Using the Path Tool
You can use the Path tool to draw curves on an image. Measurements are shown with the annotation in 2D and 3D views and are also available in the lower section of the Data Properties and Settings panel, as shown below. Additional options available for the Path tool include profiling the intensity values along its length (see Profiling Intensity).
Path properties and settings
The measurements and tools available for paths are described in the following table.
|
|
Description |
|---|---|
|
Thickness |
Indicates the thickness, in screen percentage, of the annotation.
|
|
Path |
Indicates the length of the path. See Selecting the Views Preferences for information about choosing a default unit and significant digits for measurements. You can also change the default measurement units while you work. See 2D Scene's Views Properties for information about changing the default units for the selected scene. |
|
Area |
For closed paths, indicates the precise area inside the contour line that defines the region. You should note that Dragonfly calculates sub-pixels* for area measurements. Closed… Select this option to automatically close the selected path and calculate the area described by the contour line. |
|
Smooth |
Allows you to smooth curves by a selected magnitude.
|
|
Resample |
Allows you to reduce the number of control points that define the path.
|
|
|
Click the Profile tool to profile intensity values along the length of the path (see Profiling Intensity). |
* Sub-pixel resolution, which can be used to measure within an accuracy that exceeds the nominal pixel resolution of an image, can be obtained in images that contain well-defined lines, points, or edges.
How to Create a Path with the Path Tool
Whenever you create a path with the Path tool, control points are added along the path automatically as you drag to create the required curve. Dragonfly will automatically compute a Catmull-Rom spline to link the points that define the curve. You should note that Catmull-Rom splines are a family of cubic interpolating splines formulated such that the tangent at each point is calculated using the previous and next point on the spline.
- Maximize the required image, recommended.
- Click the Path
tool in the Annotate panel. - Click and then drag to create the path.
The length of the path is indicated at its starting point and in the bottom section of the Data Properties and Settings panel.
Editing Paths
A number of editing options are available for paths. You can adjust the position of the control points that define the path, add additional control points, and extend the length of a path. You can also smooth curves and resample paths. Refer to the table Path measurements and tools for more information about these options.
How to Adjust a Path
You can adjust a path by repositioning one or more of its control points.
- Select the required path, either directly in the 2D view or in the top section of the Data Properties and Settings panel.
- Click inside the control point or points you need to adjust and then drag.
The path measurements are updated automatically.
- Click inside the selected control point(s) to de-select.
How to Move a Path
- Select the required path, either directly in the 2D view or in the top section of the Data Properties and Settings panel.
- Select any section of the path between its control points and then drag to reposition the annotation.
How to Add or Remove Control Points
- Select the required path, either directly in the 2D view or in the top section of the Data Properties and Settings panel.
- Do the following, as required:
- Hold down Left Shift and then double-click the path between control points to add a control point.
- Hold down Left Shift and then double-click a control point to remove it from the path.
How to Extend a Path
- Click the Path tool in the Annotate panel.
- Select the required path, either directly in the 2D view or in the top section of the Data Properties and Settings panel.
- Hold down Left Ctrl (or your configured key) and then click and drag one of the path end points.
The path measurements are updated automatically.
- Click inside the selected control point to de-select it.
Configured Actions for Paths
A number of configured actions and keyboard shortcuts are available for creating and editing paths. The default settings for these actions are listed in the following table.
|
Action |
Key |
Mouse |
|---|---|---|
|
Create a path in Path mode |
- |
Left mouse |
|
Edit a path in Path mode |
- |
Left mouse |
|
Add or remove control points from paths and regions |
Left Shift |
Double-click |
|
Extend a path with the Path tool |
Left Ctrl |
Left mouse |
|
enterStatePathEditAddFromEdit |
Left Ctrl |
Left mouse |
|
Switch to Path mode |
- |
- |
