The Visia Avatar

The supplied avatar provided by the ViSiCAST Control v2.0 is Visia, shown below.

An Overview of Bones within MaskVR

The avatar's mesh is wrapped over a 'skeleton' which is composed of 78 'bones'. These bones act as control values for the mesh deformation algorithm. They do not necessarily represent anatomical bones (although in the case of the main body and hands they do). Each bone is represented as 13 floating point values, and can be represented in either two forms: Global or Local. A globalised bone has its values defined in terms of the global co-ordinate system, whilst a localised bone is defined in the co-ordinate system of a parent. Bones are always aligned along their x-axis. The following table describes each value required to describe a bone.

Description

 

Global Mode

Local Mode

Length

 

Length of the bone in within the global co-ordinate system.

Length of the bone in within the global co-ordinate system.

X Axis

X

Given in the global co-ordinate system.

Given in the parent's co-ordinate system.

 

Y

 

Z

Y Axis

X

Given in the global co-ordinate system.

Given in the parent's co-ordinate system.

 

Y

 

Z

Z Axis

X

Given in the global co-ordinate system.

Given in the parent's co-ordinate system.

 

Y

 

Z

Position

X

Defined in the global co-ordinate system scale.

Each unit is defined as the length of the parent bone.

 

Y

 

Z

Visia's Bones

Visia is composed from 78 bones, which form a hierarchy. The hierarchy is described in the following table.

Index

Name

Parent

0

lower_back

1

1

mid_back

2

2

top_back

-1

3

neck

2

4

head

3

5

left_shoulder

2

6

left_upper_arm

5

7

left_forearm

6

8

left_hand

7

9

right_shoulder

2

10

right_upper_arm

9

11

right_forearm

10

12

right_hand

11

13

left_slap

6

14

right_slap

10

15

neck_slap

2

16

left_upper_corner_lip

4

17

left_upper_lip

4

18

right_upper_lip

4

19

right_upper_corner_lip

4

20

left_lower_corner_lip

4

21

left_lower_lip

4

22

right_lower_lip

4

23

right_lower_corner_lip

4

24

left_brow

4

25

right_brow

4

26

right_jaw

4

27

left_jaw

4

28

chin

4

29

left_cheek

4

30

right_cheek

4

31

necky

3

32

left_eyelid

4

33

right_eyelid

4

34

left_eye

4

35

right_eye

4

36

left_ThumbMagic

8

37

left_ThumbTMJ

36

38

left_ThumbMPJ

37

39

left_ThumbIJ

38

40

left_IndexMCJ

8

41

left_IndexMPJ

40

42

left_IndexPIJ

41

43

left_IndexDIJ

42

44

left_SecondMCJ

8

45

left_SecondMPJ

44

46

left_SecondPIJ

45

47

left_SecondDIJ

46

48

left_ThirdMCJ

8

49

left_ThirdMPJ

48

50

left_ThirdPIJ

49

51

left_ThirdDIJ

50

52

left_PinkyMCJ

56

53

left_PinkyMPJ

52

54

left_PinkyPIJ

53

55

left_PinkyDIJ

54

56

left_PinkyMagic

8

57

right_ThumbMagic

12

58

right_ThumbTMJ

57

59

right_ThumbMPJ

58

60

right_ThumbIJ

59

61

right_IndexMCJ

12

62

right_IndexMPJ

61

63

right_IndexPIJ

62

64

right_IndexDIJ

63

65

right_SecondMCJ

12

66

right_SecondMPJ

65

67

right_SecondPIJ

66

68

right_SecondDIJ

67

69

right_ThirdMCJ

12

70

right_ThirdMPJ

69

71

right_ThirdPIJ

70

72

right_ThirdDIJ

71

73

right_PinkyMCJ

77

74

right_PinkyMPJ

73

75

right_PinkyPIJ

74

76

right_PinkyDIJ

75

77

right_PinkyMagic

12

Bones of the Body

The bones of the body (torso, arms and neck) are show in the following diagram.

There are three so-called, slap bones in the body: left_slap right_slap and neck_slap. These are used in areas were x-axis rotations are common and can cause significant folding effect on the mesh. Each slap bone is oriented in the same x-axis of a counter-part bone (i.e. right_forearm, left_forearm or neck), but with an approximately 90 degrees rotation about the x-axis. The mesh attachment in these areas are specially set up in order to minimise folding during mesh deformation.

Bones of the Face

Bones of the Hands

The following diagram shows the named bones of the left hand. Each bone is represented as a double pyramid. As always the bone lies along its x-axis. This axis, together with a triangle representing the XY plane has been highlighted in white. There are two special bones in the hand called 'Thumb Magic' and 'Pinky Magic'. 'Thumb Magic' is responsible for allowing the rotation of the thumb about the axis formed by the index knuckle and the meta-carpal joint. 'Pinky Magic' allows for the curving of the palm caused by the Pinky Meta Carpal Joint bone, about the axis formed by the third knuckle and the base of the Pinky MCJ.

ã September 2000 Televirtual LTD