Open4D: research infrastructure for time-varying mesh experiments

[u/Impressive-Sea-2470]

Open4D is an early research-software project for experiments on 3D geometry that changes over time. The current shared layer focuses on making codec and reconstruction experiments comparable rather than presenting a product launch.

The lightweight core provides:

- a finite `Sequence[Frame[TriangleMesh]]` model with timestamps and topology declarations;

- lazy OBJ/PLY frame-folder loading and manifested directories;

- headless `--info` validation for frame counts, duration, topology, and bounds;

- a common viewer and OpenUSD packer;

- a reference-versus-decoded comparison tool.

The comparison deliberately does not assume identical connectivity. It measures decoded→reference and reference→decoded nearest-neighbour distances, supports point-to-point and MPEG-style point-to-plane definitions, and reports the worse direction as the symmetric result. A fixed reference bounding-box diagonal is used as the PSNR peak, and a fixed sequence-wide colour scale avoids making per-frame errors visually incomparable. CSV output is available for downstream analysis.

The repository also documents the minimum record expected for performance claims: exact revision, configuration, dataset/frame range, encoded byte count, runtime environment, and metric implementation.

Repository: https://github.com/open4dfoundation/Open4D

Status disclosure: the project-authored Python core is MIT-licensed and usable from source. Historical codec snapshots, datasets, media, and native integrations in the same research tree still have unresolved third-party provenance, so the full repository is not release-ready. I would value feedback on the shared abstractions and whether the comparison metrics are sufficient for cross-codec experiments.