ICON: Implicit Clothed humans Obtained from Normals
Yuliang Xiu1Jinlong Yang1Dimitrios Tzionas1Michael J. Black1
1Max Planck Institute for Intelligent Systems
CVPR 2022

   Google Colab

Introduction Video
Current methods for learning realistic and animatable 3D clothed avatars need either posed 3D scans or 2D images with carefully controlled user poses. In contrast, our goal is to learn the avatar from only 2D images of people in unconstrained poses. Given a set of images, our method estimates a detailed 3D surface from each image and then combines these into an animatable avatar. Implicit functions are well suited to the first task, as they can capture details like hair or clothes. Current methods, however, are not robust to varied human poses and often produce 3D surfaces with broken or disembodied limbs, missing details, or non-human shapes. The problem is that these methods use global feature encoders that are sensitive to global pose. To address this, we propose ICON ("Implicit Clothed humans Obtained from Normals"), which uses local features, instead. ICON has two main modules, both of which exploit the SMPL(-X) body model. First, ICON infers detailed clothed-human normals (front/back) conditioned on the SMPL(-X) normals. Second, a visibility-aware implicit surface regressor produces an iso-surface of a human occupancy field. Importantly, at inference time, a feedback loop alternates between refining the SMPL(-X) mesh using the inferred clothed normals and then refining the normals. Given multiple reconstructed frames of a subject in varied poses, we use SCANimate to produce an animatable avatar from them. Evaluation on the AGORA and CAPE datasets shows that ICON outperforms the state of the art in reconstruction, even with heavily limited training data. Additionally, it is much more robust to out-of-distribution samples, e.g., in-the-wild poses/images and out-of-frame cropping. ICON takes a step towards robust 3D clothed human reconstruction from in-the-wild images. This enables creating avatars directly from video with personalized and natural pose-dependent cloth deformation.
ICON: Implicit Clothed humans Obtained from Normals
Google Colab
Main Contributions

ICON takes, as input, an RGB image of a segmented clothed human and a SMPL body estimated from the image. The SMPL body is used to guide two of ICON’s modules: one infers detailed clothed-human surface normals (front and back views), and the other infers a visibility-aware implicit surface (iso-surface of an occupancy field).

Errors in the initial SMPL estimate, however, might misguide inference. Thus, at inference time, an iterative feedback loop refines SMPL (i.e. its 3D shape, pose and translation) using the inferred detailed normals, and vice versa, leading to a refined implicit shape with better 3D details.

Qualitative Results (Only Geometry)

Application: create an animatable avatar from 400 images

Human Digitization with Implicit Representation
  title={{ICON}: {I}mplicit {C}lothed humans {O}btained from {N}ormals},
  author={Xiu, Yuliang and Yang, Jinlong and Tzionas, Dimitrios and Black, Michael J.},
  booktitle={IEEE/CVF Conf.~on Computer Vision and Pattern Recognition (CVPR)},
  month = jun,
© 2022 Max-Planck-Gesellschaft -Imprint-Privacy Policy-License