ROS Resources: Documentation | Support | Discussion Forum | Index | Service Status | ros @ Robotics Stack Exchange
Ask Your Question
1

What are the information represented by echo the topic of camera_info and image_raw?

asked 2021-12-06 21:48:26 -0500

aash gravatar image

Hi, I am using a multi camera plugin with SDF and the left and right images are published well in Rviz2. I wish to know the depth/distance of the object from the camera based on the images produced hence I try to echo the topic of camera_info and image_raw. For camera_info, I get: d : - 0.0 - 0.0 - 0.0 - 0.0 - 0.0

k: - 476.703... - 0.0 - 400.5 - 0.0 - 476.703... - 400.5 - 0.0 - 0.0 - 0.0 - 1.0

r: - 1.0 - 0.0 - 0.0 - 0.0 - 1.0 - 0.0 - 0.0 - 0.0 - 1.0

p: - same as k

while for image_raw topic, i get number range from 153 to 158.

May i know what are all these information means? And how can I use these information for my purpose to identify the distance of object?

Thank you in advanced.

edit retag flag offensive close merge delete

1 Answer

Sort by ยป oldest newest most voted
1

answered 2021-12-29 03:11:47 -0500

rodrigo55 gravatar image

Hi, there are three main topics advertised in most RGBD cameras:

  • camera_info displays information related to the camera itself, like the size of the image and those parameters that "calibrate" it
  • image_raw is the image itself, like the name suggests. Each number corresponds to pixel intensity
  • depth/points is the one you are interested, as it displays the distance for each reading. You can also view this topic in rviz

If you want, I made explaining the topics from a depth camera: https://youtu.be/G0U-s0KOqa0

edit flag offensive delete link more

Comments

Hi thank you so much for the explanation video. May I know what is the plugin that you're using in the video?

aash gravatar image aash  ( 2021-12-29 04:33:25 -0500 )edit

Question Tools

2 followers

Stats

Asked: 2021-12-06 21:48:26 -0500

Seen: 475 times

Last updated: Dec 29 '21