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<h3>Geometric analysis</h3>

<p>Take a look into the <a href="/tutorials/GeometricAnalysis.html">Geometric analysis</a> tutorial to learn how to analyze the 3D geometry of a vascular segment and into the <a href="/tutorials/SurfaceForMeshing.html">Preparing a Surface for Meshing</a> tutorial to learn how to prepare a surface for mesh generation.</li></p>

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<pre><code>// Generate a vtp file containing the data on the bifurcation vectors

vmtksurfacereader -ifile foo.vtp --pipe vmtkcenterlines -seedselector openprofiles --pipe vmtkbranchextractor --pipe vmtkbifurcationreferencesystems --pipe vmtkbifurcationvectors -ofile foo_bv.vtp

//Compute curvature and torsion

vmtkcenterlinegeometry -ifile foo_cl.vtp -smoothing 1 -ofile foo_clgm.vtp

//Smoothing a surface

vmtksurfacesmoothing -ifile foo.vtp -passband 0.1 -iterations 30 -ofile foo_sm.vtp

//Adding flow extensions

vmtksurfacereader -ifile foo.vtp --pipe vmtkcenterlines -seedselector openprofiles --pipe vmtkflowextensions -adaptivelength 1 -extensionratio 20 -normalestimationratio 1 -interactive 0 --pipe vmtksurfacewriter -ofile foo_ex.vtp </code></pre>

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<p>Quantifying geometric features of the vascular segment,

those associated to <code>bifurcations</code>, such as bifurcation planes

and bifurcation angles, and those associated to branches, such

as <code>curvature and torsion</code>. Curvature and torsion are tightly linked

to the definition of the Frenet line frame, constituted by a tangent,

a normal and the binormal.

<p>Increase surface smoothness prior to building the mesh.

Image segmentation can result in bumpy surfaces, especially if the

image quality is not high and one didn’t use any curvature term in level

sets evolution. <code>Flow extensions</code> are cylindrical extensions added to the

inlets and outlets of a model. They are important for ensuring that the

flow entering and leaving the computational domain is fully developed, so

that fully developed boundary conditions aren’t forcing the solution in the

actual vessel.