YiChenCityU / SC-LeGO-LOAM

LiDAR SLAM: Scan Context + Lego-LOAM

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SC-LeGO-LOAM

  • LiDAR SLAM: Scan Context (18 IROS) + Lego-LOAM (18 IROS)
  • This repository is an example use-case of Scan Context C++ , the LiDAR place recognition method, for LiDAR SLAM applications.
  • Just include Scancontext.h. For details see the file mapOptmization.cpp.

Features

  • Light-weight: a single header and cpp file named "Scancontext.h" and "Scancontext.cpp"
    • Our module has KDtree and we used nanoflann . nanoflann is an also single-header-program and that file is in our directory.
  • Easy to use: A user just remembers and uses only two API functions; makeAndSaveScancontextAndKeys and detectLoopClosureID.
  • Fast: The loop detector runs at 10-15Hz (for 20 x 60 size, 10 candidates)

Examples

Scan Context integration

  • For implementation details, see the mapOptmization.cpp; all other files are same as the original LeGO-LOAM.
  • Some detail comments
    • We use non-conservative threshold for Scan Context's nearest distance, so expect to maximise true-positive loop factors, while the number of false-positive increases.
    • To prevent the wrong map correction, we used Cauchy (but DCS can be used) kernel for loop factor. See mapOptmization.cpp for details. (the original LeGO-LOAM used non-robust kernel). We found that Cauchy is emprically enough.
    • We use both two-type of loop factor additions (i.e., radius search (RS)-based as already implemented in the original LeGO-LOAM and Scan context (SC)-based global revisit detection). See mapOptmization.cpp for details. SC is good for correcting large drifts and RS is good for fine-stitching.
    • Originally, Scan Context supports reverse-loop closure (i.e., revisit a place in a reversed direction) and examples in here (py-icp slam) . Our Scancontext.cpp module contains this feature. However, we did not use this for closing a loop in this repository because we found PCL's ICP with non-eye initial is brittle.

How to use

  • Place the directory SC-LeGO-LOAM under user catkin work space
  • For example,
    cd ~/catkin_ws/src
    git clone https://github.com/irapkaist/SC-LeGO-LOAM.git
    cd ..
    catkin_make
    source devel/setup.bash
    roslaunch lego_loam run.launch
    

MulRan dataset

Dependencies

  • All dependencies are same as LeGO-LOAM (i.e., ROS, PCL, and GTSAM).

About

LiDAR SLAM: Scan Context + Lego-LOAM


Languages

Language:C++ 99.3%Language:CMake 0.7%