Vicon Calibration

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Vicon Calibration: How to calibrate the vicon system.

In this tutorial you will learn

  • How to move and place the MX-F40 cameras
  • How to calibrate the Vicon system
  • How to set the point of origin for the 3D space.

Moving and Placing the MX-F40 Cameras

One main goal of camera movement/placement is to cover the active area that you would like to track using as many cameras as possible. In general the more cameras that can see the reflective markers the better.

Camera movement is composed of the following steps

  1. Good camera placement can be achieved by placing a few reflective markers along each corner of the display. For example, place 1 marker one corner, 2 in the next, then 3, and 4 for the last corner. Also, place your calibration wand (5-Marker wand) on the display surface.
  2. Position each camera so that they can rougly see all of the markers.
  3. Make sure that each camera is plugged into the MX Ultranet and that it is turned on.
  4. Start the Vicon Nexus software on the host computer.
  5. On the left system sidebar, select the first MX-F40 camera. Notice that a blue LED appears on the selected camera.
  6. Go to the perspective window and change the view from perspective to camera, you are now seeing what the camera sees.
  7. Adjust the view of the camera with the blue LED until the camera can see all of the reflective markers.
  8. Repeat steps 5-7 for each camera.
  9. Now select all of the cameras in the left system sidebar, notice that there might be bright white circles in the camera views. This could be the LED rings or reflections from other MX-F40 cameras. These need to be removed so we don't acidentally track these blobs as points in the system.
  10. Click on the pen tool and draw out all of the white rings in your view. You can reset the drawings using the eraser or X button.
  11. Calibrate the Vicon System

Calibrate the Vicon System

Once you've moved the cameras into the apropriate location, the next step is to calibrate the cameras. This is a good opportunity to evaluate the quality of the camera placement in the previous step. This step is short and should be repeated every day or every few days of use as the cameras may shift over time.

Use the following procedure to calibrate the Vicon system

  1. Remove any visible markers and place the 5 marker mini calibration frame in the view of all cameras.
  2. In the Vicon Nexus software click on the Calibrate MX-Cameras button on the right task panel. The orange lights on the MX-F40 cameras will begin to flash slowly. This represents it's progress in the calibration process.
  3. Pick up the mini calibration frame and move it around the space that people will be using the system. The orange lights will flash faster until they are finished and a green light appears. Ideally all MX-F40 will turn green at approximately the same time. Cameras that take a long time to turn green are not calibrating correctly and should be moved/repositioned.
  4. Look at the right task panel, there should be a green bar that indicates the progress of the calibration processing. When it is finished check the accuracy values of each camera in the right task panel. They should all be under or around .30 and green in colour. If they are not then those cameras should be moved/repositioned.
  5. You are now finished calibrating, set the volume origin.

Set the Volume Origin

When calibration is completed the 3D perspective view should reveal the cameras placed in an odd location in the 3D space. This is because the position of Camera 1 has been selected as the point of origin for all cameras.

If you would like to define your own Volume Origin following the next few steps.

  1. Place the Mini 5-marker L-Frame on the location that you would like to set as (0,0,0). Please note the 0 point is taken from the base of the L-Frame at the intersection of the T.
  2. Make sure that the Vicon Nexus software is not set to track any objects in the left system panel.
  3. Click the Set Volume Origin button on the right task panel. This gets the system ready to look for a mini 5-marker L-frame.
  4. Click the Set Volume Origin button again to set the new origin.

From this point on all coordinates are relative to the new volume origin set by the mini 5-marker L-frame position.