FE ExcarnateOp

# ExcarnateOp

*Reduces a physical body to a skeleton.*

## Inputs

The **Input Surface** can be any collection of points connected by primitives.
The **Output Surface** is the resulting collection of lines representing the body.

## Parameters

If an input **Point Group** is given,
only points in that group will be affected.
The **Root** gives a general location where the first generated line should start,
perhaps the base of a tree or the hip center of a character.

Selecting **Degenerate** activates the method of progressive degeneration.
Polygons are incrementally collapsed by selectively unifying
a pair of points connected by an edge into a single point.
With this turned off, the prior method involves averaging points
on adjacent faces, like a simple smoothing algorithm.

The number of **Reductions** is the number of iterations.
For the degeneration method, it is optimal to use 1 if the input surface
only contains triangles and 2 if it may also contains quads.
If there are polygons with many sides,
the best number would be the maximum number of sides minus two.
Additional iterations would have no additional effect.
For the naive smoothing method,
additional iterations will simply continue to converge.

The **Expand** option will collocate nearby points
closer than the **Fusion** distance.
Currently, the redundant points are not removed,
such as a Fuse operator might do.

If **Output Degenerate Surface** is on,
the collapsed surface will be written to the output.
This may not be particularly useful except for debugging.

If **Output Skeletal Lines** is on,
newly generated representative lines will be written to the output.
There is nothing preventing both the degenerate surface
and skeletal lines to be written to the output.

## Status

DEVELOPING

testing in Houdini

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