Very cool. The tinkerer in me wanted to see how quickly I could come up with a function that wouldn't be approximated well.
Math.cos(x * Math.exp(Math.cos(x * x))) is the best I got so far as it is highly composite, which leads to rapid oscillations and steep gradients that can't easily be approximated by Chebyshev.
It does but we don't have a battery powered option (yet) so power availability is the bigger issue. Our sensors can only be outlet powered. Each sensor can cover cover roughly 5,000 sq.ft. or about two tennis courts.
Outstanding write-up! We actually built a business based on this technology (occuspace.io) and have had to address almost all the questions that you brought up. To answer some of them here:
Q: How accurate is BLE beacon count, as a proxy for occupancy?
A: It's very highly correlated but different dining locations, classrooms and library floors have very different correlation factors. Consider using other, perhaps more complex features, as well.
Q: How accurate is BLE beacon availability time, as a proxy for dwell time?
A: We don't believe it is very accurate given that BT MAC's randomize every 8-20 mins depending on manufacturer.
Q: Can we improve the accuracy by setting an RSSI minimum, for which devices weaker than it do not count, to ensure only those who are really nearby get counted?
A: That's a great idea. It's worth noting that different types of spaces and depending on where you installed your sensor, will have different threshold levels.
Occuspace | Senior Full-Stack Engineer (Go, TypeScript & React) | Los Angeles and Remote | Full-time
We are looking for a Sr. Full Stack Engineer to join Occuspace's software engineering team. We are a Series A funded startup looking for candidates to take on a high impact role where they will have the opportunity to work on the core of Occuspace’s Spatial Intelligence Platform. This platform is built on a stack of React, Typescript, Go, and RDS, Serverless and GraphQL. We run our application in AWS.
Occuspace's Spatial Intelligence Platform helps customers understand their patterns of space usage throughout their portfolio while serving as the interface for all analytics data that Occuspace generates on behalf of customers. In this role you would help drive core customer facing features that are a part of this platform. This includes the visualizations and analytics presented to customers through our dashboards, the transferring, aggregation, and storage of data pertaining to these features, and the APIs that customers use to programmatically interface with Occuspace data.
Occuspace expects senior engineers to be technical leaders within the team possessing both depth of knowledge and broad influence. Senior engineers are strong communicators, passionate mentors, and effective cross-functional operators.
Reach out to "linus at occuspace dot io" with a letter and resume.
A couple questions:
- How was the training/testing data split? Was it split window-wise or participant-wise?
- How does the system perform at elevated heart rates? Seems like it was mostly tested at resting/normal heart rates