System Structure

System setup © Phoenix Technologies, 2015

Marker System

The Marker System powers the markers and makes each marker uniquely distinguishable from another to eliminate any marker ID swapping problem.

Sensor System

The Sensor System controls the marker system to turn on the markers in the user-desired sequence, captures the position of each marker, and transmits the marker data to the host computer. It may consist of a single tracker (‘single-tracker system’) or multiple trackers (‘multi-tracker system’ or MTS).

Single-Tracker System

This is the most basic Visualeyez motion capture system. It is useful for simple motion capture and measurement applications typical in many scientific projects as well as relatively simple entertainment applications such as facial expression capture.

Multi-Tracker System (MTS)

When motion capture from multiple views is required, such as simultaneous complex full-body motion capture, a multi-tracker system is normally required. The trackers in a MTS continue to operate independently, however the user normally expects the captured data to be expressed in terms of a user-defined view (‘coordinate reference frame’). To accomplish this, the multiple trackers must first be physically ‘calibrated relative to each other’, and the multiple data streams they generate must be combined (‘fused’) together to become a single stream expressed in the user-desired view. These functions are carried out by the system Software.

Software

The system Software allows the user to setup and control how the system operates, how to manage a multi-tracker system, how to deal with marker occlusion, process the captured data, generate the user-desired information and stream the final results to other application software in real-time or offline via numerous plugins. Currently, plugins are available for many software including:

Matlab, LabView, Visual3D, VRCO, VRPN, Quest 3D
3D Max, Maya, MotionBuilder, Softimage, Famous 3D.

System Features

Huge capture space

Motion capture range © Phoenix Technologies, 2015

Each Visualeyez system tracker can capture over a huge 190m3 space. This is due to its widest angle operation of all optical motion capture systems in the world (see Specifications). As a result, a 4-tracker system can be easily arranged to yield almost 6m x 6m full-body capture space.

Fully automatic calibration

By using the recently released VZAutoCal, even a multi-tracker Visualeyez system is now fully automatically calibrated. No manual user calibration effort is required any more. Should any tracker gets bumped or moved during a capture, just wait for a second or two, and the system will recover the calibration by itself!

Continuous adaptive calibration

VZAutoCal will also update the system calibration continuously if the user so chooses. It will make use of the data captured during a session and optimize the system calibration at intervals chosen by the user. The updating can be stopped at any time by the user if desired.

Set up in any way you like

Positioning the system © Phoenix Technologies, 2015

Visualeyez systems do not require any strobers or ring-lights to sense the marker positions. The trackers can face each other without causing any blinding problem! Hence the system can be laid out and oriented in any way to capture the desired motions. For example, the chest motions can be captured even when a person is bending down by simply laying a tracker on the ground and pointing up at the chest area.

Easy operation

It’s very easy to operate even a multi-tracker Visualeyez system for most motion capture applications:

• Turn on the system.
• Click on ‘Auto Configure’ (to connect the trackers to the computer)
• Start ‘Auto Detect Targets’ (to find out which markers have been attached to the subjects)
• Set desired sampling period or capture frame rate
• Press ‘Record’ to start motion capture

Reliable high accuracy data

Every individual Visualeyez tracker is factory-calibrated by instruments with 3D accuracies traceable to international standards. All data filters can be turned on or off. You can fully control the system and trust the data you get with absolute confidence.

Intrinsic marker ID tracking

Each marker of a Visualeyez system is automatically assigned a distinct ID number during operation. The captured 3D data is automatically associated with this ID by the system. No data cleaning, no special marker arrangement, no special actor motions, nor any post-processing is ever required to help the system correctly identify a marker. Absolutely no marker swapping problem will ever occur!

Very high resolution

Micrometer resolution enables a Visualeyez tracker to detect minute movements even at a distance. Closely spaced markers can be easily distinguished for capturing complex motions such as facial expressions, finger movements, or machine vibrations. Combining this with the wide-angle operation, large coarse motions and small intricate motions can be captured simultaneously.

Arbitrary sampling frequency

The marker sampling frequency of a Visualeyez system can be set to any value to suit an application. For tracking a slow motion the sampling rate can be set to be extremely low, for days or even weeks of continuous capture. Since there is no marker identification problem, high frequency sampling is not necessary except for tracking very high speed motions. For applications in which very high-speed and low-speed motions occur simultaneously, ‘multi-rate sampling’ (see below) can be applied to make the most effective use of the system capabilities.

Extendable capture distance

The nominal operating distance of a Visualeyez tracker is stated in the Specifications. By increasing the ‘Extended Exposure’ setting via the provided VZSoft GUI, the capture distance can be easily increased with some tradeoff to the maximum possible sampling frequency. This is very useful when long sensing distance is more important.

Software

Software for motion capture © Phoenix Technologies, 2015

The Visualeyez™ family of products include a full suit of software to facilitate user applications. These consist of:

– a graphical user interface (GUI)
– a multi-tracker system data fuser which comes with our revolutionary ‘completely automatic and adaptive calibrator’
– a toolbox full of functions for captured data analysis and occlusion handling
– a utility software for controlling 3rd-party analog data acquisition in synchronism with the motion capture
– a tool for distributing the captured motion data to more than one computers for simultaneous parallel applications, which can also merge data captured by more than one Visualeyez™ systems for virtual interaction applications
– a software development kit (SDK) and a host of plug-ins to allow user-written or 3rd-party software to access the motion capture data in real-time or during replay for any real-time or offline user applications.

Computer Requirements:

A PTI Visualeyez motion capture system alone requires very little computer power to operate.

For high speed real-time motion capture we recommend using a computer with good I/O communication bus design.

Currently one standard PCI card slot is required to control up to 4 trackers.

A VZ4000v system will accumulate up to 5MB of motion data per minute of capture at the highest sampling rate. Therefore, depending on how long will the longest capture session last, the computer should also have sufficient RAM for accumulating these data.