architectural-drawing-parser

What this skill does

# Architectural Drawing Parser

## Overview

Vision AI pipeline to extract structured building data from architectural drawings, floor plans, and IBC/IRC code compliance documents. Uses Claude's vision capabilities to read and interpret professional drawings, returning a normalized JSON object suitable for downstream 3D modeling or code validation workflows.

Supports IBC occupancy types (A-1 through U), construction types (I-A through V-B), sprinkler systems (NFPA 13/13R/13D), building dimensions, unit breakdowns, egress data, and floor plan elements (rooms, walls, doors, windows).

## Instructions

### Supported Drawing Types

| Drawing Type | What Is Extracted |
|---|---|
| IBC/IRC code compliance drawings | Occupancy, construction type, heights, stories, areas, egress, units |
| Floor plans (unit-level) | Rooms, dimensions, wall layouts, door/window positions |
| Site plans | Building footprint, setbacks, parking |
| Building area analysis tables | Unit types, SF per unit, occupant loads, travel distances |

### Output Data Structure

The parser returns a `BuildingData` JSON object with these fields:

- **occupancy** -- IBC occupancy type (e.g., "R-2", "A-2", "B")
- **constructionType** -- IBC construction type (e.g., "V-B", "I-A")
- **sprinklerSystem** -- "NFPA 13", "NFPA 13R", "NFPA 13D", or "None"
- **stories** -- `{ permitted, actual }`
- **height** -- `{ permitted: { feet, meters }, actual: { feet, meters } }`
- **totalBuildingArea** -- `{ sqft, sqm }`
- **units** -- Array of `{ name, area: { sqft, sqm }, occupantLoad, loadFactor, count }`
- **travelDistances** -- Array of `{ floor, maximum: { feet, meters } }`
- **scale** -- Scale notation string (e.g., `1/16" = 1'-0"`)
- **rooms** -- Array of `{ name, type, estimatedArea, dimensions }` (floor plans only)

### Parsing Approach

1. Send the drawing image to Claude's vision API with a structured extraction prompt
2. Request all building data as a single JSON object
3. Convert all areas to both sqft and sqm (1 sqft = 0.0929 sqm)
4. Convert all distances to both feet and meters (1 foot = 0.3048 m)
5. Parse the JSON from the response text

### Best Practices

- Use 150 DPI or higher for scanned drawings
- JPEG or PNG format; convert PDFs to images first (`pdftoppm -jpeg -r 150 drawing.pdf output`)
- Process multi-sheet PDFs one page at a time, then merge results
- Always verify extracted data against the source before structural calculations

## Examples

### Example 1: Parsing a Floor Plan PDF

A developer receives a scanned floor plan of a 2-bedroom apartment unit and needs room dimensions for a renovation estimate.

```
Input: apartment_unit_plan.jpg (scanned at 200 DPI, 1/4" = 1'-0" scale)

Extracted JSON:
{
  "rooms": [
    { "name": "Living Room", "type": "living", "estimatedArea": { "sqft": 240, "sqm": 22.3 }, "dimensions": { "width": 16, "depth": 15, "units": "feet" } },
    { "name": "Kitchen", "type": "kitchen", "estimatedArea": { "sqft": 120, "sqm": 11.1 }, "dimensions": { "width": 12, "depth": 10, "units": "feet" } },
    { "name": "Master Bedroom", "type": "bedroom", "estimatedArea": { "sqft": 168, "sqm": 15.6 }, "dimensions": { "width": 14, "depth": 12, "units": "feet" } },
    { "name": "Bedroom 2", "type": "bedroom", "estimatedArea": { "sqft": 132, "sqm": 12.3 }, "dimensions": { "width": 12, "depth": 11, "units": "feet" } },
    { "name": "Bathroom", "type": "bathroom", "estimatedArea": { "sqft": 48, "sqm": 4.5 }, "dimensions": { "width": 8, "depth": 6, "units": "feet" } }
  ],
  "scale": "1/4\" = 1'-0\""
}
```

The developer uses the room dimensions to calculate material quantities for flooring (708 sqft total) and wall paint coverage.

### Example 2: Extracting Building Data from an IBC Compliance Drawing

An architect submits a code compliance sheet for a 3-story apartment building. The parser extracts all building classification and egress data.

```
Input: ibc_compliance_sheet.jpg (building area analysis table + egress diagram)

Extracted JSON:
{
  "occupancy": "R-2",
  "constructionType": "V-B",
  "sprinklerSystem": "NFPA 13",
  "stories": { "permitted": 4, "actual": 3 },
  "height": {
    "permitted": { "feet": 60, "meters": 18.29 },
    "actual": { "feet": 35, "meters": 10.67 }
  },
  "totalBuildingArea": { "sqft": 8910, "sqm": 827.9 },
  "units": [
    { "name": "Type A", "area": { "sqft": 834, "sqm": 77.5 }, "occupantLoad": 5, "loadFactor": "1/200 SF", "count": 6 },
    { "name": "Type B", "area": { "sqft": 645, "sqm": 59.9 }, "occupantLoad": 4, "loadFactor": "1/200 SF", "count": 6 }
  ],
  "travelDistances": [
    { "floor": "Level 1", "maximum": { "feet": 66, "meters": 20.1 } },
    { "floor": "Level 2", "maximum": { "feet": 66, "meters": 20.1 } },
    { "floor": "Level 3", "maximum": { "feet": 66, "meters": 20.1 } }
  ]
}
```

This data feeds into the `ibc-building-codes` skill for compliance validation and the `spec-to-3d` skill for 3D model generation.

## Guidelines

- Accuracy depends on drawing quality and image resolution; low-res scans may produce incorrect dimensions
- Very small text (title blocks, fine notes) may be misread -- zoom in for detail drawings
- Complex overlapping hatching or linework may confuse room detection
- Proprietary symbols or non-standard abbreviations may not be recognized
- Always treat extracted data as an estimate; verify critical measurements manually
- For multi-sheet sets, parse each sheet separately and merge the structured data
- The parser works best with US-standard architectural drawings; metric-only drawings may need prompt adjustments