Latency (the time delay between the moment something is initiated and the moment its first effect take place) is a widely discussed subject amongst active motion capture users around the world today. As the demand for low latency gets higher, particularly in research environments, users and potential users turn to us for figures on latency in our motion capture system.
Latency depends on the setup and may vary from one measurement to the other depending on the number of markers, cameras as well as third party software and computer performance. Each step in the processing pipeline adds its share to the total latency – from image exposure to the processing of data in 3rd party software.
Recently, Qualisys tested the real-time performance of Oqus and QTM with AIM (Automatic Identification of Markers). An Oqus 6-camera-system ran at 160 Hz with a 36 marker set-up. Tests showed a latency of less than 6 ms (equaling 1 frame) from start of exposure, to when the identified 3D data was available in third-party software. For visualization, it is not interesting to run at frame rates higher than around 25-30 fps – the highest speed at which the human eye is able to register movement. However, in other applications, where higher frame rates might be required, it is clear that the camera still can perform, with minimal delay.