To create isosurfaces and plane cuts from 3D structured data, read in the grid files, scalar files and, if desired, vector files. Pull down the "Modules" menu of the "Viewer" to "Isolev". (For unstructured data, use "Isolevu", which is similar, but different. See the FAST user guide or talk to the graphics support coordinator for more information.)
The "Isolev:Data" window will pop up. Select the appropriate grid and scalar field, then click on "Read". You may now close this window.
You should now see the window for the "Isolev" module.
The slider changes controls the value of the isosurface. Often, I find it faster to enter a value in the text input box just below the slider. This box is labeled "IsoValue". If you click on the "Sweep?" box, the isovalue will automatically change from the min value of the slider to the max value of the slider. The box "Steps" controls the number of values between min and max that the sweep uses.
This module also displays the data cut by a plane. To display a cut, you must click on the box next to "Cutting Plane", the box next to "Arb" and then specify a plane by choosing a point and a normal. Enter these values at in the appropriate boxes at the bottom of "Isolev" window. Whenever you change the point specifying the cutting plane, click on "Use Point". When you change the normal, click on "Use Arb Norm".