In 3D CAD system, a shape model may include a wide variety of n-sided regions. Among the n-sided regions, concave regions are very difficult to be well interpolated. This paper presents an approach to fill a concave region with a bi-cubic B-spline surface.We generate many points outside the concave region and fit cubic B-spline curves or a bi-cubic B-spline surface across them by the least squares method. The boundary curves of the concave region trim the generated B-spline surface and lie on the surface within user-specified tolerance. With this method, smooth and satisfactory surfaces can be generated in case of a concave region and a region with hole.
This paper estimates detection errors of image rotation angles in our RPSA method in which the frequency spectrum for each image is carefully considered to detect the image rotation angle reliably and accurately. Spatial filtering effects on detection errors are obtained for four types of synthetic images. It is made clear that the image binarization lowers the detection accuracy and smooth-filtering heightens the accuracy, and that errors changes periodically with some frequencies as the rotation angle increases. Detection errors are analyzed from the results and causes of the errors are made clear.
A data hiding method for ordered dither images with keeping enough picture quality was proposed and studied for typical threshold ordering methods. The proposed method only embeds the data to the restricted block patterns found in flat area, which dominate the occurring block patterns, and makes the pattern to be also one of the restricted patterns after data embedding. This method has also the effect to prevent the data embedding on text area, which usually causes strong damage to the image quality. It is acknowledged that the embedded images using proposed method are better than those using conventional method in picture quality and also in data compression ratio. By controlling the data embedding frequency, we succeeded to introduce the unnoticeable embedding rate for various images.
We are studying new image composite methods named environmental synthesis studios. In an environmental synthesis, a natural virtual scene is generated by matching the environments of a real space and a virtual space. There is a camera parameter estimation method in the element technology of an environmental synthesis. We present a simple camera parameter estimation method using infrared LEDs, infrared camera and rotary encoder embedded in the camera lens. We have experimentally examine the effectiveness of the method.
This report proposes a new video communication system which transmits “awareness ” at very low bit rate in usual, and displays normal “video” sending additional information on demand. The “awareness” means information without “privacy” related details and it expresses “existence” or “motion”, e.g. The proposed system decomposes a person's region into (a) basic layer which contains awareness and (b) enhancing layer which contains other information. This processing is implemented by basic components of the JPEG 2000 such as wavelet transform and bit plane decomposition. The basic layer contains (1) person's region, (2) more significant bit plane, and (3) preceded band signals. As a result, the awareness is transmitted at very low bit rate.
Collaborative work discuss common problems by sharing visualization data in grid environment is a useful method in order to understand each other. However, real-time transmission and sharing technique for large-scale visualization data have been insufficient, it is important to develop an effective remote visualization technique. The speed-up of processing is considered as one of demands for remote visualization of large-scale data. In this paper, we implemented RBUDP (Reliable Blast UDP) protocol which is high-speed quality and reliance quality with our remote visualization system. In addition, we implemented a parallel processing method of data transmission by using multi-thread to improve the effect for waiting time in visualization processing. We have evaluated in long-distance network environment, and proved to be available the speed-up of remote visualization.
The noncontact input device is essential for the virtual reality system. For this purpose, we propose a noncontact input method based on the custom designed real-time motion capture system with colored markers. As the applications of the proposed input method, we have developed the virtual orchestra performance system and the virtual canvas system. In these systems, the view direction and the gestures of the operator are gathered through the motion capture system and are used to control 3D CG images and music.
The technical core of computer visualization lies in the selection of proper schemes to fully represent a given dataset in a graphical form. Software support, which helps the users select the best mapping schemes,leads to a collaborative visualization environment, where they are allowed to explore large-scale and complex datasets from the first personal point of view. In this article, the state-of-the-art of related R&Ds at Institute of Fluid Science, Tohoku University is introduced.