In addition to the preparations described in Prepare your Vicon Evoke system, depending on your requirements, you may also want to make the following changes listed in this section.

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For information on customizing Evoke and changing the way the panels are arranged, see Customize views and layouts.

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Change camera settings

The default settings for Viper cameras are suitable for many typical usage scenarios. Viper cameras are sensitive to the infrared light emitted by the Pulsar marker LEDs. They are factory-configured with the aperture set to F8 and back-focused to a depth of field 0.8m to ∞. No additional hardware setup is required on site, however, in some circumstances (eg, if you have a small volume with little IR noise) you may benefit from adjusting the Threshold setting in the Processing panel in Evoke.

Note
When using the Viper cameras' tap-to-select feature, note that taps that are also registered by other cameras mounted nearby are ignored. To minimize the effects of vibrations on the rigging, tap lightly.

Change the auto-save interval

Evoke settings are automatically saved while you're using Evoke, as well as when you exit.

The interval at which Evoke saves your settings is determined by the Auto-save interval, a setting in the Preferences panel.

All auto-saved files except preferences and subject view preset files are located in this folder:

C:\Users\Public\Documents\Vicon\Evoke1.#\LastRun\username

Preferences and subject view preset files are located in this folder so that they are available between Evoke versions:

C:\Users\Public\Documents\Vicon\Evoke1.x\username

To change the interval at which files are auto-saved:

On the Settings menu, click Preferences (or press Shift+P) to open the Preferences dialog box.
In the User Preferences, go to the General section and change the value in the Auto-save interval field from the default (60 seconds).

Note
If you have system settings that you are likely to re-use, we recommend saving them by clicking System Settings

at the top right of the Evoke toolbar, selecting Manage and then clicking the Save button, rather than relying on the auto-save feature.

To find out more, see Auto save in the Vicon Evoke Reference Guide.

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Reduce processing rate for large numbers of objects

Normally, when the system is heavily loaded, to avoid dropping frames, you must reduce the system frame rate. When the (Advanced) option Halve Processing Rate is selected in the Processing panel, you can keep the system frame rate high, but reduce the rate of subsequent processing (eg, object and character tracking). A high frame rate may improve tracking quality (particularly for fast movements) while subsequent processing is reduced, lowering processing load requirements on the host PC.

When using the Halve Processing Rate option, note the following points:

2D centroid detection always happens at the system frame rate
Subsequent processing depends on whether Halve Processing Rate is selected or not:
- When cleared (the default), every frame is processed as normal
- When selected, every other frame is dropped (giving a tracking rate of 1:2)
When using the Datastream, if Halve Processing Rate is selected, dropped frames occur at every other frame.
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Use High Speed mode for Vicon Vantage cameras

When your system is upgraded to the latest firmware (Firmware 725 and later), Evoke enables you to use High Speed mode with your Vantage cameras without having to change the field of view (FOV) or lens. When you capture optical data, subsampling (selectively reducing the pixel count) enables you to run at high camera frame rates without reducing the FOV (frame size). You can change frame rates during capture and you don't need to set up your cameras again when you increase the frame rate, as the FOV is unchanged.

Note that because the higher speeds are achieved through subsampling (removing some pixels from the frames), some reduction in resolution is incurred. For details, see High-speed mode in the Vicon Vantage Reference Guide.

To select high-speed mode:

At the top of the System panel, set the frame rate to the speed you want to use in High Speed mode.

A warning may temporarily be displayed, alerting you to the discrepancy between the requested frame rate and the actual system frame rate, until you select high speed mode for all the relevant cameras, as explained next.
In the System tree, select one or more cameras.
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In the Properties pane below, ensure the Advanced properties are displayed and in the Optical Setup section, click the Sensor Mode list and select High Speed.

In the Cameras view in the Workspace, notice that the High Speed mode icon is displayed to the right of the other information about the selected camera(s).

After a few moments, the system runs at the new speed.

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