Install
openclaw skills install @datadrivenconstruction/ifc-qto-extractionIfc Qto Extraction
Extract quantities from IFC/Revit models for quantity takeoff. Uses DDC converters to get element counts, areas, volumes, lengths with grouping and reporting.
IFC Quantity Takeoff Extraction
Extract structured quantity data from BIM models (IFC, Revit) for cost estimation, material ordering, and progress tracking.
Business Case
Problem: Manual quantity takeoff is:
- Time-consuming (40-80 hours for medium project)
- Error-prone (human counting mistakes)
- Not repeatable (changes require full rework)
- Disconnected from design (no live updates)
Solution: Automated QTO from BIM that:
- Extracts all quantities in minutes
- Groups by type, level, zone
- Updates instantly with model changes
- Exports to Excel for pricing
ROI: 90% reduction in QTO time, near-zero counting errors
DDC Tools Used
┌──────────────────────────────────────────────────────────────────────┐
│ QTO EXTRACTION PIPELINE │
├──────────────────────────────────────────────────────────────────────┤
│ │
│ INPUT CONVERT ANALYZE │
│ ┌─────────┐ ┌─────────┐ ┌─────────┐ │
│ │ .rvt │ │ DDC │ │ Python │ │
│ │ .ifc │─────────►│Converter│───────────►│ pandas │ │
│ │ .dwg │ │ │ │ │ │
│ └─────────┘ └─────────┘ └─────────┘ │
│ │ │ │
│ ▼ ▼ │
│ ┌─────────┐ ┌─────────┐ │
│ │ .xlsx │ │ Grouped │ │
│ │ raw data│ │ QTO │ │
│ └─────────┘ └─────────┘ │
│ │ │
│ OUTPUT ▼ │
│ ┌─────────────────────────────────────────────────────────────┐ │
│ │ QTO Report │ │
│ │ • Element counts by type │ │
│ │ • Areas (m², ft²) │ │
│ │ • Volumes (m³, ft³) │ │
│ │ • Lengths (m, ft) │ │
│ │ • Weights (kg, tons) │ │
│ │ • Grouped by level/zone/system │ │
│ └─────────────────────────────────────────────────────────────┘ │
│ │
└──────────────────────────────────────────────────────────────────────┘
CLI Commands
Revit to Excel (with BBox for volumes)
# Basic extraction
RvtExporter.exe "C:\Models\Building.rvt"
# Full extraction with bounding boxes (for volume calculations)
RvtExporter.exe "C:\Models\Building.rvt" complete bbox
# Include schedules (Revit's built-in QTO)
RvtExporter.exe "C:\Models\Building.rvt" complete bbox schedule
IFC to Excel
# Extract IFC data
IfcExporter.exe "C:\Models\Building.ifc"
# Output: Building.xlsx with all IFC entities
DWG to Excel (2D areas)
# Extract DWG blocks and areas
DwgExporter.exe "C:\Drawings\FloorPlan.dwg"
Python Implementation
import pandas as pd
import numpy as np
from pathlib import Path
import subprocess
from typing import List, Dict, Optional
from dataclasses import dataclass
@dataclass
class QuantityItem:
"""Single quantity line item"""
category: str
type_name: str
count: int
area: float = 0.0
volume: float = 0.0
length: float = 0.0
weight: float = 0.0
unit_area: str = "m²"
unit_volume: str = "m³"
unit_length: str = "m"
level: str = ""
zone: str = ""
class BIMQuantityExtractor:
"""Extract quantities from BIM models using DDC converters"""
def __init__(self, converter_path: str):
self.converter_path = Path(converter_path)
def convert_model(self, model_path: str, options: List[str] = None) -> Path:
"""Convert BIM model to Excel"""
model = Path(model_path)
options = options or ["complete", "bbox"]
# Determine converter
ext = model.suffix.lower()
converters = {
'.rvt': 'RvtExporter.exe',
'.rfa': 'RvtExporter.exe',
'.ifc': 'IfcExporter.exe',
'.dwg': 'DwgExporter.exe',
'.dgn': 'DgnExporter.exe'
}
converter = self.converter_path / converters.get(ext, 'RvtExporter.exe')
# Build command
cmd = [str(converter), str(model)] + options
# Execute
result = subprocess.run(cmd, capture_output=True, text=True)
if result.returncode != 0:
raise RuntimeError(f"Conversion failed: {result.stderr}")
# Return path to generated Excel
xlsx_path = model.with_suffix('.xlsx')
return xlsx_path
def load_bim_data(self, xlsx_path: str) -> pd.DataFrame:
"""Load converted BIM data from Excel"""
xlsx = Path(xlsx_path)
if not xlsx.exists():
raise FileNotFoundError(f"Excel file not found: {xlsx}")
# Read main data sheet
df = pd.read_excel(xlsx, sheet_name=0)
# Clean column names
df.columns = df.columns.str.strip()
return df
def extract_quantities(
self,
df: pd.DataFrame,
group_by: str = "Type Name",
include_categories: List[str] = None
) -> List[QuantityItem]:
"""Extract quantities grouped by type"""
# Filter categories if specified
if include_categories and 'Category' in df.columns:
df = df[df['Category'].isin(include_categories)]
# Group and aggregate
quantities = []
for (category, type_name), group in df.groupby(['Category', group_by]):
item = QuantityItem(
category=str(category),
type_name=str(type_name),
count=len(group)
)
# Extract area
area_cols = ['Area', 'Surface Area', 'Gross Area', 'Net Area']
for col in area_cols:
if col in group.columns:
item.area = group[col].sum()
break
# Extract volume
vol_cols = ['Volume', 'Gross Volume', 'Net Volume']
for col in vol_cols:
if col in group.columns:
item.volume = group[col].sum()
break
# Extract length
len_cols = ['Length', 'Curve Length', 'Unconnected Height']
for col in len_cols:
if col in group.columns:
item.length = group[col].sum()
break
# Extract level if available
if 'Level' in group.columns:
levels = group['Level'].dropna().unique()
item.level = ', '.join(str(l) for l in levels)
quantities.append(item)
return quantities
def extract_by_level(
self,
df: pd.DataFrame,
group_by: str = "Type Name"
) -> Dict[str, List[QuantityItem]]:
"""Extract quantities grouped by level"""
result = {}
if 'Level' not in df.columns:
result['All Levels'] = self.extract_quantities(df, group_by)
return result
for level, level_df in df.groupby('Level'):
level_name = str(level) if pd.notna(level) else 'Unassigned'
result[level_name] = self.extract_quantities(level_df, group_by)
return result
def calculate_concrete_quantities(self, df: pd.DataFrame) -> dict:
"""Calculate concrete quantities for typical elements"""
concrete_categories = [
'Floors', 'Structural Floors',
'Walls', 'Structural Walls',
'Structural Foundations', 'Foundation',
'Structural Columns', 'Columns',
'Structural Framing', 'Beams'
]
concrete_df = df[df['Category'].isin(concrete_categories)]
return {
'total_volume_m3': concrete_df['Volume'].sum() if 'Volume' in concrete_df.columns else 0,
'by_category': concrete_df.groupby('Category')['Volume'].sum().to_dict() if 'Volume' in concrete_df.columns else {},
'element_count': len(concrete_df)
}
def calculate_wall_quantities(self, df: pd.DataFrame) -> dict:
"""Calculate wall quantities"""
wall_categories = ['Walls', 'Basic Wall', 'Curtain Wall']
walls = df[df['Category'].isin(wall_categories)]
result = {
'total_area_m2': 0,
'total_length_m': 0,
'by_type': {}
}
if 'Area' in walls.columns:
result['total_area_m2'] = walls['Area'].sum()
if 'Length' in walls.columns:
result['total_length_m'] = walls['Length'].sum()
if 'Type Name' in walls.columns:
for type_name, group in walls.groupby('Type Name'):
result['by_type'][type_name] = {
'count': len(group),
'area': group['Area'].sum() if 'Area' in group.columns else 0,
'length': group['Length'].sum() if 'Length' in group.columns else 0
}
return result
def generate_qto_report(
self,
quantities: List[QuantityItem],
output_path: str,
project_name: str = "Project"
) -> str:
"""Generate QTO Excel report"""
# Convert to DataFrame
records = []
for q in quantities:
records.append({
'Category': q.category,
'Type': q.type_name,
'Count': q.count,
'Area (m²)': round(q.area, 2),
'Volume (m³)': round(q.volume, 3),
'Length (m)': round(q.length, 2),
'Level': q.level
})
df = pd.DataFrame(records)
# Sort by category and type
df = df.sort_values(['Category', 'Type'])
# Write to Excel with formatting
with pd.ExcelWriter(output_path, engine='openpyxl') as writer:
# Summary sheet
summary = df.groupby('Category').agg({
'Count': 'sum',
'Area (m²)': 'sum',
'Volume (m³)': 'sum',
'Length (m)': 'sum'
}).round(2)
summary.to_excel(writer, sheet_name='Summary')
# Detail sheet
df.to_excel(writer, sheet_name='Detail', index=False)
# By Level sheet
if 'Level' in df.columns and df['Level'].notna().any():
level_summary = df.groupby(['Level', 'Category']).agg({
'Count': 'sum',
'Area (m²)': 'sum',
'Volume (m³)': 'sum'
}).round(2)
level_summary.to_excel(writer, sheet_name='By Level')
return output_path
def generate_html_report(
self,
quantities: List[QuantityItem],
output_path: str,
project_name: str = "Project"
) -> str:
"""Generate interactive HTML QTO report"""
# Group by category
by_category = {}
for q in quantities:
if q.category not in by_category:
by_category[q.category] = []
by_category[q.category].append(q)
# Calculate totals
total_count = sum(q.count for q in quantities)
total_area = sum(q.area for q in quantities)
total_volume = sum(q.volume for q in quantities)
html = f"""
<!DOCTYPE html>
<html>
<head>
<title>QTO Report - {project_name}</title>
<style>
body {{ font-family: Arial, sans-serif; margin: 20px; }}
.header {{ background: #2c3e50; color: white; padding: 20px; margin-bottom: 20px; }}
.summary {{ display: flex; gap: 20px; margin-bottom: 20px; }}
.summary-card {{ background: #ecf0f1; padding: 15px; border-radius: 5px; flex: 1; }}
.summary-card h3 {{ margin: 0 0 10px 0; color: #7f8c8d; font-size: 14px; }}
.summary-card .value {{ font-size: 24px; font-weight: bold; color: #2c3e50; }}
table {{ width: 100%; border-collapse: collapse; margin-bottom: 20px; }}
th {{ background: #34495e; color: white; padding: 10px; text-align: left; }}
td {{ padding: 8px; border-bottom: 1px solid #ddd; }}
tr:hover {{ background: #f5f5f5; }}
.category-header {{ background: #3498db; color: white; font-weight: bold; }}
.number {{ text-align: right; }}
</style>
</head>
<body>
<div class="header">
<h1>Quantity Takeoff Report</h1>
<p>Project: {project_name}</p>
</div>
<div class="summary">
<div class="summary-card">
<h3>Total Elements</h3>
<div class="value">{total_count:,}</div>
</div>
<div class="summary-card">
<h3>Total Area</h3>
<div class="value">{total_area:,.2f} m²</div>
</div>
<div class="summary-card">
<h3>Total Volume</h3>
<div class="value">{total_volume:,.3f} m³</div>
</div>
<div class="summary-card">
<h3>Categories</h3>
<div class="value">{len(by_category)}</div>
</div>
</div>
<table>
<thead>
<tr>
<th>Category / Type</th>
<th class="number">Count</th>
<th class="number">Area (m²)</th>
<th class="number">Volume (m³)</th>
<th class="number">Length (m)</th>
</tr>
</thead>
<tbody>
"""
for category, items in sorted(by_category.items()):
cat_count = sum(i.count for i in items)
cat_area = sum(i.area for i in items)
cat_volume = sum(i.volume for i in items)
html += f"""
<tr class="category-header">
<td>{category}</td>
<td class="number">{cat_count:,}</td>
<td class="number">{cat_area:,.2f}</td>
<td class="number">{cat_volume:,.3f}</td>
<td class="number">-</td>
</tr>
"""
for item in sorted(items, key=lambda x: x.type_name):
html += f"""
<tr>
<td> {item.type_name}</td>
<td class="number">{item.count:,}</td>
<td class="number">{item.area:,.2f}</td>
<td class="number">{item.volume:,.3f}</td>
<td class="number">{item.length:,.2f}</td>
</tr>
"""
html += """
</tbody>
</table>
</body>
</html>
"""
with open(output_path, 'w', encoding='utf-8') as f:
f.write(html)
return output_path
# Usage Example
def extract_qto_from_model(
model_path: str,
converter_path: str,
output_dir: str = None
) -> dict:
"""Complete QTO extraction workflow"""
from datetime import datetime
extractor = BIMQuantityExtractor(converter_path)
# Convert model
print(f"Converting: {model_path}")
xlsx_path = extractor.convert_model(model_path, ["complete", "bbox"])
# Load data
print(f"Loading data from: {xlsx_path}")
df = extractor.load_bim_data(xlsx_path)
# Extract quantities
quantities = extractor.extract_quantities(df)
# Generate reports
output_dir = output_dir or Path(model_path).parent
timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
excel_path = Path(output_dir) / f"QTO_{timestamp}.xlsx"
html_path = Path(output_dir) / f"QTO_{timestamp}.html"
extractor.generate_qto_report(quantities, str(excel_path))
extractor.generate_html_report(quantities, str(html_path))
# Calculate specific quantities
concrete = extractor.calculate_concrete_quantities(df)
walls = extractor.calculate_wall_quantities(df)
return {
'excel_report': str(excel_path),
'html_report': str(html_path),
'summary': {
'total_elements': len(df),
'categories': df['Category'].nunique() if 'Category' in df.columns else 0,
'types': df['Type Name'].nunique() if 'Type Name' in df.columns else 0
},
'concrete': concrete,
'walls': walls
}
if __name__ == "__main__":
result = extract_qto_from_model(
model_path=r"C:\Projects\Building.rvt",
converter_path=r"C:\DDC\Converters",
output_dir=r"C:\Projects\QTO"
)
print(f"Excel: {result['excel_report']}")
print(f"HTML: {result['html_report']}")
print(f"Concrete Volume: {result['concrete']['total_volume_m3']:.2f} m³")
n8n Workflow Integration
name: BIM QTO Extraction
trigger:
type: webhook
path: /qto-extract
steps:
- convert_model:
node: Execute Command
command: |
"C:\DDC\RvtExporter.exe" "{{$json.model_path}}" complete bbox schedule
- load_excel:
node: Spreadsheet File
operation: read
file: "={{$json.model_path.replace('.rvt', '.xlsx')}}"
- group_quantities:
node: Code
code: |
const grouped = {};
items.forEach(item => {
const type = item.json['Type Name'];
if (!grouped[type]) {
grouped[type] = {
count: 0,
area: 0,
volume: 0
};
}
grouped[type].count++;
grouped[type].area += parseFloat(item.json['Area'] || 0);
grouped[type].volume += parseFloat(item.json['Volume'] || 0);
});
return Object.entries(grouped).map(([type, data]) => ({
type,
...data
}));
- generate_report:
node: Code
code: |
// Generate HTML report
return generateHTMLReport(items);
- save_report:
node: Write Binary File
path: "={{$json.output_path}}"
Best Practices
- Model Quality: Ensure BIM model has proper levels and types assigned
- Units: Verify model units match expected output units
- Categories: Use consistent category naming for grouping
- Updates: Re-run QTO after design changes
- Validation: Cross-check totals against manual spot checks
Common Quantity Formulas
# Concrete formwork area (approximate)
formwork_area = concrete_volume * 6 # m² per m³ of concrete
# Rebar quantity (approximate)
rebar_weight = concrete_volume * 100 # kg per m³ (typical)
# Paint area from wall area
paint_area = wall_area * 2 # both sides
# Ceiling area from floor area
ceiling_area = floor_area * 0.95 # typical ratio
"Measure twice, cut once. Or better yet, measure automatically from the model."
- Downloads
- Security audit
- Review
- Last updated
- 2mo ago
- Current version
- v2.0.0
- License
- MIT-0