adding more nodes

docs/nodes/Polynomial Distortion.md

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+# Polynomial Distortion
+
+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.
+
+## Inputs
+
+| Name | Type | Required | Description |
+|------|------|----------|-------------|
+| field | DATA_FIELD | Yes | Input field with scanner distortion |
+
+## Outputs
+
+| Name | Type | Description |
+|------|------|-------------|
+| corrected | DATA_FIELD | Distortion-corrected field |
+
+## Controls
+
+| Name | Type | Default | Description |
+|------|------|---------|-------------|
+| k1_x | FLOAT | 0.0 | Linear distortion coefficient for the x axis (-1.0–1.0) |
+| k2_x | FLOAT | 0.0 | Quadratic distortion coefficient for the x axis (-1.0–1.0) |
+| k3_x | FLOAT | 0.0 | Cubic distortion coefficient for the x axis (-1.0–1.0) |
+| k1_y | FLOAT | 0.0 | Linear distortion coefficient for the y axis (-1.0–1.0) |
+| k2_y | FLOAT | 0.0 | Quadratic distortion coefficient for the y axis (-1.0–1.0) |
+| k3_y | FLOAT | 0.0 | Cubic distortion coefficient for the y axis (-1.0–1.0) |
+
+## Notes
+
+- k1 controls linear stretching/compression, k2 controls barrel/pincushion-like quadratic distortion, and k3 controls cubic (S-shaped) distortion.
+- Coefficients for x and y are independent, allowing correction of anisotropic scanner nonlinearities.
+- Small values (0.01–0.1) are typical for real scanner corrections; large values produce extreme warping.
+- Set all coefficients to 0.0 to pass the field through unchanged.