Since the codec can only code integer positions, using Vec3<double> for
position data requires repeated inefficient format conversions.  This
commit changes the internal representation to Vec3<int32_t>.

Hyejung Hur authored Nov 13, 2019 and David Flynn committed Nov 21, 2019

This commit enables sharing of LoDs between attributes of the same
slice if certain preconditions are met.

Sebastien Lasserre authored Jun 10, 2019 and David Flynn committed Nov 21, 2019

This commit introduces planar modes, in the three x,y, and directions,
as new representations of the geometry. Planar modes are activated at
eligible nodes through a planar mode activation flag coded in the
bitstream.  Extra syntax is added to the bitstream to indicate the
position of the plane associated with activated planar modes.

A local eligibility criteria avoids using planar modes in adverse
regions of the point cloud and thus avoiding worse compression
performance, particularly on dense point clouds.

Xiang Zhang authored Jun 10, 2019 and David Flynn committed Nov 21, 2019

This adoption permits coding geometry with non-cubic bounding boxes.
Since the depth of the tree remains constant for cubic and non-cubic
bounding boxes with identical largest dimensions, quad-tree and
binary-tree partitions are introduced to avoid coding 'fractional'
positions.

The following configuration options control the placement of non-octree
partitions within the coding tree:

 --max_num_implicit_qtbt_before_ot
 --min_implicit_qtbt_size_log2

Xiang Zhang authored Aug 19, 2019 and David Flynn committed Nov 21, 2019

This extends the geometry based quantisation scheme to:
 - add a per-slice QP offset, and
 - permit uniform quantisation of the whole slice without
   requiring signalling of an additional node QP offset.

Per node QP offset signalling is disabled by setting
positionQuantisationOctreeDepth=-1

Xiang Zhang authored Aug 19, 2019 and David Flynn committed Nov 21, 2019

This introduces a quantization scheme into the octree coding process,
enables adaptive geometry quantization for different regions of the
point cloud.  This in-loop scheme is independent of the any quantisation
performed in non-normative pre-processing at the input to the encoder.

At a particular depth of the octree, the remaining (uncoded) position
bits of each point are quantised according to a per-node (or rather,
per-subtree) QP.  The QP itself is signalled as an offset to a base QP.

The following configuration parameters are added:
  positionQuantisationEnabled
  positionBaseQp
  positionQuantisationOctreeDepth

Noritaka Iguchi authored Sep 27, 2019 and David Flynn committed Nov 21, 2019

A per-slice region may be defined with a qp offset.  Points within
the region have an offset applied to the per-level QP.

Some imput formats and colour spaces have a different bitdepth
for their chroma (non-primary) component.  This commit adds
support to signal their bitdepth as described by the codec
independent code points.

This commit enables signalling a colour matrix index using
cicp_matrix_coefficients_idx (ISO/IEC 23001-8 codec independent code
points).

It adds the following options that replace the existing colorTransform
option:

 - colourMatrix: The coded representation according to ISO/IEC 23001-8.

 - convertPlyColourspace: Enables conversion to/from RGB using the
   indicated matrix.

Configuration files are updated to use the new option and to
signal the identity matrix in the case of direct GBR coding.

Sehoon Yea authored Sep 25, 2019 and David Flynn committed Nov 21, 2019

This adoption permits prediction of residuals between components of
the same attribute, coding the residual resulting from this second
prediction.

Yiting Shao authored Sep 23, 2019 and David Flynn committed Nov 21, 2019

This adoption allows determining the weights of each point's
predicting neighbours with a reduced influence of the, for
instance, z component.

This adoption permits encoding the geometry positions in an order other
than {x,y,z}.  The --geometry_axis_order option causes the encoder to
load data from the ply file in a different order.  The order is
signalled in the SPS and the decoder will label the output axis as
appropriate.

This adds:
 - a frame_idx syntax element to every geometry slice header.
 - (decoder) handling of a frame boundary data unit.

Frame boundaries are represented by changes in the value of frame_idx
or by the presence of a frame boundary data unit.

Satoru KUMA authored May 31, 2019 and David Flynn committed Nov 21, 2019

This provides a means to achieve spatial scalability for a G-PCC
bitstream.  For bitstreams encoded with aps_scalable_enabled_flag set,
the decoder may partially decode the geometry octree
(minGeomNodeSizeLog2) and the corresponding point attributes.  The
functionality is achieved by constraining the LoD generation process to
align with partial geometry decoding.

David Flynn authored Feb 13, 2019 and David Flynn committed Aug 12, 2019

Rather than code bypass bins using a simplified mode of the
arithmetic coder, this commit adds the ability to signal bypass bins
in a separate byte-reversed sub-stream.

Noritaka Iguchi authored Jul 02, 2019 and David Flynn committed Aug 12, 2019

This commit allow individual QP offsets to be specified for each
LoD/RAHT layer in attribute coding.

For each 2×2×2 block, a predicted block is produced by upconverting the
previous transform level.  The prediction is transformed and subtracted
from the transformed attributes at the encoder.

When the same geom_box_log2_scale is used for all slices, it is not
necessary to store them in slice headers.  This commit permits
signalling of the common value in the GPS.

Toshiyasu Sugio authored Mar 01, 2019 and David Flynn committed Apr 16, 2019

This commit introduces prediction by previously coded points within
the same level of detail using the predicting attribute coder.
The feature is controlled using --intraLodPredictionEnabled=0|1.

This method has been replaced by an LoD decimation method.

Valery Valentin authored Mar 05, 2019 and David Flynn committed Apr 16, 2019

This LoD generation (subsampling) method uses the Morton-based ordering
of points that is used to determine prediction neighbours.  Each LoD
level comprises 3/4 of the points of the previous.

This commit permits signalling a per-slice delta QP for luma and
chroma attribute components.  The delta is relative to the base
value derived from the APS.

NB: while syntax support and derivation processes are provided,
this commit does not contain any method to control the delta
QP value at the encoder.

Noritaka Iguchi authored Mar 27, 2019 and David Flynn committed Apr 16, 2019

This commit introduces control of the quantisation step size using
the familiar HEVC | AVC quantisation parameter.

This is part of a series attempting to remove unhelpful typedefs.

The commit adds a flag to conditionally enable/disable the feature.

Vladyslav Zakharchenko authored Dec 14, 2018 and David Flynn committed Feb 06, 2019

This uses a binary-tree to generate the levels-of-details for the
lifting/predicting transforms as an alternative to Euclidean distance
thresholding methods.

The configuration parameters seq_bounding_box_xyz0 and
seq_bounding_box_whd allow overriding the automatic derivation of
frame (sequence) bounding box, forcing the depth of the geometry
tree.

NB: seq_bounding_box_xyz0 and seq_bounding_box_whd are specified
    using unscaled co-ordinates.

NB: this patch does not signal these parameters in the SPS.

 - signal geom_slice_id / attr_geom_slice_id in geometry / attribute
   header.

 - attr_geom_slice_id set to current geom_slice_id to maintain
   relationship between attribute and geometry.

 - increment geom_slice_id after each round of encoding.

 - decoder checks that the attribute payload's attr_geom_slice_id
   corresponds to the most recently decoded geometry payload.

This commit provides trisoup_node_size_log2 as a replacement for
the following HLS syntax variables:
 - geom_codec_type (redundant wrt. triangle node size derivation)
 - trisoup_depth (redundant wrt. bounding box)
 - trisoup_triangle_level (semantics simplified)

The following config options have been removed:
 - geometryCodec (redundant wrt. trisoup_node_size_log2)
 - triSoupLevel  (replaced by trisoup_node_size_log2)
 - triSoupDepth  (unnecessary)
 - triSoupIntToOrigScale (redundant wrt. positionQuantizationScale)

Khaled Mammou authored Sep 22, 2018 and David Flynn committed Nov 01, 2018

Replace the k-d tree based nearest neighbour search with an approximate
search based upon the points in Morton order.

Toshiyasu Sugio authored Sep 20, 2018 and David Flynn committed Nov 01, 2018

This commit provides an ability to vary the number of direct neighbours
used in the predicting transform.  Mode 0 corresponds to the existing
averaging, and mode n selects the n-th nearest neighbour for direct
prediction.

The provided code has been reworked to:
 - rewrite unary coding to be a little more obvious
 - tidy the mode decision path
 - add configuration for max_num_direct_predictors (renamed from
   MaxNumPredCand)
 - now counts the number of single predictors, rather than prediction
   modes.

This commit provides a method to predict the child occupancy bits of a
node based on the node's 26 neighbours.  The prediction is used to
contextualise coding of each occupancy bit.

This tool requires the use of the occupancyAtlas for neighbour lookup.
NB: a restriction in the current implementation requires that the
atlas size is at most 8³.

intra_pred_max_node_size_log2: 6

Bitwise geometry occupancy coding uses a mapping table to select entropy
contexts.  This commit employs a dynamic mapping which is updated after
each coding operation, replacing the previous static mapping tables.

NB: the proposed version used a context with a halving period
(max_count) of 64 symbols.  However, this conflicts with another
adoption (512 symbols), and a wholesale replacement of the arithmetic
codec and context model.  To resolve the conflict, the existing halving
period (128) is used.

Khaled Mammou authored Sep 19, 2018 and David Flynn committed Nov 01, 2018

This commit allows bytewise encoding of occupancy symbols using the
dual-lut coder.

Khaled Mammou authored Aug 22, 2018 and David Flynn committed Aug 29, 2018

This commit removes the ability to vary quant_step_size on a per-LoD
basis.  This greatly simplifies the codec configuration, especially
when used in conjunction with dist2 derivation.

cfg update:
 - rename quantizationSteps* -> quantizationStep*
 - update quantizationStep* to single values:
   - lossless-geom lossy-attrs:        8, 16, 32, 64, 128, 256 [8bit]
   - lossless-geom nearlossless-attrs: no change
   - lossless-geom lossless-attrs:     no change
   - lossy-geom    lossy-attrs:        8                       [8bit]

 => 16-bit cat3 sequences are have 8-bit qs values multipled by 255

Khaled Mammou authored Aug 22, 2018 and David Flynn committed Aug 29, 2018

This commit replaces the hard coded threshold values with APS signalling.
The default configuration maintains the hard-coded threshold values based
on bitdepth.

This is an editorial change to improve naming clarity: attr_count
represents the number of elements (dimensionality) in an attribute
set rather than the total number of attributes.