  We present a billboard-based free-viewpoint video synthesizing algorithm for
sports scenes that can robustly reconstruct and render a high-fidelity
billboard model for each object, including an occluded one, in each camera. Its
contributions are (1) applicable to a challenging shooting condition where a
high precision 3D model cannot be built because a small number of cameras
featuring wide-baseline are equipped; (2) capable of reproducing appearances of
occlusions, that is one of the most significant issues for billboard-based
approaches due to the ineffective detection of overlaps. To achieve
contributions above, the proposed method does not attempt to find a
high-quality 3D model but utilizes a raw 3D model that is obtained directly
from space carving. Although the model is insufficiently accurate for producing
an impressive visual effect, precise objects segmentation and occlusions
detection can be performed by back-projecting it onto each camera plane. The
billboard model of each object in each camera is rendered according to whether
it is occluded or not, and its location in the virtual stadium is determined
considering the location of its 3D model. We synthesized free-viewpoint videos
of two soccer sequences recorded by five cameras with the proposed and
state-of-art methods to demonstrate its performance.
