9 research outputs found
SeamlessNeRF: Stitching Part NeRFs with Gradient Propagation
Neural Radiance Fields (NeRFs) have emerged as promising digital mediums of
3D objects and scenes, sparking a surge in research to extend the editing
capabilities in this domain. The task of seamless editing and merging of
multiple NeRFs, resembling the ``Poisson blending'' in 2D image editing,
remains a critical operation that is under-explored by existing work. To fill
this gap, we propose SeamlessNeRF, a novel approach for seamless appearance
blending of multiple NeRFs. In specific, we aim to optimize the appearance of a
target radiance field in order to harmonize its merge with a source field. We
propose a well-tailored optimization procedure for blending, which is
constrained by 1) pinning the radiance color in the intersecting boundary area
between the source and target fields and 2) maintaining the original gradient
of the target. Extensive experiments validate that our approach can effectively
propagate the source appearance from the boundary area to the entire target
field through the gradients. To the best of our knowledge, SeamlessNeRF is the
first work that introduces gradient-guided appearance editing to radiance
fields, offering solutions for seamless stitching of 3D objects represented in
NeRFs.Comment: To appear in SIGGRAPH Asia 2023. Project website is accessible at
https://sites.google.com/view/seamlessner
RecolorNeRF: Layer Decomposed Radiance Fields for Efficient Color Editing of 3D Scenes
Radiance fields have gradually become a main representation of media.
Although its appearance editing has been studied, how to achieve
view-consistent recoloring in an efficient manner is still under explored. We
present RecolorNeRF, a novel user-friendly color editing approach for the
neural radiance fields. Our key idea is to decompose the scene into a set of
pure-colored layers, forming a palette. By this means, color manipulation can
be conducted by altering the color components of the palette directly. To
support efficient palette-based editing, the color of each layer needs to be as
representative as possible. In the end, the problem is formulated as an
optimization problem, where the layers and their blending weights are jointly
optimized with the NeRF itself. Extensive experiments show that our
jointly-optimized layer decomposition can be used against multiple backbones
and produce photo-realistic recolored novel-view renderings. We demonstrate
that RecolorNeRF outperforms baseline methods both quantitatively and
qualitatively for color editing even in complex real-world scenes.Comment: To appear in ACM Multimedia 2023. Project website is accessible at
https://sites.google.com/view/recolorner
ME-PCN: Point Completion Conditioned on Mask Emptiness
Point completion refers to completing the missing geometries of an object
from incomplete observations. Main-stream methods predict the missing shapes by
decoding a global feature learned from the input point cloud, which often leads
to deficient results in preserving topology consistency and surface details. In
this work, we present ME-PCN, a point completion network that leverages
`emptiness' in 3D shape space. Given a single depth scan, previous methods
often encode the occupied partial shapes while ignoring the empty regions (e.g.
holes) in depth maps. In contrast, we argue that these `emptiness' clues
indicate shape boundaries that can be used to improve topology representation
and detail granularity on surfaces. Specifically, our ME-PCN encodes both the
occupied point cloud and the neighboring `empty points'. It estimates
coarse-grained but complete and reasonable surface points in the first stage,
followed by a refinement stage to produce fine-grained surface details.
Comprehensive experiments verify that our ME-PCN presents better qualitative
and quantitative performance against the state-of-the-art. Besides, we further
prove that our `emptiness' design is lightweight and easy to embed in existing
methods, which shows consistent effectiveness in improving the CD and EMD
scores.Comment: Accepted to ICCV 2021; typos correcte
Mass spectrometric and first principles study of AlC clusters
We study the carbon-dope aluminum clusters by using time-of-flight mass
spectrum experiments and {\em ab initio} calculations. Mass abundance
distributions are obtained for anionic aluminum and aluminum-carbon mixed
clusters. Besides the well-known magic aluminum clusters such as Al
and Al, AlC cluster is found to be particularly stable among
those AlC clusters. Density functional calculations are performed to
determine the ground state structures of AlC clusters. Our results show
that the AlC is a magic cluster with extremely high stability, which
might serve as building block of the cluster-assembled materials.Comment: 4 pages, 6 figure
Differentiation of Human Induced Pluripotent Stem Cells to Mammary-like Organoids
Human induced pluripotent stem cells (iPSCs) can give rise to multiple cell types and hold great promise in regenerative medicine and disease-modeling applications. We have developed a reliable two-step protocol to generate human mammary-like organoids from iPSCs. Non-neural ectoderm-cell-containing spheres, referred to as mEBs, were first differentiated and enriched from iPSCs using MammoCult medium. Gene expression profile analysis suggested that mammary gland function-associated signaling pathways were hallmarks of 10-day differentiated mEBs. We then generated mammary-like organoids from 10-day mEBs using 3D floating mixed gel culture and a three-stage differentiation procedure. These organoids expressed common breast tissue, luminal, and basal markers, including estrogen receptor, and could be induced to produce milk protein. These results demonstrate that human iPSCs can be directed in vitro toward mammary lineage differentiation. Our findings provide an iPSC-based model for studying regulation of normal mammary cell fate and function as well as breast disease development