W-RGB-D: Floor-plan-based indoor global localization using a depth camera and WiFi

Localization approaches typically rely on an already available map to identify the position of the sensor in the environment. Such maps are usually built beforehand and often require the user to record data from the same sensor used for localization. In this paper, we relax this assumption and present a localization approach based on architectural floor plans. In general, floor plans are readily available for most man-made buildings but only represent basic architectural structures. The incomplete knowledge leads to ambiguous pose estimates. To solve this problem, we present W-RGB-D, a new method for indoor global localization based on WiFi and an RGB-D camera. We introduce a sensor model for RGB-D cameras that is suitable to be used with abstract floor plans. To resolve ambiguities during global localization, we estimate a coarse initial distribution about the sensor position using the WiFi signal strength. We evaluate our W-RGB-D localization method in indoor environments and compare its performance with RGB-D-based Monte Carlo localization. Our results demonstrate that the use of WiFi information as proposed with our approach improves the localization in terms of convergence speed and quality of the solution.