[compression] Can we support GPU to accelerate?

[whatisor]

Current evaluation:
Environment: Windows 10 Intel(R) Core(TM) i7-8750H CPU @ 2.20GHz 2.21 GH
PointCloud: Realsense

Input:
pcl::io::compression_Profiles_e compressionProfile = pcl::io::MANUAL_CONFIGURATION;
const double pointResolution_arg = 0.005;
const double octreeResolution_arg = 0.005;
bool doVoxelGridDownDownSampling_arg = true;
const unsigned int iFrameRate_arg = 30;
bool doColorEncoding_arg = true;
const unsigned char colorBitResolution_arg = 5;

Result:
Frame ID: 773
Encoding Frame: Prediction frame
Number of encoded points: 135760
XYZ compression percentage: 3.664678%
XYZ bytes per point: 0.439761 bytes
Color compression percentage: 36.146324%
Color bytes per point: 1.445853 bytes
Size of uncompressed point cloud: 2121.250000 kBytes
Size of compressed point cloud: 249.991211 kBytes
Total bytes per point: 1.885614 bytes
Total compression percentage: 11.785089%
Compression ratio: 8.485298

Encode time 133 ms
Decode time 47 ms

Can we implement by GPU such as Cuda, WebGL?

[mvieth]

Could be possible to make encoding and decoding faster by using the GPU or using multiple CPU threads. We maintainers probably don't have the time right now to look into this, but you are of course welcome to investigate and share your findings or open a pull request. Or maybe someone else sees this and is interested. Starting points could be Octree2BufBase and the octree implementation in the gpu module.