title: Use NURBS in SharpGL
body: <p>I wrote a program to display some pressure-measurements. I want to use NURBS for a detail visualisation. So I orientated me to 
  <a href="https://stackoverflow.com/questions/13500458/opengl-nurbs-surface">enter link description here</a> </p>
  
  <p>My field has a range of 40x48 squares. So 40 rows and 48 columns. The Z component(the height) should be variable. </p>
  
  <p>But I don't understand how to define </p>
  
  <pre><code>glMap2f(GL_MAP2_VERTEX_3, 0, 1, 3, 4, 0, 1, 12, 4, &amp;ctrlpoints[0][0][0]);
  
  // Parameter:
          //   target:
          //     What the control points represent (e.g. MAP2_VERTEX_3).
          //
          //   u1:
          //     Range of the variable 'u'.
          //
          //   u2:
          //     Range of the variable 'u.
          //
          //   ustride:
          //     Offset between beginning of one control point and the next.
          //
          //   uorder:
          //     The degree plus one.
          //
          //   v1:
          //     Range of the variable 'v'.
          //
          //   v2:
          //     Range of the variable 'v'.
          //
          //   vstride:
          //     Offset between beginning of one control point and the next.
          //
          //   vorder:
          //     The degree plus one.
          //
          //   points:
          //     The data for the points.
  </code></pre>
  
  <p>I don't know how to set the parameters in my case. 
  For example what is u1 and u2? OR what are my ControlPoints?</p>