How is integration time measured in the Shad-o-Box camera?
The Shad-o-Box camera (or, more specifically, the RadEye sensor inside the camera) uses what is often called a rolling shutter. The image is scanned one row at a time, starting at the top of the sensor. The signal charge collected in the photodiodes in each pixel is reset as each row is scanned. Because of the sequential nature of the readout, this means that row 1 is reset a few tenths of milliseconds before row 2, which in turn is reset before row 3 etc. The whole process of reading an entire image typically takes a few hundred milliseconds. When the last row is scanned, the camera can either start over again with the first row, or wait a certain amount of time before reading the next image. Because the photodiodes in the RadEye sensor are always collecting charge, the integration time is simply the number of seconds between one frame readout and the next. Because the delay from the start of the frame readout is constant (but different) for each row, the integration time is also the
