Add 3D semantic segmentation code example

[innat]

#2092

[innat]

@mattdangerw
I addressed all the feedback you made here. Please check it.

[innat]

@mattdangerw
A gentle reminder.

[innat]

@mattdangerw
Could you please take a look this PR? Is it suitable for keras code example, otherwise I will close the PR.

[divyashreepathihalli]

/gemini review

[gemini-code-assist]

Code Review

The code changes introduce a 3D semantic segmentation pipeline for medical imaging, specifically brain tumor segmentation using the BraTS dataset. The code is well-structured, but there are opportunities to improve maintainability, clarity, and correctness through refactoring repetitive code blocks, clarifying visualization logic, and simplifying computations.

[gemini-code-assist]

The logic to reconstruct the single-channel prediction map relies on a specific order of assignments to handle overlapping regions. While the current order is correct, the code would be more self-documenting and easier to maintain if you add a comment explaining why this order is important.

prediction[segment[..., 1] == 1] = 2  # Whole Tumor (WT)
prediction[segment[..., 0] == 1] = 1  # Tumor Core (TC)
prediction[segment[..., 2] == 1] = 4  # Enhancing Tumor (ET)

[innat]

@divyashreepathihalli
A review from human would be appreciated. Thanks.