37 research outputs found
ImFace++: A Sophisticated Nonlinear 3D Morphable Face Model with Implicit Neural Representations
Accurate representations of 3D faces are of paramount importance in various
computer vision and graphics applications. However, the challenges persist due
to the limitations imposed by data discretization and model linearity, which
hinder the precise capture of identity and expression clues in current studies.
This paper presents a novel 3D morphable face model, named ImFace++, to learn a
sophisticated and continuous space with implicit neural representations.
ImFace++ first constructs two explicitly disentangled deformation fields to
model complex shapes associated with identities and expressions, respectively,
which simultaneously facilitate the automatic learning of correspondences
across diverse facial shapes. To capture more sophisticated facial details, a
refinement displacement field within the template space is further
incorporated, enabling a fine-grained learning of individual-specific facial
details. Furthermore, a Neural Blend-Field is designed to reinforce the
representation capabilities through adaptive blending of an array of local
fields. In addition to ImFace++, we have devised an improved learning strategy
to extend expression embeddings, allowing for a broader range of expression
variations. Comprehensive qualitative and quantitative evaluations demonstrate
that ImFace++ significantly advances the state-of-the-art in terms of both face
reconstruction fidelity and correspondence accuracy.Comment: Project page:
https://github.com/MingwuZheng/ImFace/tree/imface%2B%2B. arXiv admin note:
text overlap with arXiv:2203.1451
Dendrimer-entrapped gold nanoparticles as potential CT contrast agents for blood pool imaging
The purpose of this study was to evaluate dendrimer-entrapped gold nanoparticles [Au DENPs] as a molecular imaging [MI] probe for computed tomography [CT]. Au DENPs were prepared by complexing AuCl4- ions with amine-terminated generation 5 poly(amidoamine) [G5.NH2] dendrimers. Resulting particles were sized using transmission electron microscopy. Serial dilutions (0.001 to 0.1 M) of either Au DENPs or iohexol were scanned by CT in vitro. Based on these results, Au DENPs were injected into mice, either subcutaneously (10 μL, 0.007 to 0.02 M) or intravenously (300 μL, 0.2 M), after which the mice were imaged by micro-CT or a standard mammography unit. Au DENPs prepared using G5.NH2 dendrimers as templates are quite uniform and have a size range of 2 to 4 nm. At Au concentrations above 0.01 M, the CT value of Au DENPs was higher than that of iohexol. A 10-μL subcutaneous dose of Au DENPs with [Au] ≥ 0.009 M could be detected by micro-CT. The vascular system could be imaged 5 and 20 min after injection of Au DENPs into the tail vein, and the urinary system could be imaged after 60 min. At comparable time points, the vascular system could not be imaged using iohexol, and the urinary system was imaged only indistinctly. Findings from this study suggested that Au DENPs prepared using G5.NH2 dendrimers as templates have good X-ray attenuation and a substantial circulation time. As their abundant surface amine groups have the ability to bind to a range of biological molecules, Au DENPs have the potential to be a useful MI probe for CT
Towards Practical Capture of High-Fidelity Relightable Avatars
In this paper, we propose a novel framework, Tracking-free Relightable Avatar
(TRAvatar), for capturing and reconstructing high-fidelity 3D avatars. Compared
to previous methods, TRAvatar works in a more practical and efficient setting.
Specifically, TRAvatar is trained with dynamic image sequences captured in a
Light Stage under varying lighting conditions, enabling realistic relighting
and real-time animation for avatars in diverse scenes. Additionally, TRAvatar
allows for tracking-free avatar capture and obviates the need for accurate
surface tracking under varying illumination conditions. Our contributions are
two-fold: First, we propose a novel network architecture that explicitly builds
on and ensures the satisfaction of the linear nature of lighting. Trained on
simple group light captures, TRAvatar can predict the appearance in real-time
with a single forward pass, achieving high-quality relighting effects under
illuminations of arbitrary environment maps. Second, we jointly optimize the
facial geometry and relightable appearance from scratch based on image
sequences, where the tracking is implicitly learned. This tracking-free
approach brings robustness for establishing temporal correspondences between
frames under different lighting conditions. Extensive qualitative and
quantitative experiments demonstrate that our framework achieves superior
performance for photorealistic avatar animation and relighting.Comment: Accepted to SIGGRAPH Asia 2023 (Conference); Project page:
https://travatar-paper.github.io
Normal Values of Myocardial Deformation Assessed by Cardiovascular Magnetic Resonance Feature Tracking in a Healthy Chinese Population: A Multicenter Study
Reference values on atrial and ventricular strain from cardiovascular magnetic resonance (CMR) are essential in identifying patients with impaired atrial and ventricular function. However, reference values have not been established for Chinese subjects. One hundred and fifty healthy volunteers (75 Males/75 Females; 18–82 years) were recruited. All underwent CMR scans with images acceptable for further strain analysis. Subjects were stratified by age: Group 1, 18–44 years; Group 2, 45–59 years; Group 3, ≥60 years. Feature tracking of CMR cine imaging was used to obtain left atrial global longitudinal (LA Ell) and circumferential strains (LA Ecc) and respective systolic strain rates, left ventricular longitudinal (LV Ell), circumferential (LV Ecc) and radial strains (LV Err) and their respective strain rates, and right ventricular longitudinal strain (RV Ell) and strain rate. LA Ell and LA Ecc were 32.8 ± 9.2% and 40.3 ± 13.4%, respectively, and RV Ell was −29.3 ± 6.0%. LV Ell, LV Ecc and LV Err were −22.4 ± 2.9%, −24.3 ± 3.1%, and 79.0 ± 19.4%, respectively. LV Ell and LV Ecc were higher in females than males (P < 0.05). LA Ell, LA Ecc, and LV Ecc decreased, while LV Err increased with age (P < 0.05). LV Ell and RV Ell were not shown to be associated with age. Normal ranges for atrial and ventricular strain and strain rates are provided using CMR feature tracking in Chinese subjects
SPG-VTON: Semantic Prediction Guidance for Multi-Pose Virtual Try-on
10.1109/TMM.2022.3143712IEEE TRANSACTIONS ON MULTIMEDIA241233-124