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

EOL Distro	Last release
ROS1 Noetic (u20.04)
ROS 2 Iron (u22.04)

mp2p_icp

C++ libraries for multi primitive-to-primitive (MP2P) ICP algorithms and flexible point cloud processing pipelines. mp2p_icp is used in the mola_lidar_odometry framework:

• Main library documentation and C++ API
• License: New BSD 3-Clause (Note that each module of MOLA has its own license)

Introduction

The project provides these C++ libraries:

• mp2p_icp_map: Provides the mp2p_icp::metric_map_t generic metric map container and related utilities for working with point cloud data structures. Metric map files with extension *.mm are serializations of instances of this class.
• mp2p_icp: With ICP algorithms, matchers (point-to-point, point-to-plane, point-to-line, covariance-to-covariance, adaptive), solvers (Horn, OLAE, Gauss-Newton), and quality evaluators. It depends on mp2p_icp_map.
• mp2p_icp_filters: With point cloud filtering and manipulation algorithms including decimation, voxelization, statistical outlier removal, edge/plane extraction, and various geometric transformations. It depends on mp2p_icp_map.

Command-Line Applications

The full repository also includes these applications (see apps/ directory):

Data Conversion Tools

• kitti2mm: Converts KITTI dataset LIDAR binary files (.bin) with (X,Y,Z, Intensity) data into mp2p_icp metric map files (.mm). Supports custom layer names, numeric IDs, and label strings.

• txt2mm: Converts plain-text point cloud data (TXT/CSV) into metric map (.mm) files. Supports multiple formats: XYZ, XYZI, XYZIRT, XYZRGB, with configurable column mapping and layer names.

• sm2mm: Converts a simple map (.simplemap) from a SLAM mapping session into a metric map (.mm) using a configurable processing pipeline. Essential for post-processing SLAM outputs into structured metric representations.

Data Export Tools

• mm2ply: Exports metric map layers to PLY point cloud files. Supports both ASCII and binary formats, selective field export, and preserves all point attributes (coordinates, colors, intensities, etc.).

• mm2txt: Exports metric map layers as space-delimited CSV/TXT files with header rows. Ideal for data analysis in spreadsheet applications or custom processing pipelines. Supports selective layer and field export.

• mm2las: Exports metric maps to industry-standard LAS 1.4 format with Point Format 8 support. Includes automatic color mapping, extra dimensions for custom fields. Compatible with CloudCompare, QGIS, and ArcGIS.

Map Processing & Analysis Tools

• mm-filter: Applies mp2p_icp_filters pipelines to metric map files. Can operate in pipeline mode (applying complete YAML-defined filter chains) or rename mode (simply renaming layers). Supports custom plugin loading.

• mm-info: Displays a summary of metric map contents including layers, point counts, and metadata.

• mm-georef: Extracts or injects geo-referencing information between metric map files (.mm) and standalone georeferencing files (.georef).

Visualization Tools

• mm-viewer: GUI application to visualize metric map (.mm) files. Supports loading additional 3D scenes and trajectory files in TUM format.

• icp-log-viewer: Interactive GUI for debugging ICP pipelines. Visualizes ICP log files (.icplog) with autoplay mode and detailed inspection of registration results. Essential for understanding and optimizing ICP algorithm performance.

ICP Execution Tools

• icp-run: Standalone program to execute ICP pipelines from the command line.

SimpleMaps Manipulation

• sm-cli: Swiss-army knife for simple map (.simplemap) manipulation. Commands include: info (analyze contents), cut (extract by keyframe index), trim (extract by bounding box), join (merge maps), level (make horizontal), tf (apply SE(3) transform), export-keyframes (save trajectories as TUM), and export-rawlog (convert to RawLog format).

Key Features and Components

Key C++ classes provided by this project (see full documentation):

Core Data Structures

• mp2p_icp::metric_map_t: A generic data type to store raw or processed point clouds, including support for multiple layers, segmented data, and discrete extracted features.

ICP Algorithms and Matchers

• mp2p_icp::ICP: A uniform API for matching generic point clouds with support for:
  • Point-to-Point matching (various distance metrics)
  • Point-to-Plane matching (planes extracted from point clouds)
  • Point-to-Line matching (edges/lines extracted from point clouds)
  • Covariance-to-Covariance matching (Gaussian distributions)
  • Adaptive matching (automatically selects best matcher)

Solvers

• Horn’s method: Closed-form solution for point-to-point alignment
• OLAE (Optimal Linear Attitude Estimator): For attitude/rotation estimation
• Gauss-Newton: Iterative solver for complex matching scenarios

Filters and Generators

The mp2p_icp_filters library provides extensive filtering capabilities:

• Decimation: FilterDecimate, FilterDecimateVoxels, FilterDecimateAdaptive
• Outlier removal: FilterSOR (Statistical Outlier Removal), FilterVoxelSOR

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Changelog for package mp2p_icp

2.10.0 (2026-05-02)

• CI: Update actions for new ROS rolling
• icp-log-viewer: better formatting of uncertainties
• demo sm2mm file: store as independent keyframes
• Merge pull request #60 from MOLAorg/feat/censi3d-covariance Feat: Censi3D covariance method
• feat: Add new covariance method (Censi, 3D version)
• demo sm2mm files: add Keyframe map variant
• Contributors: Jose Luis Blanco-Claraco

2.9.1 (2026-04-29)

• Merge pull request #59 from MOLAorg/fix/cov2cov-covariance-whitening Fix cov2cov whitening and add residual-variance scaling in covariance()

• Fix cov2cov whitening and add residual-variance scaling in covariance() The cov2cov branch in covariance.cpp whitened residuals with the full information matrix (cov_inv * e), so the assembled Hessian became J\^T * cov_inv\^2 * J instead of J\^T * cov_inv * J. Combined with hundreds of pairings this drove down to ~1e-20 and made the estimate unusable.

  - Use the Cholesky factor L\^T (with L L\^T = cov_inv) to whiten the cov2cov residual, matching what optimal_tf_gauss_newton accumulates.

  - Multiply the inverse-Hessian by chi\^2 / (m - 6), the standard a-posteriori unit-weight variance, to rescale the (otherwise optimistic) result by the empirical residual level.

• Merge pull request #58 from MOLAorg/feat/icp-viewer-show-prior feat: icp-logs now store the prior SE(3) PDF

• feat: icp-logs now store the prior SE(3) PDF

• icp-log-viewer: safer against exceptions in gui thread

• demo sm2mm files: ignore_accelerometer=true in all deskew stages by default (prevent noisy maps from low-quality IMUs)

• Contributors: Jose Luis Blanco-Claraco

2.9.0 (2026-04-22)

• Merge pull request #57 from MOLAorg/feat/deskew-filter-ignore-acc FilterDeskew: add new option "ignore_accelerometer"
• Merge pull request #55 from MOLAorg/feat/mm-viewer-read-bin-files mm-viewer: can be also open .bin files with serialized CGenericPointsMap
• Merge pull request #54 from MOLAorg/feat/mm-apps-plugins mm-info, mm2grid, mm2las, mm2ply, mm2txt now have a --load-plugins flag
• Optimization in PointCloudToVoxelGridSingle
• Add <stdexcept> to all required files (don't depend on transitive includes)
• mm-info, mm2grid, mm2las, mm2ply, mm2txt now have a --load-plugins flag
• Merge branch 'generator-generic-cloud' into develop
• cloud rendering: Implement observing the autoBoundingBoxOutliersPercentile
• Merge pull request #53 from MOLAorg/generator-generic-cloud Generator: creates CGenericPointsMap by default; add sanity checks in most filters
• remove more old mrpt version guards
• New sanity check function: warn_on_field_padding_mismatch()
• FilterDeskew: guard against new MRPT behavior to keep all field lengths in sync
• Add sanity checks in filters
• Bump minimum MRPT version to 2.15.4 (and remove now old dead code)
• Generator new param 'filterOutPointsAtZero', set to true in demo pipelines
• Generator: now has a param 'default_pointcloud_class' which defaults to 'CGenericPointsMap'
• Code clean up (remove now dead code; mrpt backwards compatibility)
• Merge pull request #52 from MOLAorg/icp-log-viewer-quality-filter icp-log-viewer: add --min-quality filter CLI flag
• Contributors: Jose Luis Blanco-Claraco

2.8.1 (2026-04-06)

• Merge pull request #51 from MOLAorg/fix/new-mrpt-api Update to build against mrpt >=2.15.13
• Update to build against mrpt >=2.15.13 (pointcloud field names as std::string instead of string_view)

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