User:Tohline/vtk/Quadric

Generating Spheroids, Ellipsoids, and Quadrics

Getting Started

Here we explore the vtkQuadric method, which has been used to generate Figure 5-2 (§5.1, p. 77) of the VTK User's Guide, authored and published by Kitware, Inc., in an effort to learn how to draw two-dimensional spheroidal structures, three-dimensional ellipsoidal structures, and other analytically specifiable configurations.

1. Inside VisTrails, open, then execute "VisQuad.vt" without making any changes to the default pipeline or to any module parameters:

• Follow this directory path: VisTrails/examples/vtk_examples/VisualizationAlgorighms/VisQuad.vt
• The default workflow pipeline is shown in the top panel of the following figure. Upon execution, the default composite image that pops up in the VisTrails spreadsheet window is shown in the bottom panel.

Figure 1:     Default

• In the workflow, the vtkQuadric module has been highlighted, so the inset window to the right of the workflow pipeline displays the values of the 10 separate model coefficients that have been used to generate the default "Quadric" configuration. Presumably, these values correspond, respectively, to coefficients <math>~a0, a1, a2, a3 \ldots a9</math> as they appear in the quadric function definition as provided in the default module documentation and as reprinted here:

vtkQuadric Module Documentation
vtkQuadric - evaluate implicit quadric function Superclass: vtkImplicitFunction vtkQuadric evaluates the quadric function F(x,y,z) = a0*x^2 + a1*y^2 + a2*z^2 + a3*x*y + a4*y*z + a5*x*z + a6*x + a7*y + a8*z + a9. vtkQuadric is a concrete implementation of vtkImplicitFunction.