1. Start ParaView (see <link> for information on how to launch ParaView)

2. Create a test source by selecting RTAnalyticSource from VTK -> Sources
   menu. Click Accept.

   <insert source.jpg>

3. Click the Contour button on the toolbar.

   <insert toolbar-contour.jpg>

4. In the contour parameters window, type 220 in the "New Value" entry
   and press enter.

   <insert firstcontour.jpg>

5. Next add a iso-surface with a value of 200.

6. To be able to see both contours, you can clip the data. Click
   the Clip button on the toolbar. Click "Use Camera Normal" on the
   properties notebook and click Accept.

   <insert toolbar-clip.jpg>
   <insert result.jpg>
