recolour/m49407: improve point cloud recolouring

This commit implements the recolouring method described in m47800, which
notably uses a distance-weighted average rather than the previous
unweighted average.

doc/README.options.md

@@ -282,3 +282,57 @@ Only applies when `attribute=colour`.
 
 ### `--aps_slice_qp_deltas_present_flag=0|1`
 Enables signalling of per-slice QP values.
+
+
+Attribute recolouring (encoder only)
+------------------------------------
+
+The following options configure the recolouring module, used when resampling
+a point cloud, or if the geometry coding process invents new points.
+
+### `--searchRange=INT-VALUE`
+Attribute space search range for optimal attribute transfer.
+
+### `--numNeighboursFwd=INT-VALUE`
+Number of source points used at the neighborhood of a target point to create
+the forward points list.
+
+### `--numNeighboursBwd=INT-VALUE`
+Number of target points used at the neighborhood of a source point to create
+the backward points list.
+
+### `--useDistWeightedAvgFwd=0|1`
+Use distance-weighted average for forward list.
+
+### `--useDistWeightedAvgBwd=0|1`
+Use distance-weighted average for backward list.
+
+### `--skipAvgIfIdenticalSourcePointPresentFwd=0|1`
+Do not use forward points list if an identical source point exists.
+
+### `--skipAvgIfIdenticalSourcePointPresentBwd=0|1`
+Do not use backward points list if an identical source point exists.
+
+### `--distOffsetFwd=REAL-VALUE`
+Distance offset to avoid infinite weight when distance between a forward
+list point and the target is zero.
+
+### `--distOffsetBwd=REAL-VALUE`
+Distance offset to avoid infinite weight when distance between a backward
+list point and target is zero.
+
+### `--maxGeometryDist2Fwd=REAL-VALUE`
+Maximum allowed squared distance of a source point from target to get into
+the forward list.
+
+### `--maxGeometryDist2Bwd=REAL-VALUE`
+Maximum allowed squared distance of a source point from target to get into
+the backward list.
+
+### `--maxAttributeDist2Fwd=REAL-VALUE`
+Maximum allowed squared attribute value difference of a source point for
+inclusion in the forward list.
+
+### `--maxAttributeDist2Bwd=REAL-VALUE`
+Maximum allowed squared attribute value difference of a source point for
+inclusion in the backward list.

tmc3/PCCTMC3Encoder.h

@@ -43,6 +43,7 @@
 #include "PayloadBuffer.h"
 #include "PCCMath.h"
 #include "PCCPointSet.h"
+#include "PCCPointSetProcessing.h"
 #include "hls.h"
 
 namespace pcc {
@@ -85,6 +86,9 @@ struct EncoderParams {
 
   // Depth of octree used by PartitionMethod::kOctreeUniform
   int partitionOctreeDepth;
+
+  // attribute recolouring parameters
+  RecolourParams recolour;
 };
 
 //============================================================================

tmc3/TMC3.cpp

@@ -458,6 +458,63 @@ ParseParameters(int argc, char* argv[], Parameters& params)
   ("aps_slice_qp_deltas_present_flag",
     params_attr.aps.aps_slice_qp_deltas_present_flag, false,
     "Enable signalling of per-slice QP values")
+
+  // This section is just dedicated to attribute recolouring (encoder only).
+  // parameters are common to all attributes.
+  (po::Section("Recolouring"))
+
+  ("recolourSearchRange",
+    params.encoder.recolour.searchRange, 8,
+    "")
+
+  ("recolourNumNeighboursFwd",
+    params.encoder.recolour.numNeighboursFwd, 8,
+    "")
+
+  ("recolourNumNeighboursBwd",
+    params.encoder.recolour.numNeighboursBwd, 1,
+    "")
+
+  ("recolourUseDistWeightedAvgFwd",
+    params.encoder.recolour.useDistWeightedAvgFwd, true,
+    "")
+
+  ("recolourUseDistWeightedAvgBwd",
+    params.encoder.recolour.useDistWeightedAvgBwd, true,
+    "")
+
+  ("recolourSkipAvgIfIdenticalSourcePointPresentFwd",
+    params.encoder.recolour.skipAvgIfIdenticalSourcePointPresentFwd, true,
+    "")
+
+  ("recolourSkipAvgIfIdenticalSourcePointPresentBwd",
+    params.encoder.recolour.skipAvgIfIdenticalSourcePointPresentBwd, false,
+    "")
+
+  ("recolourDistOffsetFwd",
+    params.encoder.recolour.distOffsetFwd, 4.,
+    "")
+
+  ("recolourDistOffsetBwd",
+    params.encoder.recolour.distOffsetBwd, 4.,
+    "")
+
+  ("recolourMaxGeometryDist2Fwd",
+    params.encoder.recolour.maxGeometryDist2Fwd, 1000.,
+    "")
+
+  ("recolourMaxGeometryDist2Bwd",
+    params.encoder.recolour.maxGeometryDist2Bwd, 1000.,
+    "")
+
+  ("recolourMaxAttributeDist2Fwd",
+    params.encoder.recolour.maxAttributeDist2Fwd, 1000.,
+    "")
+
+  ("recolourMaxAttributeDist2Bwd",
+    params.encoder.recolour.maxAttributeDist2Bwd, 1000.,
+    "")
+
   ;
   /* clang-format on */
 
@@ -641,6 +698,7 @@ ParseParameters(int argc, char* argv[], Parameters& params)
   } else {
     po::dumpCfg(cout, opts, "Encoder", 4);
     po::dumpCfg(cout, opts, "Geometry", 4);
+    po::dumpCfg(cout, opts, "Recolouring", 4);
 
     for (const auto& it : params.encoder.attributeIdxMap) {
       // NB: when dumping the config, opts references params_attr

tmc3/encoder.cpp

@@ -266,7 +266,7 @@ PCCTMC3Encoder3::compressPartition(
 
   if (recolourNeeded) {
     recolour(
-      inputPointCloud, _sps->seq_source_geom_scale_factor,
+      params->recolour, inputPointCloud, _sps->seq_source_geom_scale_factor,
       _sps->seq_bounding_box_xyz0, _sliceOrigin, &pointCloud);
   }