Gunakar-book (Survey Area Calculation by Quadrilateral Decomposition)

Command Type: AutoLISP routine (optimized for AutoCAD, GstarCAD, and BricsCAD platforms)
Developed by: Trishunya, trishunya.com

Designed specifically for rigorous manual area verification, this routine automates the process of land boundary decomposition. It breaks down complex surveying boundaries into simpler geometric shapes (quadrilaterals and triangles) and generates a comprehensive, transparent calculation table ideal for printed documentation.

Overview

AREA_TO is an advanced calculation tool that selects a closed boundary polyline and decomposes it into fundamental geometric regions. It intelligently handles arcs by computing corner regions and allows for interactive user definition of quadrilaterals. After decomposition, the routine generates a highly detailed native CAD table containing all constituent dimensions (Long L1/L2, Width L1/L2) and areas, concluding with a strict sanity check against the original polyline's area.

How to Use

1. Load Gunakar-book.lsp into your CAD session (drag-and-drop the file onto the drawing window, or use the APPLOAD command).
2. Type AREA_TO at the command line and press Enter.
3. Select the closed LWPOLYLINE boundary you wish to analyze.
4. Decomposition Phase:

• If the polyline has exactly 4 vertices, it automatically processes the shape.
• If it has more vertices, the tool prompts an interactive phase where you manually click 4 points per quadrilateral to decompose the total area.

1. Click an insertion point to place the comprehensive Area Table (top-left corner).
2. A sanity check will compare the calculated sum against the original CAD polyline area to ensure absolute accuracy.

Why Use It

• Printed Manual Area Verification, Generates a transparent, step-by-step breakdown of area calculations (lengths, widths, and multipliers) that can be easily verified by hand on printed survey drawings.
• Automated Table Generation, Instantly draws a formatted native CAD table detailing quad numbers, longitudinal dimensions, width dimensions, and partial areas.
• Arc & Corner Processing, Intelligently calculates inner and outer corner regions derived from arcs and bulges, factoring them correctly into the final area.
• Built-in Sanity Checks, Automatically compares the decomposed total area against the source boundary area, warning the user if the deviation exceeds a defined tolerance (default 1.0%).

Where to Use It

• Complex land boundary decomposition where area breakdowns must be explicitly documented.
• Cadastral or land-survey reporting requiring verifiable, tabular dimension breakdowns rather than just a final area number.
• Any project requiring legal or administrative manual area verification across professional CAD environments.

Notes

• All generated geometry, text, and tables are automatically placed on a dedicated layer named gunakar book maap.
• Ensure your selected boundary is a fully closed LWPOLYLINE for the routine to function correctly.
• The routine visually aids the interactive quadrilateral definition process by placing temporary tracking points and hatching corner regions.
• During the area comparison, the original boundary polyline is retained, colored red, given a 0.35mm lineweight, and brought to the front for easy visualization.

Credits

Developed and shared for the AEC and CAD community by Trishunya. Website: http://trishunya.com/ Free and open-source, use it, modify it, share it, for professional or commercial work alike.