Drawing Analyzer for Construction
Overview
Analyze construction drawings (PDF, DWG) to extract dimensions, annotations, symbols, title block data, and support automated quantity takeoff and design review.
Business Case
Drawing analysis automation enables:
- Faster Takeoffs: Extract quantities from drawings
- Quality Control: Verify drawing completeness
- Data Extraction: Pull metadata for project systems
- Design Review: Automated checking against standards
Technical Implementation
from dataclasses import dataclass, field
from typing import List, Dict, Any, Optional, Tuple
import re
import pdfplumber
from pathlib import Path
@dataclass
class TitleBlockData:
project_name: str
project_number: str
sheet_number: str
sheet_title: str
discipline: str
scale: str
date: str
revision: str
drawn_by: str
checked_by: str
approved_by: str
@dataclass
class Dimension:
value: float
unit: str
dimension_type: str # linear, angular, radial
location: Tuple[float, float]
associated_text: str
@dataclass
class Annotation:
text: str
annotation_type: str # note, callout, tag, keynote
location: Tuple[float, float]
references: List[str]
@dataclass
class Symbol:
symbol_type: str # door, window, equipment, etc.
tag: str
location: Tuple[float, float]
properties: Dict[str, Any]
@dataclass
class DrawingAnalysisResult:
file_name: str
title_block: Optional[TitleBlockData]
dimensions: List[Dimension]
annotations: List[Annotation]
symbols: List[Symbol]
scale_factor: float
drawing_area: Tuple[float, float]
quality_issues: List[str]
class DrawingAnalyzer:
"""Analyze construction drawings for data extraction."""
# Common dimension patterns
DIMENSION_PATTERNS = [
r"(\d+'-\s*\d+(?:\s*\d+/\d+)?\"?)", # Feet-inches: 10'-6", 10' - 6 1/2"
r"(\d+(?:\.\d+)?)\s*(?:mm|cm|m|ft|in)", # Metric/imperial with unit
r"(\d+'-\d+\")", # Compact feet-inches
r"(\d+)\s*(?:SF|LF|CY|EA)", # Quantity dimensions
]
# Common annotation patterns
ANNOTATION_PATTERNS = {
'keynote': r'^\d{1,2}[A-Z]?$', # 1A, 12, 5B
'room_tag': r'^(?:RM|ROOM)\s*\d+',
'door_tag': r'^[A-Z]?\d{2,3}[A-Z]?$',
'grid_line': r'^[A-Z]$|^\d+$',
'elevation': r'^(?:EL|ELEV)\.?\s*\d+',
'detail_ref': r'^\d+/[A-Z]\d+',
}
# Scale patterns
SCALE_PATTERNS = [
r"SCALE:\s*(\d+(?:/\d+)?)\s*[\"']\s*=\s*(\d+)\s*['\-]", # 1/4" = 1'-0"
r"(\d+):(\d+)", # 1:100
r"NTS|NOT TO SCALE",
]
def __init__(self):
self.results: Dict[str, DrawingAnalysisResult] = {}
def analyze_pdf_drawing(self, pdf_path: str) -> DrawingAnalysisResult:
"""Analyze a PDF drawing."""
path = Path(pdf_path)
all_text = ""
dimensions = []
annotations = []
symbols = []
quality_issues = []
with pdfplumber.open(pdf_path) as pdf:
for page in pdf.pages:
# Extract text
text = page.extract_text() or ""
all_text += text + "\n"
# Extract dimensions
page_dims = self._extract_dimensions(text)
dimensions.extend(page_dims)
# Extract annotations
page_annots = self._extract_annotations(text)
annotations.extend(page_annots)
# Extract from tables (often contain schedules)
tables = page.extract_tables()
for table in tables:
symbols.extend(self._parse_schedule_table(table))
# Parse title block
title_block = self._extract_title_block(all_text)
# Determine scale
scale_factor = self._determine_scale(all_text)
# Quality checks
quality_issues = self._check_drawing_quality(
title_block, dimensions, annotations
)
result = DrawingAnalysisResult(
file_name=path.name,
title_block=title_block,
dimensions=dimensions,
annotations=annotations,
symbols=symbols,
scale_factor=scale_factor,
drawing_area=(0, 0), # Would need image analysis
quality_issues=quality_issues
)
self.results[path.name] = result
return result
def _extract_dimensions(self, text: str) -> List[Dimension]:
"""Extract dimensions from text."""
dimensions = []
for pattern in self.DIMENSION_PATTERNS:
matches = re.findall(pattern, text)
for match in matches:
value, unit = self._parse_dimension_value(match)
if value > 0:
dimensions.append(Dimension(
value=value,
unit=unit,
dimension_type='linear',
location=(0, 0),
associated_text=match
))
return dimensions
def _parse_dimension_value(self, dim_text: str) -> Tuple[float, str]:
"""Parse dimension text to value and unit."""
dim_text = dim_text.strip()
# Feet and inches: 10'-6"
ft_in_match = re.match(r"(\d+)'[-\s]*(\d+)?(?:\s*(\d+)/(\d+))?\"?", dim_text)
if ft_in_match:
feet = int(ft_in_match.group(1))
inches = int(ft_in_match.group(2) or 0)
if ft_in_match.group(3) and ft_in_match.group(4):
inches += int(ft_in_match.group(3)) / int(ft_in_match.group(4))
return feet * 12 + inches, 'in'
# Metric with unit
metric_match = re.match(r"(\d+(?:\.\d+)?)\s*(mm|cm|m)", dim_text)
if metric_match:
return float(metric_match.group(1)), metric_match.group(2)
# Just a number
num_match = re.match(r"(\d+(?:\.\d+)?)", dim_text)
if num_match:
return float(num_match.group(1)), ''
return 0, ''
def _extract_annotations(self, text: str) -> List[Annotation]:
"""Extract annotations from text."""
annotations = []
lines = text.split('\n')
for line in lines:
line = line.strip()
if not line:
continue
for annot_type, pattern in self.ANNOTATION_PATTERNS.items():
if re.match(pattern, line, re.IGNORECASE):
annotations.append(Annotation(
text=line,
annotation_type=annot_type,
location=(0, 0),
references=[]
))
break
# General notes
if line.startswith(('NOTE:', 'SEE ', 'REFER TO', 'TYP', 'U.N.O.')):
annotations.append(Annotation(
text=line,
annotation_type='note',
location=(0, 0),
references=[]
))
return annotations
def _extract_title_block(self, text: str) -> Optional[TitleBlockData]:
"""Extract title block information."""
# Common title block patterns
patterns = {
'project_name': r'PROJECT(?:\s*NAME)?:\s*(.+?)(?:\n|$)',
'project_number': r'(?:PROJECT\s*)?(?:NO|NUMBER|#)\.?:\s*(\S+)',
'sheet_number': r'SHEET(?:\s*NO)?\.?:\s*([A-Z]?\d+(?:\.\d+)?)',
'sheet_title': r'SHEET\s*TITLE:\s*(.+?)(?:\n|$)',
'scale': r'SCALE:\s*(.+?)(?:\n|$)',
'date': r'DATE:\s*(\d{1,2}[/-]\d{1,2}[/-]\d{2,4})',
'revision': r'REV(?:ISION)?\.?:\s*(\S+)',
'drawn_by': r'(?:DRAWN|DRN)\s*(?:BY)?:\s*(\S+)',
'checked_by': r'(?:CHECKED|CHK)\s*(?:BY)?:\s*(\S+)',
}
extracted = {}
for field, pattern in patterns.items():
match = re.search(pattern, text, re.IGNOR