## Symmetry Menu

The symmetry menu contains options for labelling templates with symmetry matching information and performing simple calculations relating to symmetry.

### Labelling Symmetry

The main way to label symmetrically matched points (e.g. outer eye corners on mouth corners) is to use the "Automated Pair Points" option. Load an example mesh and Template file. Select "Automated Pair Points" from the menu and each point in the Template should be highlighted in red in turn. When a point is highlighted, click on the mirror image point, for points down the midline simply click on the highlighted point itself. Note that once two points have been paired the neither will be highlighted again. Save the resulting symmetry labels using the Save option from the menu and use the file extension .sym2.

### Measuring symmetry

Symmetry can be measured as either absolute distances from matched points or as vector displacements (x, y and z values). Before the distances are measured the template is flipped about the x-axis and (optionally) orientated using rotation, scaling and translation to minimize the sum of squared distances between matched points. The output is generated to a spreadsheet format (.csv) with columns contain the measurements.

### Flipping the data

Sometimes it might be useful to generate a mirror image version of a mesh and/or template. For templates this is simply a matter of moving each point to the location of its mirror image location flipped about the x=0 plane. For meshes, the vertices are flipped about x=0 and the template is also flipped. If you want to do other operations with these mirrored meshes and templates (such as morphing, volume measurements etc), it is sometimes necessary to warp a "standard" mesh into the shape of the original and mirrored meshes.