Calibrate selected cameras

WIth Shogun 1.6 and later, you can mask and calibrate or recalibrate multiple selected Vicon optical cameras or Vicon Vue video cameras, as well as supported third-party video cameras, without having to completely re-calibrate the whole system.

Any cameras that are not selected are locked, so that any existing calibration is unaffected, and the global coordinate system is maintained.

To add new cameras to a calibration:

1. Connect the new cameras into the Vicon Shogun system that contains the calibrated cameras.
2. In the System panel, select the new cameras that are not yet calibrated (indicated by a cyan icon).

   

3. Instead of masking all the cameras, on the Camera Calibration tab, in the Masking section, ensure the advanced options are displayed and clear the Clear Previous Masks check box.

   This prevents your original masking from being overwritten.

4. To add the new masking to selected cameras only, in the Masking section, click Selected.

   The Selected button now displays Stop and Auto Mask Active is displayed at the top of the Workspace.

   

5. When the cameras are masked, click Stop.
6. In the same way, with the new cameras still selected, in the Calibration Wave section, select Selected and, with Auto Stop selected, wave the wand for just the selected cameras and wait for the calibration to finish.

You don’t need to re-set the origin as the world coordinate system remains valid.

SDI lens calibration example

You can use Shogun Live's ability to calibrate selected cameras to add an SDI camera to your system.

With Shogun Live, you can obtain the camera extrinsics (the camera position relative to the world) and the intrinsics (information about the lens, such as its focal length and radial lens distortion). As this enables you to accurately overlay 3D data onto the 2D data, it provides a quick way to assess the quality of the calibration.

To add an SDI camera to a calibration:

1. Connect the SDI camera into a Blackmagic Decklink card on the PC that is part of a Vicon Shogun system.

   It is displayed as Decklink in the Video Cameras section of the System panel.

   

2. Select Decklink to display the video stream.

3. As in Calibrate selected cameras, mask the selected additional camera and complete a wand wave for it.

   Tip: When waving the wand for the new video camera, bear in mind that you also need several other optical cameras to be able to gain enough information from the wand wave to be able to position the additional camera within 3D space successfully. You may find that holding the wand at an angle may give a better result.

   When the wand wave is complete, the SDI video camera is calibrated and added into the existing calibration. It is displayed in the 3D View.

   Because the calibration has provided extrinsics as well as intrinsic data about the camera, you can accurately overlay 3D data on top of the 2D data. This gives a quick way of assessing the quality of the calibration as, using the 3D Opacity control in the View Filters, you can see how closely the 3D image matches the 2D data beneath.

   

   Because this process is so fast and consistent, you can make changes the lens (eg, use a different focal distance) or even swap it entirely and produce a new calibration very quickly.