Geometry Reconstruction from MicroCT Images
Previously acquired micro-computed tomographic (microCT) images of the
scaffold (Liu et al., 2018) (Fig. 2A) were used to generate
computational models (Fig. 2B). Image data were imported into Simpleware
ScanIP (Synopsys, Inc.) for segmentation and directly transformed into a
volumetric mesh containing both solid and fluid domains. Images were
filtered to remove noise and smoothed by applying a mean filter (filter
radius = 1 pixel). Grayscale stacked images were then segmented to
separate solid from the air (threshold value taken from our previous
model (Liu et al., 2018)). The scaffold image data were presented as a
voxel model after the segmentation. Next, a voxel model of a cylinder
was created to trim the scaffold into a smaller domain (1.2 mm
thickness, 2 mm diameter) for shorter computation. Boolean operation
intersection between the cylinder and scaffold voxel model was used to
create the final solid domain (Foley, 1996). Boolean operation
subtraction was used to generate the fluid domain from the image
(scaffold) voids (Fig. 2C). Finally, the two domains were meshed
together by replacing existing voxels directly to volumetric tetrahedral
elements. The final mesh contains both solid and fluid domain with
watertight assembly and interfaces with shared nodes (Fig. 3A).