I’m currently working on a similar proprietary system that is similar to the one described in this article, and I can tell you that there is much more involved here than “counting people in a room”. Claiming someone with a clicker in front of a door is a better solution misses dozens of other use cases where this isn’t at all possible or cost effective...
But you know, everyone on HN is an expert in everything.
But you know, everyone on HN is an expert in everything.