NavMap

NavMap is an open-source C++ and ROS 2 library for representing navigable surfaces for mobile robot navigation and localization.
Unlike classic grid-based maps, NavMap stores the environment as triangular meshes (NavCels), enabling efficient queries and multi-surface environments (e.g., multi-floor buildings).

✨ Features

• Triangular cell mesh representation with adjacency relations.
• Dynamic runtime layers: per-cell or per-vertex attributes (occupancy, elevation, cost, traversability, etc.).
• Locate API: find the NavCel under/around a 3D position using BVH acceleration and raycasting.
• Raytracing: Möller–Trumbore intersection with a simple BVH for efficiency.
• Multi-surface support: naturally supports multiple disconnected surfaces (e.g., separate floors).

📂 Repository structure

This repository is organized into several ROS 2 packages:

• navmap_core/
  Core C++ library implementing NavMap. Minimal dependencies (Eigen3).

• navmap_ros/
  ROS 2 conversions and message definitions:
  • navmap::NavMap ↔ navmap_ros_interfaces::msg::NavMap
  • nav_msgs::msg::OccupancyGrid ↔ navmap::NavMap
• navmap_rviz_plugin/
  RViz2 plugin for visualization of NavMap messages:
  • Displays surfaces and layers.
  • Optional per-cell normal rendering.
  • Layer-based coloring.

• navmap_tools/
  Tools and utilities for building and testing NavMaps (mesh import/export, conversions, etc.)

• navmap_examples/
  Practical examples demonstrating the usage of NavMap, both core C++ API and ROS 2 integrations.

⚙️ Build instructions

NavMap can be built as a standalone C++ library or within a ROS 2 workspace.

ROS 2 colcon build

# Clone into your ROS 2 workspace
cd ~/ros2_ws/src
git clone https://github.com/<your-org>/NavMap.git

# Build
cd ~/ros2_ws
colcon build --packages-up-to navmap_core navmap_ros navmap_rviz_plugin navmap_tools navmap_examples

# Source workspace
source install/setup.bash

Dependencies

• C++23 compiler
• Eigen3
• ROS 2 (tested with Humble, Iron, Jazzy)
• RViz2 (for the visualization plugin)
• PCL (for mesh construction utilities)

🚀 Usage (C++ API)

C++ API

This section shows small, self-contained snippets that demonstrate how to create a NavMap, add geometry, attach layers, query values, and locate the triangle (NavCel) corresponding to a 3D position.

Note: After modifying geometry (vertices, triangles, or surfaces), always call rebuild_geometry_accels() before performing queries such as locate_navcel() or raycast().

1. Create a minimal NavMap (single square floor with two triangles)

```cpp #include <navmap_core/NavMap.hpp> #include <Eigen/Core>

using navmap::NavMap; using navmap::NavCelId;

NavMap nm;

// Create a surface std::size_t surf_idx = nm.create_surface(“map”);

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