DRE: Direct Radar Estimation

dre is a ROS 2 package that brings together the full ASRL direct-radar estimation stack for online operation and real-time visualization in RViz2:

• Dr-PoGO (Direct Radar Pose-Graph Optimization, preprint here): combines Direct Radar Odometry (DRO) with RaPlace loop-closure detection and a pose-graph optimizer to produce globally consistent trajectories from FMCW radar data.
• Dr-BA (Direct Radar Bundle Adjustment, from the Dr-BA paper): here used live to incrementally build a persistent voxel map from DRO's local maps and pose-graph-corrected poses (no bundle-adjustment refinement online — that stays an offline step).
• DRL (Direct Radar Localization): localizes a live DRO stream against a previously built voxel map.

This package was formed by merging the online ROS 2 pipeline from dr_pogo with the mapping and localization code from the offline dr_ba repository, so all four estimation stages can now run live against a single vendored ba library. An offline branch of the original Dr-PoGO repo still contains the standalone version of that pipeline as used in its paper.

If you find this code useful, please consider citing our papers:

Dr-PoGO

@inproceedings{legentil2026drpogo,
  title={Dr-PoGO: Direct Radar Pose-Graph Optimization},
    author={{Le Gentil}, Cedric, Weican, Li, Brizi, Leonardo, Barfoot, Timothy D.},
  booktitle={IEEE International Conference on Robotics and Automation (ICRA)},
  year={2026}
}

DRO

@inproceedings{legentil2025dro,
  title={Dro: Doppler-aware direct radar odometry},
  author={{Le Gentil}, Cedric, Brizi, Leonardo, Lisus, Daniil, Qiao, Xinyuan, Grisetti, Giorgio, Barfoot, Timothy D.},
  booktitle={Robotics: Science and Systems (RSS)},
  year={2025}
}

Dr-BA

@article{legentil2026drba,
  title={Dr-BA: Separable Optimization for Direct Radar Bundle Adjustment \& Localization},
  author={{Le Gentil}, Cedric and Barfoot, Timothy D.},
  journal={arXiv preprint arXiv:2605.07041},
  year={2026}
}

The loop-closure detection module is directly adapted from RaPlace's original code here, so please also consider citing their work.

Architecture overview

mode_node (Python) is the process manager mode_launch.py starts: given a mode (see Launch a pipeline), it launches exactly the nodes below that mode needs as raw subprocesses (so it fully owns their lifecycle), and republishes the active mode on /operational_mode so long-lived nodes can tell what's going on around them.

Data source (optional)

Not started by mode_launch.py — run manually alongside a pipeline, or replaced entirely by your own live data (see Feed it data).

Node	Language	Role
boreas_player	Python	Replays a Boreas sequence as the three input topics (/boreas/radar_image, /boreas/radar_info, /boreas/imu)

Dr-PoGO pipeline (odometry, loop closure, pose graph)

Node	Language	Role
dro_node	Python	Doppler-aware direct radar odometry
raplace_node	Python	Loop-closure detection using RaPlace
registration_node	Python	Feature-based registration and direct refinement of loop-closure transformations
pogo_node	C++	Pose-graph optimizer (Ceres)

Dr-BA mapping (online, no BA refinement)

Node	Language	Role
mapping_node	C++	Incrementally builds an inverse-variance-weighted voxel map from DRO's local maps and keeps it corrected against pose-graph updates, saving voxel_map.bin and keyframe images to disk periodically
map_viz_node	Python	Renders the on-disk voxel map (whichever /map_path it is pointed at) as an image topic, with an optional live pose overlay

DRL (localization against a pre-built map)

Node	Language	Role
loc_node	C++	Loads a voxel_map.bin, aligns each incoming DRO local map against it via direct optimization, and publishes a DRLEstimate
initial_pose_selector	Python	One-shot interactive tool (matplotlib click) to pick/confirm the initial pose used to seed loc_node, unless skip_selector is set
loc_viz_node	Python	Visualizes the live scan overlaid on the map plus the current pose estimate

Dependencies

ROS 2 (provided by your ROS 2 installation)

• rclpy, rclcpp
• sensor_msgs, nav_msgs, geometry_msgs, std_msgs
• message_filters
• cv_bridge
• yaml-cpp

C++ libraries (system)

• Ceres Solver
• Eigen3
• OpenCV
• OpenMP

These can typically be installed via your package manager (e.g., sudo apt install libceres-dev libeigen3-dev libopencv-dev on Ubuntu).

C++ libraries (vendored, git submodules)

The dre/ba directory vendors the Dr-BA library (voxel_map, local_map_scan, and the BA/localization solvers) along with its own dependencies as submodules under dre/ba/deps/:

• lgmath — Lie-group math (SE(2)/SO(2) transformations)
• unordered_dense — fast hash map used by the voxel map

Make sure to clone with --recurse-submodules (or run git submodule update --init --recursive after cloning).

Python (pip)

Install all Python dependencies with:

pip install -r requirements.txt

The requirements.txt covers: numpy, pandas, scipy, scikit-learn, scikit-image, opencv-python, matplotlib, PyYAML, pyboreas, torch, torchvision.

Build

First clone this repository (with submodules) into your ROS 2 workspace's src/ directory, then build with:

cd <your_ros2_workspace>/src
git clone --recurse-submodules git@github.com:utiasASRL/dre.git

Then build the workspace with:

cd <your_ros2_workspace>
colcon build --packages-select dre --symlink-install
source install/setup.bash

--symlink-install is required: it installs config files as symlinks back to src/, so editing a config takes effect immediately without rebuilding.

Usage

1. Prepare the config files

config/config_dro.yaml ships populated with Boreas RT defaults (also kept as a reference preset under config/templates/) — edit it directly, or restore it from the template if needed. You can also customize the RaPlace, registration, pose-graph, mapping, and localization config files if desired (all parameters should have reasonable defaults though).

Note that by default, the registration node is set to use GPU if available. Depending on your hardware and the size of the local maps, this may slow down the processing of DRO's odometry (both nodes can compete for GPU resources). If you want to disable GPU usage for loop registration, simply set use_gpu_if_available: false in the config/config_registration.yaml file. It will be slower to compute the loop registration (using only 1 CPU thread), but DRO's behaviour will be more predictable.

2. Launch a pipeline

mode_launch.py is the single entry point: it starts a mode_node, which itself launches (and, on a later re-launch with a different mode, restarts) whichever set of nodes the requested mode needs, plus a matching RViz preset.

ros2 launch dre mode_launch.py mode:=mapping

Argument	Default	Description
mode	dro	Which pipeline to run: dro, pogo, mapping, or localization (see mode_node.py's MODE_TABLE)
headless	false	If true, skip RViz for the chosen mode

Mode	Nodes started	Use case
dro	dro_node + RViz	Odometry only
pogo	dro_node, raplace_node, registration_node, pogo_node + RViz	Dr-PoGO pipeline (odometry + loop closure + pose graph, no mapping)
mapping	All of the above plus mapping_node, map_viz_node	Full online pipeline: odometry, loop closure, pose graph, and live voxel-map building
localization	dro_node, raplace_node, registration_node, loc_node, initial_pose_selector, loc_viz_node, map_viz_node + RViz	Localize live DRO output against a voxel map built in a previous run (DRL)

mode_node also publishes the active mode (latched) on /operational_mode, which nodes that behave differently per mode (e.g. raplace_node, querying vs. inserting into its history) read to know what's going on around them.

Legacy per-pipeline launch files (superseded by mode_launch.py)

dro_launch.py, dr_pogo_launch.py, mapping_launch.py, dre_launch.py, and drl_launch.py still exist and work, but each only covers one fixed pipeline (dre_launch.py and mapping_launch.py are identical to each other, and to mode_launch.py mode:=mapping; the others map to mode_launch.py mode:=dro/pogo/localization respectively). Prefer mode_launch.py going forward.

Note: The DRO code will attempt to leverage torch compilation if the config/config_dro.yaml file contains the following parameters:

radar:
  nb_azimuths: XXX
  doppler_enabled: true/false
  resolution: Y.YYYY

If you chose to enable compilation, the initialization of the dro_node will take significantly longer (something like 30sec?). When the comilation is done and DRO is ready to process data, you should see the following message in the terminal:

If you want to disable compilation, simply remove one of the above parameters from the config file (e.g., resolution).

3. Feed it data: playback or live

dro_node (and everything downstream of it) doesn't care where its input comes from — it just needs these three topics published:

Topic	Type	Notes
/boreas/radar_image	sensor_msgs/Image	Radar chirp data as an image
/boreas/radar_info	dre/RadarInfo	Per-scan metadata (azimuths, timestamps, resolution); time-synchronized against /boreas/radar_image
/boreas/imu	sensor_msgs/Imu	Buffered and matched to each radar scan's time span (waits up to 0.2s for IMU coverage before giving up on a scan)

Option A — replay a Boreas sequence:

ros2 run dre boreas_player -p <path_to_sequence> -r <playback_rate>
# Example:
ros2 run dre boreas_player -p /data/boreas/boreas-2024-12-03-12-54 -r 1.0

You can also make it play as fast as DRO allows by setting -r 0 (preventing to wait between messages if your hardware is fast enough to process the data faster than real-time, and allows for slower hardware to keep up by slowing down the playback rate as needed).

Option B — feed live data: publish the same three topics yourself (e.g. from a radar driver node) instead of running boreas_player. As long as the types and timestamps line up, the rest of the pipeline behaves identically to playback.

4. Localize against a previously built map (DRL)

Point config/config_loc.yaml's map_path at a voxel_map.bin produced by a previous mapping_node run (or an offline dr_ba map), set an initial_pose (or leave skip_selector: false to pick one interactively when initial_pose_selector starts), then:

ros2 launch dre mode_launch.py mode:=localization

Configuration

All YAML config files live under config/.

File	Node	Key parameters
config_dro.yaml	dro_node	Sensor extrinsics (T_axle_radar), range limits, GP lengthscales
config_raplace.yaml	raplace_node	min_time_diff, max_odom_drift, max_img_size
config_registration.yaml	registration_node	lowe_ratio, ransac_thr, max_img_size, use_gpu_if_available
config_pogo.yaml	pogo_node	Odometry/loop noise std-devs, loss scales, estimate_bias
config_mapping.yaml	mapping_node	voxel_map_resolution, max_dist, keyframe gate (max_kf_dist, max_kf_rot), intensity noise model, worker-thread throttling (max_moved_per_update, min_moved_per_update)
config_loc.yaml	loc_node, initial_pose_selector, loc_viz_node	map_path, initial_pose, scan-blurring and optimization parameters

Custom messages

Message	Fields
RadarInfo	Radar scan metadata (timestamps, frequency, etc.)
LocalMapInfo	Accumulated local map header, resolution, 2-D pose (x, y, theta)
LoopCandidate	Query/candidate timestamps, match score, image paths, local map resolution
DRLEstimate	Localization pose (x, y, theta) with solver iterations and final cost

Output

Atop ROS2 topics shown in RViz, the pipeline outputs the following. With mode_launch.py, output lives under the dre package's source directory (not the install space, so it survives a clean rebuild) at output/poses/<sequence_id>/ (DRO/pogo) and output/maps/<sequence_id>/ (mapping) — each node nests its own <sequence_id> subdirectory, learned from the first RadarInfo message:

• odometry_result/<sequence_id>.txt: DRO odometry trajectory using the Boreas format.
• pose_graph_traj.txt: Pose-graph optimized trajectory in with timestamp(us) x y theta format.
• voxel_map.bin, local_maps/, cumulated_returns/: mapping_node's persistent voxel map and the keyframe images backing it.

(The legacy dre_launch.py/mapping_launch.py instead default to the install space, under <ros2_ws>/install/dre/share/dre/<sequence_id>/, with the map tree rooted at output/boreas-live/ via their map_output_path argument.)

TODOs

• Making the dense loop registration refinement faster !! (need to profile first)
• Improving documentation
• Looking at making DRO even faster? (real time on my RTX 500 Mobile GPU (30W), so not a priority)
• Adding the 3D odometry output as for 3DRO
• Adding a live-switchable "dre" mode to mode_launch.py that demotes nodes to idle instead of fully restarting them on a mode switch (needs each node to support demotion first)
• Retiring the legacy per-pipeline launch files now that mode_launch.py covers all four pipelines