  Natural image stitching (NIS) aims to create one natural-looking mosaic from
two overlapping images that capture the same 3D scene from different viewing
positions. Challenges inevitably arise when the scene is non-planar and the
camera baseline is wide, since parallax becomes not negligible in such cases.
In this paper, we propose a novel NIS method using depth maps, which generates
natural-looking mosaics against parallax in both overlapping and
non-overlapping regions. Firstly, we construct a robust fitting method to
filter out the outliers in feature matches and estimate the epipolar geometry
between input images. Then, we draw a triangulation of the target image and
estimate multiple local homographies, one per triangle, based on the locations
of their vertices, the rectified depth values and the epipolar geometry.
Finally, the warping image is rendered by the backward mapping of piece-wise
homographies. Panorama is then produced via average blending and image
inpainting. Experimental results demonstrate that the proposed method not only
provides accurate alignment in the overlapping regions but also virtual
naturalness in the non-overlapping region.
