URML (substrate-neutral robot intent language) — RFC requesting feedback on RTAB-Map visual-inertial SLAM manifest mapping + license clarification

[idoco2003]

Hi IntRoLab / RTAB-Map team,

URML (urml.dev) is a small, opinionated, human-readable language for describing robot intent — Apache-2.0, substrate-neutral by design. URML's perception manifest declares lidar, camera, and radar sensors today but needs to declare a visual-inertial SLAM substrate; RTAB-Map is the production-friendly visual-inertial choice complementing Cartographer (lidar) and ORB-SLAM3 (canonical academic visual-SLAM reference).

This is a proposal-only RFC, posted as part of URML's Move #16 substrate-spine wave (16 engageable RFCs). Sibling RFCs cover Cartographer (RFC-0205), ORB-SLAM3 (RFC-0206), and Stella VSLAM (RFC-0211 community-fork).

Full RFC: https://github.com/URML-MARS/URML/blob/main/docs/rfcs/0207-rtabmap-outreach.md

URML's manifest will declare perception.slam_substrate: rtabmap plus sensor-topology mode, database path, loop-closure threshold, and feature-detector selection. The license-clarification ask is gating: the repo is GitHub-classified as Other (mixed LGPL/BSD per README); URML adapter posture depends on per-module license clarity.

Asks for the IntRoLab / RTAB-Map maintainers:

1. License clarification. Per-module LGPL / BSD-3 boundary — can the README or LICENSE file declare per-directory licensing for downstream packager clarity?
2. SLAM-substrate enum value. URML's manifest enum value preference (rtabmap, rtab_map)?
3. Database-path manifest field. Persistent database is RTAB-Map's memory model; manifest declaration shape?
4. Loop-closure-threshold field. Performance-tier hint; preferred manifest shape?
5. Feature-detector enumeration. SURF / SIFT / ORB / BRIEF / KAZE / GFTT — manifest-declared, or always launch-param?
6. Adapter home. Future URML reference/ros2-runtime/RTABMapAdapter (in-repo, pending license clarity), RTAB-Map-side, or cross-citation only?
7. Conformance listing. Would IntRoLab consider a README link to URML's compatible-runtimes registry (RFC-0014) once a working adapter ships?
8. Anything else.

Thanks for the visual-inertial SLAM that people actually deploy.

Ido Yahalomi (URML maintainer, urml.dev, greenvh@gmail.com)

AI-assisted prose, maintainer-reviewed before posting (see VIBE.md). Human-only correspondence available on request.