# SC-A-LOAM

## What is SC-A-LOAM?

- A real-time LiDAR SLAM package that integrates A-LOAM and ScanContext.

## Repository Information

### Original Repository link

[https://github.com/gisbi-kim/SC-A-LOAM](<https://github.com/gisbi-kim/SC-A-LOAM>)

### Required Sensors

- LIDAR \[VLP-16, HDL-32, HDL-64, Ouster OS1-64\]

### Prerequisites (dependencies)

- ROS
- GTSAM version 4.x.

- If GTSAM is not installed, follow the steps below.

  ```bash
    wget -O ~/Downloads/gtsam.zip https://github.com/borglab/gtsam/archive/4.0.2.zip
    cd ~/Downloads/ && unzip gtsam.zip -d ~/Downloads/
    cd ~/Downloads/gtsam-4.0.2/
    mkdir build && cd build
    cmake -DGTSAM_BUILD_WITH_MARCH_NATIVE=OFF ..
    sudo make install -j8
  ```

### ROS Compatibility

- ROS 1

## Build &amp; Run

### 1\) Build

- First, install the above mentioned dependencies and follow below lines.

  ```bash
   mkdir -p ~/catkin_scaloam_ws/src
   cd ~/catkin_scaloam_ws/src
   git clone https://github.com/gisbi-kim/SC-A-LOAM.git
   cd ../
   catkin_make
   source ~/catkin_scaloam_ws/devel/setup.bash
  ```

### 2\) Set parameters

- After downloading the repository, change topic and sensor settings on the launch files.

### Scan Context parameters

- If encountering ghosting error or loop is not closed, change the scan context parameters.
- Adjust the scan context settings with the parameters in the marked area.

### 3\) Run

```bash
roslaunch aloam_velodyne aloam_mulran.launch
```

## 4\) Saving as PCD file

```bash
  rosrun pcl_ros pointcloud_to_pcd input:=/aft_pgo_map
```

## Example Results

### Riverside 01, MulRan dataset

- The MulRan dataset provides lidar scans (Ouster OS1-64, horizontally mounted, 10Hz) and consumer level gps (u-blox EVK-7P, 4Hz) data.
- About how to use (publishing data) data: see here [https://github.com/RPM-Robotics-Lab/file\_player\_mulran](<https://github.com/RPM-Robotics-Lab/file_player_mulran>)
- example videos on Riverside 01 sequence.

  ```bash
  1. with consumer level GPS-based altitude stabilization: https://youtu.be/FwAVX5TVm04
  2. without the z stabilization: https://youtu.be/okML_zNadhY
  ```

- example result:

### KITTI 05

- For KITTI (HDL-64 sensor), run using the command

  ```bash
  roslaunch aloam_velodyne aloam_velodyne_HDL_64.launch # for KITTI dataset setting
  ```

- To publish KITTI scans, you can use mini-kitti publisher, a simple python script: [https://github.com/gisbi-kim/mini-kitti-publisher](<https://github.com/gisbi-kim/mini-kitti-publisher>)
- example video (no GPS used here): [https://youtu.be/hk3Xx8SKkv4](<https://youtu.be/hk3Xx8SKkv4>)
- example result:

## Contact

- Maintainer: [paulgkim@kaist.ac.kr](<mailto:paulgkim@kaist.ac.kr>)