Optical Tracking Explained

Optical tracking is a 3D localization technology based on monitoring a defined measurement space using two or more cameras. Each camera is equipped with an infrared (IR) pass filter in front of the lens, and a ring of IR LEDs around the lens to periodically illuminate the measurement space with IR light. This light is not visible to the human eye and its intensity is completely safe for human beings to work with.

Objects that need to be tracked are equipped with retro-reflective markers, which reflect the incoming IR light back to the cameras. The IR reflections are detected by the cameras and then internally processed by the optical tracking system. This system calculates the 2D marker position in image coordinates with high precision. Using multiple cameras, the 3D position of each marker can be derived.

The 3D position can be measured by using a single marker in the measurement space. To be able to also measure the orientation of an object or to track multiple objects simultaneously, multiple markers are placed on each object. Such a configuration is easily created by simply sticking markers randomly onto the object, making sure multiple markers can be seen from each angle. By using a model of this configuration of each object, the optical tracking system is able to distinguish between objects and determine the 3D position and orientation of each object.

Optical Tracking and its advantages

Optical tracking has proved to be a valuable alternative to tracking systems based on other technologies, such as magnetic, acoustic, gyroscopic and mechanical. There are various advantages to optical tracking, such as:

  • Optical tracking is less susceptible to noise from the environment. For instance, metal in the environment influence the accuracy of the   measurements of magnetic tracking systems
  • Optical tracking does not suffer from drift problems, like for instance inertial sensors, which cause measurements to slowly deviate from the actual values
  • Optical tracking allows for many objects to be tracked simultaneously
  • Interaction devices can be lightweight and wireless. As such, users are not hampered by wires or limited in manipulating the object


​Click here to see typical use of the optical tracker at Dassault Systemes.

Optical Tracking in use

The PST Iris optical bar tracker and the  PST Base compact 3D workstation bar tracker share the same principle and can be seen in use in these video's:

Plug and Play optical tracking

Track any object

Extend tracking space

Optical Tracking Technology for industrial applications

PS-Tech’s optical trackers are used in a range of industrial applications, which require accurate and robust measurement of the 3D location and sometimes also orientation of one or more objects in a pre-defined space. Typically, such applications require tracking in a larger area and often higher frame rates than for instance virtual reality applications. Additionally, static and dynamic measurement accuracy needs to be low, resulting in precise distance measurement capabilities and low measurement noise.

Our systems can work together to cover a larger working space, while maintaining a single reference measurement system (or origin). This means that for instance distance measurements between markers are consistent throughout the environment, independent of which tracking system actually sees the markers at each moment.

Since each tracking system is pre-calibrated at high precision and due to the robust and stable design of our trackers, the system is easy to setup and maintain and can get you going within minutes. Watch the video from Universität der Bundeswehr.

Optical Tracking Technology for Virtual Reality Applications

Virtual Reality InteractionIn Virtual Reality Environments, seamless interaction with the virtual world is often required in order to offer a fully immersive experience.

The optical tracking technology of PS-Tech is used to accurately track simultaneously the position and orientation of multiple objects. By equipping arbitrary objects, such as glasses and pointers, with reflective marker configurations, the PST optical tracking system can be used for head tracking and 3D interaction. For example, head tracking in immersive powerwalls or CAVEs.

Some external examples:

See how the tracker works in 3DVIA studio

3D AR games developed by Relais d’Sciences (Caen)

Discover our optical trackers

PST Base

Designed to track in compact spaces

PST Iris

Ideal system to track large volumes