Point cloud compression in 3D Tiles Next

[pjcozzi]

3D Tiles Next moves from

• .pnts files and Draco compression to
• glTF with POINTS for the primitive mode and EXT_meshopt_compression for compression.

See

• Conversion of Existing Tile Formats, and
• Using glTF for point clouds in the announcement blog

We want to evaluate the encode speed, decode speed, compression ratio, and quality of

• EXT_meshopt_compression
• LEPCC - Limited Error Point Cloud Compression
• KHR_draco_mesh_compression al la a new extension like KHR_draco_point_compression that supports points
• Anything else? JPEG? See JPEG Pleno Point Cloud – Use Cases and Requirements v1.3

This evaluation can guide how many compression types are needed for different use cases from runtime streaming to a tile with a fast moving viewer to server-side analytics distributed across the cloud.

Looking forward to collaborating with @Tamrat-B, @wallabyway, and anyone else in the community

[pjcozzi]

Also noticed:

• Corto - mesh and point cloud
  • It is supposed to be designed for decompression speed.
  • The LGPL license encoder and decoder license; may need to be packaged as a plugin with many types of software
• Cintoo
  • States 10-30x point cloud compression. Decode speed?

[pjcozzi]

@wallabyway would you be able to share any compression test results?

[lilleyse]

I recently ran some tests for Draco vs. meshopt in CesiumJS

• Source data: https://zenodo.org/record/5578198#.YhzAVlvMJzU
• Number of points: 313,605,932
• Properties: position, color (other properties in the source data were removed)
• Compression Error: 0.01 meters (bit depth varies based on tile dimensions)
• Tested with CesiumJS 1.90.0, Draco 1.5.2, Meshopt 0.17.0

===============================
 File size
===============================

* LAS (format 3)    = 12.3 GiB

* pnts              = 4.38 GiB
* glb               = 4.68 GiB
* pnts draco        = 1.19 GiB
* glb meshopt       = 1.01 GiB

* pnts gzip         = 3.72 GiB
* glb gzip          = 3.67 GiB
* pnts draco gzip   = 0.85 GiB
* glb meshopt gzip  = 0.86 GiB

=====================
 Performance
=====================

* Network speed (throttled): 50Mbps
* Screen-space error: 4

* pnts		    = 33.3 seconds
* pnts draco        = 9.25 seconds
* glb meshopt       = 9.46 second (*)

• Meshopt decoder doesn't support Web Workers yet - expecting to see even better decode performance. Also Meshopt seems to be faster when unthrottled. I ran a similar test for a photogrammetry tileset and saw 11.15s (Draco) vs. 12.95s (Meshopt) throttled and 5.69s (Draco) vs. 5.07s (Meshopt) when unthrottled. I'll update this comment once I try unthrottled on the point cloud.

[lilleyse]

See also the new COLOR filter added to KHR_meshopt_compression.