Configure Vicon optical cameras for data capture

As part of setting up your Vicon system, you must specify the required settings for Vicon optical cameras. To do this, you use the Vicon Cameras node in the System Resources pane. You can configure the settings for an individual camera, several cameras, or all cameras at once.

The Vicon Cameras node is displayed under the Local Vicon System node when Vicon Nexus is connected to a Vicon system and is in Live mode. It is displayed under the Vicon Data node when Nexus is in Offline mode. It lists each Vicon optical camera connected to your Vicon system. For each camera, the node name includes the device position number, any display name specified in the Identification property, and the camera type in parentheses, for example, #1 Over Door (Vantage 16)

If you are setting up a mixed camera system (that is, a system that includes both Vicon MX T-Series cameras as well as other current Vicon cameras), see also Set up mixed Vicon camera systems.

To configure Vicon optical cameras for data capture:

1. Ensure Vicon Nexus is in Live mode. If it is not, in the Resources pane, click Go Live.

2. To visualize your capture volume, from the view pane menu, select Camera.

   

3. In the System Resources tree, select the node(s) for the camera(s) whose properties you wish to configure, either:
   
   • Vicon Cameras node for all Vicon cameras
     or
   • A sub node for a specific Vicon camera. The camera sub-nodes on the System tab correspond to the Names you set in the Properties pane (see below).
     Note that If no Lock+ or MX Giganet is present in the Vicon system, the sub-node for the Vicon camera acting as the synchronization master is displayed in bold.
     When a camera is selected, a blue status light on its strobe unit lights up.
   Tip: In many cases, it is best to start by selecting all of the cameras, to find a common baseline. You can then adjust individual cameras as required.
4. In the capture volume, have someone wave the calibration wand and ensure that you can see marker images moving in the Camera view.
5. In the Properties pane at the bottom of the System tab, click Show Advanced to show additional properties.
   When you first set up your Vicon system, configure the following camera properties in the order shown. (If you are not sure what a particular setting means, you can display a tooltip by hovering the mouse over the relevant field or control):
   Identification section:
   • Name (If you wish to distinguish it from the other cameras)
   Settings section:
   
   • Strobe Intensity In most cases, keep its default setting (1). However, if your Vicon system consists of a mix of MX T-Series cameras and other current Vicon cameras, and if it is crucial to your work that the shutter periods for all are precisely aligned, ensure that your firmware is upgraded to version 700 or later, and set the Strobe Intensity for the T-Series camera(s) to the maximum. For more information, see Set up mixed Vicon camera systems.
   • Gain Only adjust this setting if the markers appear too faint or the cameras have trouble distinguishing them; otherwise, leave at its default setting (x1). Vicon does not recommend using a setting higher than x2.
   • Grayscale Mode This setting determines what data is sent from the camera to the computer. Ensure this is set to the default setting (Auto) for capturing data. If the camera recognizes a blob as a circle, only centroid data is sent. If the camera cannot distinguish the blob as a circle, full grayscale data is sent so that Nexus can attempt to circle-fit the blobs. Circle fitted markers are displayed as crosshairs in the Camera view.
   Centroid Fitting section:
   
   • Threshold This setting differentiates between markers and ambient light. A value in the region of 0.2 (the default) to 0.5 is usually appropriate, but Vicon strongly recommends that you view static markers in the volume to establish an appropriate setting. If cameras are evenly spaced around the volume, the same Threshold value is usually sufficient for all cameras.
   • Minimum Circularity Ratio The circularity threshold used by the centroid-fitting algorithms in a Vicon camera to fit centroids to grayscale blobs. The higher the value, the more stringent the centroid fitter is. For camera calibration, you may wish to apply higher settings to ensure that the Vicon system selects the best markers and thus provides the best possible calibration. For data capture, a lower value may be appropriate. When a blob is fitted with a centroid, it is represented by crosshairs. The default setting is 0.5.
   Tip: If adjusting these settings does not easily enable you to eliminate reflections, create camera masks to eliminate reflections and other unwanted light sources that occur in parts of the capture volume. For information on masking, see Mask unwanted reflections.
   Centroid Tracking section:
   • Enable Centroid Tracking Tracking 2D camera centroids provides extra information that maintains marker labels in real time when only one camera can see a marker. When enabled, the 2D track calculations are performed by a camera's onboard sensors. When disabled, the 2D track calculation is performed by the PC (in Nexus). The default is off.
   • Marker Velocity Maximum velocity at which a marker will be tracked, expressed as the percentage of image width per second. The default is 5.
6. When you have finished adjusting the Vicon Cameras settings, in the Settings section, ensure that Grayscale Mode is set to Auto.

7. At the top of the System tab, click the Save button to save your system configuration settings to a .system file in the Systems Configurations folder (see Manage configurations in Vicon Nexus).

   

Set up mixed Vicon camera systems

Vicon Nexus (version 2.4 and later) enables you to run mixed Vicon camera systems consisting of Vicon Vero cameras (v1.3 and v2.2), Vicon Vantage cameras (V5, V8, V16) and/or MX T-Series cameras (T10, T20, T40, T160, or S Edition) and Bonita Optical cameras (B3, B10). You can also use Vicon Vue and Bonita Video cameras in the same mixed system.

For systems involving only Vero, Vantage and Bonita cameras, the shutter period characteristics for all cameras match exactly. Irrespective of individual cameras' strobe (shutter) settings, the center alignment of these periods in any Vero/Vantage/Bonita camera in the same system align exactly. You do not need to make any adjustments to ensure that this alignment occurs.

However, for systems involving Vicon MX T-Series cameras, depending on your requirements (see When are differences in strobe timings important?), you may need to make some manual adjustment (see the following steps).

Due to the differences in strobe timings between the current Vicon cameras (Vero, Vantage and Bonita cameras) and the MX T-Series cameras, in situations where very small timing differences are considered to be relevant and greater than other accepted limitations (such as skin movement artifacts), ensure that the camera strobe periods match by setting the Strobe Intensity for the MX T-Series camera(s) to maximum as described below.

To obtain consistent strobe timing and sensor exposure in mixed camera systems that include T-series:

1. In the System Resources tree, select the MX T-Series camera(s).
2. In the selected camera's Properties pane, in the Settings section, ensure the Strobe Intensity is set to its maximum.

This ensures that the center of the strobe pulse and shutter period for the Vero/Vue/Bonita cameras matches that of the MX T-Series cameras.

When are differences in strobe timings important?

In situations where very small timing differences are considered to be relevant and greater than other accepted limitations (such as skin movement artifacts), ensure that all the camera strobe periods match by setting an appropriate value in the Strobe Intensity for the cameras you are using. If all cameras are of the same type, this value is the same for all cameras, but for systems that include both T-series and other current Vicon cameras, set the TSeries' Strobe Intensity to its maximum, as described above. Situations that may warrant this consideration include studies where very fast ballistic movements are expected and/or where very small markers are likely to be in close proximity.