Transform
The Transform tool provides geometric transformation operations for modifying the spatial properties of volume and mask data. Use this tool to reorient images, adjust physical dimensions, translate the origin, or center data at the scene origin.
Accessing the Tool
- Navigate to the Image tab in the ribbon.
- Click Transform in the Transform section.
Tabs
The Transform tool organizes operations into four tabs:
Reorient Tab
Rotate volume and mask datasets around a specified axis.
Parameters
| Parameter | Description |
|---|---|
| Target objects | Select which objects to transform (active, selected, or all volume/mask objects) |
| Angle | Rotation angle in degrees |
| Axis | Rotation axis as X, Y, Z unit vector or preset (X, Y, Z axis) |
| Volume interpolation | Interpolation method for volume data (Nearest, Linear, Cubic) |
| Mask interpolation | Interpolation method for mask data (Nearest recommended) |
Reorientation Methods
| Method | Description |
|---|---|
| Angle + Axis | Specify rotation angle and axis vector |
| Preset orientations | Quick rotations (90°, 180°, 270° around principal axes) |
Use Nearest interpolation for masks to preserve label values without introducing interpolation artifacts.
Rescale Tab
Modify the physical dimensions or pixel spacing of the datasets.
Physical Dimensions Mode
Specify the desired physical size in millimeters:
| Parameter | Description |
|---|---|
| X (mm) | Target physical width |
| Y (mm) | Target physical height |
| Z (mm) | Target physical depth |
| Maintain aspect ratio | Lock proportional scaling |
Pixel Spacing Mode
Directly set the voxel spacing values:
| Parameter | Description |
|---|---|
| X spacing (mm) | Distance between voxel centers in X |
| Y spacing (mm) | Distance between voxel centers in Y |
| Z spacing (mm) | Distance between voxel centers in Z |
Rescaling only modifies the spacing metadata. The voxel data itself is not resampled. To change the number of voxels, use the Resample tool.
Translate Tab
Move the origin of the datasets.
Parameters
| Parameter | Description |
|---|---|
| Translation X (mm) | Shift along X axis |
| Translation Y (mm) | Shift along Y axis |
| Translation Z (mm) | Shift along Z axis |
Options
| Option | Description |
|---|---|
| Set origin | Set absolute origin coordinates |
| Translate origin | Move origin by specified offset |
Center Tab
Move datasets so their geometric center aligns with the scene origin (0, 0, 0).
This is useful for:
- Aligning data from different sources
- Preparing data for symmetric operations
- Simplifying coordinate calculations
Click Center to apply the operation to the selected target objects.
Workflow
Reorienting a Volume
- Open the Transform tool.
- Select the Reorient tab.
- Choose target objects from the dropdown.
- Set the rotation angle (e.g., 90°).
- Select the rotation axis (e.g., Z-axis).
- Choose interpolation methods for volumes and masks.
- Click Apply.
Adjusting Spacing
- Open the Transform tool.
- Select the Rescale tab.
- Enter new spacing values or physical dimensions.
- Enable Maintain aspect ratio if proportional scaling is needed.
- Click Apply.
Apply Transformation Matrix
For advanced use cases, you can apply transformations via the Python scripting API.
See the VolumeOperations API Reference for available transformation methods including reorient(), transform(), change_spacing(), translate_origin(), change_origin(), and center_at_origin().
Geometric transformations may cause DICOM metadata to become desynchronized with the image data. Verify coordinate alignment after transformations if metadata accuracy is required.