For a mobile & pervasive computing course paper. This app is a proof-of-concept breathing rate measurement device using the TrueDepth cameras on iPhone X or later models.
The program is very simple architecturally. The depth image streamed from the TrueDepth camera has its values normalized to between 0 and 255, and pixels <= 128 are counted. This gives the area as a discrete function in time (t). A fast fourier transform is then performed on the Area function. The highest peak between 0 and 1 Hz (the normal range of human breathing) is considered the respiratory rate of the user.
There's an iOS app that has to be run on an iPhone that supports Face ID. It's
based on Apple's
Streaming Depth Data from the TrueDepth Camera
code example, albeit with the point cloud component removed and the ability to
record a minute of data to be uploaded to a server component (under server/)
added. We fix the recording at 5 fps, which is still above the Nyquist
frequency for human breathing (2Hz.)
The server component is responsible for calculating the breathing rate. Writing the calculation of the breathing rate to the phone in Swift is left as an exercise to the reader.
Here's how to test the app:
- Prop your phone up at about arm's length at neck height, in landscape mode (I propped it up against my monitor.)
- Use a metronome such as the one at https://www.musicca.com/metronome; set the bpm to your target breathing rate * 2, then alternate breathing in and out with every beat.
- Start the server in
server/simple_server.py. Make sure your phone and Mac are connected to the same network. - Update the URLs in
TrueBreath/CameraViewController.swiftto target your computer, then build and run the app. Wait for the app to launch. - Take a few breaths, then tap record, maintaining the same breathing rate
- Wait one minute, then the server should print your breathing rate to stdout
Copyright © 2024 Mohamed Gaber
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Streaming Depth Data from the TrueDepth Camera
Copyright © 2021 Apple Inc.
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.