PLELEV-bgol (Vertex Elevation Labels from 3D Polyline)

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 vertex-elevation labeling utilities used in CAD/survey 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

3DEV converts the hidden Z (elevation) values stored in a 3D polyline's vertices into visible plain-text elevation labels placed at each vertex. It solves the common problem that a 3D polyline's elevation data is invisible in plan view, normally you'd have to click vertex-by-vertex in the Properties palette to read each Z value.

How to Use

1. Load PLELEV-bgol.lsp into your CAD session (drag-and-drop the file onto the drawing window, or use the APPLOAD command).
2. Type 3DEV at the command line and press Enter.
3. Select one or more 3D polylines (or elevation-varying LWPOLYLINEs).
4. The routine walks every vertex of every selected polyline and drops a plain TEXT label showing that vertex's Z value.
5. All labels are placed on a dedicated layer, BGOL-3DEV (colour yellow), so they can be frozen or hidden without touching the source geometry.
6. The original polylines are left completely untouched.

Why Use It

• Visibility, makes elevation data readable directly on the drawing, instead of requiring vertex-by-vertex Properties/grip inspection.
• Reusable output, the generated text is plain TEXT, not an annotation tied to the 3D entity, so it can be selected, edited, exported, or fed into other LISP routines/workflows.
• Faster QA, elevation typos or anomalies become visually obvious at a glance instead of requiring manual probing.
• Non-destructive, outputs land on their own layer, leaving the original 3D polyline geometry untouched.

Where to Use It

• Reviewing/QA of 3D polylines produced from survey data (breaklines, drain/pipe inverts, road centerlines) where each vertex carries elevation information.
• Preparing longitudinal section or profile drawings where elevation call-outs are needed at each break point.
• Any drafting step where a 3D polyline needs to be "flattened" into an annotated, 2D-readable drawing without losing elevation information.

Notes

• Works on both legacy 3D POLYLINE entities (walking their VERTEX sub-entities) and LWPOLYLINE entities carrying a single elevation value.
• Text height and decimal precision are set via the *bgol-3dev-height* and *bgol-3dev-precision* constants near the top of the .lsp file, edit these to match your drawing scale.
• 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.