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Hi,

My knowledge of ROS/Linux is limited, so I'm hoping someone could kindly help me.

I am using Virtual Box running Linux 14.04, and ROS Indigo.

I am trying to use a dual camera setup in order to obtain stereo vision via ROS. The cameras are on this USB module that I can access, and when I try to open it in Windows, I see the cameras as two different devices. I can also see them as two video devices on my VM.

ls /dev/video*

/dev/video0 /dev/video1

However, both cheese nor GTK UVC video viewer was unable to open the device. Cheese says "There was an error playing video from the webcam" even though I can see the device being selected in its Preferences. GTK UVC just captures blackness.

I also tried to use cv_camera but that did not give me a launch file to use. So I tried libuvc_camera but that also didn't give me a launch file.

I basically did these and not sure how to go from there, without a launch file:

sudo apt-get install ros-indigo-cv-camera

sudo apt-get install ros-indigo-libuvc-camera

I don't know how to get them to work. I then tried to do the same with the usb_camera package, which has a launch file:

roslaunch usb_cam usb_cam-test.launch

But when I used the launch, I get these errors:

setting /run_id to e42f368a-4a2b-11e6-a2c1-08002755c1aa

process[rosout-1]: started with pid [11222]

started core service [/rosout]

process[usb_cam-2]: started with pid [11236]

process[image_view-3]: started with pid [11240]

[ INFO] [1468546306.052415844]: Using transport "raw"

[ INFO] [1468546306.480381780]: using default calibration URL

[ INFO] [1468546306.480561586]: camera calibration URL: file:///home/max/.ros/camera_info/head_camera.yaml

[ INFO] [1468546306.480649985]: Unable to open camera calibration file [/home/max/.ros/camera_info/head_camera.yaml]

[ WARN] [1468546306.480709246]: Camera calibration file /home/max/.ros/camera_info/head_camera.yaml not found.

[ INFO] [1468546306.480765315]: Starting 'head_camera' (/dev/video0) at 640x480 via mmap (yuyv) at 30 FPS

[ERROR] [1468546306.742666755]: VIDIOC_STREAMON error 5, Input/output error

[usb_cam-2] process has died [pid 11236, exit code 1, cmd /opt/ros/indigo/lib/usb_cam/usb_cam_node __name:=usb_cam __log:=/home/max/.ros/log/e42f368a-4a2b-11e6-a2c1-08002755c1aa/usb_cam-2.log]. log file: /home/max/.ros/log/e42f368a-4a2b-11e6-a2c1-08002755c1aa/usb_cam-2*.log

Basically 1) I don't know if my webcam is actually connected and 2) I don't know how to use the packages that might help me extract the camera data (let alone stereo data). I know I need to do camera calibration at some point, but I thought libuvc_camera is the best option for that.

I'm very stuck, so any help is appreciated. Thank you.


Originally posted by QCBKoala on ROS Answers with karma: 11 on 2016-07-14

Post score: 0

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1 Answer 1

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Hi, I'm doing the same thing as yours. I have successfully use ucv_camera as camera driver with a launch file below:

mono.launch (use to open one camera)

<launch>
    <group ns="camera">
        <node pkg="uvc_camera" type="uvc_camera_node" name="mycam">
            <!-- Parameters used to find the camera -->
            <param name="device" value="/dev/video0"/>
        </node>
     </group>
</launch>

stereo.laumch (open two camera)

<launch>
      <group ns="stereo">
           <node pkg="uvc_camera" type="uvc_stereo_node" name="mycam">
           <!-- Parameters used to find the camera -->
           <param name="left/device" value="/dev/video0"/>
           <param name="right/device" value="/dev/video1"/>
           <param name="width" value="640" />
           <param name="height" value="480" />
           </node>
      </group>
</launch>

You can set other parameter as well.

And use image_view to check if driver works.

Hope this hlep you.


Originally posted by ponsheng with karma: 106 on 2016-08-02

This answer was ACCEPTED on the original site

Post score: 2


Original comments

Comment by QCBKoala on 2016-08-02:
It seems to have worked, with some modifications and in combination with another package. Thanks :)

And I spent all day today trying to extract depth data using the stereo images - with little success. If this is similar to what you're doing, do you think we can share notes? Thanks!

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