ELEVDIST-bgol (Interpolate Elevation at Distance Interval)

Command Type: AutoLISP routine (works in AutoCAD, BricsCAD, ZWCAD and most AutoLISP-compatible CAD platforms)
Developed by: BGol Community, bgol.in

Inspired by the general concept of distance-driven elevation interpolation used in survey and profile drafting. This is an original, independently written routine, new file name, new command name, new source code, created so the CAD community has a free, editable, open-source alternative.

Overview

ELVD takes two known elevation text labels and automatically fills in as many intermediate elevation labels as fit between them, spaced at a fixed real-world distance interval you choose (e.g. every 3 m or 5 m), instead of a fixed point count. The number of interpolated points adapts to the actual distance between the two references.

How to Use

1. Load ELEVDIST-bgol.lsp into your CAD session (drag-and-drop the file onto the drawing window, or use the APPLOAD command).
2. Type ELVD at the command line and press Enter.
3. Select the first (start) elevation TEXT entity.
4. Select the second (end) elevation TEXT entity.
5. Enter the desired distance interval.
6. Intermediate elevation labels are linearly interpolated and placed along the straight line between the two references, spaced at that interval, on layer BGOL-ELVD.

Why Use It

• Distance-based thinking, lets you think in real spacing terms ("a value every 5 meters") rather than "give me N points," which matches how cross-section/profile intervals are usually specified.
• Adapts automatically, the number of generated labels adjusts to fit the actual distance between the two reference points.
• No manual math, removes manual linear-interpolation arithmetic and label placement, reducing transcription errors on long runs of elevation data.

Where to Use It

• Filling in intermediate spot elevations along a straight survey or formation line at a standard distance interval (e.g. every 5 m or 10 m, a common cross-section/profile interval in road, rail, and irrigation projects).
• Any drafting task needing evenly-spaced, linearly interpolated elevation labels between two known values without manually placing or calculating each one.

Notes

• Interpolated points are placed along the straight line connecting the two reference text insertion points; for a curved alignment, interpolate between closer point pairs for better accuracy.
• Text height for the new labels matches the first reference text's height (falls back to 2.5 if unavailable).
• If the entered interval is larger than the distance between the two references, no intermediate points are generated and a message is shown.
• Source code is fully open, feel free to study, modify, and redistribute it under the same open, free-for-all spirit.

Credits

Developed and shared for the CAD community by BGol Community. Website: https://bgol.in/ Free and open-source, use it, modify it, share it, for personal or commercial work alike.