ISO/IEC DIS 23090-9

Information technology -- Coded representation of immersive media

Technologies de l'information -- Représentation codée de média immersifs

General Information

• Status: Published
• Publication Date: 30-Mar-2023
• ICS: 35.040.40 - Coding of audio, video, multimedia and hypermedia information
• Technical Committee: ISO/IEC JTC 1/SC 29 - Coding of audio, picture, multimedia and hypermedia information
• Drafting Committee: ISO/IEC JTC 1/SC 29/WG 7 - MPEG 3D Graphics coding
• Current Stage: 4099 - Full report circulated: DIS approved for registration as FDIS
• Start Date: 05-Mar-2021

Standards Content (Sample)

INTERNATIONAL ISO/IEC
STANDARD 23090-9
First edition
2023-03
Information technology — Coded
representation of immersive media —
Part 9:
Geometry-based point cloud
compression
Technologies de l'information — Représentation codée de média
immersifs —
Partie 9: Compression des nuages de points basée sur la géométrie
Reference number
ISO/IEC 23090-9:2023(E)
© ISO/IEC 2023

---------------------- Page: 1 ----------------------
ISO/IEC 23090-9:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
  © ISO/IEC 2023 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/IEC 23090-9:2023(E)
Contents Page
Foreword .vii
Introduction .viii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General terms . 1
3.2 Terms related to high-level syntax and entropy coding . 3
3.3 Terms related to tree structure . 6
3.4 Terms related to geometry coding. 7
3.5 Terms related to attribute coding . 7
4 Abbreviated terms . 8
5 Conventions . 9
5.1 General . 9
5.2 Symbolic names . 9
5.3 Numerical representation . 10
5.4 Arithmetic operators . 10
5.5 Logical operators . 10
5.6 Relational operators . 10
5.7 Bit-wise operators . 11
5.8 Assignment operators . 11
5.9 Range notation . 11
5.10 Mathematical functions .12
5.10.1 General .12
5.10.2 IntAtan2 .13
5.10.3 IntCos and IntSin . 13
5.10.4 IntSqrt . 14
5.10.5 IntRecipSqrt. 14
5.10.6 Div . 15
5.10.7 Morton .15
5.10.8 FromMorton . 16
5.11 Order of operation precedence . 16
5.12 Named expressions. 17
5.12.1 General . 17
5.12.2 Scope of a named expression . . 18
5.12.3 Arguments of named expressions . 18
5.12.4 Sub-expressions . 19
5.12.5 Definitions with multiple statements . 19
5.12.6 Textual definitions . 19
5.13 Variables, syntax elements and tables. 19
6 Point cloud format and relationship to coded and output representations .20
6.1 General format . 20
6.2 Attributes . 20
6.2.1 General .20
6.2.2 Colour . 20
6.2.3 Opacity . 21
6.2.4 Reflectance . 21
6.2.5 Normal vector . 21
6.2.6 Material identifier . 21
6.2.7 Frame number/index . 21
6.2.8 User defined attributes . 22
6.3 Codec-derived attributes . .22
6.3.1 General .22
iii
© ISO/IEC 2023 – All rights reserved

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ISO/IEC 23090-9:2023(E)
6.3.2 Slice identifier .22
6.3.3 Slice tag . 22
6.3.4 Canonical point order . .22
6.3.5 Point Morton order .23
6.4 Coded point cloud format .23
6.4.1 Sequence coordinate system . 23
6.4.2 Coding coordinate system . 24
6.4.3 Coded point cloud sequence . 25
6.4.4 Coded point cloud frame . 25
6.4.5 Slice of a coded point cloud frame . 25
6.4.6 Repetition of slices .26
6.4.7 Relationship between tiles and slices . 26
6.4.8 Parameter sets . 27
6.5 Output point cloud format .28
6.5.1 General .28
6.5.2 Coordinate system .28
6.5.3 Fixed-point conformance output .28
6.5.4 Attributes .28
6.5.5 Output point cloud sequence .28
6.5.6 Output point cloud frame.28
7 Syntax and semantics .29
7.1 Method of specifying syntax in tabular form . .29
7.2 Specification of syntax functions and descriptors .30
7.3 Syntax in tabular form . 30
7.3.1 General .30
7.3.2 Parameter sets, ancillary data and byte alignment . 31
7.3.3 Geometry data unit . 37
7.3.4 Attribute data unit . 42
7.3.5 Defaulted attribute data unit syntax.44
7.4 Semantics .44
7.4.1 General .44
7.4.2 Parameter sets, ancillary data and byte alignment . 45
7.4.3 Geometry data unit .58
7.4.4 Attribute data unit . 59
7.4.5 Defaulted attribute data unit semantics . 59
8 Decoding process .60
8.1 General decoding process .60
8.2 Frame decoding processes . .60
8.2.1 General .60
8.2.2 Frame counter .60
8.3 Slice decoding processes .60
8.3.1 General .60
8.3.2 State variables . 61
8.3.3 Geometry decoding process . 61
8.3.4 Default attribute values . 61
8.3.5 Attribute decoding process . 61
8.3.6 At the end of a slice . 61
9 Slice geometry .62
9.1 General . 62
9.2 Occupancy tree . 62
9.2.1 General . 62
9.2.2 Coded occupancy tree . 62
9.2.3 Occupancy tree syntax element semantics.64
9.2.4 Node dimensions per tree level .65
9.2.5 State representation . .65
9.2.6 Occupancy tree node coding .66
9.2.7 Occupied neighbourhood patterns . 70
iv
  © ISO/IEC 2023 – All rights reserved

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ISO/IEC 23090-9:2023(E)
9.2.8 Neighbourhood-permuted node occupancy bitmap .72
9.2.9 Dictionary coding of occupancy_byte .73
9.2.10 Bitwise occupancy coding . 78
9.2.11 Planar occupancy coding .84
9.2.12 Direct nodes .90
9.2.13 Angular coding .95
9.2.14 Subtree scaling .104
9.3 Predictive tree .109
9.3.1 General .109
9.3.2 Syntax element semantics .109
9.3.3 Tree traversal for reconstruction of point positions . 110
9.3.4 Reconstruction of point coordinates . 111
10 Slice attributes . 113
10.1 General .113
10.2 Point coordinates .113
10.2.1 General .113
10.2.2 Conversion to scaled angular coordinates . 114
10.3 Syntax element semantics . 114
10.3.1 Attribute data unit coefficients . 114
10.3.2 Attribute coefficient tuples . 114
10.3.3 Raw attribute values .115
10.4 Raw attribute decoding .115
10.5 Attribute decoding using the region-adaptive hierarchical transform .115
10.5.1 General .115
10.5.2 Transform tree .115
10.5.3 Coefficient order .118
10.5.4 Coefficient scaling . 119
10.5.5 Transform domain prediction .121
10.5.6 Inverse transform .125
10.5.7 Reconstructed attribute values .127
10.6 Attribute decoding using levels of detail .127
10.6.1 General .127
10.6.2 Syntax element semantics .128
10.6.3 Reconstruction process .128
10.6.4 State variables .128
10.6.5 Levels of detail.129
10.6.6 Predictor search .135
10.6.7 Reconstruction of attribute values . 141
10.6.8 Prediction mode coding . 142
10.6.9 Scaling .144
10.6.10 Coefficient prediction .144
10.6.11 Transform coefficient weights . 145
10.6.12 Transform .146
10.7 Attribute quantization parameters . 147
10.7.1 Syntax element semantics . 147
10.7.2 Per-point regional QP offset .148
10.7.3 Attribute coefficient QP.14
...

FINAL
INTERNATIONAL ISO/IEC
DRAFT
STANDARD FDIS
23090-9
ISO/IEC JTC 1/SC 29
Information technology — Coded
Secretariat: JISC
representation of immersive media —
Voting begins on:
2022-11-14
Part 9:
Voting terminates on:
Geometry-based point cloud
2023-01-09
compression
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/IEC FDIS 23090-9:2022(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. © ISO/IEC 2022

---------------------- Page: 1 ----------------------
ISO/IEC FDIS 23090-9:2022(E)
FINAL
INTERNATIONAL ISO/IEC
DRAFT
STANDARD FDIS
23090-9
ISO/IEC JTC 1/SC 29
Information technology — Coded
Secretariat: JISC
representation of immersive media —
Voting begins on:
Part 9:
Voting terminates on:
Geometry-based point cloud
compression
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
RECIPIENTS OF THIS DRAFT ARE INVITED TO
ISO copyright office
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
CP 401 • Ch. de Blandonnet 8
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
CH-1214 Vernier, Geneva
DOCUMENTATION.
Phone: [phone]
IN ADDITION TO THEIR EVALUATION AS
Reference number
Email: [e-mail]
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/IEC FDIS 23090­9:2022(E)
Website: www.iso.org
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
Published in Switzerland
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
ii
  © ISO/IEC 2022 – All rights reserved
NATIONAL REGULATIONS. © ISO/IEC 2022

---------------------- Page: 2 ----------------------
ISO/IEC FDIS 23090-9:2022(E)
Contents Page
Foreword .vii
Introduction .viii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General terms . 1
3.2 Terms related to high-level syntax and entropy coding . 3
3.3 Terms related to tree structure . 6
3.4 Terms related to geometry coding. 7
3.5 Terms related to attribute coding . 7
4 Abbreviated terms . 8
5 Conventions . 9
5.1 General . 9
5.2 Symbolic names . 9
5.3 Numerical representation . 10
5.4 Arithmetic operators . 10
5.5 Logical operators . 10
5.6 Relational operators . 10
5.7 Bit­wise operators . 11
5.8 Assignment operators . 11
5.9 Range notation . 11
5.10 Mathematical functions .12
5.10.1 General .12
5.10.2 IntAtan2 .13
5.10.3 IntCos and IntSin . 13
5.10.4 IntSqrt . 14
5.10.5 IntRecipSqrt. 14
5.10.6 Div . 15
5.10.7 Morton .15
5.10.8 FromMorton . 16
5.11 Order of operation precedence . 16
5.12 Named expressions. 17
5.12.1 General . 17
5.12.2 Scope . 18
5.12.3 Arguments of named expressions . 18
5.12.4 Sub-expressions . 19
5.12.5 Definitions with multiple statements . 19
5.12.6 Textual definitions . 19
5.13 Variables, syntax elements and tables. 19
6 Point cloud format and relationship to coded and output representations .20
6.1 General format . 20
6.2 Attributes . 20
6.2.1 General .20
6.2.2 Colour . 20
6.2.3 Opacity . 21
6.2.4 Reflectance . 21
6.2.5 Normal vector . 21
6.2.6 Material identifier . 21
6.2.7 Frame number/index . 21
6.2.8 User defined attributes . 22
6.3 Codec­derived attributes . .22
6.3.1 General .22
iii
© ISO/IEC 2022 – All rights reserved

---------------------- Page: 3 ----------------------
ISO/IEC FDIS 23090-9:2022(E)
6.3.2 Slice identifier .22
6.3.3 Slice tag . 22
6.3.4 Canonical point order . .22
6.3.5 Point Morton order .23
6.4 Coded point cloud format .23
6.4.1 Sequence coordinate system . 23
6.4.2 Coding coordinate system . 24
6.4.3 Coded point cloud sequence . 25
6.4.4 Coded point cloud frame . 25
6.4.5 Slice of a coded point cloud frame . 25
6.4.6 Repetition of slices .26
6.4.7 Relationship between tiles and slices . 26
6.4.8 Parameter sets . 27
6.5 Output point cloud format .28
6.5.1 General .28
6.5.2 Coordinate system .28
6.5.3 Fixed-point conformance output .28
6.5.4 Attributes .28
6.5.5 Output point cloud sequence .28
6.5.6 Output point cloud frame.28
7 Syntax and semantics .29
7.1 Method of specifying syntax in tabular form . .29
7.2 Specification of syntax functions and descriptors .30
7.3 Syntax in tabular form . 30
7.3.1 General .30
7.3.2 Parameter sets, ancillary data and byte alignment . 31
7.3.3 Geometry data unit . 37
7.3.4 Attribute data unit . 42
7.3.5 Defaulted attribute data unit syntax.44
7.4 Semantics .44
7.4.1 General .44
7.4.2 Parameter sets, ancillary data and byte alignment . 45
7.4.3 Geometry data unit .58
7.4.4 Attribute data unit . 59
7.4.5 Defaulted attribute data unit semantics . 59
8 Decoding process .60
8.1 General decoding process .60
8.2 Frame decoding processes . .60
8.2.1 General .60
8.2.2 Frame counter .60
8.3 Slice decoding processes .60
8.3.1 General .60
8.3.2 State variables . 61
8.3.3 Geometry decoding process . 61
8.3.4 Default attribute values . 61
8.3.5 Attribute decoding process . 61
8.3.6 At the end of a slice . 61
9 Slice geometry .62
9.1 General . 62
9.2 Occupancy tree . 62
9.2.1 General . 62
9.2.2 Coded occupancy tree . 62
9.2.3 Occupancy tree syntax element semantics.64
9.2.4 Node dimensions per tree level .65
9.2.5 State representation . .65
9.2.6 Occupancy tree node coding .66
9.2.7 Occupied neighbourhood patterns . 70
iv
  © ISO/IEC 2022 – All rights reserved

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ISO/IEC FDIS 23090-9:2022(E)
9.2.8 Neighbourhood-permuted node occupancy bitmap .72
9.2.9 Dictionary coding of occupancy_byte .73
9.2.10 Bitwise occupancy coding . 78
9.2.11 Planar occupancy coding .84
9.2.12 Direct nodes .90
9.2.13 Angular coding .95
9.2.14 Subtree scaling .103
9.3 Predictive tree .108
9.3.1 General .108
9.3.2 Syntax element semantics .109
9.3.3 Tree traversal for reconstruction of point positions . 110
9.3.4 Reconstruction of point coordinates . 111
10 Slice attributes . 113
10.1 General .113
10.2 Point coordinates .113
10.2.1 General .113
10.2.2 Conversion to scaled angular coordinates .113
10.3 Syntax element semantics . 114
10.3.1 Attribute data unit coefficients . 114
10.4 Raw attribute decoding . 114
10.5 Attribute decoding using the region­adaptive hierarchical transform .115
10.5.1 General .115
10.5.2 Transform tree .115
10.5.3 Coefficient order .118
10.5.4 Coefficient scaling . 119
10.5.5 Transform domain prediction .121
10.5.6 Inverse transform .125
10.5.7 Reconstructed attribute values .127
10.6 Attribute decoding using levels of detail .127
10.6.1 General .127
10.6.2 Syntax element semantics .128
10.6.3 Reconstruction process .128
10.6.4 State variables .128
10.6.5 Levels of detail.129
10.6.6 Predictor search .135
10.6.7 Reconstruction of attribute values . 141
10.6.8 Prediction mode coding . 142
10.6.9 Scaling .144
10.6.10 Coefficient prediction .144
10.6.11 Transform coefficient weights .
...

ISO/IEC FDIS 23090-9:2022(E)
ISO/IEC JTC 1/SC 29/WG 7
Date: 2022-10-28
Secretariat: JISC
Information technology — — Coded representation of immersive media — — Part 9:
Geometry-based point cloud compression

FDIS stage

Warning for WDs and CDs
This document is not an ISO International Standard. It is distributed for review and comment. It is subject to
change without notice and may not be referred to as an International Standard.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of
which they are aware and to provide supporting documentation.

---------------------- Page: 1 ----------------------
ISO/IEC FDIS 23090-9:2022(E)
© ISO/IEC 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no
part of this publication may be reproduced or utilized otherwise in any form or by any means,
electronic or mechanical, including photocopying, or posting on the internet or an intranet, without
prior written permission. Permission can be requested from either ISO at the address below or ISO’s
member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.orgwww.iso.org
Published in Switzerland
© ISO/IEC 2022 – All rights reserved
ii © ISO/IEC 2022 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/IEC FDIS 23090-9:2022(E)
Contents
Foreword . viii
Introduction . ix
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General terms . 1
3.2 High-level syntax and entropy coding terms . 3
3.3 Tree structure terms . 5
3.4 Geometry coding terms . 6
3.5 Attribute coding terms . 7
4 Abbreviated terms . 8
4.1 Acronyms . 8
4.2 Mnemonics. 8
5 Conventions . 9
5.1 General . 9
5.2 Symbolic names . 9
5.3 Numerical representation . 9
5.4 Arithmetic operators . 9
5.5 Logical operators . 10
5.6 Relational operators . 10
5.7 Bit-wise operators . 10
5.8 Assignment operators . 10
5.9 Range notation . 11
5.10 Mathematical functions . 11
5.10.1 General . 11
5.10.2 IntAtan2 . 12
5.10.3 IntCos and IntSin . 12
5.10.4 IntSqrt . 13
5.10.5 IntRecipSqrt . 13
5.10.6 Div . 14
5.10.7 Morton . 14
5.10.8 FromMorton . 15
5.11 Order of operation precedence . 15
5.12 Named expressions . 16
5.12.1 General . 16
5.12.2 Scope . 17
5.12.3 Arguments of named expressions . 17
5.12.4 Sub-expressions . 17
5.12.5 Definitions with multiple statements . 17
5.12.6 Textual definitions . 17
© ISO/IEC 2022 – All rights reserved © ISO/IEC iii
2022 – All rights reserved

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ISO/IEC FDIS 23090-9:2022(E)
5.13 Variables, syntax elements and tables . 18
6 Point cloud format and relationship to coded and output representations . 18
6.1 General format . 18
6.2 Attributes . 19
6.2.1 General . 19
6.2.2 Colour . 19
6.2.3 Opacity . 19
6.2.4 Reflectance . 20
6.2.5 Normal vector . 20
6.2.6 Material identifier . 20
6.2.7 Frame number/index . 20
6.2.8 User defined attributes . 20
6.3 Codec-derived attributes . 21
6.3.1 General . 21
6.3.2 Slice identifier . 21
6.3.3 Slice tag . 21
6.3.4 Canonical point order . 21
6.3.5 Point Morton order . 21
6.4 Coded point cloud format. 21
6.4.1 Sequence coordinate system . 21
6.4.2 Coding coordinate system . 22
6.4.3 Coded point cloud sequence . 23
6.4.4 Coded point cloud frame . 23
6.4.5 Slice of a coded point cloud frame . 23
6.4.6 Repetition of slices . 24
6.4.7 Relationship between tiles and slices. 24
6.4.8 Parameter sets . 25
6.5 Output point cloud format . 26
6.5.1 General . 26
6.5.2 Coordinate system . 26
6.5.3 Fixed-point conformance output . 26
6.5.4 Attributes . 26
6.5.5 Output point cloud sequence . 26
6.5.6 Output point cloud frame . 26
7 Syntax and semantics . 26
7.1 Method of specifying syntax in tabular form . 26
7.2 Specification of syntax functions and descriptors . 27
7.3 Syntax in tabular form . 28
7.3.1 General . 28
7.3.2 Parameter sets, ancillary data and byte alignment . 28
7.3.3 Geometry data unit . 35
7.3.4 Attribute data unit . 40
7.3.5 Defaulted attribute data unit syntax . 42
7.4 Semantics . 42
7.4.1 General . 42
7.4.2 Parameter sets, ancillary data and byte alignment . 42
7.4.3 Geometry data unit . 55
© ISO/IEC 2022 – All rights reserved
iv © ISO/IEC 2022 – All rights reserved

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ISO/IEC FDIS 23090-9:2022(E)
7.4.4 Attribute data unit . 56
7.4.5 Defaulted attribute data unit semantics . 56
8 Decoding process . 57
8.1 General decoding process . 57
8.2 Frame decoding processes . 57
8.2.1 General . 57
8.2.2 Frame counter . 57
8.3 Slice decoding processes . 57
8.3.1 General . 57
8.3.2 State variables . 57
8.3.3 Geometry decoding process . 58
8.3.4 Default attribute values . 58
8.3.5 Attribute decoding process . 58
8.3.6 At the end of a slice . 58
9 Slice geometry . 59
9.1 General . 59
9.2 Occupancy tree . 59
9.2.1 General . 59
9.2.2 Coded occupancy tree . 59
9.2.3 Occupancy tree syntax element semantics . 61
9.2.4 Node dimensions per tree level . 62
9.2.5 State representation . 62
9.2.6 Occupancy tree node coding . 62
9.2.7 Occupied neighbourhood patterns . 66
9.2.8 Neighbourhood-permuted node occupancy bitmap . 69
9.2.9 Dictionary coding of occupancy_byte . 70
9.2.10 Bitwise occupancy coding . 75
9.2.11 Planar occupancy coding . 81
9.2.12 Direct nodes . 87
9.2.13 Angular coding . 92
9.2.14 Subtree scaling . 100
9.3 Predictive tree . 105
9.3.1 General . 105
9.3.2 Syntax element semantics . 105
9.3.3 Tree traversal for reconstruction of point positions. 107
9.3.4 Reconstruction of point coordinates . 108
10 Slice attributes . 110
10.1 General . 110
10.2 Point coordinates . 110
10.2.1 General . 110
10.2.2 Conversion to scaled angular coordinates . 110
10.3 Syntax element semantics . 110
10.4 Raw attribute decoding . 111
10.5 Attribute decoding using the region-adaptive hierarchical transform . 111
10.5.1 General . 111
10.5.2 Transform tree . 112
10.5.3 Coefficient order . 115
10.5.4 Coefficient scaling . 116
© ISO/IEC 2022 – All rights reserved © ISO/IEC v
2022 – All rights reserved

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ISO/IEC FDIS 23090-9:2022(E)
10.5.5 Transform domain prediction . 118
10.5.6 Inverse transform . 122
10.5.7 Reconstructed attribute values . 124
10.6 Attribute decoding using levels of detail . 124
10.6.1 General . 124
10.6.2 Syntax element semantics . 125
10.6.3 Reconstruction process . 125
10.6.4 State variables . 125
10.6.5 Levels of detail . 126
10.6.6 Predictor search . 132
10.6.7 Reconstruction of attribute values . 138
10.6.8 Prediction mode coding . 139
10.6.9 Scaling . 141
10.6.10 Coefficient prediction . 141
10.6.11 Transform coefficient weights . 142
10.6.12 Transform . 143
10.7 Attribute quantization parameters . 143
10.7.1 Syntax element semantics . 143
10.7.2 Per-point regional QP offset . 145
10.7.3 Attribute coefficient QP . 145
10.7.4 Definition of AttrQstep . 145
11 Parsing process . 145
11.1 General . 145
11.2 Data unit buffer . 148
11.2.1 General . 148
11.2.2 State . 148
11.2.3 Initialization at the start of parsing a data unit . 148
11.2.4 Initialization at the start of parsing a geometry data unit footer . 148
11.2.5 Definition of DuNextBit . 148
11.3 Chunked bytestream parsing . 148
11.3.1 General . 148
11.3.2 Chunk syntax . 149
11.3.3 Chunk semantics . 149
11.3.4 State . 149
11.3.5 Span of chunked bytestream data within a data unit . 150
11.3.6 The chunk buffer . 150
11.3.7 State update at the start of every CBS . 150
1
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