32 lines
1.4 KiB
Markdown
32 lines
1.4 KiB
Markdown
# Curvature
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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.
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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 topographic field |
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| mask | IMAGE | No | Binary mask for including or excluding regions from the quadratic fit |
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## Outputs
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| Name | Type | Description |
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|------|------|-------------|
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| output | ANNOTATION_SOURCE | Field with principal-axis lines overlaid |
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| measurements | RECORD_TABLE | Curvature radii, principal-axis directions, center position and value |
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| profile_a | LINE | Height profile along principal axis 1 |
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| profile_b | LINE | Height profile along principal axis 2 |
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## Controls
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| Name | Type | Default | Description |
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|------|------|---------|-------------|
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| masking | dropdown | ignore | How to use the mask: ignore (fit all pixels), include (fit only masked pixels), or exclude (fit unmasked pixels) |
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## Limitations
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- Requires at least six usable pixels for the quadratic fit; fewer pixels produce no output.
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- The fit assumes a globally smooth quadratic surface; locally rough or step-like surfaces give unreliable results.
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- Requires compatible XY and Z physical units (e.g. both in metres).
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