Coding with ASCII: compact, yet textbased 3D content

1
Coding with ASCIIcompact, yet text-based 3D
content

• Martin Isenburg Jack Snoeyink
• University of North Carolina at Chapel
  HillandINRIA Sophia-Antipolis

2
Overview

• Motivation
• Polygon Meshes
• Coding of Indices
• Position Indices TexCoord Indices
• Quantizing Coding of Coordinates
• Positions Texture Coordinates
• Example
• Results, Demos Conclusion

3
Motivation
4
Why ASCII?

• authors like text-based 3D formats
• wide acceptance
• read modify scene with any text editor
• Web3D Developer survey very important
• ? many Web3D APIs only support ASCII(rather than
  supporting two formats)
• ? no binary VRML specification

5
Why Compression?

• authors want compressed 3D content
• faster download
• Web3D Developer survey very important
• data-heavy nodes
• audio
• images
• video
• geometry
• interpolators

6
Approaches

• readable text-based format
• support only ASCII content
• exception standard binary data
• VRML and its variants
• binary format
• one (or more) binary files
• automatically protects the content
• proprietary (Cult, Shockwave, Viewpoint ...)

7
Compression Standards (1)

• binary compression standards
• image data JPEG, GIF
• audio data MP3
• movie data MPEG
• geometry data ? (MPEG-4/7 ??)
• interpolator data ? (MPEG-4/7 ??)
• read edit write software is plentiful

8
Compression Standards (2)

• the structure of 3D data is more complex
• audio sequence of numbers
• image block of numbers
• video sequence of blocks of numbers
• geometry positions triangles (or
  polygons ?) texcoords (1, 2, 3, or 8 layers
  ?) normals or smoothing groups (?)
  colors (per-face or per-vertex ?) bones (1,
  2 or 3 attachments ?)

9
Download on Demand

• java-based browsers
• Shout3D, Blaxxun3D, CortonaJet, Hotmedia
• provide decoder with the model.
• light-weight important
• it has to be downloaded also
• download less was motivation to compress
• proposed decoder gtgt 5381 bytes ltlt

10
Polygon Meshes
11
Polygon Meshes

• Polygon Mesh Indexed Face Set (IFS)
• minimally
• p positions float 3p
• f faces with c corners int f c
• optionally
• t texCoords float 2t
• f faces with c corners int f c

12
Example a box

• IndexedFaceSet
• coord Coordinate
• point -1.0 1.0 -1.0 , -1.0 -1.0 -1.0 ,
  1.0-1.0 -1.0 , 1.0 1.0 -1.0 , -1.0 -1.0 1.0 ,
  1.0 -1.0 1.0, -1.0 1.0 1.0, 1.0 1.0 1.0
• coordIndex 0 1 2 3 -1 3 2 5 7 -1 1 4 5 2 -1 6
  0 3 7 -1 6 4 1 0 -1 6 7 5 4 -1

13
coord (Geometry)
14
coordIndex (Connectivity)
5
3
face0 0 1 2 3
face1 3 2 5 7
0
4
1
face2 1 4 5 2
face3 6 0 3 7
2
face4 6 4 1 0
face5 6 7 5 4
15
Example a textured box

• IndexedFaceSet
• . . . . . .
• texCoord Coordinate
• point 0.4 0.5 , 0.4 0.3 , 0.6 0.3 , 0.6 0.5,
  0.8 0.3 , 0.8 0.5 , 0.4 0.1 , 0.6 0.1 , 0.2 0.5 ,
  0.2 0.3 , 0.4 0.7 , 0.6 0.7 , 0.4 0.9 , 0.6 0.9
• texCoordIndex 0 1 2 3 -1 3 2 4 5 -1 1 6 7 2-1
  10 0 3 11 -1 8 9 1 0 -1 10 11 13 12 -1

16
texCoord (Property Values)








17
texCoordIndex (Property Mapping)
5
10
11


10
11
3
8
5
face0 0 1 2 3
0
3


3
face1 3 2 4 5
0
0
3
0
4
1
face2 1 6 7 2
1
2
1
2


face3 10 0 3 11
1
2
2
4
9
face4 8 9 1 0
6
7


13
12
face5 10 11 13 12
18
Coding of Indices (1)Position Indices
19
Coding Position Indices

• gt dont code indices directly lt
• Assumption
• order of position doesnt matter
• Approach
• change order of positions
• code connectivity graph
• enumerate positions based on traversal order
• re-order accordingly
• gt code indices implicitly lt

20
Connectivity Coders

• ? for Triangle Meshes
• Topological Surgery, Taubin et al., 97
• Triangle Mesh Compression, Touma Gotsman, 98
• Cut-Border-Machine, Gumhold Strasser, 98
• Edgebreaker, Rossignac, 99
• ? for Polygon Meshes
• Face Fixer, Isenburg Snoeyink, 00
• Degree Duality Coder, Isenburg, 02
• Near-Optimal Connectivity Encoding, Khodakovsky,
  Alliez, Desbrun Schröder, 02

21
Face Fixer

• region growing
• encodes connectivity graph as a sequence of
  labels
• one label . . . . per
  face
• one label per hole
• one label per handle
• labels and fix it all
  together
• number of labels number of edges
• reverse decoding

22
Face Fixer
23
Encoding
29

0

6

91

27

14


68

5

72

98


53

86

31

67

77

9


22



11
25



43


2
78


24
Encoding
29

0

6

91

27

14


68

5

72

98


53

86


31


67

77

9


22



11
25



43


2
78


25
Encoding
29

0

6

91

27

14


68

5

72

98


53

86


31


67

77

9


22



11
25



43


2
78


26
Encoding
29

0

6

91

27

14


68

5

72

98


53

86


31


67

77

9


22



11
25


43


2
78


27
Encoding
29

0

6

91

27

14


68

5


72

98



53

86


31


67


77

9


22



11
25


43


2
78


28
Encoding
29

0

6

91

27

14


68

5


72

98



53

86


31


67


77


9


22



11
25


43


2
78


29
Encoding
29

0

6

91

27

14


68

5


72

98



53

86


31


67


77


9


22


11
25


43


2
78


30
Encoding
29

0

6

91

27

14


68

5


72

98



53

86


31


67


77


9


22


11
25


43

2
78


31
Mapping Labels to ASCII

• Resulting label sequence

. . .
. . .
. . .
. . .
32
Decoding
14

12

23

11

13


47

24


26

26



46

27


25


44


43


42


45


61

33
Decoding
14

12

23

11

13


47

24


26

26



46

27


25


44


43


42


45


61


62

34
Decoding
14

12

23

11

13


47

24


26

26



46

27


25


44


43


42


45



63
61



62

35
Decoding
14

12

23

11

13


47

24


26

26



46

27


25


44


43

42


45



63
61



62

36
Decoding
14

12

23

11

13


47

24

26

26


46

27


25


44

43

42


45



63
61



62

37
Decoding
14

12

23

11

13


47

24

26

26


46

27


25


44

43

42


45



63
61



64


62

38
Decoding
14

12

23

11

13


47

24

26

26


46

27


25


44

43

42


45



63
61



64


62

39
Decoding
14

12

23

11

13


47

24

26

26


46

27

25

44

43

42


45



63
61



64


62

40
Non-Manifold Meshes





















41
Coding ofIndices (2)TexCoord Indices
42
Coding TexCoord Indices

• gt dont code indices directly lt
• Assumption
• order of texCoords doesnt matter
• Approach
• change order of texCoords
• code on top of connectivity graph
• enumerate texCoords based on traversal order
• re-order accordingly
• gt code indices implicitly lt

43
Per-Corner Mappings

• edge bits, Gumhold StrasserReal-time
  compression of triangle mesh connectivity,
  SIGGRAPH 98
• discontinuity bits, Taubin et al.Geometry
  coding and VRML, Proceedings of the IEEE 98
• vertex and corner bits, Isenburg Snoeyink
  Face Fixer Compressing Polygon Meshes with
  Properties, SIGGRAPH 00

44
Vertex and Corner Bits (1)
45
Vertex and Corner Bits (2)

46
Vertex and Corner Bits (3)
47
Encoding





1

48
Encoding





1
0

0
49
Encoding





1
0

0
1
50
Encoding





1
0
0

0
1
51
Encoding





1
1
0
0

0
1
52
Encoding

1
0




1
1
0
0

0
1
53
Encoding

1
0

0



1
1
0
0

0
1
54
Encoding

1
0

0
0



1
1
0
0

0
1
55
Encoding

1
0

1
0
0



1
1
0
0

0
1
56
Encoding

0
1
0

1
0
0



1
1
0
0

0
1
57
Encoding

0
0
1
0

1
0
0



1
1
0
0

0
1
58
Encoding

0
0
1
0

1
0
0

0
1


1
1
0
0

0
1
59
Encoding

0
0
1
0

1
0
0

0
1
1


1
1
0
0

0
1
60
Encoding

0
0
1
0

1
0
0
1

0
1
1


1
1
0
0

0
1
61
Encoding

0
0
1
0

1
0
0
0
1

0
1
1


1
1
0
0

0
1
62
Encoding

0
0
1
0

1
0
0
0
1

0
1
1


1
0
1
1
0
0

0
1
63
Encoding

0
0
1
0

1
0
0
0
1

0
1
1


1
0
0
1
1
0
0

0
1
64
Encoding

0
0
1
0

1
0
0
0
1

0
1
1
1

1

0
0
1
1
0
0

0
1
65
Encoding

0
0
1
0

1
0
0
0
1

0
1
1
0
1

1

0
0
1
1
0
0

0
1
66
Encoding
1

0
0
1
0

1
0
0
0
1

0
1
1
0
1

1

0
0
1
1
0
0

0
1
67
Encoding
1

0
0
1
0

1
0
0
0
1

0
1
1
0
1

1

0
0
1
1
0
0

0
1
68
Quantizing Coding of Coordinates
69
Quantize

• calculate bounding box
• (minx, miny, minz) and (maxx, maxy maxz)
• calculate extends of bounding box
• rangex maxx minx
• rangey maxy miny
• quantize with longest extend getting n bits

70
Delta Code

• coordinates are integer numbers
• only write difference to last
• resulting sequence has lower dispersion
• there are much better schemes !!!
• why delta-coding ???
• simple, light-weight implementation
• submission deadline was close

71
Decoding Example
72
code_words
438 3 0 0 6 0 0 6 0 0 7 -1 6 0
-1 4 5 5 0
0
1


indices


texindices
73
code_words
438 3 0 0 6 0 0 6 0 0 7 -1 6 0
-1 4 5 5 0
2
0

1



indices


texindices
74
code_words
438 3 0 0 6 0 0 6 0 0 7 -1 6 0
-1 4 5 5 0
3

2

0

1



indices


texindices
75
code_words
438 3 0 0 6 0 0 6 0 0 7 -1 6 0
-1 4 5 5 0
3

0
2

1
3
0

2
1



indices
-1
1
0
3
2


texindices
-1
76
code_words
438 3 0 0 6 0 0 6 0 0 7 -1 6 0
-1 4 5 5 0
3

0
4

2

1
3
0

2
1



indices
-1
1
0
3
2


texindices
-1
77
code_words
438 3 0 0 6 0 0 6 0 0 7 -1 6 0
-1 4 5 5 0
3

0
4

2

1
3
0

2
1

5



indices
-1
1
0
3
2


texindices
-1
78
code_words
438 3 0 0 6 0 0 6 0 0 7 -1 6 0
-1 4 5 5 0
3

0
7
4

2

1
6
3
8
0

2
1

5
5



indices
-1
1
0
3
2
4
3
5
0
-1


texindices
-1
-1
79
code_words
438 3 0 0 6 0 0 6 0 0 7 -1 6 0
-1 4 5 5 0
3

0
7
4

2

1
6
3
8
0

2
1

5
5

6



indices
-1
1
0
3
2
4
3
5
0
-1


texindices
-1
-1
80
code_words
438 3 0 0 6 0 0 6 0 0 7 -1 6 0
-1 4 5 5 0
3

0
7
4

2

1
6
3
8
0

2
1

5
5

7

6



indices
-1
1
0
3
2
4
3
5
0
-1


texindices
-1
-1
81
code_words
438 3 0 0 6 0 0 6 0 0 7 -1 6 0
-1 4 5 5 0
3

0
7
4

2

1
6
1
0
3
8
0

2
1

5
5

hole
7

6



indices
-1
1
0
3
2
4
3
5
0
-1


texindices
-1
-1
1
0
82
code_words
438 3 0 0 6 0 0 6 0 0 7 -1 6 0
-1 4 5 5 0
3

0
7
4

2

1
6
1
0
0

2
1

5
5

hole
4

7

6



indices
-1
1
0
3
2
4
3
5
0
-1


texindices
-1
-1
1
0
83
code_words
438 3 0 0 6 0 0 6 0 0 7 -1 6 0
-1 4 5 5 0
3

0
7
4

2

1
6
1
0
0

2
1

5
5

12
hole
4

10
11
7

6



indices
4
-1
1
0
3
2
4
3
5
0
-1
1
-1
7


texindices
-1
-1
1
0
-1
84
code_words
438 3 0 0 6 0 0 6 0 0 7 -1 6 0
-1 4 5 5 0
3

7
0
4

2

6
1
1
0
16
2
0
0
2

1
1

2
15
5
2
5

12
14
hole
4

10
11
7

6



indices
4
4
1
2
-1
4
3
-1
5
1
0
3
2
1
-1
7
0
-1


texindices
2
-1
-1
2
1
2
-1
0
-1
85
Results
86
fish scene

• Shape appearance Appearance material
  Material modulateTextureWithDiffuse
  true diffuseColor 1 1 1 texture
  ImageTexture url fish.jpg geometry
  IndexedFaceSet coord Coordinate point
  -0.0715 4.7609 6.3930 -0.0715 ... -0.4479 -4.5153
  4.5304 coordIndex 7 6 209 204 -1 4 217
  210 4577 -1 4577 4223 4222 -1 texCoord
  TextureCoordinate point 0.3735 0.9441
  0.3289 0.9315 0.2666 0.4990 0.1082
  texCoordIndex 0 1 2 3 -1 4 5 6 7 -1 8
  4311 -1 4311 4293 4683 -1

87
fish scene

• Shape appearance Appearance material
  Material modulateTextureWithDiffuse
  true diffuseColor 1 1 1 texture
  ImageTexture url fish.jpg geometry
  IndexedFaceSet coord Coordinate point
  -0.0715 4.7609 6.3930 -0.0715 ... -0.4479 -4.5153
  4.5304 coordIndex 7 6 209 204 -1 4 217
  210 4577 -1 4577 4223 4222 -1 texCoord
  TextureCoordinate point 0.3735 0.9441
  0.3289 0.9315 0.2666 0.4990 0.1082
  texCoordIndex 0 1 2 3 -1 4 5 6 7 -1 8
  4311 -1 4311 4293 4683 -1

88
lossless-coded fish scene

• Shape appearance Appearance material
  Material modulateTextureWithDiffuse
  true diffuseColor 1 1 1 texture
  ImageTexture url fish.jpg geometry
  CodedIndexedFaceSet coord Coordinate point
  -0.1195 -2.0148 ... -4.5153 4.5304 -0.4689
  -4.4092 4.4136 texCoord TextureCoordinate
  point 0.0150 0.5031 0.2549 0.3889 0.2581
  0.3825 0.2520 code 24045 3 0 3 1 1 2 0 0
  0 0 0 0 3 5 0 5 0 5 0 5 0 6 0 0 0 0 2

89
lossy-coded fish scene

• Shape appearance Appearance material
  Material modulateTextureWithDiffuse
  true diffuseColor 1 1 1 texture
  ImageTexture url fish.jpg geometry
  CodedIndexedFaceSet coord Coordinate point
  -2 -4 -1 -3 -3 0 -4 -47 ... 37 4 -21 24 -0.4689
  -4.4092 4.4136 texCoord TextureCoordinate
  point 0 0 0 0 0 -4 0 1 -1 -1 0 0 0 -1 5 3
  -4 0 2 2 0.3825 0.2520 code 24045 3 0 3 1
  1 2 0 0 0 0 0 0 3 5 0 5 0 5 0 5 0 6 0 0 0 0 2
  pos 4.884e-3 tex 3.8234e-3

90
Results Dense Scenes
model
plain
coded
quantized
lion 441.6 201.6 46 66.2 15
wolf 183.1 84.5 46 29.4 16
raptor 199.8 100.7 50 34.9 17
fish 122.9 55.4 45 22.8 19
snake 312.3 138.1 44 34.8 11
horse 266.4 124.3 47 40.9 15
cat 267.3 128.4 48 39.9 15
dog 186.2 87.3 47 34.6 19
91
Results Sparse Scene
33 indexed face sets 5 position interpolators 27
orientation interpolators
66
31
file size of swing.wrl.gz in bytes
--- 29895 IFS 18364 61
92
Demos
93
Demos

• Shout3D ASCII coder gt local web lt
• Various Scenes
• Swing (static) gt local web lt
• Swing (animated) gt local web lt
• Fish gt local web lt
• Lion gt local web lt
• Snake gt local web lt

http//www.cs.unc.edu/isenburg/asciicoder/
94
Conclusion

• geometry coding for ASCII formats
• compressed, but not binary
• authors not forced to change habits
• VRML / X3D geometry compression
• long wanted feature (96)
• VRML-CBF proposal refused (98)
• BF call for proposals unanswered (00)
• Conformance ASCII BINARY

95
Current Work

• Arithmetic ASCII
• (nearly) as compact as a compressed binary
  format
• straight-forward mapping to binary
• no compromise on binary compression rates
• same decoding algorithm for binary and ASCII
  version of a node
• good for rapid prototyping / proof-of-concept

96
Acknowledgements

• Paul Isaacs for telling me
• no, we dont have
  geometrycompression because the Shout3D API does
  not support binary input
• Curious Labs Shout3D for the models
• ARC TéléGeo of INRIA Sophia-Antipolis for partial
  funding

97
Thank You.http//www.cs.unc.edu/isenburg/ascii
coder/