3D-Recon: VINS-RGBD voxblox

Recently we are trying to create dataset for 3D perception, so we need to create a 3D scanned environment like meta Replica-Dataset. Our solution is to use a RGBD sensor with IMU (e.g. Realsense L515 or Azure Kinect) with VINS system like VINS-RGBD and Kimera to generate the pose for the sequence and use voxblox to generate the mesh. So much for the talk, let's head into the tutorial.

Build VINS-RGBD & VoxBlox

Building VINS-RGBD is similar to the ones with VINS-Mono , make sure you have ros environment. The project was tested with:

1. Ubuntu 18.04
2. ROS version Melodic fully installation
3. Ceres Solver (1.14.0)
4. Sophus (checkout a621ff)
5. Pangolin (0.6)
6. OpenCV (3.4)
7. Realsense ROS wrapper or Azure Kinect ROS Driver

Build with Docker

If you are tired of configuring all kinds of environments, there is a docker env shipped with this solution: recon_docker. You can skip this if you want to configure your own environment locally.

cd docker/
./build-dokcer-image.bash

⚠️ Please replace the registry and proxy server with your own address in build-docker-image.bash and run-docker-image.bash:

docker build -t registry.server.com:5000/midea/vinsrgbd \ <== replace it
    --build-arg http_proxy=http://proxyserver.com:7890 \ <== replace it
    --build-arg https_proxy=http://proxyserver.com:7890 \ <== replace it
    --build-arg USER=${user} \
    --build-arg UID=${uid} \
    --build-arg GROUP=${group} \
    --build-arg GID=${gid} \
    ${file_dir}

⚠️ you need to make sure your display id is the current one:

$ echo $DISPLAY
:0

And modify this based on docker/dockerfile:

Ln201    RUN echo 'export DISPLAY=:0' >> /etc/profile

After build your docker image, run it and it will pompt out the terminator, note that it supports OpenGL and X11. So that you can run rviz with your remote docker.

To verify it, run the following command in your remote server:

./docker/run-docker-image.bash

ssh to remote server in your local computer:

ssh -p 3752 work@server.address.com

Then type the following command to see if the gears pompt out:

glxgears

If so, congratulations, you can run rviz remotely!

Now we can head into compiling the VINS-RGBD and voxblox ros nodes.

Build Locally

Initialize ros environment:

mkdir -p ~/catkin_ws/src
cd ~/catkin_ws
catkin init
catkin config --extend /opt/ros/melodic
catkin config --cmake-args -DCMAKE_BUILD_TYPE=Release
catkin config --merge-devel

# vins-rgbd
git clone https://github.com/rancheng/Reconstruction_Pipeline.git
cd Reconstruction_Pipeline
mv VINS-RGBD ~/catkin_ws/src/
mv voxblox ~/catkin_ws/src/

# voxblox
cd ~/catkin_ws/src/
git clone https://github.com/ethz-asl/voxblox.git
wstool init . ./voxblox/voxblox_https.rosinstall
wstool update

# build project
catkin_make

Run VINS-RGBD

To run with the VINS-RGBD system, one need to use the following command:

# Realsense L515
roslaunch vins_estimator realsense_color.launch

# Azure Kinect
roslaunch vins_estimator azure_color.launch

Run the Rviz for VINS-RGBD

roslaunch vins_estimator vins_rviz.launch

To run the L515 or Azure Kinect use the following command:

# Realsense L515
roslaunch realsense2_camera rs_camera.launch \
device_type:=l515 enable_gyro:=true enable_accel:=true \
align_depth:=true unite_imu_method:=linear_interpolation \
color_width:=1280 color_height:=720 color_fps:=30 \
depth_fps:=30 enable_pointcloud:=true

# Azure Kinect
roslaunch azure_kinect_ros_driver driver.launch \
depth_mode:=WFOV_2X2BINNED \
color_resolution:=720P \
fps:=30 \
imu_rate_target:=200

To run the rosbag if you want to record the raw imu ,rgb, depth with point cloud topics:

# Realsense L515
rosbag record /camera/aligned_depth_to_color/image_raw \
/camera/color/image_raw /camera/imu /camera/depth/metadata \
/camera/color/metadata /camera/color/camera_info \
/camera/depth/color/points

# Azure Kinect
rosbag record /rgb/image_raw \
/depth_to_rgb/image_raw /imu \
/depth_to_rgb/camera_info /rgb/camera_info \
/points2

Run VoxBlox

To run the voxblox, use the following command:

# Realsense L515
roslaunch voxblox_ros rgbd_dataset_l515.launch

# Azure Kinect
roslaunch voxblox_ros rgbd_dataset_azure.launch

The launch file is configured as following (L525 for example):

<?xml version="1.0" encoding="ISO-8859-15"?>
<launch>
  <arg name="robot_name" default="l515" />
  <arg name="voxel_size" default="0.05" />
  <arg name="voxels_per_side" default="16" />
  <arg name="world_frame" default="world" />
  <node name="voxblox_node" pkg="voxblox_ros" type="tsdf_server" output="screen" args="--alsologtostderr" clear_params="true">
    <remap from="pointcloud" to="/camera/depth/color/points"/>
    <remap from="voxblox_node/esdf_map_out" to="esdf_map" />
    <param name="tsdf_voxel_size" value="$(arg voxel_size)" />
    <param name="tsdf_voxels_per_side" value="$(arg voxels_per_side)" />
    <param name="color_mode" value="color" />
    <param name="voxel_carving_enabled" value="true" />
    <param name="publish_esdf_map" value="true" />
    <param name="update_mesh_every_n_sec" value="1.0" />
    <param name="min_time_between_msgs_sec" value="0.0" />
    <param name="publish_pointclouds" value="true" />
    <param name="use_tf_transforms" value="false" />
    <param name="update_mesh_every_n_sec" value="0.5" />
    <param name="allow_clear" value="true" />
    <remap from="transform" to="/vins_estimator/camera_transform" />
    <param name="clear_sphere_for_planning" value="true" />
    <param name="world_frame" value="$(arg world_frame)" />
    <rosparam file="$(find voxblox_ros)/cfg/l515.yaml"/>
    <param name="mesh_filename" value="$(find voxblox_ros)/mesh_results/l515.ply" />
  </node>
</launch>

If you have another sensor, please make sure you can export the point cloud data to your own topic name and remap it to voxblox in above launch file:

 <remap from="pointcloud" to="/camera/depth/color/points"/>

also, please change the transform to your own topic:

<remap from="transform" to="/vins_estimator/camera_transform" />

Note that the transform message should be the following format:

geometry_msgs::TransformStamped

Since VINS-RGBD output pose is camera pose so that we do not need to configure the transformation matrix in cfg:

# actually T_R_C (C = cam0, R = rgbd cam)
T_B_C:
- [1.0, 0.0, 0.0, 0.0]
- [0.0, 1.0, 0.0, 0.0]
- [0.0, 0.0, 1.0, 0.0]
- [0.0, 0.0, 0.0, 1.0]
invert_T_B_C: false

# actually T_V_C (C = cam0, V = vicon)
T_B_D:
- [1.0, 0.0, 0.0, 0.0]
- [0.0, 1.0, 0.0, 0.0]
- [0.0, 0.0, 1.0, 0.0]
- [0.0, 0.0, 0.0, 1.0]
invert_T_B_D: false

To visualize the voxblox result, please open the rviz config from here:

voxblox/voxblox_ros/cfg/voxblox_vis.rviz

and make sure your frame id is world, and Image Topic is the corresponding topic published by your sensor:

# Relsense L515
# line 71
Image Topic: /camera/color/image_raw
# line 91
Image Topic: /camera/aligned_depth_to_color/image_raw

# Azure Kinect
# line 71
Image Topic: /rgb/image_raw
# line 91
Image Topic: /depth_to_rgb/image_raw

To export the built mesh file, please run the following command in another terminal:

rosservice /voxblox_node/generate_mesh

The output mesh will be exported to here: voxblox_ros/mesh_results/l515.ply

Here's the visualization of 3D reconstruction of my room with MeshLab:

If you can not get your mesh updated in the rviz or the mesh topic is always empty, please make sure you have two major components ready:

• your point cloud message

• your pose message

Among them, the point cloud message should be type:

sensor_msgs/PointCloud2

the pose message should be type:

geometry_msgs/TransformStamped

If your localization sensor is different from your LIDAR sensor, please transform it use the voxblox_ros/cfg/xxx.yaml file to transform it to the sensor which produce the point cloud.

You can implement your own publisher to convert the camera pose to the desired message type:

void pubCameraTransform(const Estimator &estimator, const std_msgs::Header &header)
{
    int idx2 = WINDOW_SIZE - 1;

    if (estimator.solver_flag == Estimator::SolverFlag::NON_LINEAR)
    {
        int i = idx2;
        Vector3d P = estimator.Ps[i] + estimator.Rs[i] * estimator.tic[0];
        Quaterniond R = Quaterniond(estimator.Rs[i] * estimator.ric[0]);
        geometry_msgs::TransformStamped tf_msg;
        tf_msg.header = header;
        tf_msg.header.frame_id = "world";
        tf_msg.transform.translation.x = P.x();
        tf_msg.transform.translation.y = P.y();
        tf_msg.transform.translation.z = P.z();
        tf_msg.transform.rotation.x = R.x();
        tf_msg.transform.rotation.y = R.y();
        tf_msg.transform.rotation.z = R.z();
        tf_msg.transform.rotation.w = R.w();

        //"camera_pose"
        pub_camera_transform.publish(tf_msg);
    }
}

This is an example of modifying VINS-RGBD publisher.

Make sure your message xxx_msg.header.frame_id is set to world.

In order to obtain a better reconstructed mesh. the best practice is to save the point cloud and pose stamps into a new bagfile and set the reconstruction resolution to 0.001m and play the bag 10x slower.

To be continued with boundfusion cuda backend with realtime high-res reconstruction pipeline.