Real-time adaptable and coherent rendering for outdoor augmented reality

This paper describes the development and evaluation of a color estimation method that is able to create more natural lighting conditions for outdoor-purposed augmented reality (AR) technology. In outdoor AR systems, the real outdoor light source (i.e., the sun) illuminates real objects, while a virtual light source illuminates the augmented virtual objects. These two light sources result in color differentials, with the real object and virtual object being visualized as a mixture of the colors induced by the two light sources. As such, there is a visible difference in color between the real object and the virtual object. Consequently, this visible color difference will vitiate the sense of immersion felt by the AR user. Thus, to overcome this problem, we have defined each RGB color channel value by analyzing the color generated by the outdoor light source and applied the defined values to the virtual light source to reduce the visibility of the color differential between the two light sources, thereby reducing the visualized incompatibility between the virtual object and the real background. In addition, using virtual objects to express weather events, in combination with the color estimation method, we were able to demonstrate that the proposed method can adequately adapt to and manage the weather changes that affect outdoor AR. The proposed method has the potential to improve the visual coincidence between the real outdoor background and virtual objects.