6,932 research outputs found
Towards multiple 3D bone surface identification and reconstruction using few 2D X-ray images for intraoperative applications
This article discusses a possible method to use a small number, e.g. 5, of conventional 2D X-ray images to reconstruct multiple 3D bone surfaces intraoperatively. Each bone’s edge contours in X-ray images are automatically identified. Sparse 3D landmark points of each bone are automatically reconstructed by pairing the 2D X-ray images. The reconstructed landmark point distribution on a surface is approximately optimal covering main characteristics of the surface. A statistical shape model, dense point distribution model (DPDM), is then used to fit the reconstructed optimal landmarks vertices to reconstruct a full surface of each bone separately. The reconstructed surfaces can then be visualised and manipulated by surgeons or used by surgical robotic systems
Finite Element Based Tracking of Deforming Surfaces
We present an approach to robustly track the geometry of an object that
deforms over time from a set of input point clouds captured from a single
viewpoint. The deformations we consider are caused by applying forces to known
locations on the object's surface. Our method combines the use of prior
information on the geometry of the object modeled by a smooth template and the
use of a linear finite element method to predict the deformation. This allows
the accurate reconstruction of both the observed and the unobserved sides of
the object. We present tracking results for noisy low-quality point clouds
acquired by either a stereo camera or a depth camera, and simulations with
point clouds corrupted by different error terms. We show that our method is
also applicable to large non-linear deformations.Comment: additional experiment
Non-Rigid Structure from Motion for Complex Motion
Recovering deformable 3D motion from temporal 2D point tracks in a monocular video is an open problem with many everyday applications throughout science and industry, or the new augmented reality. Recently, several techniques have been proposed to deal the problem called Non-Rigid Structure from Motion (NRSfM), however, they can exhibit poor reconstruction performance on complex motion. In this project, we will analyze these situations for primitive human actions such as walk, run, sit, jump, etc. on different scenarios, reviewing first the current techniques to finally present our novel method. This approach is able to model complex motion into a union of subspaces, rather than the summation occurring in standard low-rank shape methods, allowing better reconstruction accuracy. Experiments in a
wide range of sequences and types of motion illustrate the benefits of this new approac
Nonrigid reconstruction of 3D breast surfaces with a low-cost RGBD camera for surgical planning and aesthetic evaluation
Accounting for 26% of all new cancer cases worldwide, breast cancer remains
the most common form of cancer in women. Although early breast cancer has a
favourable long-term prognosis, roughly a third of patients suffer from a
suboptimal aesthetic outcome despite breast conserving cancer treatment.
Clinical-quality 3D modelling of the breast surface therefore assumes an
increasingly important role in advancing treatment planning, prediction and
evaluation of breast cosmesis. Yet, existing 3D torso scanners are expensive
and either infrastructure-heavy or subject to motion artefacts. In this paper
we employ a single consumer-grade RGBD camera with an ICP-based registration
approach to jointly align all points from a sequence of depth images
non-rigidly. Subtle body deformation due to postural sway and respiration is
successfully mitigated leading to a higher geometric accuracy through
regularised locally affine transformations. We present results from 6 clinical
cases where our method compares well with the gold standard and outperforms a
previous approach. We show that our method produces better reconstructions
qualitatively by visual assessment and quantitatively by consistently obtaining
lower landmark error scores and yielding more accurate breast volume estimates
A 3D computer assisted Orthopedic Surgery Planning approach based on planar radiography
Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Informática Médica)The main goal of this work consisted in develop a system to perform the 3D reconstruction
of bone models from radiographic images. This system can be then integrated with a commercial
software that performs pre-operative planning of orthopedic surgeries. The benefit of performing
this 3D reconstruction from planar radiography is that this modality has some advantages over
other modalities that perform this reconstruction directly, like CT and MRI.
To develop the system it was used radiographic images of the femur obtained from medical
image databases online. It was also used a generic model of the femur available in the online
repository BEL. This generic model completes the information missing in the radiographic images.
It was developed two methods to perform the 3D reconstruction through the deformation of the
generic model, one uses triangulation of extracted edge points and the other don't.
The first method was not successful, the final model had very low thickness, possibly because
the triangulation process was not performed correctly. With the second method it was obtained a
3D bone model of the femur aligned with the radiographic images of the patient and with the same
size as the patient's bone. However, the obtained model still needs some adjustment to coincide
fully with reality. To perform this is necessary to enhance the deformation step of the model so that
it will have the same shape as the patient's bone.
The second method is more advantageous because it doesn't need the parameters of the x-ray
imaging system. However, it's necessary to enhance the step deformation of this method so that
the final model matches patient's anatomy.O principal objetivo deste trabalho consistiu em desenvolver um sistema capaz de realizar a
reconstrução 3D de modelos ósseos a partir de imagens radiográficas. Este sistema pode posteriormente
ser integrado num produto comercial que realiza o planeamento pré-operativo de cirurgias
ortopédicas. O benefício de realizar esta reconstrução 3D a partir de radiografias está relacionado
com o facto desta modalidade ter vantagens em relação às outras modalidades que fazem esta
reconstrução diretamente, como as modalidades CT e MRI.
Para desenvolver este sistema foram usadas imagens radiográficas do fémur obtidas através
de bases de dados online de imagens médicas. Também foi usado um modelo genérico do fémur
disponível no repositório online BEL. Este modelo genérico completa a informação que está em falta
nas imagens radiográficas. Foram desenvolvidos dois métodos, que realizam a reconstrução 3D
através da deformação do modelo genérico sendo que num é feita a triangulação de pontos dos
contornos e noutro não.
O primeiro método não foi bem sucedido, visto que o modelo final tinha uma espessura muito
pequena, possivelmente devido ao facto do processo de triangulação não ter sido executado corretamente.
Com o segundo método foi obtido um modelo 3D do fémur alinhado com as imagens
radiográficas do paciente e com o mesmo tamanho do osso do paciente. No entanto, o modelo
obtido carece ainda de alguma afinação de modo a coincidir na íntegra com a realidade. Para fazer
isto é necessário melhorar o passo de deformação do modelo, para que este fique com a mesma
forma do osso do paciente.
O segundo método é mais vantajoso porque não necessita dos parâmetros dos sistema de raios-
X. No entanto, é necessário melhorar o passo de deformação deste método para que o modelo final
coincida com a anatomia do paciente
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