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[[Markerless, inside-out trackingFile:Intel Project Alloy.jpg|thumb|Figure 1. Intel's Project Alloy (Image: gizmodo.com)]] is a composite term derived from two separate concepts, and refers to a method of tracking objects in three dimensional space.

[[markerless Positional tracking|'Marker-less']] refers is an essential component of both [[virtual reality]] (VR) and [[augmented reality]] (AR), contributing to the lack a greater sense of [[fiducial markersimmersion]] and [[presence]] used . It determines the position and orientation of an object within the environment. In VR, this allows for the movements of the user to be translated into the virtual environment, and in this type AR it is essential for the placement of digital content into real objects or spaces. Markerless inside-out tracking is a composite term that defines a form of positional tracking that uses two specific methods: [[markerless tracking, while ]] and [[inside-out tracking|'Inside-Out']] refers to the method by which data is gathered . <ref name=”1”> Boger, Y. (2014). Overview of positional tracking technologies for the virtual reality. Retrieved from http://www.roadtovr.com/overview-of-positional-tracking-technologies-virtual-reality/</ref> <ref name=”2”> Ziegler, E. (2010). Real-time markerless trackingof objects on mobile devices.Bachelor Thesis, University of Koblenz and Landau</ref>

Markerless tracking is a method of motion tracking that avoids the use of markers (also known as [[File:F2Ak4iEfiducial markers]]). These markers are usually placed in the environment or in the head-mounted displays (HMDs), helping the system determine the users or camera position.jpg|thumbnail|A room covered The Markerless method uses instead natural features already present in fiducial markers the environment, for inside out tracking, at [[Valve Corporation]]purposes. <refname=”3”>Youtube, VideoVirtual Reality Society. Virtual reality motion tracking technology has all the moves. Retrieved from https: 'Steam Dev Days'//www.vrs.org.uk/virtual-reality-gear/motion-tracking</ref> <ref name=”4”> Klein, on Channel: ValveG. (2006). Visual tracking for augmented reality. Ph.D. thesis, Published on Feb 11University of Cambridge, 2014Department of Engineering</ref>]]==Marker-less Tracking== Because of This method is considered more flexible and effective since there isn’t the difficult computations required need for a software to interpret live camera inputprepared environment with markers. <ref name=”5”> Zikas, P., Bachlitzanakis, V., Papaefthymiou, M. and Papagiannakis, G. (2016). A mobile, AR inside-out positional tracking solutions that rely on cameras sometimes place [[fiducial markers]] algorithm, (which may look like QR codesMARIOPOT), suitable for modern, affordable cardboard-style VR HMDs. In Digital Heritage. Progress in view cultural heritage: documentation, preservation, and protection. Springer International Publishing, Switzerland</ref> <ref name=”6”> 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> The decreasing cost of the computer vision is another factor that has made markerless tracking an attractive alternative of tracking. However, this method still has some problems, such as motion blur and fast motion affecting tracking camera. This gives the software a known pattern to look <ref name=”7”> Fang, W., Zheng, L., Deng, H. and Zhang, H. (2017). Real-time motion tracking formobile augmented/virtual reality using adaptive visual-inertial fusion. Sensors, which makes computation simpler 17</ref> It also demands a trade-off between precision and fasterefficiency. <ref name=”2”></ref>

Thus Inside-out is a term that defines the position of the cameras or other sensors relative to the object to be tracked. If they are placed in a stationary location exterior to the termHMD, for example, it is considered [[outside-in tracking]]. In inside-out, the camera is placed in the HMD. <ref name=”8”> Boger, 'markerY. (2014). Positional tracking: "Outside-in" vs. "Inside-out." Retrieved from https://vrguy.blogspot.pt/2014/08/positional-tracking-outside-in-vs.html</ref> There is great interest in inside-less' refers out tracking since it simplifies the setup and allows the user a greater sense of freedom by not being limited to a system that is robust enough specific tracking space. Inside-out positional tracking has the potential to make VR completely wireless, more convenient and accessible. Some have gone as far as saying that it does not need was the aid of printed markers to aid in its interpretation “holy grail” of the three dimensional spaceVR scene. <ref name=”9”> Robertson, A. (2017). Self-tracking headsets are 2017’s big VR trend — but they might leave your head spinning. Retrieved from https://www.theverge.com/2017/1/12/14223416/vr-headset-inside-out-tracking-intel-qualcomm-microsoft-ces-2017</ref> <ref name=”10”> Durbin, J. (2016). Google: Wireless positional tracking “solved”, but heat still a problem for VR. Retrieved from https://uploadvr.com/inside-out-google-solve-tracking/</ref>

==InsideAdvantages of markerless inside-Out Trackingout tracking==Tracking systems that make use The benefits of a camera may be organized into two main branches, 'using markerless inside-out' and 'outside-in' tracking. Both terms refer to are those that come from the placement individual advantages of the tracking camera itself, with reference to what it is each trackingmethod.

In an [[inside-out tracking|'inside-out' system]]===Markerless===* Can work within unprepared environment;* No special hardware required;* No fiducial markers;* Able to use natural features to calculate position and orientation. <ref name=”5”></ref> <ref name=”7”></ref> <ref name=”11”> Hsia, the tracking camera is placed within the item being tracked J.S. (for our purposes, like a [[Virtual_Reality#Devices|head mounted display]]2017), . Markerless AR: 4 Things developers need to know. Retrieved from which vantage point it look ''out'' at the world around ithttps://developer. It uses its changing perspective on the outside world to note changes in positionatt.com/blog/markerless-ar-developers</ref>

In an [[outside===Inside-in tracking|'outside-in' system]], out===* Increased mobility and freedom; * No need for external sensors; * Not affected by occlusion; * Provides a tracking camera deeper sense of immersion since the user is not tethered. <ref name=”9”></ref> <ref name=”12”> Langley, H. (or cameras are2017) placed around the space within which the tracked object will move. Inside-out v Outside-in: How VR tracking works, and use their changing view of the object itself how it's going to measure its changes change. Retrieved from https://www.wareable.com/vr/inside-out-vs-outside-in position.-vr-tracking-343</ref>

==Relative MeritsProject Tango and Project Alloy==[[Tango]] is a [[Google]]’s project that allows smartphones and other mobile devices to understand their location in space. It is a software and hardware solution that offers inside-out technology and markerless tracking. According to Google Tango’s director of engineering, Johnny Lee, “As you can see [inside-out positional tracking] clearly works on this phone…We’ve even had people strap a tablet sized device with Tango built in into a custom VR headset and the positional tracking worked just as well as it does here…The only thing really holding us back right now are the thermals. Right now, phones just get way too hot if we ask them to run positional tracking and split-screen stereoscopic image at 90 fps…As Daydream matures and Tango continues to improve, the sophistication around tracking will also evolve over the next 2-3 years.“ <ref name=”10”></ref>

Both systems have merits; 'In 2016, Intel announced [[Project Alloy]] (Figure 1) - a VR system. It is also a markerless inside-out' tracking is notable because it can require no outside equipment, which is ideal for a portable device. UnfortunatelyDuring CES 2017, in Intel showed off a developer kit of the case project. Project Alloy uses a tiny camera array called Intel RealSense. These cameras are able to make a 3D map of the environment (e.g. a room) and the objects in it. The headsetdoes not need wires, and it places the burden of computation on the headset itselfis powered by a battery. <ref name=”13”> Nunez, M. (A burden which 2017). Intel’s Project Alloy is exacerbated when no fiducial markers are used.) 'Outside-in' tracking can what a VR system should be less computationally demanding, and can make use of multiple cameras to make results more stable and consistent. This comes in part Retrieved from the reduced chance of [[occlusion]]http://gizmodo. Unfortunately it requires com/intels-project-alloy-is-what-a controlled environment and more extensive equipment.-vr-system-should-be-1790818104</ref>