WO2020246508A1

WO2020246508A1 - Physics computing device, physics computing method, and program

Info

Publication number: WO2020246508A1
Application number: PCT/JP2020/021977
Authority: WO
Inventors: 昭西山
Original assignee: 株式会社ソニー・インタラクティブエンタテインメント
Priority date: 2019-06-07
Filing date: 2020-06-03
Publication date: 2020-12-10
Also published as: JP2020201622A

Abstract

Provided is a physics computing device comprising: a first physics computing unit that predicts the position of a first object on a time-series basis on the assumption that an external force applied to the first object displayed in a virtual three-dimensional space remains constant; and a second physics computing unit that predicts the position or speed of the first object on a time-series basis on the assumption that an external force applied to the first object changes if the position of the first object is included in a region associated with a second object displayed in the three-dimensional space.

Description

Physics unit, physics method and program

The present invention relates to a physical arithmetic unit, a physical arithmetic method, and a program.

A technique is known for calculating the position of an object moving in a virtual space displayed on a display or the like by physical calculation. For example, Patent Document 1 describes an object control program using a physics engine that calculates the velocity and position information of an object drawn in a game by using software that simulates physical laws such as mass, velocity, friction, and wind. Have been described.

Japanese Unexamined Patent Publication No. 2013-000208

In object control as described above, it may be advantageous to suppress the amount of calculation of physics in order to speed up processing or enable operation on hardware with limited calculation resources. ..

Therefore, an object of the present invention is to provide a physics arithmetic unit, a physics calculation method, and a program capable of suppressing the amount of physics calculation by simplifying the physics calculation under a predetermined condition.

According to one aspect of the present invention, a first predicting the time-series position of a first object, assuming that the external force applied to the first object displayed in a virtual three-dimensional space does not change. Assuming that the external force applied to the first object changes when the physical calculation unit and the position of the first object are included in the area related to the second object displayed in the three-dimensional space. A physical calculation device including a second physical calculation unit that predicts the position or speed of one object in time series is provided.

According to another aspect of the present invention, the step of predicting the position of the first object in time series on the assumption that the external force applied to the first object displayed in the virtual three-dimensional space does not change. , When the position of the first object is included in the area related to the second object displayed in the three-dimensional space, assuming that the external force applied to the first object changes, the first object A physical calculation method is provided that includes a step of predicting a position or speed in a time series.

According to yet another aspect of the present invention, the position of the first object in time series is predicted on the assumption that the external force applied to the first object displayed in the virtual three-dimensional space does not change. It is assumed that the external force applied to the first object changes when the physical calculation unit of 1 and the position of the first object are included in the area related to the second object displayed in the three-dimensional space. A program for operating a computer as a physical calculation device including a second physical calculation unit that predicts a position or speed of a first object in time series is provided.

According to the above configuration, the physics is simplified by assuming that the external force applied to the object does not change if the position of the first object is not included in the area associated with the second object. The amount of calculation of physical calculation can be suppressed.

It is a block diagram which shows the schematic structure of the system which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the physical calculation part of the arithmetic unit shown in FIG. It is a figure for demonstrating the example of the physical calculation in one Embodiment of this invention. It is a flowchart which shows the example of the processing of the physical calculation in one Embodiment of this invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals, so that duplicate description will be omitted.

FIG. 1 is a block diagram showing a schematic configuration of a system according to an embodiment of the present invention. In the illustrated example, the system 10 includes a capture device 100, an arithmetic unit 200 (physical arithmetic unit), a drawing device 300, and a display device 400. The capture device 100 captures the movement of the user by using, for example, three-dimensional measurement or an IMU (inertial measurement unit). Specifically, for example, the capture device 100 includes a plurality of cameras and arithmetic units for three-dimensional measurement, an IMU, and the like. The capture device 100 transmits data indicating the captured user's movement to the arithmetic unit 200.

The arithmetic unit 200 includes a data correction unit 210, a complement / prediction unit 220, a physical calculation unit 230, and a coordinate correction unit 240. The arithmetic unit 200 is implemented by, for example, a computer having a communication interface, a processor, and a memory, and the functions of the data correction unit 210, the complement / prediction unit 220, the physical calculation unit 230, and the coordinate correction unit 240 are stored in the memory. It is realized by operating according to the program received via the communication interface. The functions of each part will be further described below.

The data correction unit 210 outputs data indicating the user's movement by executing noise removal, loss complementation, packet loss correspondence, etc. of the data received from the capture device 100 at a predetermined cycle (for example, 30 fps to 60 fps). Correct the data to be continuous at predetermined intervals.

The complement / prediction unit 220 predicts the time-series position of the object displayed in the virtual three-dimensional space based on the data indicating the movement of the user. In the present embodiment, the complement / prediction unit 220 predicts the position of the object in a cycle shorter than the cycle of the data indicating the movement of the user provided by the data correction unit 210, for example, by the complement processing by internal / external insertion.

The physics calculation unit 230 executes a physics calculation that simulates the laws of physics in order for the completion / prediction unit 220 to predict the position of the object in the time series. The physics unit 230 executes a physics calculation based on, for example, an external force exerted on the object by the user, which is determined according to data indicating the movement of the user in addition to the mass, initial velocity, and gravity set on the object. By doing so, the position of the object in time series is predicted.

The coordinate correction unit 240 corrects the coordinates of the position prediction result of the object by the complement / prediction unit 220, reflecting the position of the object as necessary. The coordinate correction unit 240 does not necessarily have to be provided. The position prediction result of the object after the correction by the coordinate correction unit 240 (when the coordinate correction unit 240 is not provided, the position prediction result of the object by the complement / prediction unit 220) is transmitted to the drawing device 300.

The drawing device 300 is implemented by a computer in the same manner as the arithmetic unit 200, and displays an image of an object in a virtual three-dimensional space with reference to the position prediction result of the object at a predetermined period (refresh rate. As an example. Draw at 120 fps to 240 fps). The display device 400 is, for example, an HMD (head-mounted display), and displays an image drawn by the drawing device 300 as a viewpoint image toward the user.

In the system 10 as described above, by suppressing the amount of calculation of the physical calculation executed by the physical calculation unit 230, it is possible to operate the system 10 as the arithmetic unit 200 even with hardware having limited calculation resources. Further, for example, since the position prediction cycle can be made shorter than the drawing cycle of the drawing device 300 (for example, 1000 fps or more), it corresponds to the improvement of the refresh rate of the display device 400 in the future, for example. Even if the drawing cycle of the drawing device 300 is shortened, the processing on the arithmetic unit 200 side can be dealt with without being changed.

FIG. 2 is a block diagram showing a configuration of a physical arithmetic unit of the arithmetic unit shown in FIG. In the illustrated example, the physics unit 230 includes a first physics unit 231 and a second physics unit 232. The first physics unit 231 predicts the position of an object displayed in a virtual three-dimensional space in time series on the assumption that the external force applied to the object does not change. The second physics unit 232 predicts the position in the time series on the assumption that the external force applied to the object changes.

Here, in the present specification, "the external force does not change" means that, for example, the external force does not apply to the object, the magnitude of the external force applied to the object does not change, and a constant ratio with respect to the mass or velocity of the object. Means that a proportional external force is applied. When no external force is applied to the object, the object moves at a constant velocity. When an external force that does not change in magnitude, such as gravity, is applied, the object moves at a constant acceleration. In constant velocity motion and constant acceleration motion, the position of an object in a time series over the future can be predicted by a calculation formula using only time as a variable. In addition, even when an external force proportional to the speed or mass of an object is applied, such as air resistance or friction, the motion of an object can be described by a formula that uses only time as a variable. The future position of an object in time series can be predicted by a simple calculation.

On the other hand, in the present specification, changing the external force means that an external force that has not been applied to the object is applied due to a collision between the objects, for example. The external force may be applied instantaneously, temporarily for a predetermined time, or continuously after a certain time. A collision between objects occurs, for example, when an object that is a moving object in a three-dimensional space comes into contact with another object that is fixedly arranged in the three-dimensional space or another object that is a moving object in the three-dimensional space. appear. Here, other objects may move according to the movement of the user. Assuming that the external force applied to the object changes, for example, the arithmetic unit 200 updates the position of the object at a predetermined cycle, and determines whether or not a collision with another object occurs at the updated position. To do. Then, when a collision with another object occurs, the arithmetic unit 200 can calculate the velocity of the object after the collision from the direction and magnitude of the external force applied to the object by the collision.

In the physical calculation unit 230 of the calculation device 200 according to the present embodiment, the first object which is a moving object in the virtual three-dimensional space and the moving object in the three-dimensional space or in the three-dimensional space. For the second object that is fixedly arranged, if the collision between the first object and the second object does not occur, it is assumed that the external force applied to the object by the first physical calculation unit 231 does not change. Predict the position in time series. On the other hand, the physics unit 230 assumes that the external force applied to the object by the second physics unit 232 changes when a collision between the first object and the second object may occur. Predict the time-series position or velocity of an object.

Here, whether or not a collision between the first object and the second object may occur depends on, for example, whether or not the position of the first object is included in the area related to the second object. It can be determined. This area is, for example, an area including a position where the first object collides with the second object. For example, when the position where the first object collides with the second object can be specified by predicting the position in the time series by the first physical calculation unit 231, the second physical calculation unit 232 uses the first object. Predicts the velocity after reaching this position and colliding with a second object. As will be described later, the second physics unit 232 may predict the velocity of the first object after the collision by using the coefficient of restitution between the first object and the second object. Since it can be assumed that the external force applied to the object does not change again after the collision with the second object, the first physics unit 231 may predict the position of the first object in the time series.

Alternatively, the area related to the second object may be an area where the second object can exist. For example, when the second object moves in the three-dimensional space according to the user operation, the movement of the second object is irregular, so that the first object is predicted by the first physics unit 231 in time series position. It is difficult to pinpoint where the second object collides. In this case, when the position of the first object predicted by the first physics unit enters the region where the second object can exist, the second physics unit 232 predicts the position of the first object. To do. The second physics unit 232 updates the position of the first object at a predetermined cycle, for example, and when the position of the first object and the position of the second object come into contact with each other or overlap, the second physical calculation unit 232 causes a collision. The velocity of the object after the collision is calculated from the direction and magnitude of the external force applied to the object. In this case, the second physics unit 232 predicts the time-series position and velocity of the first object. When the second object is also a moving object, the first physics unit 231 and the second physics unit 232 predict the time-series position and velocity of the second object in the same manner as the first object. You may.

FIG. 3 is a diagram for explaining an example of physics calculation in one embodiment of the present invention. In the illustrated example, the physics unit 230 predicts the time-series positions of objects obj1 (first object) and objects obj2 (second object), which are moving objects in a virtual three-dimensional space. At time t, the objects obj1 and obj2 are distant from each other and are moving at velocities v1 and v2 in the direction of approaching each other.

In the reference example shown in FIG. 3A, the second physics unit 232 sets the position of the object in the time series on the assumption that the external force applied to the object changes in the entire section from the time t to the time t + 4. I'm predicting. More specifically, the second physics unit 232 sequentially calculates the positions of the objects obj1 and obj2 at the time t + 1, t + 2 based on the positions of the objects obj1 and obj2 at the time t and the velocities v1 and v2. At time t + 2, the calculated positions of the objects obj1 and obj2 overlap. The second physics unit 232 uses a constraint solver to correct the positions of the objects obj1 and obj2 at time t + 2. More specifically, for example, the second physical calculation unit 232 simulates the collision behavior of the objects obj1 and obj2 that occur between the time t + 1 and the time t + 2, and transmits the behavior between the objects obj1 and obj2. The velocity of the objects obj1 and obj2 after the collision is calculated from the direction and magnitude of the external force applied, and the positions of the objects obj1 and obj2 at time t + 2 are calculated based on the velocities of the objects obj1 and obj2 after the collision. After that, the second physics unit 232 sequentially calculates the positions of the objects obj1 and obj2 at times t + 3 and t + 4.

On the other hand, in the example of the present embodiment shown in FIG. 3B, since the objects obj1 and obj2 do not collide with each other at the time t, the first physics unit 231 first sends the objects obj1 and obj2 to the objects obj1 and obj2. The time-series positions of the objects obj1 and obj2 are predicted on the assumption that the applied external force does not change. In this case, the time-series position of the object can be predicted by the calculation formula using only time as a variable as described above, and the time t + n when the object obj1 reaches the position where it collides with the object obj2 (example of (a) above). In the case of, the time between time t + 1 and time t + 2) can also be easily specified. The velocities of the objects obj1 and obj2 after the time t + n are predicted on the assumption that the external force applied to the object by the second physics unit 232 changes. More specifically, for example, the second physics unit 232 calculates the velocity of the objects obj1 and obj2 after the collision by using the coefficient of restitution between the object obj1 and the object obj2 as in the example described later. Alternatively, the second physics unit 232 may calculate the velocity of the objects obj1 and obj2 after the collision by simulating the behavior of the objects obj1 and obj2 at the time of collision as in the example of (a) above. .. Based on the calculated velocity, the first physics unit 231 again predicts the time-series positions of the objects obj1 and obj2 from the time t + n to the time t + m (n <m).

In the example of (b) above, the physics calculation unit 230 executes the physical calculation for the time from time t to time t + n by predicting the positions of the objects obj1 and obj2 using a calculation formula using only time as a variable. The amount of calculation can be suppressed. Further, in the example of (b), since the time t + n of the collision of the objects obj1 and obj2 can be specified, the position is corrected after it is found that the objects obj1 and obj2 overlap at the time t + 2 as in the example of (a). The amount of calculation can be suppressed as compared with the case of doing.

In the following, a specific example of calculating the velocity after a collision on the assumption that the external force applied to the object obj1 does not change will be further described. In the following example, the objects obj1 and obj2 are treated as mass points for the sake of simplicity, but the size of each object is actually considered.

For example, when the object obj1 is a moving object in the three-dimensional space and the object obj2 is an object fixedly arranged in the three-dimensional space, for example, the ground plane (y position is 0), the position of the object obj1 at time t ( x, y, z) is the initial position _{_{_{(x 0, y 0, z}}} 0) initial velocity _{_{_{(v x0, v y0, v}}} z0), and the initial acceleration _{_{_{(a x0, a y0, a}}} z0) as follows from the Can be calculated.

・ Calculation of collision time t _C with the ground plane y + v _y0 * t _C + a _y0 * t _C ² * Calculate collision time t _{C such} that 1/2 = 0 ・ Constant acceleration motion at time t ≦ t _C x = x ₀ + v _x0 * t + a _x0 * t ² * 1/2
y = y ₀ + v _y0 * t + a _y0 * t ² * 1/2
z = z ₀ + v _z0 * t + a _z0 * t ² * 1/2
_-Calculate the velocity v _y in the y direction at time t> t _C using the coefficient of restitution e (velocities v _x0 and v _z0 do not change).
v _y = -e (v _y0 + a _y0 * t)
・ Constant acceleration motion at time t> t _C x = x ₀ + v _x0 * t + a _x0 * t ² * 1/2
y = y ₀ + v _y0 * t _C- e (v _y0 + a _y0 * t) ( _tt _C ) + a _y0 * t ² * 1/2
z = z ₀ + v _z0 * t + a _z0 * t ² * 1/2

On the other hand, the object obj1, if obj2 is a mobile in either the three-dimensional space, the initial position of the object _{_{obj1 (x 0 1, y 0}} 1, z 0 1) initial velocity _{_{(v x0 1, v y0 1}} , v _z0 1), and initial acceleration (a _x0 1, a _y0 1, a _z0 1), and initial position of object obj2 (x ₀ 2, y ₀ 2, z ₀ 2) initial velocity (v _x0 2, v _y0 2) , V _z0 2), and the initial acceleration (a _x0 2, a _y0 2, a _z0 2) are used to calculate the collision time t _C as follows, and the collision time is calculated using the repulsion coefficient as in the above example. it is possible to calculate the position of the object obj1, obj2 at time t before and after t _C.

-Calculation of collision time t _C | x ₀ 1 + v _x0 1 * t _C + a _x0 1 * t _C ² * 1 / 2-x ₀ 2 + v _x0 2 * t _C + a _x0 2 * t _C ² * 1/2 | + | y ₀ 1 + v _y0 1 * t _C + a _y0 1 * t _C ² * 1 / 2-y ₀ 2 + v _y0 2 * t _C + a _y0 2 * t _C ² * 1/2 | + | z ₀ 1 + v _z0 1 * t _C Calculate the collision time t _{C such} that + a _z0 1 * t _C ² * 1 / 2-z ₀ 2 + v _z0 2 * t _C + a _z0 2 * t _C ² * 1/2 | = 0.

FIG. 4 is a flowchart showing an example of processing of physical calculation in one embodiment of the present invention. When the physical calculation unit 230 of the arithmetic unit 200 executes the physical calculation of the object displayed in the virtual three-dimensional space, it first determines whether or not the object has reached the collision area (step S101). For example, the physics unit 230 determines that an object has reached the collision area when the object overlaps with another object. Alternatively, when the first physics unit 231 predicts the position of the object on the assumption that the external force does not change (step S102), the physics unit 230 makes contact with another object or the predicted position touches another object. If there is a collision, it is determined that the object has reached the collision area.

When it is determined in step S101 that the object has not reached the collision area, the first physics unit 231 predicts the position of the object on the assumption that the external force applied to the object does not change (step S102). ). At this time, the first physics unit 231 may predict the position of the object in the next cycle of the position prediction of the object, or collectively predict the position of the time series until the object reaches the collision area. You may. The position prediction of the object by the first physics unit 231 is repeated until the object reaches the collision region (step S101).

On the other hand, when it is determined in step S101 that the object has reached the collision region, the second physics unit 232 predicts the position or velocity of the object on the assumption that the external force applied to the object changes. (Step S103). The second physics unit 232 may predict the position of the time series while the object is in the collision area, or may determine the velocity of the object after it has changed in the collision area equal to the collision position as in the above example. You may predict. The position prediction of the object by the second physics unit 232 is repeated until the object leaves the collision area (step S104).

By repeating the prediction of the position of the object by the first physical calculation unit 231 and the second physical calculation unit 232 as described above until the end of the physical calculation (step S105), the time series of the objects colliding with other objects The position of can be predicted with a suppressed amount of calculation.

Although some embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to such examples. It is clear that a person having ordinary knowledge in the field of technology to which the present invention belongs can come up with various modifications or modifications within the scope of the technical ideas described in the claims. It is naturally understood that these also belong to the technical scope of the present invention.

10 ... system, 100 ... capture device, 200 ... arithmetic unit, 210 ... data correction unit, 220 ... prediction unit, 230 ... physical calculation unit, 231 ... first physical calculation unit, 232 ... second physical calculation unit, 240 ... Coordinate correction unit, 300 ... Drawing device, 400 ... Display device.

Claims

A first physics unit that predicts the time-series position of the first object on the assumption that the external force applied to the first object displayed in the virtual three-dimensional space does not change.
The first, assuming that the external force applied to the first object changes when the position of the first object is included in the area related to the second object displayed in the three-dimensional space. A physics unit comprising a second physics unit that predicts the position or velocity of an object in time series.
The area is an area including a position where the first object collides with the second object.
The second physics unit predicts the velocity of the first object after colliding with the second object by using the coefficient of restitution between the first object and the second object. The physics calculation device according to claim 1.
The second object is a moving object in the three-dimensional space.
The first physics unit predicts the time-series position of the second object on the assumption that the external force applied to the second object does not change.
The second physics unit assumes that when the position of the first object is included in the region related to the second object, the external force applied to the second object changes. The physics unit according to claim 1 or 2, which predicts the time-series position or velocity of two objects.
The physical arithmetic unit according to claim 1 or 2, wherein the second object is fixedly arranged in the three-dimensional space.
The second object moves in the three-dimensional space according to a user operation,
The physical arithmetic unit according to claim 1, wherein the region is a region in which the second object can exist.
A step of predicting the time-series position of the first object on the assumption that the external force applied to the first object displayed in the virtual three-dimensional space does not change, and
The first, assuming that the external force applied to the first object changes when the position of the first object is included in the area associated with the second object displayed in the three-dimensional space. A physical calculation method that includes steps to predict the position or velocity of an object in time series.
A first physics unit that predicts the time-series position of the first object on the assumption that the external force applied to the first object displayed in the virtual three-dimensional space does not change.
The first, assuming that the external force applied to the first object changes when the position of the first object is included in the area associated with the second object displayed in the three-dimensional space. A program for operating a computer as a physical calculation device including a second physical calculation unit that predicts the position or velocity of an object in time series.