set by interpolating the color inside the polygon.

Now, the principle of the Gouraud shading will be described. As shown in FIG.
Assuming that the coordinates of each vertex of the polygon are P0, P1, and P2, and the colors corresponding to each vertex are C0, C1, and C2, the color Cg of the pixel i is calculated using the following equations (10) to (12). .

(I) Color C01 of point P01 to be interpolated between vertices P0 and P1 at a ratio of t: (1-t): C01 = C0. (1.0-t) + C1.t (0.0≤t≤1.0) (10) (ii) The color C02 of the point P02 to be interpolated between the vertices P0 and P2 at a ratio of s: (1-s): C02 = C0. (1.0-s) + C1.s (0.0.ltoreq.s.ltoreq.1.0 (11) (iii) The color of the point (the color of the pixel i) to be interpolated between the vertices P01 and P02 at the ratio of k: (1-k) Cg: Cg = C01 （(1.0-k) + C02 ・ k (0.0 ≦ k ≦ 1.0)… (12)

(G) Means for producing a flame image by synthesizing the color of each polygon determined for all particles. When projecting a plurality of particles distributed three-dimensionally into a two-dimensional image space, if particles arranged in the same projection direction are overlapped, a process of adding the polygon color in the depth direction for that part is performed. That's what you do. This addition of polygon colors
FIG. 9 conceptually shows a case where three polygons are related to one pixel (pixel). As shown in FIG. 9, for a plurality of triangles set as shown in FIG. This is equivalent to performing Gouraud shading without performing hidden surface removal processing.

Specifically, at the time of the Gouraud shading, the hidden surface elimination processing of the overlapping polygons is not performed.
The pixel value before shading is PXi-1 and the color of particle i is C
When i is set, the pixel value PXi after shading is calculated by the following equation (13). However, in this expression, alpha is an arbitrary constant between 0 and 1.

PXi = PXi−1 + alpha · Ci (0.0 <alpha <1.0) (13)

(H) A means for performing pixel value smoothing processing on an image for which polygon color synthesis (addition) has been completed. That is, a 3 × 3 filter shown in FIG. 10 is applied to each pixel constituting an image of one frame after the addition of polygon colors is completed, and a pixel value n (i, j) at the center thereof is calculated by: Using the neighboring pixel values of the horizontal and vertical directions, the following (14),
This corresponds to a processing function for averaging each using the equation (15).

N (i, j) = (n (i-1, j) + n (i, j) + n (i + 1, j)) / 3.0 (14) n (i, j) = ( n (i, j-1) + n (i, j) + n (i, j + 1)) / 3.0 (15)

By performing the above calculation process while generating a plurality of particles from the source for each calculation step and moving them, a flame animation image consisting of frames corresponding to all calculation steps can be produced. it can.

Next, the operation of the present embodiment will be described with reference to the flowchart of FIG.

First, in step 1, flame particle information is input. That is, the shape (source) to which particles are added is specified by the parameter specifying device 16 and input from the shape input device 10, and the radius, pseudo energy, and center color of the particles shown in Table 1 are specified as initial values. Enter

Next, in step 2, information on the particle motion rules is input. That is, the parameters for calculating the ascending, vortex field, and reverse movement vectors shown in Table 1 are designated and input by the parameter designating device 16.

Next, in step 3, the flame image producing apparatus 18 calculates the time (t) in the step (1).
The process of changing the particle information calculated by Equations (9) to (9) is performed, and in step 4, based on the changed particle information, the processes of the above-described polygon replacement of each particle and addition of the polygon color in the depth direction are performed. Perform the following flame image production processing, and step 5
Outputs a flame image for one frame at time t.

In the next step 6, if there is a frame to be produced in the next calculation step, at time t + 1,
Steps 3 to 5 are repeated until the last frame is reached. With the above processing, the production of the flame animation image ends.

According to the above-described embodiment, as shown in FIGS. 12 to 14, which are partial frame images extracted to clarify the characteristics, a flame image expressing the fluctuation of the flame is produced. can do.

Although the present invention has been specifically described above, the present invention is not limited to the above-described embodiment, and can be variously modified without departing from the gist thereof.

For example, in the above-described embodiment, the case where the radius of the particle is changed by the equation (8) has been described. However, the present invention is not limited to this. It may be changed.

Further, the case where the number of polygons at the time of replacing a particle with polygons is 4 has been described, but the present invention is not limited to this. Further, the shape of the polygon is not limited to a triangle.

[0065]

As described above, according to the present invention,
Realistic flame images can be easily produced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of an image composition system including a flame image production device according to an embodiment.

FIG. 2 is an explanatory diagram showing a method for setting an initial position of a particle.

FIG. 3 is a diagram conceptually showing a vortex constituting a vortex field.

FIG. 4 is a diagram conceptually showing vortex growth.

FIG. 5 is a diagram conceptually showing the decline of a vortex.

FIG. 6 is an explanatory view conceptually showing a configuration of a flame.

FIG. 7 is an explanatory diagram conceptually showing polygon replacement of particles.

FIG. 8 is a diagram for explaining the principle of Gouraud shading;

FIG. 9 is an explanatory diagram conceptually showing a process of adding polygon colors.

FIG. 10 is an explanatory diagram showing the principle of a smoothing process.

FIG. 11 is a flowchart showing the operation of the embodiment.

FIG. 12 is an explanatory diagram showing an example of a flame image for one frame produced according to the embodiment;

FIG. 13 is an explanatory diagram showing another example of a flame image for one frame produced according to the embodiment;

FIG. 14 is an explanatory diagram showing still another example of a flame image for one frame produced by the embodiment.

FIG. 15 is a diagram for explaining a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Shape input device 12 ... Light and camera information input device 14 ... Projection processing device 16 ... Flame parameter designation device 18 ... Flame image production device

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akira Sato 1-1-1 Ichigaya Kagacho, Shinjuku-ku, Tokyo Inside Dai Nippon Printing Co., Ltd.

Claims (1)

[Claims] 1. A flame image producing apparatus for producing a virtual flame image by generating a plurality of particles which are a source of a flame from a predetermined source for each calculation step, wherein at least a center position coordinate for the particles is provided. Means for setting particle information comprising a radius and a center color; means for moving the particles in accordance with preset movement rules; means for changing the radius of the particles; and coordinates of the center position of the particles. Means for replacing a plurality of polygons with a common vertex and inscribed in a circle having the same radius, based on a center color set for the common vertex and a color of an inscribed vertex separately set for each polygon Means for determining the color of each polygon by interpolation calculation of the color inside the polygon, and means for producing a flame image by combining the colors of each polygon determined for all particles. Flame image production apparatus according to claim and.