To configure your Vicon Vantage system, complete the following steps:
Ensure you are in Live mode and that a Camera view is displayed.
In the System Resources pane, select one camera.
Notice that the Properties for this camera are listed at the bottom of the pane.
Have someone wave the calibration wand in the capture volume and ensure that you can see markers moving in the view pane.
Note the Grayscale Mode property. The default setting is Auto, which tells the cameras to send to the Vicon software all the centroid data for grayscale blobs it can circle fit. If any grayscale blobs cannot be circle fitted, the grayscale data is sent to the Vicon software so it can try to circle fit the blobs.
Look at the Strobe Intensity setting. With a value of 1, the cameras send as much light as possible into the volume.
Zoom in to a marker by right-clicking and dragging the mouse. Notice how the pixels change as you lower the light (to view pictures from a grayscale blob, Grayscale Mode must be set to All).
Notice the Threshold property. It tells the camera how bright a pixel must be to be accepted by the camera. Zoom in to a marker and notice how the pixels change as you adjust the property.
Adjust the Strobe and Threshold settings so that you see only the 2D circular-shaped markers in your volume. Adjust the Strobe Intensity setting only as low and the Threshold only as high as needed.
Set camera focus and aperture
Place three markers in the middle and on the far side of the capture volume.
Leaving the focus on infinity (∞), close the aperture to as high an f-stop value as possible, so that you can still see the markers at the furthest distance required.
In general, it’s better to run with a low Threshold setting and more closed aperture, than a high Threshold and open aperture. (See Threshold in Adjust camera settings.)
The illustration (right) shows the focus and aperture rings on a Vicon 18 mm lens.
For each camera, turn the aperture ring (the ring with the f-stops) until the aperture is fully open. Later you will turn the ring back, increasing the f-stop number and closing the aperture.
In the System Resources pane, select all the cameras by Shift-clicking. In the Properties section at the bottom of the window, change Grayscale Mode to All.
In the System Resources pane, select a camera. For each marker:
In the view pane, zoom in to the center of the marker.
Vantage cameras are supplied pre-focused for typical motion capture use, so in most situations, no focusing is necessary. The following step (b) is applicable only if you need to re-focus the camera, otherwise, go straight to step c.
- If required, turn the camera focus ring (shown in the previous illustration) until the 2D image of the marker in the view pane is clear and sharp. As you rotate the focus ring, note that the marker images get smaller and then begin to get larger again. Good focus is when the marker is at its smallest size.
- Observe that, with the aperture fully open, the markers appear fully saturated, with very little grayscale gradation and some merging, as in the following image.
Adjust the aperture ring to change the amount of light that hits the image sensor. Turn the aperture ring to close the aperture and obtain good, clear images of markers even when they are close together.
If you turn the aperture ring too far, until the aperture is almost closed, the markers appear very small, lack any bright grayscale pixels and the circle-fitting is poor, as shown below.
Adjust the aperture ring so that the markers are not too small, and the center is just off-white (not fully saturated) when viewed from the middle of the volume.
Repeat Step 5 for each camera.
When you are happy with the focus and aperture, to prevent the rings from moving if the camera is knocked, tighten the locking screws.
To avoid damaging the rings, do not over-tighten the locking screws.
Select all of the cameras and change the Grayscale Mode property back to Auto.
Mask unwanted reflections
From the capture volume, remove any unnecessary objects, such as the calibration device, markers, or other objects likely to cause reflections.
Make sure Camera view is displayed. In the System Resources pane, select all cameras.
In your Vicon software, click Start:
- Nexus: System Preparation Tools pane > Mask Cameras section
- Tracker: Calibrate tab > Create Camera Masks section
- Shogun Live: Camera Calibration Tools pane > Wand section
After a few seconds, when all reflections appear to have been covered, click Stop.
If you still see unwanted reflections, you can start and stop camera masking again until you are satisfied.
Alternatively, use the Manual Camera Masking tools.
Calibrate the cameras
You calibrate the cameras to enable the cameras to capture subject movements throughout the volume.
You can also set the volume origin and orientation of axes in relation to the capture volume and to one another.
To calibrate your Vicon Vantage cameras, use the supplied Vicon calibration device.
Remove from the capture volume any unnecessary objects, such as calibration objects and markers.
In your Vicon application software, ensure the following are selected:
- All the cameras
- The calibration device you will be using
- An appropriate number of Refinement Frames
- Auto Stop
In the Calibrate Cameras section, click Start.
Make sure Ensure that the tracks are evenly distributed throughout the volume. You can view Check the distribution of the tracks in the view pane.
When all cameras have captured the number of frames set by the Refinement Frames option, the calibration stops.
Additional information about setup, calibration and object tracking can be found in the online help of your Vicon software.