36 research outputs found
Reverse engineering of CAD models via clustering and approximate implicitization
In applications like computer aided design, geometric models are often
represented numerically as polynomial splines or NURBS, even when they
originate from primitive geometry. For purposes such as redesign and
isogeometric analysis, it is of interest to extract information about the
underlying geometry through reverse engineering. In this work we develop a
novel method to determine these primitive shapes by combining clustering
analysis with approximate implicitization. The proposed method is automatic and
can recover algebraic hypersurfaces of any degree in any dimension. In exact
arithmetic, the algorithm returns exact results. All the required parameters,
such as the implicit degree of the patches and the number of clusters of the
model, are inferred using numerical approaches in order to obtain an algorithm
that requires as little manual input as possible. The effectiveness, efficiency
and robustness of the method are shown both in a theoretical analysis and in
numerical examples implemented in Python
Trivariate Spline Representations for Computer Aided Design and Additive Manufacturing
Digital representations targeting design and simulation for Additive
Manufacturing (AM) are addressed from the perspective of Computer Aided
Geometric Design. We discuss the feasibility for multi-material AM for B-rep
based CAD, STL, sculptured triangles as well as trimmed and block-structured
trivariate locally refined spline representations. The trivariate spline
representations support Isogeometric Analysis (IGA), and topology structures
supporting these for CAD, IGA and AM are outlined. The ideas of (Truncated)
Hierarchical B-splines, T-splines and LR B-splines are outlined and the
approaches are compared. An example from the EC H2020 Factories of the Future
Research and Innovation Actions CAxMan illustrates both trimmed and
block-structured spline representations for IGA and AM.Comment: 30 pages, 14 figures. This project has received funding from the
European Union's Horizon 2020 research and innovation programme under grant
agreement No 68044
Binary segmentation of medical images using implicit spline representations and deep learning
We propose a novel approach to image segmentation based on combining implicit
spline representations with deep convolutional neural networks. This is done by
predicting the control points of a bivariate spline function whose zero-set
represents the segmentation boundary. We adapt several existing neural network
architectures and design novel loss functions that are tailored towards
providing implicit spline curve approximations. The method is evaluated on a
congenital heart disease computed tomography medical imaging dataset.
Experiments are carried out by measuring performance in various standard
metrics for different networks and loss functions. We determine that splines of
bidegree with coefficient resolution performed optimally
for resolution CT images. For our best network, we achieve an
average volumetric test Dice score of almost 92%, which reaches the state of
the art for this congenital heart disease dataset.Comment: 17 pages, 5 figure
Real-time processing of high-resolution video and 3D model-based tracking for remote towers
High quality video data is a core component in emerging remote tower
operations as it inherently contains a huge amount of information on which an
air traffic controller can base decisions. Various digital technologies also
have the potential to exploit this data to bring enhancements, including
tracking ground movements by relating events in the video view to their
positions in 3D space. The total resolution of remote tower setups with
multiple cameras often exceeds 25 million RGB pixels and is captured at 30
frames per second or more. It is thus a challenge to efficiently process all
the data in such a way as to provide relevant real-time enhancements to the
controller. In this paper we discuss how a number of improvements can be
implemented efficiently on a single workstation by decoupling processes and
utilizing hardware for parallel computing. We also highlight how decoupling the
processes in this way increases resilience of the software solution in the
sense that failure of a single component does not impair the function of the
other components