Raw Alignment

Menu: Civil / Start / Alignments / Raw alignment

The Raw Alignment Tab is the default interface when selecting an alignment before horizontal alignment calculations have been performed. This tab contains the fundamental control points (PIs) that define the planimetric structure of an alignment. It is particularly useful for refining raw alignments derived from mobile LiDAR data, allowing users to find the best-fitting horizontal and vertical alignments.

1. Overview of the Raw Alignment Tab

✔ Manages the Ends & Intersections of Planimetric Lines
✔ Supports Four Alignment Types – Horizontal, Horizontal/Vertical, Road, and Pipes
✔ Allows Import & Export of LandXML Alignments
✔ Enables Best-Fit Curve Calculations for Horizontal & Vertical Alignments
✔ Supports Editing, Inversion, and Validation of Alignment Points

When an alignment originates from a point cloud dataset, the software can generate a best-fit horizontal and vertical curve for optimization.

2. Key Functions in the Raw Alignment Tab

Function	Description
Alignment Name	Specifies the name of the current alignment, which updates across all menus.
Alignment Type	Defines the alignment type: Horizontal, Horizontal/Vertical, Road, or Pipes. The first two types show only the Raw Alignment & Horizontal Curves tabs, while Road and Pipes include Vertical Curve calculations.
Save	Saves the alignment data.
Validate Points	Checks if existing Vision database points match alignment PIs and links them.
Create Points	Generates new Vision database points at the alignment's PIs.
Report	Displays a report on horizontal and vertical curves (exportable as text).
Invert Alignment	Reverses the start and end of the alignment.
Reset Alignment	Clears all alignment data for a fresh start.
Chaining & Elevation Start Values	Sets the initial stationing (chaining) and starting elevation for the alignment.
Pick Points / Pick Polyline	Allows users to manually select points or polylines from the main window for alignment creation.
Import/Export LandXML	Enables import/export of alignments in LandXML format.
Draw / Erase Alignment	Renders or removes the alignment visualization in the CAD workspace.

3. Managing Alignment Control Points (PI Tab)

The Point of Intersection (PI) Tab displays all control points used to define the alignment. The PI Type determines how segments connect:

PI Type	Description
PI (Point)	Represents a sharp vertex in the alignment.
PI_Arc	Defines an arc curve at the PI with a specified radius (positive = clockwise).
PI_Spi (Spiral)	Defines a transition spiral at the PI, requiring a minimum radius and length.
PI_SAS (Spiral-Arc-Spiral)	Defines a spiral-arc-spiral combination, used in smoother transitions.

📌 Note: The PI coordinate is always the intersection of two tangent lines, meaning arcs and spirals do not pass through the PI directly.

4. Best-Fit Curve Calculations (Fitting Section)

The Fitting Section provides automatic best-fit calculations for horizontal and vertical alignments, optimizing alignment geometry.

📌 Horizontal Curve Fitting Parameters

✔ Minimum Points – Sets the smallest number of points required per segment.
✔ Minimum & Maximum Length – Defines segment length constraints.
✔ Maximum Perpendicular Distance – Limits the max deviation between the generated alignment and raw data points.
✔ Minimum & Maximum Radius – Restricts the curve radius range for arc interpolation.
✔ Minimum Angle of Deflection – Ensures sufficient deviation between consecutive segments.
✔ Force Tangents (Add Curve) – Forces curve placement between two straight segments.
✔ Global Fit – Adjusts the entire alignment for optimal fit.
✔ Maximum Iterations – Sets a limit on optimization cycles to prevent excessive processing.

📌 Vertical Curve Fitting Parameters

✔ Minimum Points – Ensures adequate data points per vertical segment.
✔ Maximum Perpendicular Distance – Controls allowable vertical deviation.
✔ Curvature Tolerance – Defines the minimum slope variation before curves are merged.
✔ Minimum Slope Difference (%) – Prevents negligible slope variations from affecting vertical curves.
✔ Force Tangents (Add Parabola) – Forces vertical curve placement where required.
✔ Global Fit – Moves the vertical curve to best match raw data points.
✔ Maximum Iterations – Limits global fit calculations to prevent long processing times.

5. CSV Data Handling for Alignments

Function	Description
Load CSV File (NXYZ)	Imports a raw alignment from a CSV file (columns: Point Number, X, Y, Z).
Save CSV File (NXYZ)	Exports the raw alignment as a CSV file for external use.

6. Best Practices for Managing Raw Alignments

✔ Validate PIs before using an alignment in further analysis.
✔ Use best-fit calculations to optimize alignments derived from point clouds.
✔ Adjust minimum & maximum segment lengths to refine curve accuracy.
✔ Force tangent or parabola placement when necessary to ensure smooth transitions.
✔ Regularly save and export alignments in LandXML or CSV format for backup and interoperability.

🚀 Enhance Your Infrastructure Planning with Accurate Alignments!

With intelligent best-fit curve calculations, flexible PI types, and seamless LandXML integration, VisionLidar’s Civil Module provides a powerful toolkit for alignment creation and refinement. 📏🏗️🌍

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