We present a novel method to enable users to experience mobile interaction with digital content on external displays by embedding markers imperceptibly on the screen. Our method consists of two parts: marker embedding on external displays and marker detection. To embed markers, similar to previous work, we display complementary colors in alternating frames, which are selected by considering L*a*b color space in order to make the markers harder for humans to detect. Our marker detection process does not require mobile devices to be synchronized with the display, while certain constraints for the relation between camera and display update rate need to be fulfilled. In this paper, we have conducted three experiments. The results show 1) selecting complementary colors in the a*b* color plane maximizes imperceptibility, 2) our method is extremely robust when used with static contents and can handle animated contents up to certain optical flow levels, and 3) our method was proved to work well in case of small movements, but large movements can lead to loss of tracking.

We propose a knowledge-based instruction system for writing beautiful Japanese characters correctly, by using ICAI techniques. With this kind of CAI, it is important to relate the character pattern with the skill knowledge of handwriting because the rules of writing are indirectly shown as a feature of the character pattern. However, the CAI for penmanship previously reported was only based on the pattern analysis of the character. In this paper, we describe the rules of writing for this system as the skill knowledge of penmanship in the declarative way. This system evaluates and reforms the student's handwriting based on the rules of writing stored in a knowledge base. We would also introduce the error knowledge by the student's frequent handwriting mistakes. Finally, this system can estimate the student's degree of handwriting ability by their input charecters and give suitable guidance for improving their skills of writing. Students can learn the skills and the knowledge of penmanship effectively by this system. This system is also useful for foreign students learning the Japanese language.

This paper presents a method for measuring the entire three dimensional (3D) shape of an object, which is applicable for 3D digitizing into a solid modeler. The method realizes automatic acquisition of the complete surface model of the object without contact. The method employs two range finders and a turntable cooperatively: a range finder and the turntable measure the surface data of the object rapidly, and then another hand-eye range finder finds deficits in the surface data due to self-occlusion, and corrects them. This method realizes sensory fusion in acquisition of range data. Several 3D-shape data provided by two range finders are integrated into voxel data. The voxe representation allows us to handle the entire shape of an arbitrary object. The experimental system based on this method demonstrates the good flexibility and performance of the method for 3D digitizing.