OpenChisel

An open-source version of the Chisel chunked TSDF library. It contains two packages:

##open_chisel open_chisel is an implementation of a generic truncated signed distance field (TSDF) 3D mapping library; based on the Chisel mapping framework developed originally for Google's Project Tango. It is a complete re-write of the original mapping system (which is proprietary). open_chisel is chunked and spatially hashed, making it more memory-efficient than fixed-grid mapping approaches, and more performant than octree-based approaches. A technical description of how it works can be found in our RSS 2015 paper.

This reference implementation does not include any pose estimation. Therefore the pose of the sensor must be provided from an external source. This implementation also avoids the use of any GPU computing, which makes it suitable for limited hardware platforms. It does not contain any system for rendering/displaying the resulting 3D reconstruction. It has been tested on Ubuntu 14.04 in Linux with ROS hydro/indigo.

API Usage

Check the chisel_ros package source for an example of how to use the API. The ChiselServer class makes use of the chisel_ros API.

###Dependencies

• Eigen
• C++11
• catkin build system

Compilation note: For speed, it is essential to compile open_chisel with optimization. You will need to add the flag -DCMAKE_BUILD_TYPE=Release to your catkin_make command when building.

##chisel_ros chisel_ros is a wrapper around open_chisel that interfaces with ROS-based depth and color sensors. The main class chisel_ros provides is ChiselServer, which subscribes to depth images, color images, TF frames, and camera intrinsics.

Note: you will also need to get the messages package, chisel_msgs to build this.

###Supported ROS image types: Depth Images

• 32 bit floating point mono in meters (32FC1)
• 16 bit unsigned characters in millimeters (16UC1)

Color Images

• BRG8
• BGRA8
• Mono8

###Dependencies

• Eigen
• C++11
• catkin (ros-hydro or ros-indigo or higher)
• PCL 1.8 compiled with stdC++11 enabled.
• ROS OpenCV cv_bridge

A note on PCL

Unfortunately, PCL 1.7x (the standard PCL included in current versions of ROS) doesn't work with C++11. This project makes heavy use of C++11, so in order to use Chisel, you will have to download and install PCL 1.8 from source, and compile it with C++11 enabled.

1. Download PCL 1.8 from here: https://github.com/PointCloudLibrary/pcl
2. Modify line 91 of CMakeLists.txt in PCL to say SET(CMAKE_CXX_FLAGS "-Wall -std=c++11 ...
3. Build and install PCL 1.8
4. Download pcl_ros from here: https://github.com/ros-perception/perception_pcl
5. Change the dependency from PCL to PCL 1.8 in find_package of the CMakeLists.txt
6. Compile pcl_ros.
7. Rebuild Chisel

If PCL does not gain c++11 support by default soon, we may just get rid of c++11 in OpenChisel and use boost instead.

###Launching chisel_ros Server

Once built, the chisel_ros server can be launched by using a launch file. There's an example launch file located at chisel_ros/launch/launch_kinect_local.launch. Modify the parameters as necessary to connect to your camera and TF frame.

<launch>
    <!-- Use a different machine name to connect to a different ROS server-->
    <machine name="local" address="localhost" default="true"/>
    <!-- The chisel server node-->
    <node name="Chisel" pkg="chisel_ros" type="ChiselNode" output="screen"> 
        <!-- Size of the TSDF chunks in number of voxels -->
        <param name="chunk_size_x" value="16"/>
        <param name="chunk_size_y" value="16"/>
        <param name="chunk_size_z" value="16"/>
        <!--- The distance away from the surface (in cm) we are willing to reconstuct -->
        <param name="truncation_scale" value="10.0"/>
        <!-- Whether to use voxel carving. If set to true, space near the sensor will be
             carved away, allowing for moving objects and other inconsistencies to disappear -->
        <param name="use_voxel_carving" value="true"/>
        <!-- When true, the mesh will get colorized by the color image.-->
        <param name="use_color" value="false"/>
        <!-- The distance from the surface (in meters) which will get carved away when
             inconsistencies are detected (see use_voxel_carving)-->
        <param name="carving_dist_m" value="0.05"/>
        <!-- The size of each TSDF voxel in meters-->
        <param name="voxel_resolution_m" value="0.025"/>
        <!-- The maximum distance (in meters) that will be constructed. Use lower values
             for close-up reconstructions and to save on memory. -->
        <param name="far_plane_dist" value="1.5"/>
        <!-- Name of the TF frame corresponding to the fixed (world) frame -->
        <param name="base_transform" value="/base_link"/>
        <!-- Name of the TF frame associated with the depth image. Z points forward, Y down, and X right -->
        <param name="depth_image_transform" value="/camera_depth_optical_frame"/>
        <!-- Name of the TF frame associated with the color image -->
        <param name="color_image_transform" value="/camera_rgb_optical_frame"/>
        <!-- Mode to use for reconstruction. There are two modes: DepthImage and PointCloud.
             Only use PointCloud if no depth image is available. It is *much* slower-->
        <param name="fusion_mode" value="DepthImage"/>
    
        <!-- Name of the depth image to use for reconstruction -->
        <remap from="/depth_image" to="/camera/depth/image"/>
        <!-- Name of the CameraInfo (intrinsic calibration) topic for the depth image. -->
        <remap from="/depth_camera_info" to="/camera/depth/camera_info"/>
        <!-- Name of the color image topic -->
        <remap from="/color_image" to="/camera/color/image"/>
        <!-- Name of the color camera's CameraInfo topic -->
        <remap from="/color_camera_info" to="/camera/color/camera_info"/>
        
        <!-- Name of a point cloud to use for reconstruction. Only use this if no depth image is available -->
        <remap from="/camera/depth_registered/points" to="/camera/depth/points"/>
    </node>
</launch>

Then, launch the server using roslaunch chisel_ros <your_launchfile>.launch. You should see an output saying that open_chisel received depth images. Now, you can visualize the results in rviz.

Type rosrun rviz rviz to open up the RVIZ visualizer. Then, add a Marker topic with the name /Chisel/full_mesh. This topic displays the mesh reconstructed by Chisel.

Services

chisel_ros provides several ROS services you can use to interface with the reconstruction in real-time. These are:

• Reset -- Deletes all the TSDF data and starts the reconstruction from scratch.
• TogglePaused -- Pauses/Unpauses reconstruction
• SaveMesh -- Saves a PLY mesh file to the desired location of the entire scene
• GetAllChunks -- Returns a list of all of the voxel data in the scene. Each chunk is stored as a seperate entity with its data stored in a byte array.