Changes

Markerless tracking is a method of [[positional tracking]] - the determination of position and orientation of an object within its environment. This is a very important feature in [[virtual reality]] (VR) and [[augmented reality]] (AR), making it possible to know the field-of-view and perspective of the user - allowing for the virtual environment to react accordingly or the placement of augmented reality content in accordance with real objects. For a complete motion tracking experience, the tracking system needs to measure movement in six degrees-of-freedom. <ref name=”1”> Ziegler, E. (2010). Real-time markerless tracking of objects on mobile devices. Bachelor Thesis, University of Koblenz and Landau</ref> <ref name=”2”> Virtual Reality Society. Virtual reality motion tracking technology has all the moves. Retrieved from https://www.vrs.org.uk/virtual-reality-gear/motion-tracking/</ref>

Markerless tracking is a method of [[positional tracking]] - the determination of position and orientation of an object within its environment. This is a very important feature in [[virtual reality]] (VR) and [[augmented reality]] (AR), making it possible to know the field-of-view and perspective of the user - allowing for the virtual environment to react accordingly or the placement of augmented reality content in accordance with real objects. For a complete motion tracking experience, the tracking system needs to measure movement in six degrees-of-freedom. <ref name=”1”> Ziegler, E. (2010). Real-time markerless tracking of objects on mobile devices. Bachelor Thesis, University of Koblenz and Landau</ref> <ref name=”2”> Virtual Reality Society. Virtual reality motion tracking technology has all the moves. Retrieved from https://www.vrs.org.uk/virtual-reality-gear/motion-tracking/</ref>

While marker-based methods of motion tracking use specific optical markers, markerless positional tracking does not require them, making it a more flexible method. It also avoids the need for a prepared environment in which [[fiducial markers]] are placed beforehand, for example. Contrary to marked-based tracking, a markerless approach allows the user to walk freely in a room or a new environment and still receive positional feedback, expanding the applicability range.<ref name=”1”></ref><ref name=”2”></ref><ref name=”3”> Zikas, P., Bachlitzanakis, V., Papaefthymiou, M. and Papagiannakis, G. (2016). A mobile, AR inside-out positional tracking algorithm, (MARIOPOT), suitable for modern, affordable cardboard-style VR HMDs. In Digital Heritage. Progress in cultural heritage: documentation, preservation, and protection. Springer International Publishing, Switzerland</ref> <ref name=”4”> Fang, W., Zheng, L., Deng, H. and Zhang, H. (2017). Real-time motion tracking for mobile augmented/virtual reality using adaptive visual-inertial fusion. Sensors, 17</ref> <ref name=”5”> Lima, J.P., Roberto, R., Simões, F., Almeida, M., Figueiredo, L., Teixeira, J.M. and Teichrieb, V. (2017). Markerless tracking system for augmented reality in the automotive industry. Expert Systems With Applications, 82: 100-114</ref>

While marker-based methods of motion tracking use specific optical markers, markerless positional tracking does not require them, making it a more flexible method. It also avoids the need for a prepared environment in which [[fiducial markers]] are placed beforehand, for example. Contrary to marked-based tracking, a markerless approach allows the user to walk freely in a room or a new environment and still receive positional feedback, expanding the applicability range.<ref name=”1”></ref><ref name=”2”></ref><ref name=”3”> Zikas, P., Bachlitzanakis, V., Papaefthymiou, M. and Papagiannakis, G. (2016). A mobile, AR inside-out positional tracking algorithm, (MARIOPOT), suitable for modern, affordable cardboard-style VR HMDs. In Digital Heritage. Progress in cultural heritage: documentation, preservation, and protection. Springer International Publishing, Switzerland</ref><ref name=”5”> Lima, J.P., Roberto, R., Simões, F., Almeida, M., Figueiredo, L., Teixeira, J.M. and Teichrieb, V. (2017). Markerless tracking system for augmented reality in the automotive industry. Expert Systems With Applications, 82: 100-114</ref>

Markerless tracking only uses what the sensors can observe in the environment to calculate the position and orientation of the camera. <ref name=”1”></ref> The method depends on natural features instead of specific markers, and it can use a model-based approach or do image processing in order to detect features which provide data to determine position and orientation. <ref name=”5”></ref> <ref name=”6”> Boger, Y. (2014). Overview of positional tracking technologies for virtual reality. Retrieved from http://www.roadtovr.com/overview-of-positional-tracking-technologies-virtual-reality/</ref>

Markerless tracking only uses what the sensors can observe in the environment to calculate the position and orientation of the camera. <ref name=”1”></ref> The method depends on natural features instead of specific markers, and it can use a model-based approach or do image processing in order to detect features which provide data to determine position and orientation. <ref name=”5”></ref> <ref name=”6”> Boger, Y. (2014). Overview of positional tracking technologies for virtual reality. Retrieved from http://www.roadtovr.com/overview-of-positional-tracking-technologies-virtual-reality/</ref>

==Markerless tracking in VR and AR==

==Markerless tracking in VR and AR==

Markerless tracking can work with unprepared environments. Therefore, this method is preferable for mobile AR or VR in the future. Currently, there are still problems that affect the applicability and robustness of the system. These have to be surpassed and more research is needed before this method of tracking becomes completely viable. The heavy computing demands, unpredictable environments, the jitter and latency between consecutive poses still hold back this technology. Nevertheless, when these problems are solved, mobile AR and VR could see a greater level of adoption and development. <ref name=”4”></ref> <ref name=”8”> Graham, P. (2017). Scope AR updates remote AR app with markerless tracking. Retrieved from https://www.vrfocus.com/2017/06/scope-ar-updates-remote-ar-app-with-markerless-tracking/</ref>

Markerless tracking can work with unprepared environments. Therefore, this method is preferable for mobile AR or VR in the future. Currently, there are still problems that affect the applicability and robustness of the system. These have to be surpassed and more research is needed before this method of tracking becomes completely viable. The heavy computing demands, unpredictable environments, the jitter and latency between consecutive poses still hold back this technology. Nevertheless, when these problems are solved, mobile AR and VR could see a greater level of adoption and development.<ref name=”8”> Graham, P. (2017). Scope AR updates remote AR app with markerless tracking. Retrieved from https://www.vrfocus.com/2017/06/scope-ar-updates-remote-ar-app-with-markerless-tracking/</ref>

==Examples==

==Examples==