Demo bi-transparency - Fluoroscopic image sequence 6
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Description
We explore here borderline situations. This fluoroscopic sequence contains three distinct transparent layers:
The static background, which includes surgerical clips.
The set ``diaphragm and lungs''. The diaphragm is the dark mass at the bottom left of the image, and the lungs are
the bright tissues in the other half of the image. Their motions are close, so that they can be considered as forming
a single layer.
The heart is also present, even if its layer is less textured: it is the convex light grey region on the right of the
image. It can be easily seen on the last presented example.
The estimated displacements are directed toward the past to respect the notations of the Transparent Motion Constraint.
As a result they are in the opposite direction compared to the usual represented velocity direction.
Estimation result at four interesting time instants
It turns out that the method retains and correctly estimates the motions of the two best contrasted layers,
that it to say the background and the layer ``diaphragm and lungs'' (see the two last presented frames).
Interestingly, the diaphragm being static at the time instants corresponding to the two first presented frames,
its layer is merged to the background, which allows the heart motion to be estimated. This proves the
ability of the proposed method to focus on the dominant motions. It again highlights the interest of defining a
layer as a coherent-motion region, which is in line with the targeted goal: transparent motion estimation.
Whole processed sequence
We also present the overall processed sequence. It shows the estimated affine motion fields, along with the corresponding
frames.
The results are satisfactory for about 80% of time instants, even in this difficult three-layers configuration.
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