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eegkno / ustoolbox

Analysis of the spine from ultrasound images
MIT License
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Stylus calibration #8

Closed eegkno closed 6 years ago

eegkno commented 6 years ago

Generate the configuration file to perform the calibration of the stylus.

See the section Stylus calibration in: http://perk-software.cs.queensu.ca/plus/doc/nightly/user/ApplicationfCal.html

Simulation steps:

  1. Select the Device set named "TEST Simulation mode for Stylus calibration" from the drop-down box and click Connect
  2. Switch to Stylus calibration toolbox by clicking its tab on the left side of the application window
  3. Click Start button The simulation begins, the acquired points appear on the canvas on the right side as small blue dots. The green bar on the bottom shows the progress. When all the points are acquired, the calibration runs, and the results appear in the toolbox. Also, the stylus tip appears on the canvas as a green sphere, and the stylus is displayed. It moves around as the simulator feeds the new positions to it.
  4. The results can be saved by clicking on Save results button as a new XML file
  5. Go back to the Configuration toolbox and click Disconnect to make the new connection possible.
eegkno commented 6 years ago

Consideration if the error is > 1mm

Typical stylus calibration error is typically less than 0.5mm. If you have a higher error then check the followings:

  1. The tip of the stylus shall be sharp and should not move at all during pivoting
  2. The stylus shall be rotated in a large angle range as possible
  3. The stylus should not be moved quickly because most for trackers accuracy is lower if the tracked object is moving too quickly
  4. The pose marker should not be farther than a couple of centimeters from the tip of the stylus If an electromagnetic tracker is used then the pose marker on the stylus and the reference pose marker shall be well within the working range of the field generator and there should be no metallic object nearby that could cause field distortion. This includes surfaces such as tables that are supported using small metal beams
eegkno commented 6 years ago

A stylus of the size of 86mm was made. A small one allowed to keep close to the magnetic field, and the error was improved.

Also, an attachment was included in the sensor. This allowed to change the sensor from the stylus to the probe.

stylus

sensor