# ROS2 Stereo View Fails And Stereo Image Proc Doesn't Show Anything

I have set up 2 Monocular Cameras as a stereo camera in ROS2. I successfully published the 2 rectified and calibrated images through the following formats:

/left/camera_info
/left/image_rect
/parameter_events
/right/camera_info
/right/image_rect
/rosout


AND

/parameter_events
/rosout
/stereo/left/camera_info
/stereo/left/image_rect
/stereo/right/camera_info
/stereo/right/image_rect


Then, I tried to make a disparity image by running this:

ros2 run stereo_image_proc disparity_node --ros-args --params-file disparity-params.yaml


NOTE: Here, I didn't know what to use for the disparity-params.yaml so I just made a blank file called that.

Then, I ran ros2 topic list and I saw the /disparity topic. To actually see the disparity, I ran ros2 run image_view disparity_view --ros-args --remap image:=/disparity but this never displayed anything, not even a blank window. There was also no command-line output.

Also, I tried using stereo_view from the image_view package to see if that works. I this:

ros2 run image_view stereo_view --ros-args --remap stereo:=stereo --ros-args --remap image:=image_rect


This gives me the following error:

terminate called after throwing an instance of 'rclcpp::exceptions::InvalidTopicNameError'
what():  Invalid topic name: topic name must not contain repeated '/':
'/stereo/left//image'


Is there anything I can do to fix this problem? Also, let me know if there is any other information you need.

Specs:

• Ubuntu 20.04 64 bit VM
• ROS 2 Foxy
• Monocular USB Webcams
• When I look at [the documentation](wiki.ros.org/stereo_image_proc), it looks like there are defaults for the parameters, so do you really need a blank file? What happens if you omit --params-file disparity-params.yaml from the command? If you follow along with a tutorial like this, at which step exactly does it fail? – Chuck Jun 1 at 19:06
• It doesn't fail, but a disparity never shows up. When I run image_view to see and tune the disparity it never opens a window or I get a black box and if I try to use stereo_view, then I get the error above. So in the tutorial, I fail when it says, "Now, you can view the DisparityImage using the disparity_view node: ros2 run image_view disparity_view --ros-args --remap image:=/disparity"" – DragonflyRobotics Jun 1 at 19:31