1 .. _aspect_ratio_3d_page:
7 The **Aspect Ratio 3D** mesh quality criterion calculates the same parameter as the :ref:`aspect_ratio_page` criterion, but it is applied to 3D mesh elements: tetrahedrons, pentahedrons, hexahedrons, etc.
9 * The **Aspect Ratio** of a **tetrahedron** 3D element defined by vertices {a,b,c,d } is calculated by the formula:
11 .. image:: ../images/formula1.png
14 * Other element types like polyhedron, pentahedron and hexahedron use the following formula:
16 .. image:: ../images/formula2.png
19 **To apply the Aspect Ratio 3D quality criterion to your mesh:**
21 #. Display your mesh in the viewer.
22 #. Choose **Controls > Volume Controls > Aspect Ratio 3D** or click **"Aspect Ratio 3D"** button of the toolbar.
25 .. image:: ../images/image144.png
29 "Aspect Ratio 3D" button
31 Your mesh will be displayed in the viewer with its elements colored according to the applied mesh quality control criterion:
33 .. image:: ../images/image86.jpg
37 **See Also** a sample TUI Script of a :ref:`tui_aspect_ratio_3d` operation.