Creating 3D Maps of a WiFi Signal

Low-cost hardware has sparked a true WiFi revolution, enabling all sorts of configurations and projects. For example, who has thought about making a 3D map of a WiFi signal? Visualizing the exact coverage of modems, routers, and access points would be enormously useful, and over time some very interesting ideas have emerged. Today we’ll review two of them, and although they require certain technical knowledge, they are not impossible to reproduce...

The magic of microcontrollers and low-cost modules has turned the impossible into the everyday. “Dumb” devices find a path to connectivity with hardware worth a few euros on eBay. GitHub and similar platforms are bursting with code that pushes the limits of hardware. Language barriers and lack of documentation crumble before the determination of many communities.

WiFi has become a favorite among many enthusiasts for these reasons. An ESP8266 module costs less than 5 euros, and the list of compatible projects is truly impressive. Geolocation, mini-servers, pressure sensors, pollution meters... almost anything is possible with an ESP8266. So how does “see WiFi” sound? In fact, let's expand that a bit and ask: What would it be like to create 3D maps of a WiFi signal?

Creating 3D Maps of a WiFi Signal

The YouTuber known as CNLohr took one of these ESP8266 modules, connected a WS2812 LED and a compact battery to turn the whole thing into a portable solution. Once the ESP8266 is linked to a computer (with a Linux distro) and paired with the appropriate software, the LED changes color to reflect WiFi reception strength. The changes are noticeable even when moving the ESP8266 a few centimeters, and what seemed random at first ended up revealing very well-defined power levels.

The next step for CNLohr was to collect a large amount of data, create images with the pattern obtained from the signal, and then connect the ESP8266 module to a CNC system to obtain X-Y-Z values and generate a 3D map. The area is 36 by 36 by 18 centimeters, quite small compared to the coverage of a standard router, but more than enough to develop an idea of how important those power variations can be.

WiFi Photos Too

Another more complex route is the one followed on the channel The Thought Emporium. Their project started as a DIY radiotelescope, but with three weeks of work they managed to recalibrate their recorder to 2.44 GHz, exactly in the middle of the WiFi band. The video below shows part 3 of the project (the other parts have their links in the video description), with the final fully robotized design, capable of “take a WiFi photo” and identifying the hottest spots, even in front of a building. Although these images are not 3D, they certainly expose the most relevant sources of WiFi signals in the area.

Personally, I think I would start with the ESP8266-based project. The instructions are available on Hackaday.io, and the initial investment is much lower, so it's ideal for anyone who wants to dip their toes into the world of WiFi without spending too much money.