33 lines
1.6 KiB
Markdown
33 lines
1.6 KiB
Markdown
# Straighten Path
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Extract a cross-section along an arbitrary curved path defined by control points. The path is interpolated between points and data is sampled along it using `scipy.ndimage.map_coordinates`. Equivalent to Gwyddion's straighten_path.c module.
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## Inputs
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| Name | Type | Required | Description |
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|------|------|----------|-------------|
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| field | DATA_FIELD | Yes | Input height field |
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## Outputs
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| Name | Type | Description |
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|------|------|-------------|
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| straightened | DATA_FIELD | Straightened cross-section; width = n_samples, height = thickness |
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## Controls
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| Name | Type | Default | Description |
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|------|------|---------|-------------|
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| points_x | STRING | "0.25, 0.5, 0.75" | Comma-separated fractional x-coordinates of control points (0.0-1.0) |
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| points_y | STRING | "0.5, 0.3, 0.5" | Comma-separated fractional y-coordinates of control points (0.0-1.0) |
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| thickness | INT | 1 | Width of the sampled strip perpendicular to the path, in pixels (1-100) |
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| n_samples | INT | 256 | Number of sample points along the path (10-2048) |
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## Notes
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- Control points are specified as fractions of the image dimensions (0 = left/top edge, 1 = right/bottom edge). At least 2 points are required.
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- Points are connected by linear interpolation; the path is sampled at n_samples evenly spaced positions.
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- When thickness > 1, samples are taken along the local normal direction at each path position, producing a 2D strip rather than a single line.
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- The output xreal equals the physical path length (computed from pixel spacing), and yreal equals thickness times the pixel size.
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- Bilinear interpolation (order=1) is used with nearest-edge boundary handling.
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