10 PPF is the minimum for detecting and counting people in the scene. Camio tracks people on their paths across the floor-plane grid, so intermittent dips below 10 PPF are OK as long as PPF values remain above 10 PPF generally.
For example, this illustrates operation at the limits of detection with only 6 PPF, where some people on the right side of the scene aren't reliably detected:
15 PPF is the minimum for detecting and counting vehicles in the scene. Camio tracks vehicles on their paths across the floor-plane grid, so intermittent dips below 15 PPF are OK as long as PPF values remain above 15 PPF generally.
Unlike Virtual Turnstiles, Occupancy Sampling doesn't have the benefit of tracking objects as they move across the floor-plane grid. That means they're less resilient to drops in PPF. Camio really needs the minimum 10 PPF for people and 15 PPF for vehicles.
It's much less expensive to count with sampling, since the compute power is applied only to periodic snapshots rather than to the continuous tracking of each object.