Localization and degmentation of 3D intervertebral discs in MR Images by data driven estimation

This paper addresses the problem of fully-automatic localization and segmentation of 3D intervertebral discs (IVDs) from MR images. Our method contains two steps, where we first localize the center of each IVD, and then segment IVDs by classifying image pixels around each disc center as foreground (disc) or background. The disc localization is done by estimating the image displacements from a set of randomly sampled 3D image patches to the disc center. The image displacements are estimated by jointly optimizing the training and test displacement values in a data-driven way, where we take into consideration both the training data and the geometric constraint on the test image. After the disc centers are localized, we segment the discs by classifying image pixels around disc centers as background or foreground. The classification is done in a similar data-driven approach as we used for localization, but in this segmentation case we are aiming to estimate the foreground/background probability of each pixel instead of the image displacements. In addition, an extra neighborhood smooth constraint is introduced to enforce the local smoothness of the label field. Our method is validated on 3D T2-weighted turbo spin echo MR images of 35 patients from two different studies. Experiments show that compared to state of the art, our method achieves better or comparable results. Specifically, we achieve for localization a mean error of 1.6-2.0 mm, and for segmentation a mean Dice metric of 85%-88% and a mean surface distance of 1.3-1.4 mm.

Three-dimensional slope stability assessment of two-layered undrained clay

This paper uses the finite element upper and lower bound limit analysis methods to investigate the three-dimensional (3D) slope stability of two-layered undrained clay slopes. The solutions obtained from the slope stability analyses are bracketed to within ±10% or better. For comparison purposes, results from two-dimensional (2D) analyses based on the numerical limit analysis methods and the conventional limit equilibrium method (LEM) are also discussed. This study shows that 3D boundary of a slope can have significant effects on the slope stability. In addition, the results are presented in the form of stability charts which can be convenient tools for practicing engineers.

Taking the LEAP with the Oculus HMD and CAD - plucking at thin air?

Achieving adequate visualisation of designs within CAD packages remains a challenge for designers with current methods of 3D CAD visualisation requiring either a high level of technical ability, or expensive hardware and software. The recent re-emergence of consumer VR has lowered the barrier for everyday developers wanting to visualise their designs in true 3D. This paper presents the CAD Interaction Lab (CIL) which employs the Oculus Rift Head Mounted Display (HMD) and Leap Motion Controller (LMC) to provide a low cost method enabling users to use their hands to dissect a mechanic model to manipulate and inspect individual components in realistic 3D. Qualitative observations of user interactions with the CIL show that users were able to intuitively manipulate the CAD model using natural hand movements with only minimal instruction.