20 research outputs found
Segmentation Based Mesh Denoising
Feature-preserving mesh denoising has received noticeable attention recently.
Many methods often design great weighting for anisotropic surfaces and small
weighting for isotropic surfaces, to preserve sharp features. However, they
often disregard the fact that small weights still pose negative impacts to the
denoising outcomes. Furthermore, it may increase the difficulty in parameter
tuning, especially for users without any background knowledge. In this paper,
we propose a novel clustering method for mesh denoising, which can avoid the
disturbance of anisotropic information and be easily embedded into
commonly-used mesh denoising frameworks. Extensive experiments have been
conducted to validate our method, and demonstrate that it can enhance the
denoising results of some existing methods remarkably both visually and
quantitatively. It also largely relaxes the parameter tuning procedure for
users, in terms of increasing stability for existing mesh denoising methods
NormalNet: Learning based Guided Normal Filtering for Mesh Denoising
Mesh denoising is a critical technology in geometry processing, which aims to
recover high-fidelity 3D mesh models of objects from noise-corrupted versions.
In this work, we propose a deep learning based face normal filtering scheme for
mesh denoising, called \textit{NormalNet}. Different from natural images, for
mesh, it is difficult to collect enough examples to build a robust end-to-end
training scheme for deep networks. To remedy this problem, we propose an
iterative framework to generate enough face-normal pairs, based on which a
convolutional neural networks (CNNs) based scheme is designed for guidance
normal learning. Moreover, to facilitate the 3D convolution operation in CNNs,
for each face in mesh, we propose a voxelization strategy to transform
irregular local mesh structure into regular 4D-array form. Finally, guided
normal filtering is performed to obtain filtered face normals, according to
which denoised positions of vertices are derived. Compared to the
state-of-the-art works, the proposed scheme can generate accurate guidance
normals and remove noise effectively while preserving original features and
avoiding pseudo-features
Learning Sparse High Dimensional Filters: Image Filtering, Dense CRFs and Bilateral Neural Networks
Bilateral filters have wide spread use due to their edge-preserving
properties. The common use case is to manually choose a parametric filter type,
usually a Gaussian filter. In this paper, we will generalize the
parametrization and in particular derive a gradient descent algorithm so the
filter parameters can be learned from data. This derivation allows to learn
high dimensional linear filters that operate in sparsely populated feature
spaces. We build on the permutohedral lattice construction for efficient
filtering. The ability to learn more general forms of high-dimensional filters
can be used in several diverse applications. First, we demonstrate the use in
applications where single filter applications are desired for runtime reasons.
Further, we show how this algorithm can be used to learn the pairwise
potentials in densely connected conditional random fields and apply these to
different image segmentation tasks. Finally, we introduce layers of bilateral
filters in CNNs and propose bilateral neural networks for the use of
high-dimensional sparse data. This view provides new ways to encode model
structure into network architectures. A diverse set of experiments empirically
validates the usage of general forms of filters
Nextmed: Automatic Imaging Segmentation, 3D Reconstruction, and 3D Model Visualization Platform Using Augmented and Virtual Reality
The visualization of medical images with advanced techniques, such as augmented reality and virtual reality, represent a breakthrough for medical professionals. In contrast to more traditional visualization tools lacking 3D capabilities, these systems use the three available dimensions. To visualize medical images in 3D, the anatomical areas of interest must be segmented. Currently, manual segmentation, which is the most commonly used technique, and semi-automatic approaches can be time consuming because a doctor is required, making segmentation for each individual case unfeasible. Using new technologies, such as computer vision and artificial intelligence for segmentation algorithms and augmented and virtual reality for visualization techniques implementation, we designed a complete platform to solve this problem and allow medical professionals to work more frequently with anatomical 3D models obtained from medical imaging. As a result, the Nextmed project, due to the different implemented software applications, permits the importation of digital imaging and communication on medicine (dicom) images on a secure cloud platform and the automatic segmentation of certain anatomical structures with new algorithms that improve upon the current research results. A 3D mesh of the segmented structure is then automatically generated that can be printed in 3D or visualized using both augmented and virtual reality, with the designed software systems. The Nextmed project is unique, as it covers the whole process from uploading dicom images to automatic segmentation, 3D reconstruction, 3D visualization, and manipulation using augmented and virtual reality. There are many researches about application of augmented and virtual reality for medical image 3D visualization; however, they are not automated platforms. Although some other anatomical structures can be studied, we focused on one case: a lung study. Analyzing the application of the platform to more than 1000 dicom images and studying the results with medical specialists, we concluded that the installation of this system in hospitals would provide a considerable improvement as a tool for medical image visualization
Surface Denoising based on Normal Filtering in a Robust Statistics Framework
During a surface acquisition process using 3D scanners, noise is inevitable
and an important step in geometry processing is to remove these noise
components from these surfaces (given as points-set or triangulated mesh). The
noise-removal process (denoising) can be performed by filtering the surface
normals first and by adjusting the vertex positions according to filtered
normals afterwards. Therefore, in many available denoising algorithms, the
computation of noise-free normals is a key factor. A variety of filters have
been introduced for noise-removal from normals, with different focus points
like robustness against outliers or large amplitude of noise. Although these
filters are performing well in different aspects, a unified framework is
missing to establish the relation between them and to provide a theoretical
analysis beyond the performance of each method.
In this paper, we introduce such a framework to establish relations between a
number of widely-used nonlinear filters for face normals in mesh denoising and
vertex normals in point set denoising. We cover robust statistical estimation
with M-smoothers and their application to linear and non-linear normal
filtering. Although these methods originate in different mathematical theories
- which include diffusion-, bilateral-, and directional curvature-based
algorithms - we demonstrate that all of them can be cast into a unified
framework of robust statistics using robust error norms and their corresponding
influence functions. This unification contributes to a better understanding of
the individual methods and their relations with each other. Furthermore, the
presented framework provides a platform for new techniques to combine the
advantages of known filters and to compare them with available methods