Curvature
Fit a quadratic surface and report the overall principal curvature radii and directions, matching Gwyddion's curvature feature. The output annotation marks the principal cross-sections and the node also returns the two corresponding height profiles.
Inputs
| Name |
Type |
Required |
Description |
| field |
DATA_FIELD |
Yes |
Input topographic field |
| mask |
IMAGE |
No |
Binary mask for including or excluding regions from the quadratic fit |
Outputs
| Name |
Type |
Description |
| output |
ANNOTATION_SOURCE |
Field with principal-axis lines overlaid |
| measurements |
RECORD_TABLE |
Curvature radii, principal-axis directions, center position and value |
| profile_a |
LINE |
Height profile along principal axis 1 |
| profile_b |
LINE |
Height profile along principal axis 2 |
Controls
| Name |
Type |
Default |
Description |
| masking |
dropdown |
ignore |
How to use the mask: ignore (fit all pixels), include (fit only masked pixels), or exclude (fit unmasked pixels) |
Limitations
- Requires at least six usable pixels for the quadratic fit; fewer pixels produce no output.
- The fit assumes a globally smooth quadratic surface; locally rough or step-like surfaces give unreliable results.
- Requires compatible XY and Z physical units (e.g. both in metres).
