trolls.dev
03 The map — case study

Thyseus

Live object detection & GPS mapping from public cameras.

Open a public traffic-camera feed and Thyseus runs object detection in your browser. It calculates locations for the objects it detects and adds them to a map shared with other viewers.

Status
Live
Platform
Web
Price
Free — community-powered
Field
Computer vision · Mapping
Open the live map ↗ All work
thyseus.com Live
cam · I-80 EB
car 0.97
2 detections · 39.53°N, -119.81°W detected in your browser
Viewers run detection on their own devices and contribute to the same map. The bet behind it

Why we built it

A map across public camera feeds.

Transportation departments publish traffic-camera feeds, but browsing one feed at a time makes it hard to see what is happening across an area.

Running object detection across many feeds would leave us with a large server bill. We wanted to spread that processing across the devices people use to view the cameras.

Thyseus loads the detection model in the browser. Each viewer contributes the results from the feed they have open, and everyone can see those detections on the map.

The service is free to use, with contributors providing the detection work.

What we made Features
  1. 01

    Detection in the browser

    A computer-vision model processes the public camera feed on your device. It sends detection labels to the map; the video stays on your machine.

  2. 02

    Calculate each location

    Thyseus uses the camera's known position and field of view to calculate GPS coordinates for a detection.

  3. 03

    One shared map

    Contributors' detections appear on the same map in real time. You can browse public traffic cameras by state.

  4. 04

    Add cameras and detections

    Contributors can submit cameras and run detection on feeds. A leaderboard records their contributions.

Design choices

Detection runs on the viewer’s device.

Use the viewer’s device

Running detection in the browser keeps that processing off our servers. Contributors supply the computing power, which helps us keep the service free.

Use public traffic cameras

Thyseus reads government traffic-camera feeds that anyone can already open in a browser.

Show the calculated coordinates

The map displays the location calculated from each camera’s geometry, so viewers can inspect where a sighting was placed.

Further reading from the journal

We explain why we run our own products in Why we only build what we run, and how we choose their scope in In defense of small software.

Thyseus reads publicly available government traffic-camera feeds and runs detection on the viewer's own device. It is an independent project and is not affiliated with or endorsed by any transportation department.

Colophon End of Case Study 03

The map is live right now.

Open a camera to contribute detections from your browser, or browse the map to see what other viewers have found.

Open the live map ↗ More case studies →