|Category||Plugins, Visualization, Transform|
Bigwarp is a tool for manual, interactive, landmark-based deformable image alignment. It uses the BigDataViewer for visualization and navigation, and uses a Thin Plate Spline implemented in Java to build a deformation from point correspondences.
The interface enables landmark pair placement and displays the effects of the warp on-the-fly.
Bigwarp comes with Fiji. You can access it via Plugins › BigDataViewer › Big Warp, or by modifying this example script. If this is not visible in your installation, try updating Fiji with Help › Update Fiji.
Open two images in ImageJ, one moving and the other target and navigate to Plugins › BigDataViewer › Big Warp. A dialog will appear prompting selection of the moving and target images.
Press F1 at any time to open a help page with a listing of navigation and editing commands.
Landmark point placement and display in the viewer
Landmark placements is done in Landmark mode which you enter by holding Spacebar. Users place pairs of corresponding points on
The following table shows the available landmark placement commands and keystrokes.
|hold Spacebar||Toggle Landmark mode|
|<Landmark mode>+left-click||Clicking while in landmark mode adds a landmark point or selects and existing landmark.|
|<Landmark mode>+left-click+drag||Clicking an existing point and dragging changes it's position.|
|<Landmark mode>+⇧ Shift+left-click+drag|| "Move" a point. The initial click places a
landmark point for the moving image. The release places a landmark point for the target image.
|<Landmark mode>+^ Ctrl+left-click||"Pin" a point. Add a landmark at the same location for both moving and target images.|
|^ Ctrl + Z||Undo the last landmark point change.|
|^ Ctrl + Y||Redo the last landmark point change.|
|V||Toggle point visibility in the viewer.|
|N||Toggle point name visibility in the viewer.|
Landmark selection and editing in the table
Some changes to landmarks can be done by interacting with the landmark table.
|^ Ctrl+left-click||Add row to selection.|
|⇧ Shift+left-click||Select range of rows.|
|⎋ Esc||Deselect all rows.|
|<Landmark mode>+left-click||Removes one landmark.|
|right-click › Delete||Deletes a landmark pair (row in the table).|
|right-click › Delete all selected||Deletes all selected landmark pairs (row in the table).|
Notes on point addition and landmark pair selection
- Adding a new landmark pair selects that pair (row) in the table.
- If a row is "missing" a moving (target) landmark point, then it must be selected in order to add that missing point by clicking in the moving (target) viewer. Then BigWarp will find the "next" row that is missing a moving (target) landmark, and select that row automatically.
- If the selected row is not missing a landmark, the next click will add a new landmark pair.
- If multiple rows are selected when a viewer is clicked, the result will be as though only the first row was selected.
Bigwarp inherits many image navigation, visualization, and grouping features with BigDataViewer, the details of which can be found on the BigDataViewer page or on the help page. BigWarp specific features are documented below.
The following table shows the available navigation commands using the mouse:
|Q||Align the non-active viewer with the active viewer.|
|W||Align the active viewer with the non-active viewer.|
|R||Resets the active viewer.|
|U||Show warp visualization / grid dialog.|
|F6||Show moving image panel Visibility & and Grouping dialog.|
|F7||Show target image panel Visibility & and Grouping dialog.|
Import and Export
Landmarks can be exported and imported from plain text files using the drop down menu in the landmark table panel ( File › Export (Import) landmarks. )
The warped moving image can be exported as an in-memory or virtual ImagePlus. A virtual ImagePlus is generally faster to generate but slower to browse, whereas an in-memory ImagePlus will be slower to generate but faster to browse.
The exported image will have the same dimensions as the target image. Note: Take care when exporting very large data sets.