Internal:SOGP Instructions

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Contents

sogp

Dependencies

  • ros_cpp
  • std_msgs


Making

 rosmake sogp

The *sogp* package contains the newmat and sogp libraries. It builds these libraries locally in the sogp directory.


Running

To run code that does the regression and predicts new values

rosrun sogp sogp_regress

However, before you can run sogp_regress you must set several parameter values. Here's a set of parameter values and the roslaunch code for setting them to example values.

 <param name="sogp/width" type="double" value=".2"/>
 <param name="sogp/capacity" type="int" value="300"/>
 <param name="sogp/noise" type="double" value=".1"/>
 <param name="sogp/inputDimension" type="int" value="6"/>
 <param name="sogp/outputDimension" type="int" value="5"/>

Additional parameters which you can set specify file names for saving a trained sogp or loading an existing sogp save file, for example

 <param name="sogp/saveFile" type="string" value="$(find naoInvKinematics)/SOGP.txt" />

or

 <param name="sogp/saveFile" type="string" value="$(find naoInvKinematics)/SOGP.txt" />


Messages and Services

  • sogp* listens to for training the function regressor, accepting single datapoints or matrices of data points respectively.

ar/image contains the image with the tags outlined in the image

If the camera image is a rectified one with appropriate camera parameters, *ar_recog* will use them to determine the mapping between image space and physical space. However, the rectification pipeline is slow and camera calibration brittle, so the package also provides distance mapping with uncalibrated images. To use this feature, it must know your camera's horizontal angle of view. This can be provided as a ROS parameter ("aov"), or determined using the CalibrateDistance service.

  • ar_recog* defines two message types:

Tags:


and

Tag:



Calibrating Distance

  • This is only necessary when _not_ using a calibrated camera.*
 # Set up a clear, recognized AR tag at a known distance from the camera.
 # Start the *ar_recog* node and monitor the /tags message
 # Arrange the AR tag and camera so that the tag coordinates are as close as possible to the center of the image, and the xRot, yRot and zRot are as close as possible to zero. This will minimize distortion.
 # Call the CalibrateDistance service, where _dist_ is the distance between the AR tag and the camera in millimeters: 


Tips

 # The more accurately the distance is known, the better *ar_recog* is able to undistort the image. Thus you may have to repeat the service call a few times until the reported distance converges on the value you are providing.
 # Save this aov value to provide as a ROS parameter next time you use *ar_recog* with this camera. 


ARToolKit Compatibility/Interoperability

  • ar_recog* is compatible with standard ARToolKit pattern and object_data files. When not used with ROS's image_proc, *ar_recog* utilizes an ARToolkit camera_para.dat file. See the files within the `bin` directory and the ARToolKit documentation.