| Visible Light Positioning(VLP)has attracted much research effort recently.Most existing VLP approaches require special designed light or receiver,collecting light information or strict user operation(e.g.,horizontally holding the mobile phone).This incurs a high deployment,maintenance and usage overhead.This thesis presents Rainbow Light,a low-cost 3D localization system based on visible polarized light.It is easy to deploy in today’s buildings.The key finding is that light through a chip of polarizer and birefringence material produces specific interference and light spectrum at different directions to the chip.The chip doesn’t need to work with electricity,so Rainbow Light doesn’t need to work with a specifically designed circuit and receiver.Moreover,the spectrum feature just relates to the direction between camera and chip rather than the orientation of the camera.Therefore,Rainbow Light can work with little user operation requirements.Different from existing works,Rainbow Light can also be used with ambient light,so it can be used in a wider use scenario.This thesis presents a model to characterize the relation between direction,light interference,and spectrum.Exploiting the model,the system calculates the direction to a chip after taking a photo containing the chip.With multiple chips,Rainbow Light designs a fingerprint matching based method to derive the location.This thesis also implements Rainbow Light and extensively evaluate its performance in various environments.The evaluation results show that Rainbow Light achieves an average localization error of 3.3 cm in 2D and 9.6 cm in 3D for light on,and an error of 7.4 cm in 2D and 20.5 cm in 3D for light off scenario in the daytime. |
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