Study On The Three-dimensional Display Sand Table Using Integral Imaging

The sand table has been widely used since ancient times in human history especially the history of war, with the advances in technology ,sand table is used in more and more areas. Extensive use of sand table, it can display not only the image of the terrain of battlefield vividly, but also ourselves even the structure of the enemy positions, troops deployment and weapons configuration and so on. After computer technology invented, electronic sand table has been used to display the battlefield as a new technology. The sand table is also used to produce the economic development planning and large construction models. In recent years, the sand table can be widely used to identify and solve the psychology issues.Compared with technology of sand table, technology of integral image is a young technology, since Gabriel Lippmann's first proposal on integral photography in 1908, only more than 100 years passed. Comparing with other stereoscopic display technology integral image technology has many advantages: stereoscopic images shown with this method are achieved by the intersection of the real ray, so people can observe it without special viewing glasses and they will not experience visual fatigue; other method usually have a fixed view point, or at most a few discrete view points, integral image has get over these problems; in addition, it can display movies.In this paper our main purpose is producing three-dimensional display sand table using integral imaging and to explore a new production idea. We discuss the integral imaging technology, which influence on scaling of various parameters in all directions, in order to establish the base of real terrain scaling. After drawing ray image and deducing formulas we conclude that: we have got different scaling on different directions when we used different parameters in integral imaging's pickup and display system. Perpendicular to the direction of the matrix lens, zoom ratio is related to both focus and the sampling rate; in parallel to the direction it is only related to the sampling rate. So if we want the same scaling on each directions, it should be used the same focus when we pick up and display.The paper analyses the feasibility of produce sand table using integral imaging in existing conditions, after learning present mapping tools, we discover that Aerophotogrammetrical Survey should be valuable. We can not use the present productions collected by Aerophotogrammetrical Survey, because of some technical problems such as elemental images joining, position accuracy and overlapping. We can pick up the earth surface by the ideal parametric model offered in this paper, it would meet all requirements depending on integral imaging displaying, because we have estimated the error of ideal parametric model.With the swift development of computer technology, the computer simulation technology has reached a high level, this thesis studies on three-dimensional display sand table using integral imaging by computer simulation. We build virtual 3D terrain model through the Digital Elevation Model from AutoCAD programming, and the Digital Elevation Model is provided by Shuttle Radar Topography Mission from internet. The following is the process, we read Digital Elevation Model files to get the terrain information by using VBA, then create a 3D polygon mesh in AutoCAD, saved as DWG format; download the satellite images from Google Maps, Yahoo Maps, Microsoft Maps by using Universal Maps Downloader, and combine the element images to a BMP image; Import *.DWG files into the 3dsmax, after some parameters adjusted, we give the terrain model a texture mapping; create a *.ASE file which stores all information of cameras and a MAXScript file which can be operated by 3dsmax; import the *.ASE file into 3dsmax, and operate the MAXScript file; join and rotate the elemental images which are got by 3dsmax into a big image.We display the 3D sand table for a small region in laboratory due to the hardware constraints. Presswork should be used for displaying the 3D sand table, and we list its advantages. This paper is an exploratory research on a new way to produce 3D sand table by using integral image. We have achieved the entire process in the lab, and believe that this technology will be perfected in the near future.