=Surfaces= TkMedit can read and display 3d surface files. The surfaces are intersected with the displayed slices and drawn overlaid onto the anatomical data.

==Surface Configurations== There are three possible surface configurations: Main, Original, and Pial. When you first load a surface, it is read into the Main configuration, and TkMedit looks for the other two configurations with similar names.

You can manually load in another surface as the Original or Pial configuration. All three configurations can be displayed at the same time, so you can compare how a surface looks in relation to another one.

==Loading and Unloading== Use the File, Load Main Surface... command to load in the Main configuration. This will also try and load Original and Pial versions of this surface. Use the File, Load Surface Configuration... submenu to load the Original Vertices or Pial Vertices manually.

Surfaces take up a lot of memory and they some time to intersect and draw. To release these resources when you are done with a surface, use the File, Unload Surface command.

==Display Options== Each configuration is drawn in a different color. By default, the Main surface is drawn in yellow, the Original surface in green, and the Pial surface in red. You can change these colors in the View, Configure..., Surface... dialog box. You can also configure the width of the line used to draw the surface.

You can turn off surface display by unchecking the View, Main Surface, View, Original Surface, and View, Pial Surface items. You can also hide and show the surfaces with the buttons on the Reconstruction Toolbar ( Main surface, Original surface, and Pial surface). You can display the actual vertices of the surface by checking the View, Surface Vertices option.

There are two ways of determining which points to draw when intersecting the surface with the current slice; by using interpolation, and by using projection. Using interpolation will produce a smoother picture and a truer view of the surface intersection. However, the vertices that are drawn will be the interpolated intersection points of an edge and the slice, not the actual vertex. When projection is used, the vertices drawn will appear in their actual place in-plane. This diagram illustrates the methods better:

When View, Interpolate Surface Vertices is checked, the interpolation method is used. When it is unchecked, the projection method is used.

==Finding and Showing Vertices== TkMedit has a few tools for finding and displaying specific surface vertices. If you know the vertex number of the vertex you are interested in, you can use the Tools, Surface, Find Main Vertex... command to enter the number and go to that vertex. Note that if the edge width is smaller than the slice width, the vertex may be 'embedded' in the slice and the cursor will not appear right over a vertex. There are corresponding commands for the Original and Pial surfaces as well.

You can also have TkMedit find the surface vertex closest to the cursor with the Tools, Surface, Show Nearest Main Vertex command. The vertex information will be printed to the console. There are corresponding commands for the Original and Pial surfaces as well.