This is the code for a 3D Floodfill plugin in FIJI It works on one channel images. By selecting a point or points (using the multipoint tool) then give a threshold and select a filling method. Default uses a 26 neighbors floodfill by selecting 6-way floodfill a six neighbor version is used. Select output to get a binary image of the filled structure, otherwise only the volume in voxels and units will be given.