View source for Talk:Inside-out tracking

== Categorization of lighthouse-tracking ==

Why is the HTC-Vive, or lighthouse tracking in general, categorized as inside-out?

The article states that "In inside-out positional tracking, the camera or sensors are located on the device being tracked (e.g. HMD) while in outside-out the sensors are placed in a stationary location." and cites the references [1], [2] and [3]. All references are describing camera-based systems, and whenever they talk about sensors they actually mean cameras.

But lighthouse tracking is NOT a camera-based systems, so I don't think the definition of inside-out from [1], [2] and [3] can be applied to lighthouse tracking without further reconsideration.  

Moreover, in [4], which is a follow-up of [1], outside-in tracking is defined as

<blockquote>
The basic principle of optical outside-in tracking lies in estimating the pose of known rigid 3D feature-point constellations, commonly referred to as “targets”, from their projections in different views. [...]
</blockquote>

This exactly describes how lighthouse tracking works, the "targets" are the lighthouse sensors and their projections are determined via the timings of the laser sweeps. From a mathematical and technical point of view lighthouse tracking has far more in common with camera-based outside-in tracking than camera-based inside-out tracking, be it marker-less or marker-based.

Therefore, it would make much more sense to categorize it as outside-in in my opinion.

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[1] Ribo, M., Pinz, A. and Fuhrmann, A.L. (2001). A new optical tracking system for virtual and augmented reality applications. Instrumentation and Measurement Technology Conference Proceedings

[2] Boger, Y. (2014). Positional tracking: "Outside-in" vs. "Inside-out.” Retrieved from http://vrguy.blogspot.pt/2014/08/positional-tracking-outside-in-vs.html

[3] Ishii, K. (2010). Augmented Reality: Fundamentals and nuclear related applications. Nuclear Safety and Simulation, 1(1)

[4] [https://www.ims.tuwien.ac.at/publications/tuw-141612 T. Pintaric, H. Kaufmann: "Affordable Infrared-Optical Pose Tracking for Virtual and Augmented Reality"; Talk: IEEE Virtual Reality 2007, Charlotte, NC (USA); 03-14-2007 - 03-17-2007; in: "IEEE VR Workshop on Trends and Issues in Tracking for Virtual Environments", G. Zachmann (ed.); Shaker Verlag, Aachen (2007), ISBN: 978-3-8322-5967-9; 44 - 51.]