Curved planar Reformat Resampling transformation

[lassoan (Andras Lasso)]

@FloCo

What I am not sure to understand is that the displacement field is only calculated from 4 corner points of each slice planes. Then the displacement field must be interpolated for each slice from the 4 corner points and between each slice I guess ? Do you use a simple linear interpolation ?

We use linear interpolation, but by replacing vtkGridTransform by vtkBSplineTransform you can get bspline interpolation. However, then you would introduce distortion and you could no longer do accurate measurements in slices. It may be added as an option to the reformat module if somebody finds an application where smoother displacement field is more important then quantitative measurements.

@FloCo

I thought about thin-plate spine because it’s a common method to smooth interpolation even if it has a high computational cost. When I tried it I got a lot of distortions indeed but I only used points from the centerline and not from corner points as you do, I can try to see the difference.

We tried thin-plate spline transforms with control points added at certain distances from the centerline, but it did not work well. Distortion was very unpredictable and hard to control, and computation was much slower.