VisIt Export Isosurface

Contour Plot Attributes in VisIt
Contour Plot Attributes in VisIt

Saving a Wavefront OBJ file in VisIt
Saving a Wavefront OBJ file in VisIt

In VisIt, creating an isosurface is relatively straightforward. Exporting it is not difficult, if you know where to look. First, choose the variable from which you want to create the isosurface.

  1. In the Plot Manager section of the VisIt Main Window, select Plots->Contour and choose the scalar variable that you want.
  2. In the Plot Manager section, select OpAtts->Contour, This will allow you to change the contour (a.k.a., isosurface) value. By default, VisIt chooses 10 levels that are linearly spaced between the minimum and maximum values. Change the Select by pull-down menu to Value(s) and input a single value for the isosurface.
  3. Click on Apply.
  4. Click on the Draw button in the Plot Manager section.
  5. At this point, you will have an isosurface (or if you like, a single contour) displayed on the screen. Go to File->Set Save Options ,
  6. Input the desired filename in the Filename text box.
  7. Choose the File Type as obj to output a Wavefront OBJ geometry file. Alternately, you could choose to export it as an STL or VTK geometry file.
  8. Click on Save to save the file.

Example

In this example, using the 5514roll.401.vtk database:

  1. In the Plot Manager section of the VisIt Main Window, select Plots->Contour and choose the scalar variable that you want.
  2. In the Plot Manager section, select OpAtts->Contour. Change the Select by pull-down menu to Value(s) and input a single value for the isosurface, which in this case is 0.5 for the Fraction variable.
  3. Click on Apply.
  4. Click on the Draw button in the Plot Manager section.
  5. At this point, you will have an isosurface (or if you like, a single contour) displayed on the screen. Go to File->Set Save Options.
  6. Input the desired filename in the Filename text box.
  7. Choose the File Type as obj to output a Wavefront OBJ geometry file.
  8. Click on Save to save the file.

Note, that if you have colored the isosurface by a variable (as shown in the Creating an Isosurface and Coloring it by another variable tutorial), then the coloring will not be preserved in the Wavefront OBJ or STL format. Interestingly enough, VisIt does export vertex normals and texture coordinates in the OBJ file. If you have colored the isosurface by a variable, and you wish to preserve its color on exporting the geometry, then you must export it as a VTK file.

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