/*!

\page aspect_ratio_3d_page Aspect ratio 3D

\n The <b>Aspect Ratio 3D</b> mesh quality criterion calculates the same
parameter as the \ref aspect_ratio_page "Aspect ratio" criterion, but
it is applied to 3D mesh elements: tetrahedrons, pentahedrons,
hexahedrons, etc.

- The <b>Aspect Ratio</b> of a \b tetrahedron 3D element defined by
vertices {a,b,c,d } is calculated by the formula:

\image html formula1.png

- Other element types like polyhedron, pentahedron and hexahedron use
  the following formula:

\image html formula2.png

<em>To apply the Aspect Ratio 3D quality criterion to your mesh:</em>
<ol>
<li>Display your mesh in the viewer.</li>

<li>Choose <b>Controls > Volume Controls > Aspect Ratio 3D</b> or click
<em>"Aspect Ratio 3D"</em> button of the toolbar.

\image html image144.png
<center><em>"Aspect Ratio 3D" button</em></center>

Your mesh will be displayed in the viewer with its elements colored
according to the applied mesh quality control criterion:

\image html image86.jpg
</li>
</ol>

<br><b>See Also</b> a sample TUI Script of a 
\ref tui_aspect_ratio_3d "Aspect Ratio 3D quality control" operation. 

*/