Multimodal interaction in an augmented reality scenario

We describe an augmented reality system designed for online acquisition of visual knowledge and retrieval of memorized objects. The system relies on a head mounted camera and display, which allow the user to view the environment together with overlaid augmentations by the system. In this setup, communication by hand gestures and speech is mandatory as common input devices like mouse and keyboard are not available. Using gesture and speech, basically three types of tasks must be handled: (i) Communication with the system about the environment, in particular, directing attention towards objects and commanding the memorization of sample views; (ii) control of system operation, e.g. switching between display modes; and (iii) re-adaptation of the interface itself in case communication becomes unreliable due to changes in external factors, such as illumination conditions. We present an architecture to manage these tasks and describe and evaluate several of its key elements, including modules for pointing gesture recognition, menu control based on gesture and speech, and control strategies to cope with situations when vision becomes unreliable and has to be re-adapted by speech.