Sweep Compounding
=================

Reconstructs a 3D volume from one or multiple ultrasound sweeps.

Input
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The algorithm requires one or several ultrasound sweeps, each with a non-zero selection of frames.

Output
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A reconstructed 3D volume containing the ultrasound sweeps is created. The input data is not modified.

Description
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Using the geometry of the input sweep(s), a predominant axis, bounding box and spacing is automatically determined for the resulting 3D volume. The following parameters may be used to modify the default behavior of the algorithm:

* ``Spacing`` allows to specify a custom spacing, rather than automatic selection.
* ``Method`` selects which device and which gathering method shall be used. The options include:

  - *GPU*: GPU-based direct compounding scheme with linear interpolation.
  - *GPU Nearest*: GPU-based direct compounding scheme with nearest neighbor interpolation.
  - *GPU Backward*: GPU-based high-quality backward compounding scheme with linear interpolation

* ``Background intensity`` defines the image intensity outside of US frames.
* ``Frame Thickness`` describes the maximum distance of a US frame to voxel of the output volume to contribute to its intensity.
* ``Range`` sets the backward compounding range and if the full neighborhood shall be used.
* ``Neighborhood`` defines whether the full neighborhood is to be considered.
* ``Bounding Box Mode`` defines how the resulting volume should be oriented in space. Supported modes are:

  0. *Global Coordinates*: Volume will be axis-aligned.
  1. *Frame Normal*: Uses the mean frame normal direction for the z-direction.
  2. *Heuristic Alignment*: Uses a PCA-based heuristic to find an well containing bounding box for most use cases.
  3. *Fit*: Runs an iterative optimizer to find the minimal bounding box.
  
* ``Reconstruct the sweep into individual volumes`` let's you choose whether all input sweeps are compounded together into a single volume or whether each sweep is compounded into an separate volume (only available if multiple input sweeps selected).