See-through head-mounted displays (STHMDs), which superimpose the virtual environment generated by computer graphics (CG) on the real world, are expected to be able to vividly display various simulations and designs by using both the real environment and the virtual environment around us. However, we must ensure that the virtual environment is superimposed exactly on the real environment because both environments are visible. Disagreement in matching locations and size between real and virtual objects is likely to occur between the world coordinates of the real environment where the STHMD user actually exists and those of the virtual environment described as parameters of CG. This disagreement directly causes displacement of locations where virtual objects are superimposed. The STHMD must be calibrated so that the virtual environment is superimposed properly. Among the causes of such errors, we focus both on systematic errors of projection transformation parameters caused in manufacturing and differences between actual and supposed location of user's eye on STHMD when in use, and propose a calibration method to eliminate these effects. In the calibration method, the virtual cursor drawn in the virtual environment is directly fitted onto targets in the real environment. Based on the result of fitting, the least-squares method identifies values of the parameters that minimize differences between locations of the virtual cursor in the virtual environment and targets in the real environment. After we describe the calibration methods, we also report the result of this application to the STHMD that we have made. The result is accurate enough to prove the effectiveness of the calibration methods.
This paper discusses the role of Indian merchants, especially Muslims, in the match trade between Japan and India, and situates the cooperative ventures set up in the middle of the 1920s between Indian merchants and Japanese manufacturers in the context of the economy of the Bengal Bay region. Their inter-regional networks and partnerships were important not just for trade, but also for manufacturing based on the flow of technology, ideas, information, and natural resources. The paper also shows that such ventures unexpectedly caused conflicts with movements in India to promote domestic industry and with the logic of territorial nationalism that lay behind them.
It is expected that See Through Head-Mounted Display (STHMD) , which superimposes the virtual environment generated by computer graphics (CG) on the real world, can vividly execute various simulations and designs by using both of the real and virtual environment around us. In STHMDs, information given as a virtual environment has to exactly match with the real environment, because both environments are visible. This is one of the problems to be solved for practical use. Particularly for matching of locations and size between real and virtual objects, disaccordance is likely to occur between the world coordinate of the real environment where the user of STHMD actually exists and that of the virtual environment described as parameters of CG, which directly causes displacement of locations where virtual objects are superimposed.This must be calibrated so that the virtual environment is superimposed properly. Among causes of such errors, we focused both on systematic errors of visual parameters caused in manufacturing process and differences between actual and supposed location of user's eye on STHMD when in use. The former is required to be calibrated only once after the fabrication of STHMDs, whereas the latter has to be calibrated every time users start using STHMDs. We have proposed calibration methods which are suitable to properties of these causes of errors. In the method, the direct fitting of the virtual cursor drawn in the virtual environment onto targets in the real environment is performed. Then, based on the result of fitting, the least square method identifies values of the visual parameters which minimize differences between locations of virtual cursor in the virutal environment and targets in the real environment. Application of the method to the STHMD which we have made is also repored. The differences between the virtal cursor and targets in the real environment due to systematic errors caused in the manufacturing process were reduced to about 1 [mm] per target, which was less than one-thirtieth of that before the calibration. The differences between the virtual cursor and targets in the real environment due to the location of user's eyes were also reduced about 2 [mm] per target, which was a half of that before the calibration. This result was well enough to prove the effectiveness of the calibration methods.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.