Image-Based Rendering by Virtual 1D Cameras
Image-based rendering (IBR) has been used to synthesize images corresponding to a new view point from stored images. Rendering methods based on a three-dimensional plenoptic function are attractive due to the simplicity of image capture. Only a few specific discussions, however, have been done for the scaling problem to correct aspect ratio distortion, which heavily affects the quality of a synthesized image. This paper presents a rendering algorithm with a scaling scheme, which is general in that it can handle arbitrary camera paths. We model a virtual camera by a set of one-dimensional (1D) cameras. The ray representation of the 1D camera enables us to devise a rendering algorithm for the cases where the camera paths to create ray databases are arbitrary curves.
The figures shown below demonstrate new view generation from a video. First, the positions and directions of the cameras for the frames in a video were estimated by a structure from motion algorithm. Note that the camera path was not parametric curves such as lines and circles. The rough 3D structure of the captured scene were obtained as well. Using the camera path and rough structure, we can render new views associated with a virtual camera. In this experiment, the virtual camera with a forward motion was used in order to confirm the effect of the proposed scaling scheme.
The following figures show the new views. Since no aspect ratio correction was done in the first figure, the new views had the serious aspect ratio distortion which deteriorated the quality of the new views. For example, the width of the gate in the scene did not change although the virtual camera was moved. In the second figure using the proposed scaling scheme, the width of the gate gradually changed as the virtual camera was moved owing to the compensation of the aspect ratio. The quality of the new views was sufficient to emulate the virtually generated camera motion.
In summary, the experimental result with large changes in the distances between the virtual camera and the scene demonstrates that our algorithm can correct aspect ratio distortions.
Rendering without scaling.
Rendering with the proposed scaling scheme.
