Halo Light Atlas is an experimental open-source project for mapping light pollution. Halo smart glasses capture ambient light data, while the smartphone browser provides the current GPS location. The measurements are stored on a Raspberry Pi, visualized on an OpenStreetMap, and displayed historically during subsequent visits. Multiple users and Halo glasses can work with their own calibration profiles to collaboratively create a growing light pollution map.

Nighttime lighting should support visibility and safety, while simultaneously limiting unnecessary impacts such as glare, light trespass, and skyglow.

Halo Light Atlas is not intended to promote streets that are as dark or as bright as possible. Instead, it aims to highlight where lighting is applied appropriately, evenly, and purposefully, as well as where it is lacking, causes glare, or unnecessarily burdens the environment and night sky.

Connect Halo and start measuring

Detecting Overlit Streets:
0–20 unusually dark
21–50 moderate
51–75 bright
76–100 potentially excessive

Visibility Support Index – VSI:
Base brightness
+ uniformity
+ visible street contrast
- glare risk
- strong light-to-dark transitions

Dark Gap Index Along a Walking Route:
0 uniform
30 slight fluctuations
60 noticeable dark gaps
90 extreme light-to-dark changes

Relative Blue-Rich Index – BRI
blue / (red + green + blue)
Warm
Neutral
Blue-Rich