individualMarkersNoKinect with "non stable" camera doesn't work

[130s]

From @jnitsch on May 22, 2015 9:8

Hi,

I tried to detect AR tracks with a camera in an arbitrary pose using the node individualMarkersNoKinect. When turning the camera the position of the AR marker changed. When I moved and turned the AR marker, its pose change relative to the camera was alright. But its pose in the world was still wrong. When I put the arm in a position, so that the camera frame had nearly the same orientation like the base frame it seemed to work without any issues.

Is it possible that the transform towards the camera is missing? Or that the camera needs to be aligned the same way like the base frame?

The frames of the camera were published the right way. I am using Rethink Robotics robot Baxter and try to detect the AR track with its hand camera.

Best regards Julia

_Copied from original issue: sniekum/ar_trackalvar#56

[130s]

From @sniekum on May 22, 2015 13:52

Can you include your launch file? Also, what do you mean by "moved" -- with respect to which frame?

On Fri, May 22, 2015 at 5:08 AM, Julia Nitsch notifications@github.com wrote:

Hi,

I tried to detect AR tracks with a camera in an arbitrary pose using the node individualMarkersNoKinect. When turning the camera the position of the AR marker changed. When I moved and turned the AR marker, its pose change relative to the camera was alright. But its pose in the world was still wrong. When I put the arm in a position, so that the camera frame had nearly the same orientation like the base frame it seemed to work without any issues.

Is it possible that the transform towards the camera is missing? Or that the camera needs to be aligned the same way like the base frame?

The frames of the camera were published the right way. I am using Rethink Robotics robot Baxter and try to detect the AR track with its hand camera.

Best regards Julia

— Reply to this email directly or view it on GitHub https://github.com/sniekum/ar_track_alvar/issues/56.

[130s]

From @jnitsch on May 22, 2015 14:6

This is my launch file:

``` ```

about moving the camera: I turned Baxter's wrist only. But the camera is not situated in the middle of the wrist, so I changed the camera's pose and so its optical frame with respect to the base frame. But I think the parent of the hand camera frame is the wrist frame and this transform doesn't change, I think this is a static one.

[130s]

From @sniekum on May 22, 2015 14:21

I need to know what the values of those variable are (especially output_frame).

On Fri, May 22, 2015 at 10:06 AM, Julia Nitsch notifications@github.com wrote:

This is my launch file:

<node name="ar_track_alvar" pkg="ar_track_alvar" type="individualMarkersNoKinect" respawn="false" output="screen" args="$(arg marker_size) $(arg max_new_marker_error) $(arg max_track_error) $(arg cam_image_topic) $(arg cam_info_topic) $(arg output_frame)" / >

about moving the camera: I turned Baxter's wrist only. But the camera is not situated in the middle of the wrist, so I changed the camera's pose and so its optical frame with respect to the base frame. But I think the parent of the hand camera frame is the wrist frame and this transform doesn't change, I think this is a static one.

— Reply to this email directly or view it on GitHub https://github.com/sniekum/ar_track_alvar/issues/56#issuecomment-104668523 .

[130s]

From @jnitsch on May 22, 2015 14:23

Oh I am so sorry! (Copy paste error)

arg name="marker_size" default="5.0" arg name="max_new_marker_error" default="0.1" arg name="max_track_error" default="0.2" arg name="cam_image_topic" default="/cameras/right_hand_camera/image" arg name="cam_info_topic" default="/cameras/right_hand_camera/camera_info" arg name="output_frame" default="/right_hand_camera"

[130s]

From @sniekum on May 22, 2015 15:47

My guess is a TF issue. I'd switch the output frame to something stable like Baxter's torso and see if it complains about there not being an available transform.

On Fri, May 22, 2015 at 10:23 AM, Julia Nitsch notifications@github.com wrote:

Oh I am so sorry! (Copy paste error)

arg name="marker_size" default="5.0" arg name="max_new_marker_error" default="0.1" arg name="max_track_error" default="0.2" arg name="cam_image_topic" default="/cameras/right_hand_camera/image" arg name="cam_info_topic" default="/cameras/right_hand_camera/camera_info" arg name="output_frame" default="/right_hand_camera"

— Reply to this email directly or view it on GitHub https://github.com/sniekum/ar_track_alvar/issues/56#issuecomment-104672943 .

[130s]

From @jnitsch on May 22, 2015 15:56

I tried it also with the output frame base (also a stable one) and it didn't complain about not an available transform.