Omnidirectional Image Based On IBR

Panoramic and omnidirectional images are important in virtual reality. This dissertation creates full IBR(Image Based Rendering) omnidirectional images on cube face with ordinary camera and PC for the first time, and constructs a virtual reality system with the created omnidirectional image. Only panoramic image can be created before this dissertation. The main work is summarized as following:1. After the advantage and disadvantage of spherical and cube face are both analyzed, this dissertation brings forward a method to reflect and construct an omnidirectional image, i. e. using cube face to reflect omnidirctional image, creating full omnidirectional image through image stitching on cube face.2. The transforming formula between ordinary image, spherical surface, cube face and scene are deduced, the transform was carried out. Because the whole cube face is thought to be a complete function in the deduction procedure, and the perspective mapping is applied properly, there is no seam in omnidirectional image at the cubic edges. The formula from cube face to a plane is also deduced, this makes it easy to check the transforming result on cube face.3. There are some special features in image stitching on cube face, after analyzing the disturbing when stitching on cubic face, a hue-based stitching method which is based on image feature is given, it is suited to create full omnidirectional images. This can stand against the disturbing in creating omnidirectional image, accelerate the image stitching speed.4. A mathematical model of the cause and influence of image stitching error is established. Through analyzing this model in theory, the best image overlapped ratio and expectation of accumulative error arecalculated, the expectation of stitched image quality in several cases is also calculated. The validity of a method is proved in theory which distributes the accumulative error to reduce the influence of the accumulative error. A series of conclusion about omnidirectional image are obtained.5. Based on the correlation coefficient of periodic vein structure, through error correcting, a method to calibrate the camera is obtained. The calibration result is accurate enough to develop a full omnidirectional image. This dissertation also takes into account the influence of image rotation to creating omnidirectional image. Thus, two main sources which result in stitching accumulative error are eliminated, this makes the stitching more accurate. An arithmetic to distribute the accumulative error in image stitching is also put forward.6. After both panoramic image and omnidirectional image are successfully stitched on cube face and the feature of stitched omnidirectional image is analyzed, an image smoothing method is proposed, this can improve the quality of omnidirectional image.7. A virtual reality system is developed in which users can browse the cubic omnidirectional image much more freely than in other systems which are constructed by ordinary camera and personal computer. At last spherical omnidirectional image is successfully transformed from the cubic omnidirectional image.