Biomedical Engineering Reference
In-Depth Information
550
70
initialization with
result of resolution 1
500
60
450
50
400
40
initialization with
result of resolution 1
350
30
300
20
250
10
5
4
3
2
1
0
5
4
3
2
1
0
GRID LEVEL
MSE
GRID LEVEL
Computation time
Figure 8.9:
Evolution of the MSE with respect to the grid level (at finest resolu-
tion 1 mm) and computation time needed to perform the registration until a given
grid level. We observe that the MSE decreases significantly at the coarsest grid
level, whereas at the finest grid level it continues to decrease, but less rapidly.
At the same time, the computation time increases continuously. If we look at
the difference between grid level 2 (the smallest cubes are of size 2
2
×
2
2
and the incremental deformation field is affine on each cube) and grid level 0
(the smallest cubes are reduced to a voxel and the incremental deformation
field is translational for the smallest cubes), the computation time increases by
100%, whereas the MSE variation is only 5
.
3%. That suggests that, depending on
the application, the user can make a compromise between the accuracy of the
registration and the computation time if the resources are limited.
×
2
2
Figure 8.9 shows the evolution of the MSE with respect to the grid level (at
finest resolution 1 mm) and also shows the computation time needed to perform
the registration until a given grid level. We observe that the MSE decreases
significantly at coarsest grid level, whereas at the finest grid level it continues
to decrease, but less rapidly. At the same time, the computation time increases
continuously. If we look at the difference between grid level
5
2 and grid level
6
0,
the computation time increases by 100%, whereas the MSE variation is only
5
.
3%. That suggests that, depending on the application, the user can make a
compromise between the accuracy of the registration and the computation time
5
The smallest cubes are of size 2
2
×
2
2
×
2
2
and the increment deformation field is affine
on each cube.
6
The smallest cubes are reduced to a voxel and the increment deformation field is trans-
lational for the smallest cubes.
