add a few more nodes

docs/nodes/Arc Revolve.md

@@ -0,0 +1,29 @@
+# Arc Revolve
+
+Subtract a cylindrical arc background. A circular arc of the given radius is rolled under each row (or column), and the envelope it traces is subtracted as the background.
+
+## Inputs
+
+| Name | Type | Required | Description |
+|------|------|----------|-------------|
+| field | DATA_FIELD | Yes | Input field |
+
+## Outputs
+
+| Name | Type | Description |
+|------|------|-------------|
+| leveled | DATA_FIELD | Field with arc background subtracted |
+| background | DATA_FIELD | The estimated arc background |
+
+## Controls
+
+| Name | Type | Default | Description |
+|------|------|---------|-------------|
+| radius | INT | 20 | Arc radius in pixels (1–1000) |
+| direction | dropdown | horizontal | Direction to apply the arc: horizontal, vertical, or both |
+
+## Notes
+
+- Larger radii produce smoother backgrounds that follow gentle curvature. Smaller radii track finer features.
+- The "both" direction takes the minimum of horizontal and vertical backgrounds.
+- Deep outliers are suppressed before fitting so that scratches or pits do not pull the arc down.

docs/nodes/Level Rotate.md

@@ -0,0 +1,21 @@
+# Level Rotate
+
+Level by physically rotating the data plane. Fits a best-fit plane, converts its slopes to tilt angles, then rotates the surface by those angles using interpolation rather than algebraic subtraction.
+
+## Inputs
+
+| Name | Type | Required | Description |
+|------|------|----------|-------------|
+| field | DATA_FIELD | Yes | Input field to level |
+
+## Outputs
+
+| Name | Type | Description |
+|------|------|-------------|
+| leveled | DATA_FIELD | Field with tilt removed by rotation |
+
+## Notes
+
+- Unlike Plane Level (which subtracts a fitted plane), this node rotates the 3D surface to make it horizontal. The distinction matters for steep tilts where subtraction introduces distortion.
+- Uses bilinear interpolation to resample rotated z-values.
+- Edges are handled with nearest-neighbor extension.

docs/nodes/Sphere Revolve.md

@@ -0,0 +1,28 @@
+# Sphere Revolve
+
+Subtract a spherical cap background. A sphere of the given radius is rolled under the surface, and the envelope it traces is subtracted as the background.
+
+## Inputs
+
+| Name | Type | Required | Description |
+|------|------|----------|-------------|
+| field | DATA_FIELD | Yes | Input field |
+
+## Outputs
+
+| Name | Type | Description |
+|------|------|-------------|
+| leveled | DATA_FIELD | Field with spherical background subtracted |
+| background | DATA_FIELD | The estimated spherical background |
+
+## Controls
+
+| Name | Type | Default | Description |
+|------|------|---------|-------------|
+| radius | INT | 20 | Sphere radius in pixels (1–500) |
+
+## Notes
+
+- Works like Arc Revolve but in two dimensions — suitable for bowl-shaped or dome-shaped backgrounds.
+- Larger radii produce smoother backgrounds. Very small radii will track individual features.
+- Deep outliers are suppressed before fitting.

docs/nodes/Unrotate.md

@@ -0,0 +1,28 @@
+# Unrotate
+
+Auto-detect and correct in-plane scan rotation. Computes a slope angle histogram, finds the dominant feature direction for the given symmetry, and rotates the image to align features with the axes.
+
+## Inputs
+
+| Name | Type | Required | Description |
+|------|------|----------|-------------|
+| field | DATA_FIELD | Yes | Input field to correct |
+
+## Outputs
+
+| Name | Type | Description |
+|------|------|-------------|
+| leveled | DATA_FIELD | Field with rotation corrected |
+
+## Controls
+
+| Name | Type | Default | Description |
+|------|------|---------|-------------|
+| symmetry | dropdown | 4-fold | Expected symmetry of the surface features: 2-fold, 3-fold, 4-fold, or 6-fold |
+
+## Notes
+
+- Best suited for crystalline or patterned surfaces where features have a clear preferred direction.
+- 4-fold symmetry is the most common choice for cubic crystal surfaces and rectangular gratings.
+- If the detected rotation is less than 0.01°, the data is returned unchanged.
+- Uses bilinear interpolation; edges are handled with nearest-neighbor extension.

docs/nodes/Zero Maximum.md

@@ -0,0 +1,20 @@
+# Zero Maximum
+
+Shift all values so the maximum is exactly zero. All resulting values will be zero or negative.
+
+## Inputs
+
+| Name | Type | Required | Description |
+|------|------|----------|-------------|
+| field | DATA_FIELD | Yes | Input field to level |
+
+## Outputs
+
+| Name | Type | Description |
+|------|------|-------------|
+| leveled | DATA_FIELD | Field with maximum subtracted |
+
+## Notes
+
+- Equivalent to subtracting the global maximum from every pixel.
+- Useful when the highest point should represent the zero reference.

docs/nodes/Zero Mean.md

@@ -0,0 +1,20 @@
+# Zero Mean
+
+Shift all values so the mean is exactly zero. A pure offset subtraction — no plane fit or polynomial involved.
+
+## Inputs
+
+| Name | Type | Required | Description |
+|------|------|----------|-------------|
+| field | DATA_FIELD | Yes | Input field to level |
+
+## Outputs
+
+| Name | Type | Description |
+|------|------|-------------|
+| leveled | DATA_FIELD | Field with mean subtracted |
+
+## Notes
+
+- Equivalent to subtracting a constant (the mean) from every pixel.
+- Does not change relative height differences — only shifts the overall offset.