Distro	Build dev	Build releases	Stable version
ROS 2 Humble (u22.04)		amd64 arm64
ROS 2 Jazzy @ u24.04		amd64 arm64
ROS 2 Kilted @ u24.04		amd64 arm64
ROS 2 Rolling (u24.04)		amd64 arm64

mola_sm_loop_closure

Offline loop-closure engine for MOLA CSimpleMap files. Given an input simplemap produced by any MOLA odometry front-end, the package re-optimises all keyframe poses by detecting and closing loops, then writes the corrected simplemap back to disk.

Two algorithms

CLI usage

# SimplemapLoopClosure (default algorithm):
mola-sm-lc-cli -i in.simplemap -o out.simplemap \
    -p pipelines/loop-closure-lidar3d-gicp.yaml

# FrameToFrameLoopClosure:
mola-sm-lc-cli -i in.simplemap -o out.simplemap \
    -a mola::FrameToFrameLoopClosure \
    -p pipelines/loop-closure-f2f-lidar3d-gicp.yaml

Available pipelines

Key YAML knobs

SimplemapLoopClosure

• submap_max_absolute_length / submap_min_absolute_length — controls submap granularity.
• assume_planar_world: true enables annealed soft planar constraints (z, roll, pitch).
  • planar_world_initial_sigma_z, planar_world_initial_sigma_ang, planar_world_annealing_rounds — tune the annealing schedule.
  • planar_world_hard_flatten: true restores the old hard-flattening behaviour.
• use_gnss: true / gnss_add_horizontality: true — GNSS-assisted global alignment.

FrameToFrameLoopClosure

• lc_candidate_strategy — DISTANCE_STRATIFIED (default), PROXIMITY_ONLY, or MULTI_OBJECTIVE.
• assume_planar_world: true — planar-world annealing.
• use_gnss: true — per-keyframe GNSS factors (FactorGnssEnu).

See the online tutorial for a step-by-step example.

License

Copyright (C) 2018-2026 Jose Luis Blanco jlblanco@ual.es, University of Almeria

This package is released under the GNU GPL v3 license as open source, with the main intention of being useful for research and evaluation purposes. Commercial licenses available upon request.

Contributions require acceptance of the Contributor License Agreement (CLA).

Contributing to MOLA

Thank you for your interest in contributing to MOLA. This document outlines the process and expectations for contributing to this project. Please read it carefully before submitting any contribution.

MOLA is a modular SLAM and localization framework written in C++ with ROS 2 support. We welcome contributions from the community, provided they meet the quality and legal requirements described below.

Table of Contents

1. Contributor License Agreement
2. Code of Conduct
3. Types of Contributions
4. Getting Started
5. Development Workflow
6. Commit and Pull Request Guidelines
7. Coding Standards
8. Testing Requirements
9. Documentation
10. Review Process
11. Reporting Issues

1. Contributor License Agreement

All contributions to MOLA require acceptance of the Contributor License Agreement (CLA) prior to being merged.

MOLA is distributed under a dual licensing model:

• Open source: GNU General Public License v3 (GPL v3)
• Commercial: A separate commercial license is available for industry users who cannot comply with the terms of the GPL v3

The CLA ensures that the project maintainers hold the necessary rights to distribute your contribution under both licensing models. It does not transfer copyright ownership — you retain full ownership of your work.

When you open a Pull Request, an automated CLA assistant will verify whether you have previously accepted the agreement. If you have not, you will be prompted to do so before the PR can be reviewed or merged. Contributions submitted without CLA acceptance will not be considered.

2. Code of Conduct

All contributors are expected to adhere to the project’s Code of Conduct. We are committed to maintaining a welcoming and professional environment for everyone, regardless of background or experience level. Violations may result in removal from the project.

3. Types of Contributions

We welcome the following types of contributions:

• Bug fixes — corrections to incorrect or unexpected behavior
• Performance improvements — optimizations with measurable, documented impact
• New modules or algorithms — extensions to MOLA’s modular architecture
• Documentation improvements — corrections, clarifications, and additions to existing documentation
• Dataset integrations — support for additional SLAM benchmark or real-world datasets
• ROS 2 integrations — improvements to the ROS 2 interface, launch files, or message definitions
• Tests — new or improved unit, integration, or regression tests

If you are considering a large or architectural contribution, please open an issue for discussion before beginning work. This avoids duplication of effort and ensures alignment with the project roadmap.

4. Getting Started

Full setup instructions, dependencies, and build guides are available in the official documentation:

https://docs.mola-slam.org/

Ensure your development environment is fully configured and that all existing tests pass before making any changes.

5. Development Workflow

1. Fork the repository and create a new branch from main (or the relevant base branch).
2. Name your branch descriptively, e.g. fix/imu-integration-drift or feat/lidar-odometry-module.
3. Make your changes in focused, logically grouped commits.
4. Ensure all tests pass locally before opening a Pull Request.
5. Open a Pull Request against the main branch with a clear description of your changes.

Do not submit Pull Requests that bundle unrelated changes. Each PR should address a single concern.

6. Commit and Pull Request Guidelines

Commits

• Write commit messages in the imperative mood: Fix timestamp alignment in IMU handler, not Fixed or Fixes.
• Keep the subject line under 72 characters.
• Reference relevant issues in the commit body where applicable, e.g. Closes #123.

Pull Requests

• Provide a clear summary of the problem being solved and the approach taken.
• Include references to any related issues, discussions, or prior art.
• If the PR introduces a user-visible change, update the relevant documentation and changelog.
• Mark the PR as a draft if it is not yet ready for review.

File truncated at 100 lines see the full file