2,725
edits
Changes
→How Does It Work?
Base Stations are vulnerable to [[occlusion]]. They require [[line of sight]] to the tracked objects. Base Stations are designed to be scalable. 2 Base Stations are placed in opposite sides of the room to minimize this problem. More Base Station can be placed to increase the tracking range.
===Detailed Explanation===
[[HTC Vive]] uses the [[IMU]]s as the primary position tracking system. It responds extremely quickly and updates at several hundred Hz (1000Hz sampling, 500Hz reporting). However, IMUs drift due to double-integration of error. The drift is on the order of meters per second. So what Lighthouse do is squelch that error 60 times per second (both have a 60Hz global position update rate) using their laserl sensors to provide an absolute position reference.
For Lighthouse high-speed position tracking performance is down ENTIRELY to IMU performance. It wouldn't be possible at all without another absolute reference system (optical, magnetic or otherwise) but it's the IMU that's doing the grunt-work.
However, the IMU is even more important for the Lighthouse than the Constellation. Lighthouse is a scanning system: not only do you not know the positions of markers at the same point in time, you don't even get the X and Y positions at the same point in time: there is a 4ms delay (4 scans per 16ms) between each laser strike for each sensor. If a controller is moving at a modest 1ms-1 , then between laser strikes it's moved 4mm! While throwing a controller like a cricket ball is extremely ill advised, a 150mph throw (~150mph hand speed) is 45ms-1, or 180mm between scans. Using the IMU data allows you to update parts of the position (X or Y coords, or polar spherical coords relative to the basestation, depending on how Valve are doing their math) independently of each other.
==Tracking volume==
