An improved structure of a surveillance camera device is provided which permits the size of the device to be reduced. Some embodiments may use calibrated sensors to check the operation of a rotary or other positive displacement type gas meter or turbine meter. A retaining member is press-fit to the first engagement feature and is non-rotatably coupled to the second engagement feature to inhibit rotation of the adjuster relative to the housing. Computer controlled motion tracking, affected by pattern recognition algorithms with optional artificial intelligence, andor freeze frame function, andor optical or digital image stabilization, are used to stabilize view from moving vehicle. The existing SLM is then evaluated to determine how well it explains the probabilities in the second group of documents, and a weighting parameter is calculated from that evaluation.