[Question] Simple base case USB camera

[kevinlinxc]

Hi, I have the Zed camera and I would like to use it with an existing Ros melodic Ubuntu 18.04 ROS workspace.

I want to be able to launch a launch file, and then be able to see the camera output on rqt_image_view. How can I achieve this?

Some more details:

• I have installed the ZED sdk and the CUDA dependency, although I do not have a GPU

• Running ZED Display shows the camera output (so it works) but that might not work with our networking infrasturcture, so rqt image view is kind of a litmus test for something that works for me.

• Running zed_display_rviz creates nodes, but the gui shows no images and the nodes are not readable by rqt_image_view, presumablny bceause they are not the right datatype

[Myzhar]

Hi @kevinlinxc have you installed the zed-ros-wrapper for this Github repository: https://github.com/stereolabs/zed-ros-wrapper?

[kevinlinxc]

Yes, my directory looks like this: ls catkin_ws/src/cameras/ zed-ros-wrapper zed-ros-examples

[Myzhar]

Hi @kevinlinxc , I'm really sorry, but I have missed this important fact in your first post: although I do not have a GPU. The ZED SDK cannot run without an Nvidia GPU running the CUDA processing and so the ZED ROS Wrapper cannot acquire any kind of information. The ZED_Explorer tool can run without a GPU because it does not require depth processing and the stereo module is disabled for it.

You can use the ZED with ROS without a GPU by writing your own wrapper for the ZED Open Capture driver that does not require CUDA to retrieve image streams and sensors data: https://github.com/stereolabs/zed-open-capture

[kevinlinxc]

I see, thank you. I'll give it a shot.

[kevinlinxc]

Alright, I copied and modified a usb camera launch file but it looks weird, and I think it's because there's two cameras. I'm wondering if you know how to fix this problem:

Launch file:

<launch>
  <arg name="videonum" />
  <node name="usb_cam$(arg videonum)" pkg="usb_cam" type="usb_cam_node" output="screen" >
    <param name="video_device" value="/dev/video$(arg videonum)" />
    <param name="image_width" value="640" />
    <param name="image_height" value="480" />
    <param name="pixel_format" value="yuyv" />
    <param name="camera_frame_id" value="usb_cam" />
    <param name="io_method" value="mmap"/>
  </node>
  <node name="image_view$(arg videonum)" pkg="image_view" type="image_view" respawn="false" output="screen">
    <remap from="image" to="/usb_cam$(arg videonum)/image_raw"/>
    <param name="autosize" value="true" />
  </node>
</launch>

Launch using roslaunch cameras camera_viewer.launch videonum:=2 where cameras is the node name, camera_viewer.launch is the launch file, and videonum is found via ls /dev/video*

Example picture:

[Myzhar]

@kevinlinxc Please do not reply to a closed issue. It's better if you create a new issue and you cite the closed in it with a link.

To use the ZED as a "simple webcam" I suggest you explore the ZED Open Capture driver... for example, you are using the wrong image resolution.