Changes

:''See also [[Markerless inside-out tracking]], [[Markerless outside-in tracking]], [[Positional tracking]]''

:''See also [[Markerless inside-out tracking]], [[Markerless outside-in tracking]], [[Positional tracking]]''

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=”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>

For AR, a model-based approach might be used in order to determine the placement of virtual objects with real ones. The model of the real object can be encoded as a computer-aided design (CAD model). Markerless augmented reality tracking would therefore continuously search and compare the image it receives with the known 3D model. <ref name=”6”></ref>

For AR, a model-based approach might be used in order to determine the placement of virtual objects with real ones. The model of the real object can be encoded as a computer-aided design (CAD model). Markerless augmented reality tracking would therefore continuously search and compare the image it receives with the known 3D model. <ref name=”6”></ref>