Selections

TableOfContents

Selections are also called labels or ROIs. You can read or write selections from and to label files or create them from within TkMedit. Note that there is only one selection in TkMedit, even though it doesn't have to be contiguous.

TkMedit has many specialized methods of creating labels.

Display Options

Selections are drawn as a green overlay. This overlay can be turned off by unchecking Views->Selection / Label.

Selecting and Deselecting

Brushing

You can select and deselect voxels with the Select Voxels Tool, which can be activated by pushing the attachment:Icons/TkMedit/icon_edit_label.gif button on the Main Toolbar, by choosing Tools->Select Voxels, or by pressing the 's' key.

This tool is a brush tool, so it uses the global brush settings available in Tools->Configure Brush Shape... and in the Reconstruction Toolbar. You can think of selecting and deselecting voxels as painting your selection. To select voxels, use mouse button 2 to draw your selection and button 3 to erase it.

Flood Filling

You can also use a flood fill to select and deselect contiguous areas. Open the configuration dialog box with the Tools->Configure Flood Select... command. Here, you have options for the making the fill 2D or 3D, settings the source, and the fuzziness and distance parameters.

• Source Volume: Specifies which volume to use when looking for similar voxels, so that the Main, Aux, or segmentation volumes can be used to look for regions.

  Fuzziness: Determines the level of similarity to consider when finding regions. If it is 0, only voxels with exactly the same value as the voxel clicked will be set. If it is greater than 0, this is the maximum value difference from the clicked voxel that a contiguous voxel can have to be considered in the same region.

  Distance: Determines the maximum size of the region to fill from the clicked voxel. If it is 0, there will be no distance limit.

  3D: Determines if the fill is in-plane only or will fill in three dimensions.

Once you have configured your fill, perform it with shift-mouse button-2 or 3; 2 will select an area, and 3 will deselect an area.

In the shell window, you will see a progression of dots printed out while the selection is being performed. If it is taking too long, you may have been too lax in your specifications, and may wish to cancel the selection. To do this, make sure the shell window has focus, and enter ctrl-c. Note that the fill will be partially complete even if you cancel, so you may want to clear the selection.

Linear Selections

You can use the line tool, attachment:icon_line_tool.gif, to draw lines that can be turned into selections. Select the tool. Clicking with the middle button will draw a line between the last place you clicked the middle button to the current location. This will draw a green line, with the voxels that intersect the line drawn in red.

Next, select the Tools->Add Line to Selection to select the voxels that intersect the line. You can use this tool to build an accumlation of lines, if, for example, you wanted to build an outline of an area. Or, if you want to just save the current line as a label and nothing else, use the Tools->Write Line to Label... command.

If you want to save a series of labels consisting of a single line, use the dialog brought up by selecting Tools->Label Writer Helper.... This dialog box lets you create a series of label files in a directory. Select the directory in which to save the labels. Then, choose options for selecting the line before writing the label, and clearing the label after writing.

You can have the Helper automatically create label names for you with an incrementing number. Select the Use Incrementing Number for Label Name option, and fill out the three text fields. The first field should be a text prefix for the name. The second should be a number that is automatically incremented. The third is the file name suffix, normally .label. Or, you can specify a list of names to be used with the Get Label Names from File option. Choose a file that has one file name per line. You will see the next file name in the Next name area.

Then, just draw a line and click the Apply button. The label will be written according to your naming specification.

Saving and Loading

TkMedit reads and writes label files. This file format is basically a list of points in RAS coordinate space with some header information. They can be loaded into TkSurfer if they intersect with a surface.