A multisheet plane figure and its medial axis

2011 ◽  
Vol 55 (12) ◽  
pp. 34-43 ◽  
Author(s):  
I. S. Mekhedov
Keyword(s):  
Author(s):  
J. A. Eades ◽  
A. E. Smith ◽  
D. F. Lynch

It is quite simple (in the transmission electron microscope) to obtain convergent-beam patterns from the surface of a bulk crystal. The beam is focussed onto the surface at near grazing incidence (figure 1) and if the surface is flat the appropriate pattern is obtained in the diffraction plane (figure 2). Such patterns are potentially valuable for the characterization of surfaces just as normal convergent-beam patterns are valuable for the characterization of crystals.There are, however, several important ways in which reflection diffraction from surfaces differs from the more familiar electron diffraction in transmission.GeometryIn reflection diffraction, because of the surface, it is not possible to describe the specimen as periodic in three dimensions, nor is it possible to associate diffraction with a conventional three-dimensional reciprocal lattice.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ananthakrishna Thalengala ◽  
Shyamasunder N. Bhat ◽  
H. Anitha

AbstractAnalysis of scoliosis requires thorough radiographic evaluation by spinal curvature estimation to completely assess the spinal deformity. Spinal curvature estimation gives orthopaedic surgeons an idea of severity of spinal deformity for therapeutic purposes. Manual intervention has always been an issue to ensure accuracy and repeatability. Computer assisted systems are semi-automatic and is still influenced by surgeon’s expertise. Spinal curvature estimation completely relies on accurate identification of required end vertebrae like superior end-vertebra, inferior end-vertebra and apical vertebra. In the present work, automatic extraction of spinal information central sacral line and medial axis by computerized image understanding system has been proposed. The inter-observer variability in the anatomical landmark identification is quantified using Kappa statistic. The resultant Kappa value computed between proposed algorithm and observer lies in the range 0.7 and 0.9, which shows good accuracy. Identification of the required end vertebra is automated by the extracted spinal information. Difference in inter and intra-observer variability for the state of the art computer assisted and proposed system are quantified in terms of mean absolute difference for the various types (Type-I, Type-II, Type-III, Type-IV, and Type-V) of scoliosis.


Author(s):  
Charles-Olivier Dufresne Camaro ◽  
Morteza Rezanejad ◽  
Stavros Tsogkas ◽  
Kaleem Siddiqi ◽  
Sven Dickinson
Keyword(s):  

2019 ◽  
Vol 14 (11) ◽  
pp. 1955-1967
Author(s):  
Sharmin Sultana ◽  
Praful Agrawal ◽  
Shireen Elhabian ◽  
Ross Whitaker ◽  
Jason E. Blatt ◽  
...  

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