34 lines
1.6 KiB
Markdown
34 lines
1.6 KiB
Markdown
# Polynomial Distortion
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Correct nonlinear scanner distortions by applying polynomial coordinate warping independently in the x and y directions. Each axis has three polynomial coefficients controlling linear, quadratic, and cubic distortion terms. Equivalent to Gwyddion's `polydistort.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 field with scanner distortion |
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## Outputs
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| Name | Type | Description |
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|------|------|-------------|
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| corrected | DATA_FIELD | Distortion-corrected field |
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## Controls
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| Name | Type | Default | Description |
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|------|------|---------|-------------|
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| k1_x | FLOAT | 0.0 | Linear distortion coefficient for the x axis (-1.0–1.0) |
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| k2_x | FLOAT | 0.0 | Quadratic distortion coefficient for the x axis (-1.0–1.0) |
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| k3_x | FLOAT | 0.0 | Cubic distortion coefficient for the x axis (-1.0–1.0) |
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| k1_y | FLOAT | 0.0 | Linear distortion coefficient for the y axis (-1.0–1.0) |
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| k2_y | FLOAT | 0.0 | Quadratic distortion coefficient for the y axis (-1.0–1.0) |
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| k3_y | FLOAT | 0.0 | Cubic distortion coefficient for the y axis (-1.0–1.0) |
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## Notes
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- k1 controls linear stretching/compression, k2 controls barrel/pincushion-like quadratic distortion, and k3 controls cubic (S-shaped) distortion.
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- Coefficients for x and y are independent, allowing correction of anisotropic scanner nonlinearities.
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- Small values (0.01–0.1) are typical for real scanner corrections; large values produce extreme warping.
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- Set all coefficients to 0.0 to pass the field through unchanged.
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