ROSBAG Modification

You can simply download the demo rosbag file in "HumanDisk/Autoware_Data/190614_MappingData". If you just want demo file, skip this section. The instructions below are for newly recorded custom data.

Change Topic Names

In hdl_graph_slam, the GPS topic name must be in the list:

• /gps/geopoint (geographic_msgs/GeoPointStamped)
• /gps/navsat (sensor_msgs/NavSatFix)
• /gpsimu_driver/nmea_sentence (nmea_msgs/Sentence)

And the IMU topic name must be :

• /gpsimu_driver/imu_data (sensor_msgs/Imu)

I am using the rosbag file recorded in DGIST. The file 'first.bag' could be found at :

1. Access NAS. The IP now in July 2019 is (10.40.4.38). You should input ID and password.
2. Go to folder HumanDisk.
3. Go to folder "Autoware_Data/190614_MappingData".
4. Download "first.bag" to your local.

In "first.bag", the GPS topic is "/nmea_sentece (nmea_msgs/Sentence)" and IMU topic is "/imu_raw (sensor_msgs/IMU). So you must change the topic names in the rosbag file. I will introduce a way of python implementation.

1. Open any editor, copy the lines below:

from rosbag import Bag
with Bag('first_modified.bag', 'w') as Y:
    for topic, msg, t in Bag('first.bag'):
        if topic == '/velodyne_points':
            Y.write('/velodyne_points', msg, t)
        if topic == '/imu_raw':
            Y.write('/gpsimu_driver/imu_data', msg, t)
        if topic == '/nmea_sentence':
            Y.write('/gpsimu_driver/nmea_sentence', msg, t)

2. Save the python code above, and run it by python. Make sure 'first.bag' file is in same directory.
3. Check 'first_modified.bag' is created in the same directory.

Change frame_id In IMU

In "first_modified.bag", the IMU topic's frame_id is "3dm_gx5_15", which will yield an error of "failed to transform". So, you should change the frame_id of IMU. I will introduce "bag_tools" to solve it.

First, install "bag_tools". The instuctions is here: http://wiki.ros.org/bag_tools

Then, run scripts in terminal :

rosrun bag_tools change_frame_id.py -o first_modified_imu.bag -i first_modified.bag -f /velodyne -t /gpsimu_driver/imu_data

The xxx_modified_imu.bag, which are modified for hdl_graph_slam, are saved to the "HumanDisk/Autoware_Data/190614_MappingData".