Visualizing element fields using iso-surfaces
Iso-surfaces are graphical representations used to visualize 3D or 2D objects that connect every point where the value of a certain field is the same. This idea is analogous to the contour lines on a map, where a line connects every point of a certain height. In 3D this means that a surface connects every point of a certain value. An example of this is in example a7 where an iso-surface is used to show the surface where every point is at 100 degrees Celsius. For a simpler example, example a2 shows the creation of an iso-surface at x=0.5 within the simple cube mesh.
Figure 1: Iso-surfaces: This video shows some of the basics of working with iso-surfaces in cmgui, using the mesh from example a7.
As with surfaces, the detail level of iso-surfaces is determined by the element discretization setting in the general settings area of the scene editor.
Figure 2: How discretization affects iso-surface detail: The element discretization setting in the general settings section of the scene editor sets the number of divisions in each xi direction within each element. Here, an iso-surface is used to connect every point within the element cube where "temperature" is 20. The "temperature" field is shown on the surface of the element cube using a spectrum in panel A. In B, the iso-surface is shown in wireframe (green) and a single face of the cube is divided up according to the element discretization setting. You can see that the iso-surface links the discretization divisions at points where the iso-scalar is at the chosen value. These intersections are indicated by yellow circles. Panel C shows how different element discretization settings affect this iso-surface; settings of 2, 3, 4, and 8 are shown.