individualMarkersNoKinect does not publish in ar_pose_marker

asked 2018-01-13 13:02:29 -0500

mag.rod

58 ●13 ●15 ●23

updated 2018-01-20 12:11:26 -0500

jayess
6155 ●26 ●85 ●92

hello, I use ros kinetic and I downloaded the ar-track-alvar module, to read AR codes, and I want to determine how far they are. I use a usb camera of logitech and I have written the following launch file.

<launch>
    <node name="usb_cam" pkg="usb_cam" type="usb_cam_node">
        <param name="video_device" value="/dev/video0"/>
    </node>
    <node name="ar_track_alvar" pkg="ar_track_alvar" type="individualMarkersNoKinect" respawn="false" output="screen">
        <param name="marker_size" value="18"/>
        <param name="max_new_marker_error" value="0.08"/>
        <param name="max_track_error" value="0.2"/>
        <param name="camera_image" value="usb_cam/image_raw"/>
        <param name="camera_info"  value="usb_cam/camera_info"/>
        <param name="output_frame" value="head_camera"/>
    </node>
</launch>

The fact is that I show an image to the camera with an AR code and in the topic ar_pose_marker nothing is published.

Thanks for any help you can give me.

Comments

My launch file:

mag.rod ( 2018-01-19 04:23:48 -0500 )edit

mag.rod ( 2018-01-19 04:33:22 -0500 )edit

mag.rod ( 2018-01-19 04:44:32 -0500 )edit

I recommend designing your launch file on the example here. You have to specify the cam_image_topic and cam_info_topic names. Or the node doesn't receive any images.

PeteBlackerThe3rd ( 2018-01-19 06:23:32 -0500 )edit

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answered 2018-01-14 06:47:54 -0500

PeteBlackerThe3rd

flag of United Kingdom of Great Britain and Northern Ireland

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updated 2018-01-19 04:08:21 -0500

Hi There,

I have set this node up a few times. I think the problem you're having is that your camera doesn't have any calibration information associated with it. This will mean that the ar_track_alvar node has no lens model for your camera and therefore cannot determine the pose estimates of the AR tags.

If you have a look at the camera calibration node it will guide you through the process of calibrating your camera and getting the camera info messages published alongside the camera images.

When this is setup and working the ar_track_alvar node should start working as you expect.

update now that your camera calibration information is in the system there are two more things I think you need to check. The frame_id for your camera is still the default head_camera there needs to be a TF connection between this frame and the detection frame set in the launch file for ar_track_alvar or you can set them to the same frame_id to keep it simple. The other thing to double check is that the camera image and info topic names are set correctly in the launch file too.

You're very close now.

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I will investigate in this regard, thank you very much.

mag.rod ( 2018-01-15 12:29:49 -0500 )edit

No problem, let us know how you get on.

PeteBlackerThe3rd ( 2018-01-15 12:36:41 -0500 )edit

I have calibrated the camera and it still does not publish ar_pose_marker. Results after calibration:

mag.rod ( 2018-01-19 02:00:11 -0500 )edit

miguel@miguel-desktop:~$ rosrun camera_calibration cameracalibrator.py --size 11x7 --square 0.03 image:=usb_cam/image_raw camera:=usb_cam ('Waiting for service', '/usb_cam/set_camera_info', '...') OK QXcbConnection: Failed to initialize XRandr Qt: XKEYBOARD extension not present on the X server.

mag.rod ( 2018-01-19 02:14:14 -0500 )edit

libEGL warning: DRI2: failed to create any config

mag.rod ( 2018-01-19 02:15:27 -0500 )edit

raceback (most recent call last): File "/opt/ros/kinetic/lib/python2.7/dist-packages/camera_calibration/camera_calibrator.py", line 247, in on_mouse. if self.do_upload(): File "/opt/ros/kinetic/lib/python2.7/dist-packages/camera_calibration/camera_calibrator.py", line 204, in do_upload

mag.rod ( 2018-01-19 02:17:44 -0500 )edit

response = self.set_camera_info_service(info) File "/opt/ros/kinetic/lib/python2.7/dist-packages/rospy/impl/tcpros_service.py", line 435, in __call__

mag.rod ( 2018-01-19 02:20:30 -0500 )edit

return self.call(args, *kwds) File "/opt/ros/kinetic/lib/python2.7/dist-packages/rospy/impl/tcpros_service.py", line 495, in call

mag.rod ( 2018-01-19 02:21:18 -0500 )edit

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