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