123 research outputs found
SparseNeuS: Fast Generalizable Neural Surface Reconstruction from Sparse Views
We introduce SparseNeuS, a novel neural rendering based method for the task
of surface reconstruction from multi-view images. This task becomes more
difficult when only sparse images are provided as input, a scenario where
existing neural reconstruction approaches usually produce incomplete or
distorted results. Moreover, their inability of generalizing to unseen new
scenes impedes their application in practice. Contrarily, SparseNeuS can
generalize to new scenes and work well with sparse images (as few as 2 or 3).
SparseNeuS adopts signed distance function (SDF) as the surface representation,
and learns generalizable priors from image features by introducing geometry
encoding volumes for generic surface prediction. Moreover, several strategies
are introduced to effectively leverage sparse views for high-quality
reconstruction, including 1) a multi-level geometry reasoning framework to
recover the surfaces in a coarse-to-fine manner; 2) a multi-scale color
blending scheme for more reliable color prediction; 3) a consistency-aware
fine-tuning scheme to control the inconsistent regions caused by occlusion and
noise. Extensive experiments demonstrate that our approach not only outperforms
the state-of-the-art methods, but also exhibits good efficiency,
generalizability, and flexibility.Comment: Project page: https://www.xxlong.site/SparseNeuS
NeTO:Neural Reconstruction of Transparent Objects with Self-Occlusion Aware Refraction-Tracing
We present a novel method, called NeTO, for capturing 3D geometry of solid
transparent objects from 2D images via volume rendering. Reconstructing
transparent objects is a very challenging task, which is ill-suited for
general-purpose reconstruction techniques due to the specular light transport
phenomena. Although existing refraction-tracing based methods, designed
specially for this task, achieve impressive results, they still suffer from
unstable optimization and loss of fine details, since the explicit surface
representation they adopted is difficult to be optimized, and the
self-occlusion problem is ignored for refraction-tracing. In this paper, we
propose to leverage implicit Signed Distance Function (SDF) as surface
representation, and optimize the SDF field via volume rendering with a
self-occlusion aware refractive ray tracing. The implicit representation
enables our method to be capable of reconstructing high-quality reconstruction
even with a limited set of images, and the self-occlusion aware strategy makes
it possible for our method to accurately reconstruct the self-occluded regions.
Experiments show that our method achieves faithful reconstruction results and
outperforms prior works by a large margin. Visit our project page at
\url{https://www.xxlong.site/NeTO/
GaussianShader: 3D Gaussian Splatting with Shading Functions for Reflective Surfaces
The advent of neural 3D Gaussians has recently brought about a revolution in
the field of neural rendering, facilitating the generation of high-quality
renderings at real-time speeds. However, the explicit and discrete
representation encounters challenges when applied to scenes featuring
reflective surfaces. In this paper, we present GaussianShader, a novel method
that applies a simplified shading function on 3D Gaussians to enhance the
neural rendering in scenes with reflective surfaces while preserving the
training and rendering efficiency. The main challenge in applying the shading
function lies in the accurate normal estimation on discrete 3D Gaussians.
Specifically, we proposed a novel normal estimation framework based on the
shortest axis directions of 3D Gaussians with a delicately designed loss to
make the consistency between the normals and the geometries of Gaussian
spheres. Experiments show that GaussianShader strikes a commendable balance
between efficiency and visual quality. Our method surpasses Gaussian Splatting
in PSNR on specular object datasets, exhibiting an improvement of 1.57dB. When
compared to prior works handling reflective surfaces, such as Ref-NeRF, our
optimization time is significantly accelerated (23h vs. 0.58h). Please click on
our project website to see more results.Comment: 13 pages, 11 figures, refrences adde
NeRO: Neural Geometry and BRDF Reconstruction of Reflective Objects from Multiview Images
We present a neural rendering-based method called NeRO for reconstructing the
geometry and the BRDF of reflective objects from multiview images captured in
an unknown environment. Multiview reconstruction of reflective objects is
extremely challenging because specular reflections are view-dependent and thus
violate the multiview consistency, which is the cornerstone for most multiview
reconstruction methods. Recent neural rendering techniques can model the
interaction between environment lights and the object surfaces to fit the
view-dependent reflections, thus making it possible to reconstruct reflective
objects from multiview images. However, accurately modeling environment lights
in the neural rendering is intractable, especially when the geometry is
unknown. Most existing neural rendering methods, which can model environment
lights, only consider direct lights and rely on object masks to reconstruct
objects with weak specular reflections. Therefore, these methods fail to
reconstruct reflective objects, especially when the object mask is not
available and the object is illuminated by indirect lights. We propose a
two-step approach to tackle this problem. First, by applying the split-sum
approximation and the integrated directional encoding to approximate the
shading effects of both direct and indirect lights, we are able to accurately
reconstruct the geometry of reflective objects without any object masks. Then,
with the object geometry fixed, we use more accurate sampling to recover the
environment lights and the BRDF of the object. Extensive experiments
demonstrate that our method is capable of accurately reconstructing the
geometry and the BRDF of reflective objects from only posed RGB images without
knowing the environment lights and the object masks. Codes and datasets are
available at https://github.com/liuyuan-pal/NeRO.Comment: Accepted to SIGGRAPH 2023. Project page:
https://liuyuan-pal.github.io/NeRO/ Codes:
https://github.com/liuyuan-pal/NeR
NeuralUDF: Learning Unsigned Distance Fields for Multi-view Reconstruction of Surfaces with Arbitrary Topologies
We present a novel method, called NeuralUDF, for reconstructing surfaces with
arbitrary topologies from 2D images via volume rendering. Recent advances in
neural rendering based reconstruction have achieved compelling results.
However, these methods are limited to objects with closed surfaces since they
adopt Signed Distance Function (SDF) as surface representation which requires
the target shape to be divided into inside and outside. In this paper, we
propose to represent surfaces as the Unsigned Distance Function (UDF) and
develop a new volume rendering scheme to learn the neural UDF representation.
Specifically, a new density function that correlates the property of UDF with
the volume rendering scheme is introduced for robust optimization of the UDF
fields. Experiments on the DTU and DeepFashion3D datasets show that our method
not only enables high-quality reconstruction of non-closed shapes with complex
typologies, but also achieves comparable performance to the SDF based methods
on the reconstruction of closed surfaces.Comment: Visit our project page at https://www.xxlong.site/NeuralUDF
Automatic Detection of Hard Exudates in Color Retinal Images Using Dynamic Threshold and SVM Classification: Algorithm Development and Evaluation
Diabetic retinopathy (DR) is one of the most common causes of visual impairment. Automatic detection of hard exudates (HE) from retinal photographs is an important step for detection of DR. However, most of existing algorithms for HE detection are complex and inefficient. We have developed and evaluated an automatic retinal image processing algorithm for HE detection using dynamic threshold and fuzzy C-means clustering (FCM) followed by support vector machine (SVM) for classification. The proposed algorithm consisted of four main stages: (i) imaging preprocessing; (ii) localization of optic disc (OD); (iii) determination of candidate HE using dynamic threshold in combination with global threshold based on FCM; and (iv) extraction of eight texture features from the candidate HE region, which were then fed into an SVM classifier for automatic HE classification. The proposed algorithm was trained and cross-validated (10 fold) on a publicly available e-ophtha EX database (47 images) on pixel-level, achieving the overall average sensitivity, PPV, and F-score of 76.5%, 82.7%, and 76.7%. It was tested on another independent DIARETDB1 database (89 images) with the overall average sensitivity, specificity, and accuracy of 97.5%, 97.8%, and 97.7%, respectively. In summary, the satisfactory evaluation results on both retinal imaging databases demonstrated the effectiveness of our proposed algorithm for automatic HE detection, by using dynamic threshold and FCM followed by an SVM for classification
Transcriptome analysis of the hepatopancreas from the Litopenaeus vannamei infected with different flagellum types of Vibrio alginolyticus strains
Vibrio alginolyticus, one of the prevalently harmful Vibrio species found in the ocean, causes significant economic damage in the shrimp farming industry. Its flagellum serves as a crucial virulence factor in the invasion of host organisms. However, the processes of bacteria flagella recognition and activation of the downstream immune system in shrimp remain unclear. To enhance comprehension of this, a ΔflhG strain was created by in-frame deletion of the flhG gene in V. alginolyticus strain HN08155. Then we utilized the transcriptome analysis to examine the different immune responses in Litopenaeus vannamei hepatopancreas after being infected with the wild type and the mutant strains. The results showed that the ΔflhG strain, unlike the wild type, lost its ability to regulate flagella numbers negatively and displayed multiple flagella. When infected with the hyperflagella-type strain, the RNA-seq revealed the upregulation of several immune-related genes in the shrimp hepatopancreas. Notably, two C-type lectins (CTLs), namely galactose-specific lectin nattectin and macrophage mannose receptor 1, and the TNF receptor-associated factor (TRAF) 6 gene were upregulated significantly. These findings suggested that C-type lectins were potentially involved in flagella recognition in shrimp and the immune system was activated through the TRAF6 pathway after flagella detection by CTLs
Design of bifurcation junctions in artificial vascular vessels additively manufactured for skin tissue engineering
Construction of an artificial vascular network ready for its additive manufacturing is an important task in tissue engineering. This paper presents a set of simple mathematical algorithms for the computer-aided design of complex three dimensional vascular networks. Firstly various existing mathematical methods from the literature are reviewed and simplified for the convenience of applications in tissue engineering. This leads to a complete and step by step method for the construction of an artificial vascular network. Secondly a systematic parametric study is presented to illustrate how the various parameters in the vascular junction model affect the key factors that have to be controlled when designing the bifurcation junctions of a vascular network. These results are presented as a set of simple design rules and a design map which serve as a convenient guide for tissue engineering researchers when constructing artificial vascular networks
Search for single production of vector-like quarks decaying into Wb in pp collisions at TeV with the ATLAS detector
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