Grow from Seeds

Grow from Seeds creates a 3D segmentation from a few painted strokes on an NRRD asset. Paint examples of the structure you want to label and its surroundings, then preview the result across slices before applying it.

How to use Grow from Seeds

1. Paint a few strokes inside the structure with one Voxel Brush class, and strokes in the surrounding background with another class. Paint on several slices to give the tool examples throughout the volume.

2. Keep the classes you want to use as seeds visible. Hide any classes you do not want to include before initializing the preview.

3. With a Voxel Brush class selected, click Grow from Seeds in the function bar, next to Grow. Its settings appear in the options panel.

4. Click Initialize. Ango Hub grows the segmentation in a region around your strokes and displays a preview in the slice views. Scroll through the Axial, Coronal, and Sagittal views to review it, including slices where you did not paint strokes.

5. Add or erase strokes to refine the result. With Auto-update enabled, the preview updates after your edits. If you turn it off, click Update to refresh the preview.

6. Wait for the preview to finish updating, then click Apply to add the displayed result to your annotation. Save the task to keep it.

The preview is not shown in the 3D viewer and is not saved with the task. Apply uses the preview currently displayed, so wait for your latest changes to appear before applying it.

Settings

• Mask shows where growth is allowed. Change Editable Area in the Brush settings to limit growth to an existing segmentation. Enable Threshold to also limit growth to a selected intensity range. Seeds outside the allowed area do not contribute to growth.

• Seed locality controls how closely the result follows the seed strokes. Higher values keep growth closer to the strokes. Changing this value updates an initialized preview even when Auto-update is off.

• Auto-update refreshes the preview after you change strokes or masking settings. It becomes available after initialization.

• Preview opacity changes the transparency of the preview without changing the segmentation.

• Cancel discards the preview and keeps your painted strokes.

• Apply writes the preview to the annotation, following the Brush Modify other segments setting. You can undo or redo the applied result.

At least two visible Voxel Brush classes are normally required. You can use one visible class when growth is restricted by an Editable Area other than Everywhere, or when Threshold is enabled. Paint seeds within that restriction; Outside all segments and Outside all visible segments exclude the seed strokes themselves and therefore prevent growth.

Refining and restarting a preview

The tool uses the classes that were visible when you clicked Initialize. Hiding a class afterward does not remove it from the current seed set. To change which classes participate, click Cancel, adjust class visibility, and initialize again.

Switching between Voxel Brush classes keeps the preview open. Closing Grow from Seeds, deselecting the brush class, or selecting another type of labeling tool discards the preview while keeping your painted strokes.

After applying, Ango Hub may automatically hide the class identified as the surrounding background. Show it again from the class list if you want to inspect or use it for another preview.

If Ango Hub reports that the seed region is too large to compute, keep the strokes closer together and work on a smaller region.