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Description
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3D CT images of the nest-gallery system and anatomical texture of Timber A. 2D cross-sectional
images reveal the tunneling strategy in response to the physical constraints of knot 1: a the first chamber,
spaciously extended across several annual rings; b four exploratory tunnels were excavated from the first
chamber to search for less dense spots to pass the knot; c the selected tunnel, narrowly excavated on a less
dense spot at the periphery of the knot. 2D tangential images present the area around three knots, which
show the selectivity on nest-gallery excavation: d narrow passage tunnel from the first chamber to cross
knot 1, excavated along a particular annual ring at the periphery of the knot; e shape of the chamber
followed the anatomical texture of the timber; f tunnel-galleries were excavated to avoid the knot. In the
2D CT images (Fig. 3a–f), the gray value of a pixel corresponds to an index of density: the lighter the
color, the denser the area. Springwood and summerwood are indicated by the darker and lighter colors in
the images, respectively. In the 3D CT images, the gray value of voxels corresponds to the density
variation in the timber. Timber density is displayed by classifying the opacity value of the tomographic
image data. The colored areas inside the timber show the higher density areas of the timber, while
uncolored areas represent lower density areas (color figure online) |
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