The exposure period of the VET imaging and the measurement camera was 999.75 and 7.58 ms, respectively.
We used one or more visual markers, with known size, position, and distances to each other, which can be found and tracked by a measurement camera on the headset.
This simple calibration technique works well in the field, as it does not require any accurate measurements of camera position or the availability of calibration-aiding materials such as regular checkerboards, which are difficult to obtain in remote locations.
The authors used a meticulous protocol – with parallel SE, RE and BIS measurements, web camera monitoring and a computer program for noting sedative administration and interventions – to find a clinical indication for the use of entropy or BIS during ICU Ramsay Sedation Scale-targeted sedation.
The challenging problems include tracking low-contrast natural targets on the structural surface, insufficient resolution for long distance measurement, inevitable camera vibration, and image distortion due to heat haze in hot weather.
Four patients were excluded due to instrument malfunctions during measurement (CCD camera overheat, probe damage).
For both transmission measurement and camera images two cases were compared.
In order to evaluate the relative performance of the configurations, the measurements for each camera are normalized across all measurements on the same camera and then averaged on a per-configuration basis across all cameras using the same configuration.
This paper deals with the problem of where to place the cameras in order to obtain a minimal error in the 3D measurements, also called camera network design in photogrammetry.
