Civil Engineering Reference
In-Depth Information
25s
20s
15s
Overall
Neighbour
Grid
Intersection
10s
5s
0
(Triangles)
Figure 4.84
CPU time plots for the intersection of 100 spheres.
(a)
(b)
Figure 4.85
Biological systems modelled by surface intersection: (a) plants modelled by 49,235 triangles;
(b) blood vessel system created by surface intersection.
recorded them as intersection loops, which joined separate components together to form the
entire blood vessel system.
The fifth example is the intersection of a space shuttle and an analytical curved surface.
The space shuttle was arbitrarily immersed into the curved surface to produce very irregular
lines of intersection around the body of the space shuttle, as shown in Figure 4.86a. There
are 6419 nodes and 12,843 elements on the surface of the space shuttle, and the curved sur-
face is represented by 13,999 nodes and 27,548 elements. The surface interaction produces
1573 nodes from intersection segments, and 9948 elements are generated in the surface-
merging process. Figure 4.86b shows a magnified view of the intersection, and it can be seen
that sharp elongated elements have been used on the analytical curved surface to test the
algorithm. The total CPU time taken for this example is about 1 s.
The last example is the most challenging. Two triangulated surfaces constructed from a
surface scan were downloaded from the website http://lodbook.com/models/, as shown in
Figure 4.87a. There are 1,309,332 elements in the two triangulated surfaces in which there
are many pointed triangles connecting points from scanned images to model the finger
bone geometry. As shown in Figure 4.87b, 54,966 intersection segments in 16 loops are
