DOI:10.16182/j.cnki.joss.2008.19.069
第 20 卷第 19 期 2008 年 10 月
系 统 仿 真 学 报? Journal of System Simulation
Vol. 20 No. 19
Oct., 2008
Round Angle Based on Run Simulation
LIU Tian-hu, ZOU Xiang-jun, WANG Hong-jun, LUO Lu-feng, SUN Quan
(Engineering College, South China Agriculture University, Guangzhou 510642, China)
Abstract: A round angle based on simulating method was put forward to shorten modeling period of run action. When a person runs, his limbs and trunks are rounding around joints, so round angle based on run model constructs posture functions and calculates locations of each part according to round angle of joints. According to such model, a run action simulating method was put forward. A jogging simulation experiment was introduced to illustrate such simulating method.
Key words: running posture; action model; simulation
Introduction
An Internet based on collaborative exercise game is a hardware and software integrated system. By running velocity checking of sensor, signal transferring and conversing, and by behavior driving of virtual role, it connects running machine with personal computer. In such game, runner matching to a virtual role can compete with virtual role or long-distance runners on the internet, as Fig.1 shown.
In order to develop realistic collaborative game, a lifelike role and its behavior model must be developed firstly. And in order to create living run action by interpolating from animation database, a lot of different style run animations must be built. In order to create run animations quickly, suitable run modeling and simulating method seems necessary. Many researches have advanced their methods of behavior modeling or simulating for virtual person
[1-9]
Fig.1 Internet based on collaborative exercise game
movement by reverse-kinematics . Stewart developed a 3D person stepping in flat and stair environment by a restriction based method. Ortiz developed a person animation based on VRML, reverse-kinematics, face expression and behavior rule
[8]
[5]
[2]
. For example, D. Zeltzer
[1]
developed a task-classification faced animation system . In . Badler put forward a behavior simulating method based
[7]
such animation system, Control Techniques of body’s Figure are based on data checked in real world. Girard put forward a method creating trunk’s movement by dynamics, creating leg’s
on virtual person animation. F. Shi developed a behavior
[9]
Received: 2008-04-29
modeling approach for causal tracing of complex simulation.
Zhejiang University has done many researches in this field, and achieved a patent: a technical and system of generating person animation from video. Ph.d Chen Rui put forward a method creating 3D person moving animation by many synchronize Video
[13]
[10-12]
Revised: 2008-09-03
Foundation items: National Science Project with Research Grant 50775079. Project of Science and Technology of Guangdong Province with Research Grant 07300720 and 07006692. Key Project of Science and Technology of Guangdong Province with Research Grant 2007B010200068.
Biographies: LIU Tian-hu(1974-), Lectuer. His research interests are virtual reality and collaborative product design; ZOU Xiang-jun(1957-) (Corresponding author), Professor. Her research interest is virtual reality.
. PH.d Gao Song put forward a content-[14]
based human motion retrieval and motion synthesis method.
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第 20 卷第 19 期 2008 年 10 月
Vol. 20 No. 19
LIU Tian-hu, et al：Round Angle Based On Run Simulation
Oct., 2008
There are still two key problems exiting in existence behaviors modeling and simulating. The first problem is that existing theories are relatively complex, which result in operation complex, data coupling and time lag. The second problem is that it is hard to drive virtual role’s behavior by real person via those models, which lead to express living runner behavior difficulty. In this paper, we will develop a round angle based on method simulating runner behavior, which is very simple.
runner by experience, and building a series of animation, then demonstrating and revising time after time until its living. Those cases building period is very long. If round angle based on run model is used in case simulation, a series of demonstrating and revising of runner gesture can be done before frame designing, so the building period can be shortened. Process of run simulating and modeling is shown in Fig.3.
Scheme designing Predigested runner’s framework designing round angle data designing Framework revising Running simulation
1 Framework and Run Model
According to the characteristic of runner gesture and joint moving law, a sketch framework of runner skelecton can be predigest into a brief framework which have 12 parts, as shown in Fig.2.
Data revising
Fig.2 Predigested runner’s framework mode
Living judging
Animation designing
Fig.3 Role modeling process
There are three key steps, as follows: The first step is data input.
The second step is running simulation. The third step is position calculation.
Where: OA expresses trunk. Its length is l1 ; AB and AD express upper arms. Their length is l2 / l3 ; BC and DE express lower arm. Their length is l4 / l5 ; OI and OF express thigh. Their length is l6 / l7 ; FG and IJ express calf. Their length is
If position data then used in run animating, animating
period would be significantly shortened.
2.2 Simulation
A jogging case is introduced to illustrate the simulating and modeling process.
The first step: data input. Element length is:
l8 / l9 ; GH and JK express foot. Their length is l10 / l11 ;AL
express head. Its length is l12 .
Actions of a virtual person can be expressed as:
m ( t ) ? ( p ( t ), r ( t ), q ( t ),..., q ( t))
3
3
3
OA =100, AB =50, BC =40, AD =50, DE =40, OF =70, FG =60,
GH =20, EI =70, IJ =60, JK =20, AL =20. Round angle of (start
1nt
i
Where p ( t) ∈? , r ( t ) ∈ S express level movement and round, q
angle and end angle) of joints is: α1=π/2~π/2, α2=π/6~-π/6, α3=π/2~5π/6, α4=π/6~-π/6, α5=5π/6~π/2,α6=π/6~-π/6, α7=5π/6~π3/4, α8=π5/12~π7/12, α9=π/6~-π/6, α10=π3/4~π5/6, α11=π7/12~π5/12, α12:=0. The second step: running simulation.
( t ) ∈ S express round movement of joint i , 1 ≤ i ≤ n .
Not considering level movement of body (in practice, level moving distance needs only to add a level moving function, expresses as f (t) ), a series of round angle based on joints moving model can be built. Take pose function of should joint for example, it can be expressed as:
x1 (t) ? x0 (t) ? L1 cos(α1 (t)) y1 (t) ? y0 (t) ? L1 sin(α1 (t))
According to such model, a living and brief runner role
can be built easily. Its action can be simulated quickly.
In order to simulate run gesture, a simulating program is developed, key algorithm of which is round angle based on run model. Fig.4-Fig.6 are some results of those simulating experiments. Fig.4 is a series of Snapshot pictures of the experiments. Fig.5 is X value of key frame. Fig.6 is Y value of key frame.
2 Running Simulation
2.1 Simulation process
In order to build a running animation, a series of running frame must be built firstly. Traditional running case modeling and running animation building method is estimating gesture of
Fig.4 Key frame of case2
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第 20 卷第 19 期 2008 年 10 月
系 统 仿 真 学 报 Journal of System Simulation
Vol. 20 No. 19
Oct., 2008
200 150 100
x/y
50
Fig.5 X value of key frame of case2
0 -50
4
8 t
12
16
20
0
Fig.10 Position track of joints J,K,L
According to simulation result, two jog animations were built. Some snapshot pictures of one of the animation are shown in Fig.11. Series Poses of another animation are shown in Fig.12.
Fig.6 Y value of key frame of case2
The third step: position calculation.
Joints’ position track maps are shown in Fig.7 to Fig.10.
180
Fig.11 Snapshot pictures of running animation
160 140 120 100 80 60 40 20
4
8
12
20
0
0
16
Fig.7 position track of joints A,B,C
Fig.12 Series pictures of running animation
200 180
3 Conclusion
This paper puts forward a run action simulating method according to round angle based on run model. Such model builds runner role by round angle of joints. Jogging simulating experiments was introduced to illustrate such simulating method. It is obviously that if round angle based on run model is used in case building, a series of demonstrating and revising of run gesture can be done before frame designing, and animating period can be significantly shortened.
160 140 120 100 80 60 40
20
8
12
0 4 16 20
200 150
Fig.8 position track of joints D,E,F
References:
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D Zeltzer. Motor Control Techniques for Figure Animation [J]. IEEE Computer Graphics and Applications (S0272-1716), 1982, 2(9): 53-59. M Girard, A A Maciejewski. Computational modeling for the computer animation of legged figures [J]. Proceedings of SIGGRAPH’85. In
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x/y 100
50 0 -50
4
8 t
12
16
20
[3]
0 [4]
Fig.9 Position track of joints G,H,I
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A Bruderlin, T W Calvert. Goal-Directed Dynamic Animation of Human Walking [J]. Proceedings of SIGGRAPH 89, ACM Computer Graphics (S0097-8930), 1989, 23(3): 233-242.
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