Researchers at Tokyo City University in Japan recently showed in an academic paper how indoor mapping via LiDAR SLAM (simultaneous localization and mapping) and SDR can be combined to generate accurate indoor RF heatmaps. Mapping WiFi reception in indoor spaces can be challenging because accurate indoor localization is often lacking (GPS doesn't work), so it is usually done through manual measurements.

In this system, the researchers used a Raspberry Pi with a LiDAR sensor and Google Cartographer SLAM running on a connected PC to automatically locate and map out the indoor space. At the same time, a PlutoSDR measures the WiFi SNR. The result is a relative SNR WiFi heatmap.

They then derive a 3D model from the collected LiDAR SLAM data and put it into an RF ray-tracing simulation. Finally, they compared their real-world results with the ray-tracing simulation and found the results matched.