  As it is hard to calibrate single-view RGB images in the wild, existing 3D
human mesh reconstruction (3DHMR) methods either use a constant large focal
length or estimate one based on the background environment context, which can
not tackle the problem of the torso, limb, hand or face distortion caused by
perspective camera projection when the camera is close to the human body. The
naive focal length assumptions can harm this task with the incorrectly
formulated projection matrices. To solve this, we propose Zolly, the first
3DHMR method focusing on perspective-distorted images. Our approach begins with
analysing the reason for perspective distortion, which we find is mainly caused
by the relative location of the human body to the camera center. We propose a
new camera model and a novel 2D representation, termed distortion image, which
describes the 2D dense distortion scale of the human body. We then estimate the
distance from distortion scale features rather than environment context
features. Afterwards, we integrate the distortion feature with image features
to reconstruct the body mesh. To formulate the correct projection matrix and
locate the human body position, we simultaneously use perspective and
weak-perspective projection loss. Since existing datasets could not handle this
task, we propose the first synthetic dataset PDHuman and extend two real-world
datasets tailored for this task, all containing perspective-distorted human
images. Extensive experiments show that Zolly outperforms existing
state-of-the-art methods on both perspective-distorted datasets and the
standard benchmark (3DPW).
