Luis Hernan uses long exposure photography and an instrument called a Kirlian Device to try and visualize the wifi signals all around us. On his project website Digital Ethereal, Hernan explains:
The Kirlian Device is an instrument designed to reveal qualities of wireless networks. The device is named after Semyon Davidovich Kirlian, who discovered and perfected a photographic technique to capture electrical coronal discharges.
Inside, the device is powered by an Arduino UNO board connected to a Arduino WiFi Shield. Both components process and map the RSSI values of a previously specified SSID network into colour using a heatmap colour scheme. The mapped colours are then passed to a Pololu LED strip. The operation is possible by the use of two 5V lithium batteries.
