  360$^\circ$ images and videos have become an economic and popular way to
provide VR experiences using real-world content. However, the manipulation of
the stereo panoramic content remains less explored. In this paper, we focus on
the 360$^\circ$ image composition problem, and develop a solution that can take
an object from a stereo image pair and insert it at a given 3D position in a
target stereo panorama, with well-preserved geometry information. Our method
uses recovered 3D point clouds to guide the composited image generation. More
specifically, we observe that using only a one-off operation to insert objects
into equirectangular images will never produce satisfactory depth perception
and generate ghost artifacts when users are watching the result from different
view directions. Therefore, we propose a novel view-dependent projection method
that segments the object in 3D spherical space with the stereo camera pair
facing in that direction. A deep depth densification network is proposed to
generate depth guidance for the stereo image generation of each view segment
according to the desired position and pose of the inserted object. We finally
merge the synthesized view segments and blend the objects into the target
stereo 360$^\circ$ scene. A user study demonstrates that our method can provide
good depth perception and removes ghost artifacts. The view-dependent solution
is a potential paradigm for other content manipulation methods for 360$^\circ$
images and videos.
