Optical tracking
An optical tracker is used in digital image processing in the geosciences . There are linear structures - roads, rivers, canals, railway lines etc. usually - with the help of the tracker (tracker) in digital image data such. B. captured aerial or satellite images . In the case of semi-automatic detection, a starting piece is specified in which the tracker creates one-dimensional transverse profiles and determines edges in these from the gray value profile . With the recorded width information, the tracker searches for the further course of the line. The semi-automatic as well as automatic line acquisition from image data is still in its infancy. Therefore, there is currently hardly any commercial software that includes this method.
In the field of virtual reality , an optical tracker is a device that measures the position and orientation of the user (see tracking , tracker (device) ). Such a system can, for example, consist of several cameras that record markings on the user or his VR helmet . The position of the markings in space and thus that of the user can be calculated from the position of the markings on the camera images and the relative positioning of the cameras to one another. Conversely, a camera can also be attached to the user's head, which is then based on fixed markings (reference marker system) in the room (so-called inside-out tracking in contrast to the outside-in tracking described above ).
Reflective foils, infrared LEDs or special patterns, also in contrasting colors, can serve as markings. The easier it is to distinguish the markings from their surroundings, the more stable the tracker is.
Systems that can do without markings are still in the early stages of development.
Optical trackers generally offer much higher accuracy than magnetic trackers or acoustic trackers , but only work if there is a line of sight between the respective marker and the cameras. A concealment - e.g. B. by an arm - interrupts the measurement process. In addition, the identification of the markings is not always clearly possible. B. There is insufficient lighting, or sunshine or reflections impede the measurement.