CN100337250C - Method for detecting collision between body stand and flexible object - Google Patents

Abstract

The invention relates to a collision detecting method between a human body model and a flexible object, which comprises the following steps: 1, the preprocessing stage is to establish a local distance table on the surface of a human body model and record the distance information between each area of the surface of the human body model and the relative bones on the bottom layer according to certain order; 2, each top point/ surface area of a flexible object is detected, the vertical point position of the current top point/surface area on each control shaft 1 is obtained, and through the discussion of the vertical point positions and the search of the local distance table, a user can judge weather the current top point/ surface area has position collisions with the surface of the human body model at present. The present has the advantages that the requirements of a computer generating space to reality are satisfied, the requirements of a practical application system to speed is satisfied, the time and the complexity of the collision detection are only correlative to the number of the top points on the flexible object model, and the time and the complexity of the calculation of the collision detection are invariant under the condition that the human body model moves acutely.

Description

Collision detection method between a kind of manikin and flexible article

Technical field

The present invention relates to field of Computer Graphics, specifically, relate to the method for collision detection between a kind of manikin and flexible article.

Background technology

In real world, human body always contacts with various flexible articles, as the dress ornament of body worn, and the mattress quilt that sleep is used etc.If will in the computing machine span, really describe the objective world, comprise various personages, article and their motion in the objective world, need to manikin with its on every side relevant flexible article carry out motion simulation or animation simulation.Wherein one of key issue is in emulation or animation simulation process manikin and flexible article to be carried out the collision detection of locus.

In the computing machine span, flexible article and manikin are represented with polygonal mesh usually.In order to obtain the stronger sense of reality, a simple flexible article, as the model of skirt, its summit number is usually at several thousand orders of magnitude, and the dough sheet number of common manikin is usually at several ten thousand orders of magnitude.Polygonal mesh is the geometric model of no thickness, any trickle verisimilitude that all can influence visual effect that penetrates.Carry out the method for collision detection in the prior art, speed have levels faster bounding box method, volume elements method, but the computation complexity of these methods is still higher, is difficult to requirement of real time.For some real-time application, how guaranteeing under the real-time prerequisite that it is one of the research difficult point in current graphics field that thousands of summit and dough sheet are carried out the collision detection of accurate locus.

Summary of the invention

The objective of the invention is to provides a kind of locus fast, accurately collision detection method for manikin and flexible article in the computing machine span.

To achieve these goals, the collision detection method between manikin provided by the invention and flexible article comprises the steps:

1) detects pretreatment stage before, set up the local distance table on the manikin surface, the local distance table has write down the range information between each zone of human body surface and the bottom associated bone in certain sequence, this bottom associated bone is by Control Shaft 1 expression, and Control Shaft 1 is the line segment in join dependency bone two adjacent joints;

21) each summit on the traversal flexible article for each position of traversal human body, current summit, is made vertical line from current summit to working as front Control Shaft 1 place straight line, and is tried to achieve vertical point;

22) according to the position of point of hanging down, and search the local distance table, judge whether occurrence positions conflicts when the front with manikin on flexible article fooled preceding summit.

Described step 1) comprises following substep:

11) according to the characteristics of current manikin, model is carried out the position divide, draw the Control Shaft 1 at each position;

12) travel through each position, the geometric jacquard patterning unit surface when the front is carried out area dividing;

13) each regional area is called local distance to the distance of its position, place Control Shaft 1 with this distance on the computational geometry surface;

141) all local distances are deposited in certain sequence in the local distance table at this position;

142) will work as the maximal value of local distance on each section of front, deposit in the local distance table by the section order;

143) will select that the maximal value of all local distances deposits in the local distance table in the position;

144) in the beginning record position of local distance table sequence number, toponym, position section number, the number of rays of each section.

Also comprise following substep in the described step 12):

121), equally spaced make the section 9 vertical with Control Shaft 1 along this position Control Shaft 1 for working as the front;

122) traveling through each section, for current section, is the center with the intersection point of this section and its Control Shaft 1, as start ray 10, is at interval with the equal angular with the fixed-direction of agreement, outwards makes ray equably;

123) with step 122) in the intersection point on the ray of doing and surface, position, place characterize each regional area.

Described step 22) also comprise following substep:

221) in step 21) in tried to achieve the position of the point that hangs down, if the point that hangs down is positioned at beyond the Control Shaft, then can judge current summit with work as the front not occurrence positions conflict; Point is positioned on the Control Shaft if hang down, and then tries to achieve the sequence number of two sections adjacent with vertical line according to the vertical point and the distance at Control Shaft two ends;

222) search when front local distance table, if current summit to the distance of the point that hangs down greater than local distance maximum on adjacent two sections, then can judge current summit with work as the front not occurrence positions conflict; Otherwise,, try to achieve the sequence number of four rays adjacent with vertical line again according to the initial direction of making ray under vertical line direction, Control Shaft position and the current motion state when the front;

223) search when front local distance table, if current summit to the distance of the point that hangs down local distance, then can judge greater than adjacent four rays current summit with work as the front not occurrence positions conflict; Otherwise, judge current summit and taken place when the front or be about to occurrence positions to conflict.

Collision detection method between manikin provided by the invention and flexible article, its advantage is:

(a) satisfy the requirement of the computing machine span to verisimilitude, collision detection method energy provided by the invention load comprises the manikin and the flexible article model of a large amount of dough sheets.

(b) satisfy the requirement of real application systems to speed, the dough sheet number of establishing manikin is m, and the summit number on the flexible article model is n, and then the time complexity of collision detection is O (n), and is only relevant with summit number n on the flexible article model.

(c) be under the situation of strenuous exercise at manikin, the time complexity that collision detection is calculated is constant.

Under human motion state, owing to need not to upgrade the local distance table at each position, consistent under the method for therefore carrying out collision detection and the human body stationary state, algorithm complex still is O (n).And the summit number that the complexity of algorithm is conflicted with actual generation locus is irrelevant, and therefore, in the practical application that a large amount of conflicts take place, for example virtual costume is performed, and the complexity of its algorithm still remains on O (n) order of magnitude.Manikin described in the invention and the collision detection method between flexible article, can the accurate detection manikin under various states (static, motion), and the position conflict situations between the flexible article (as clothes, curtain etc.) on every side satisfies the needs of various real-time application.

Description of drawings

Fig. 1 is the synoptic diagram of a certain position of human body and associated bone thereof;

Fig. 2 is that the position between a certain position of human body and its Control Shaft concerns synoptic diagram in the motion process;

Fig. 3 is a position view of asking local distance process midship section and ray;

Fig. 4 is that several possible position at summit and a certain position of human body concerns synoptic diagram on the flexible article;

Fig. 5 is the example of manikin and flexible article in the computing machine span;

Fig. 6 is for generating the process flow diagram of local distance table among the present invention;

Fig. 7 is the process flow diagram of concrete testing process once among the present invention.

Embodiment

Generally speaking, in the computing machine span, each moment is owing to reasons such as human motion, air flow, spatial relation between manikin and the flexible article can change, and therefore need the locus conflict situations between them be detected again.

Because the characteristics of the physiological structure of human body, can be divided into several positions to manikin, wherein all there is an associated bone in each position, it serves as the axle rotation with an end points of this bone that associated bone can drive its position, place, associated bone is called Control Shaft, its end points as turning axle is called the father joint of this Control Shaft.As shown in Figure 1, be example with the position right leg 5 of manikin, its Control Shaft 1 is the line of right knee joint 2 to right ankle-joint 3, right knee joint 2 is the father joint of Control Shaft 1.Fig. 2 is that the position between a certain position of human body and its Control Shaft concerns synoptic diagram in the motion process, and wherein 1 is Control Shaft, and 4 is the father joint, and 6 is a surperficial dough sheet at this position, and 7 is the original position at this position, 8 be this position around the father joint 4 postrotational positions.As can be seen, whole position produces identical displacement and rotation together with its Control Shaft in motion process, and these characteristics have determined the distance between manikin arbitrary zone, surface and its Control Shaft can suppose to remain unchanged.

Utilize this hypothesis just, the present invention has introduced this notion of local distance table, and the local distance table has write down the range information between the relevant bottom bone with it of each regional area of human body surface in certain sequence.Because the distance between hypothesis manikin arbitrary zone, surface and its Control Shaft remains unchanged in motion process, no matter which kind of athletic posture human body is in, and the local distance information in each position local distance table all remains unchanged.

In specific implementation process, method of the present invention comprises following two steps: at first, the pretreatment stage before detecting beginning, surperficial at manikin for setting up the local distance table in each position.Secondly, in testing process,,, judge the position conflict situations between this moment flexible article and the manikin fast by searching the local distance table according to the distance between current time flexible article and the human skeleton.The present invention will be further described below in conjunction with accompanying drawing and embodiment.

1, the foundation of local distance table

The foundation of local distance table is to carry out at pretreatment stage, does not take the time overhead in the testing process.Set up the local distance table and may further comprise the steps (as shown in Figure 6):

Step 101: manikin is carried out the position divide, for each position, the definition associated bone, this associated bone is represented with the line segment that connects two adjacent segment point, is called Control Shaft.

Step 102 a: position in the selected manikin, (4 is the father joint among the figure) as shown in Figure 3, equally spaced make the section 9 vertical along this position Control Shaft 1 with Control Shaft 1, this size at interval can be arranged along the axial length of control to accuracy requirement with when the front according to application system.Generally speaking, the section number at a position is between 6～12.

Step 103: on each section, being the center with this section and Control Shaft 1 intersection point, as start ray 10, is at interval with the fixed-direction of agreement with the equal angular, and ray outwards is set uniformly.Try to achieve the intersection point of all rays and human body surface, see Fig. 3.Angle intervals between the ray also can be arranged according to the accuracy requirement of application system.Generally speaking, the number of rays on each section is between 6～18.

Step 104: calculate all rays of selected position from starting point to this ray and the distance the human body surface intersection point, this distance is become local distance.All local distances at selected position are deposited in the local distance table at this position in certain sequence.Table 1 is the example of a local distance table.

Step 105: will select the maximal value of local distance on each section at position, and deposit in the local distance table by the section order.

Step 106: will select that the maximal value of all local distances deposits in the local distance table in the position.

Step 107: the local distance that judges whether in the local distance table, to have deposited in all sites in the manikin.If be judged as be, enter step 108,, get back to step 102 if be judged as not, selected next position, repeated execution of steps 102 is to step 106.

Step 108: the local distance of all sites in the manikin has all deposited the local distance table in, and the local distance table is set up and finished.

Be noted that in the local distance table, depositing in proper order of local distance information can be carried out artificial agreement according to the subsequent query needs.Beginning general record position sequence number, toponym, the position section number of table, the number of rays of each section.

Table 1

The position sequence number	2
		Toponym	Right leg
The section number	12
		Single section number of rays	10
The local distance of No. 1 ray on No. 1 section	0.1105
		The local distance of No. 2 rays on No. 1 section	0.1110
...	0.1116
		...	0.1158
...	0.1178
		...	0.1201
...	0.1183
		...	0.1165
...	0.1134
		The local distance of No. 10 rays on No. 1 section	0.1112
Maximum local distance on No. 1 section	0.1201
		...	...
...	...
		The maximum local distance in position	0.1339

2, the detection of locus conflict situations

Concrete each time testing process may further comprise the steps (as shown in Figure 7):

Step 200: each summit on the traversal flexible article, for each position of traversal human body, current summit.

Step 201: make vertical line from current summit to working as Control Shaft place, front straight line, and try to achieve vertical point.Fig. 4 is that several possible position at summit and a certain position of human body concerns synoptic diagram on the flexible article, and wherein 1 is Control Shaft, P1, P2, P3 is respectively three summits on the flexible article, and regional A, B represent respectively corresponding to summit P2, the human body surface regional area of P3.Cross P1 respectively, P2, P3 makes the vertical line of Control Shaft 1, the some P1 ' that obtains hanging down, P2 ', P3 '.

Step 202: if the point that hangs down is positioned at beyond the Control Shaft, then can judge current summit with when the front not occurrence positions conflict (being the P1 situation among Fig. 4), get back to step 201 and detect next and organize data; Point is arranged in (being Fig. 4 P2 or P3 situation) on the Control Shaft if hang down, and enters step 203.

Step 203: calculating the distance at hang down point and Control Shaft two ends, searching local distance table, trying to achieve the sequence number of two sections adjacent with vertical line when the front.

Step 204: search when front local distance table, if current summit to the point that hangs down apart from d greater than local distance (the P2 situation among Fig. 4) maximum on adjacent two sections, then can judge current summit with when the front not occurrence positions conflict, get back to step 201 and detect next group data; Otherwise, enter step 205.

Step 205: according under vertical line direction and the current motion state when the ray initial direction of front, and the sequence number of adjacent two sections of having tried to achieve is tried to achieve the sequence number of four rays adjacent with vertical line.In step 204, obtained two sections adjacent, searched, can obtain four adjacent on these two sections rays (two adjacent rays are wherein arranged on each section) respectively with current summit when front local distance table with current summit.Be noted that under motion state, may take place with the Control Shaft when the front is rotatablely moving of rotating shaft, the ray initial direction of therefore working as the front should be that the acquiescence initial direction in the local distance table adds the angle when the front rotation.

Step 206: search when front local distance table, if current summit to the distance of the point that hangs down maximal value, then can judge greater than adjacent four ray local distances current summit with when the front not occurrence positions conflict, get back to step 201 and detect next and organize data; Otherwise, judge current summit and taken place when the front or be about to occurrence positions to conflict, enter step 207.

Step 207: judging whether to travel through each summit on the flexible article and the combination at each position of human body, is to enter step 208 if be judged as; If be judged as not, get back to step 201 and detect next group data.

Step 208: obtain testing result, the collision detection process finishes.

From above narration as can be seen, the collision detection between manikin and the flexible article can be decomposed into the collision detection between the single summit and the single position of manikin on the flexible article.If the dough sheet number of manikin is m, summit number on the flexible article model is n, generally m＞＞n, the position number of human body is generally a less constant (generally speaking less than 15), therefore (time that is collision detection is only relevant with the summit number n on the flexible article model at O (n) order of magnitude to utilize the present invention to carry out the time complexity of collision detection between manikin and the flexible article, irrelevant with the size of the dough sheet number m of manikin), be significantly less than present existed algorithms.

Under human motion state, to show apart from height owing to need not to upgrade the part at each position, consistent under the method for therefore carrying out collision detection and the human body stationary state, algorithm complex still is O (n).And the summit number that the complexity of algorithm is conflicted with actual generation locus is irrelevant, and therefore, in the practical application that a large amount of conflicts take place, for example virtual costume is performed, and the complexity of its algorithm still remains on O (n) order of magnitude.

Manikin described in the invention and the collision detection method between flexible article, can the accurate detection manikin under various states (static, motion), and the position conflict situations between the flexible article (as clothes, curtain etc.) on every side satisfies the needs of various real-time application.

Claims (5)

1, the collision detection method between a kind of manikin and flexible article is characterized in that, comprises the steps:

1) detects pretreatment stage before, set up the local distance table on the manikin surface, the local distance table has write down the range information between each zone of human body surface and the bottom associated bone in certain sequence, this bottom associated bone is by Control Shaft (1) expression, and Control Shaft (1) is the line segment in join dependency bone two adjacent joints;

21) each summit on the traversal flexible article for each position of traversal human body, current summit, is made vertical line from current summit to working as front Control Shaft (1) place straight line, and is tried to achieve vertical point;

22) according to the position of point of hanging down, and search the local distance table, judge whether occurrence positions conflicts when the front with manikin on flexible article fooled preceding summit.

2, by the collision detection method between described manikin of claim 1 and flexible article, described step 1) is characterized in that, comprises following substep:

11) according to the characteristics of current manikin, model is carried out the position divide, draw the Control Shaft (1) at each position;

12) travel through each position, the geometric jacquard patterning unit surface when the front is carried out area dividing;

13) each regional area is called local distance to the distance of its position, place Control Shaft (1) with this distance on the computational geometry surface;

141) all local distances are deposited in certain sequence in the local distance table at this position;

142) will work as the maximal value of local distance on each section of front, deposit in the local distance table by the section order;

143) will select that the maximal value of all local distances deposits in the local distance table in the position.

3, by the collision detection method between described manikin of claim 2 and flexible article, described step 12) is characterized in that, also comprises following substep:

121) for working as the front, equally spaced make the section (9) vertical with Control Shaft (1) along this position Control Shaft (1);

122) traveling through each section, for current section, is the center with the intersection point of this section and its Control Shaft (1), as start ray (10), is at interval with the equal angular with the fixed-direction of agreement, outwards makes ray equably;

123) with step 122) in the intersection point on the ray of doing and surface, position, place characterize each regional area.

4, by the collision detection method between described manikin of claim 2 and flexible article, finish described step 143) after, also have following substep:

144) in the beginning record position of local distance table sequence number, toponym, position section number, the number of rays of each section.

5, by the collision detection method between the described manikin of claim 1 and flexible article, described step 22) also comprise following substep:

221) in step 21) in tried to achieve the position of the point that hangs down, if the point that hangs down is positioned at beyond the Control Shaft, then can judge current summit with work as the front not occurrence positions conflict; Point is positioned on the Control Shaft if hang down, and then tries to achieve the sequence number of two sections adjacent with vertical line according to the vertical point and the distance at Control Shaft two ends;

222) search when front local distance table, if current summit to the distance of the point that hangs down greater than local distance maximum on adjacent two sections, then can judge current summit with work as the front not occurrence positions conflict; Otherwise,, try to achieve the sequence number of four rays adjacent with vertical line again according to the initial direction of making ray under vertical line direction, Control Shaft position and the current motion state when the front;

223) search when front local distance table, if current summit to the distance of the point that hangs down local distance, then can judge greater than adjacent four rays current summit with work as the front not occurrence positions conflict; Otherwise, judge current summit and taken place when the front or be about to occurrence positions to conflict.

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