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How to use Autoware's lidar_camera extrinsics

asked 2020-11-23 13:35:22 -0500

updated 2021-01-03 23:24:13 -0500

I am following the readme autoware.readthedocs.io and have performed the intrinsic calibration and also the extrinsic calibration successfully and left with a file similar to YYYYmmdd_HHMM_autoware_lidar_camera_calibration.yaml.

The docs in the end mention "This file can be used with Autoware's Calibration Publisher to publish and register the transformation between the LiDAR and camera. The file contains both the intrinsic and extrinsic parameters."

However, I am not sure how to use this file. The calibration_publisher uses only the intrinsics file. Where and how is the extrinsics file used? Do I just replace the intrinsics file path with the extrinsics file path? I intend to register the lidar2camera_tf.

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answered 2021-02-25 07:28:59 -0500

pedroexe gravatar image

updated 2021-02-25 08:43:30 -0500

The extrinsic parameters should be with the intrinsic parameter in a single file if you follow the instructions here. The structure of the file should be like this one, but with your specific calibration data.

The calibration publisher node will read the extrinsic parameters and register a transform between the camera and lidar coordinates with it.

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Thanks! I will try this out and give you an update.

Akhil Kurup gravatar image Akhil Kurup  ( 2021-02-26 15:43:59 -0500 )edit

Hi @Akhil Kurup,

Could you calibrate it correctly?

Thiago de Borba gravatar image Thiago de Borba  ( 2021-05-28 04:40:53 -0500 )edit

Not yet! My project and priorities have changed and I am unable to spend time with it

Akhil Kurup gravatar image Akhil Kurup  ( 2021-05-28 11:11:23 -0500 )edit
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Thanks for the clarification @pedroexe! It works now. My issue was with topic names. After fixing those, I can see a "calibrated" link between the lidar and camera on the tf tree

Akhil Kurup gravatar image Akhil Kurup  ( 2021-05-31 12:58:56 -0500 )edit

@Thiago de Borba I got it to work now. As I mentioned, the tools were performing normally. My issue was with topic names and namespaces

Akhil Kurup gravatar image Akhil Kurup  ( 2021-05-31 13:00:52 -0500 )edit

But for me the calibration extrinsics is complelty wrong. Is it working fine for you?

Thiago de Borba gravatar image Thiago de Borba  ( 2021-06-01 01:20:23 -0500 )edit

Ahh yes! With help from @djchopp here are a couple lessons learnt:

  1. The transform generated is from lidar_frame -> camera_frame. So make the appropriate change in the launch file.
  2. When you select points in RViz, it publishes to the /clickedpoint topic in your global fixed frame in rviz. What I did was to change it to the lidar_frame before selecting points. That way, the generated extrinsics were relative to the lidar.
  3. After all is said and done, be sure to change the camera_frame to the newly published calibrated_frame in the camera launch file.
Akhil Kurup gravatar image Akhil Kurup  ( 2021-06-01 09:03:55 -0500 )edit

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Asked: 2020-11-23 13:29:31 -0500

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Last updated: Feb 25 '21