Visual localization: (a) we placed checkerboards with known square sizes and obtained images of sensor pairs. Using the known checkerboard sizes, we then determined the relative translation and orientation between imaged sensor pairs, and (b) built a map of the entire sensor network. Note, while six sensors are used in the visual localization, only four sensors actively record impact data. The remaining two (placed on the cheeks) were positioned as intermediaries because the ear sensors and the eye sensors could not be reliably captured in a single image.