AI-powered construction defect detection using computer vision. Identify cracks, spalling, corrosion, and other defects in concrete, steel, and building components from images and video.
This skill implements deep learning-based defect detection for construction quality control. Analyze images and video to automatically identify structural and surface defects, classify severity, and generate inspection reports.
Detectable Defects:
import torch
import torch.nn as nn
from torchvision import transforms, models
from PIL import Image
from dataclasses import dataclass
from typing import List, Dict, Tuple
from enum import Enum
class DefectType(Enum):
CRACK = "crack"
SPALLING = "spalling"
CORROSION = "corrosion"
HONEYCOMBING = "honeycombing"
EFFLORESCENCE = "efflorescence"
DEFORMATION = "deformation"
SURFACE_DAMAGE = "surface_damage"
NO_DEFECT = "no_defect"
class SeverityLevel(Enum):
MINOR = "minor"
MODERATE = "moderate"
SEVERE = "severe"
CRITICAL = "critical"
@dataclass
class DefectDetection:
defect_type: DefectType
confidence: float
severity: SeverityLevel
bounding_box: Tuple[int, int, int, int] # x1, y1, x2, y2
area_ratio: float # Defect area as ratio of image
# Simple classifier using pretrained model
class SimpleDefectClassifier:
def __init__(self, num_classes: int = 8):
self.model = models.resnet18(pretrained=True)
self.model.fc = nn.Linear(self.model.fc.in_features, num_classes)
self.model.eval()
self.transform = transforms.Compose([
transforms.Resize((224, 224)),
transforms.ToTensor(),
transforms.Normalize([0.485, 0.456, 0.406], [0.229, 0.224, 0.225])
])
self.classes = list(DefectType)
def predict(self, image_path: str) -> DefectDetection:
"""Classify defect in image"""
image = Image.open(image_path).convert('RGB')
input_tensor = self.transform(image).unsqueeze(0)
with torch.no_grad():
outputs = self.model(input_tensor)
probs = torch.softmax(outputs, dim=1)
confidence, predicted = torch.max(probs, 1)
defect_type = self.classes[predicted.item()]
return DefectDetection(
defect_type=defect_type,
confidence=confidence.item(),
severity=self._estimate_severity(confidence.item()),
bounding_box=(0, 0, image.width, image.height),
area_ratio=1.0
)
def _estimate_severity(self, confidence: float) -> SeverityLevel:
if confidence > 0.9:
return SeverityLevel.CRITICAL
elif confidence > 0.7:
return SeverityLevel.SEVERE
elif confidence > 0.5:
return SeverityLevel.MODERATE
else:
return SeverityLevel.MINOR
# Usage
classifier = SimpleDefectClassifier()
# result = classifier.predict("concrete_image.jpg")
# print(f"Defect: {result.defect_type.value}, Confidence: {result.confidence:.2%}")
import torch
import torch.nn as nn
from torchvision import transforms
from torchvision.models.detection import fasterrcnn_resnet50_fpn
from PIL import Image
import numpy as np
from dataclasses import dataclass, field
from typing import List, Dict, Tuple, Optional
from datetime import datetime
import json
@dataclass
class BoundingBox:
x1: int
y1: int
x2: int
y2: int
@property
def width(self) -> int:
return self.x2 - self.x1
@property
def height(self) -> int:
return self.y2 - self.y1
@property
def area(self) -> int:
return self.width * self.height
@property
def center(self) -> Tuple[int, int]:
return ((self.x1 + self.x2) // 2, (self.y1 + self.y2) // 2)
@dataclass
class DetectedDefect:
defect_id: str
defect_type: DefectType
confidence: float
severity: SeverityLevel
bounding_box: BoundingBox
area_sqm: Optional[float] = None
dimensions_mm: Optional[Tuple[float, float]] = None
metadata: Dict = field(default_factory=dict)
@dataclass
class InspectionResult:
inspection_id: str
image_path: str
timestamp: datetime
location: str
element_type: str
defects: List[DetectedDefect]
overall_condition: str
recommended_actions: List[str]
class DefectDetectionModel:
"""Deep learning defect detection with object detection"""
DEFECT_CLASSES = {
1: DefectType.CRACK,
2: DefectType.SPALLING,
3: DefectType.CORROSION,
4: DefectType.HONEYCOMBING,
5: DefectType.EFFLORESCENCE,
6: DefectType.DEFORMATION,
7: DefectType.SURFACE_DAMAGE
}
def __init__(self, model_path: str = None, device: str = 'cpu'):
self.device = torch.device(device)
# Initialize Faster R-CNN
self.model = fasterrcnn_resnet50_fpn(pretrained=True)
# Modify for our classes
num_classes = len(self.DEFECT_CLASSES) + 1 # +1 for background
in_features = self.model.roi_heads.box_predictor.cls_score.in_features
self.model.roi_heads.box_predictor = FastRCNNPredictor(in_features, num_classes)
if model_path:
self.model.load_state_dict(torch.load(model_path, map_location=self.device))
self.model.to(self.device)
self.model.eval()
self.transform = transforms.Compose([
transforms.ToTensor()
])
def detect(self, image_path: str, confidence_threshold: float = 0.5,
pixels_per_mm: float = None) -> List[DetectedDefect]:
"""Detect defects in image"""
image = Image.open(image_path).convert('RGB')
image_tensor = self.transform(image).to(self.device)
with torch.no_grad():
predictions = self.model([image_tensor])
pred = predictions[0]
defects = []
for i in range(len(pred['boxes'])):
score = pred['scores'][i].item()
if score < confidence_threshold:
continue
label = pred['labels'][i].item()
box = pred['boxes'][i].cpu().numpy()
defect_type = self.DEFECT_CLASSES.get(label, DefectType.SURFACE_DAMAGE)
bbox = BoundingBox(
x1=int(box[0]),
y1=int(box[1]),
x2=int(box[2]),
y2=int(box[3])
)
# Calculate dimensions if scale provided
dimensions_mm = None
if pixels_per_mm:
width_mm = bbox.width / pixels_per_mm
height_mm = bbox.height / pixels_per_mm
dimensions_mm = (width_mm, height_mm)
severity = self._classify_severity(defect_type, bbox, image.size)
defects.append(DetectedDefect(
defect_id=f"DEF-{i:04d}",
defect_type=defect_type,
confidence=score,
severity=severity,
bounding_box=bbox,
dimensions_mm=dimensions_mm
))
return defects
def _classify_severity(self, defect_type: DefectType,
bbox: BoundingBox,
image_size: Tuple[int, int]) -> SeverityLevel:
"""Classify defect severity based on type and size"""
image_area = image_size[0] * image_size[1]
defect_ratio = bbox.area / image_area
# Severity thresholds by defect type
thresholds = {
DefectType.CRACK: {'critical': 0.1, 'severe': 0.05, 'moderate': 0.02},
DefectType.SPALLING: {'critical': 0.15, 'severe': 0.08, 'moderate': 0.03},
DefectType.CORROSION: {'critical': 0.2, 'severe': 0.1, 'moderate': 0.05},
DefectType.HONEYCOMBING: {'critical': 0.1, 'severe': 0.05, 'moderate': 0.02},
DefectType.DEFORMATION: {'critical': 0.05, 'severe': 0.02, 'moderate': 0.01}
}
t = thresholds.get(defect_type, {'critical': 0.15, 'severe': 0.08, 'moderate': 0.03})
if defect_ratio >= t['critical']:
return SeverityLevel.CRITICAL
elif defect_ratio >= t['severe']:
return SeverityLevel.SEVERE
elif defect_ratio >= t['moderate']:
return SeverityLevel.MODERATE
else:
return SeverityLevel.MINOR
class FastRCNNPredictor(nn.Module):
"""Custom predictor for Faster R-CNN"""
def __init__(self, in_channels, num_classes):
super().__init__()
self.cls_score = nn.Linear(in_channels, num_classes)
self.bbox_pred = nn.Linear(in_channels, num_classes * 4)
def forward(self, x):
scores = self.cls_score(x)
bbox_deltas = self.bbox_pred(x)
return scores, bbox_deltas
import cv2
import numpy as np
from typing import List, Tuple, Dict
class CrackAnalyzer:
"""Specialized crack detection and measurement"""
def __init__(self):
self.min_crack_length = 10 # pixels
self.min_crack_width = 2 # pixels
def detect_cracks(self, image_path: str,
pixels_per_mm: float = 1.0) -> List[Dict]:
"""Detect and measure cracks in image"""
# Load image
image = cv2.imread(image_path)
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
# Enhance contrast
clahe = cv2.createCLAHE(clipLimit=2.0, tileGridSize=(8, 8))
enhanced = clahe.apply(gray)
# Edge detection
edges = cv2.Canny(enhanced, 50, 150)
# Morphological operations to connect crack segments
kernel = np.ones((3, 3), np.uint8)
dilated = cv2.dilate(edges, kernel, iterations=1)
closed = cv2.morphologyEx(dilated, cv2.MORPH_CLOSE, kernel)
# Find contours
contours, _ = cv2.findContours(closed, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
cracks = []
for i, contour in enumerate(contours):
# Filter by length
arc_length = cv2.arcLength(contour, False)
if arc_length < self.min_crack_length:
continue
# Get bounding box
x, y, w, h = cv2.boundingRect(contour)
# Calculate crack properties
length_px = arc_length
width_px = self._estimate_crack_width(gray, contour)
# Convert to mm
length_mm = length_px / pixels_per_mm
width_mm = width_px / pixels_per_mm
# Classify crack
crack_type = self._classify_crack(length_mm, width_mm, contour)
cracks.append({
'crack_id': f"CRACK-{i:04d}",
'type': crack_type,
'length_mm': length_mm,
'width_mm': width_mm,
'bounding_box': (x, y, x + w, y + h),
'contour': contour.tolist(),
'severity': self._get_crack_severity(width_mm, length_mm),
'orientation': self._get_crack_orientation(contour)
})
return cracks
def _estimate_crack_width(self, gray_image: np.ndarray,
contour: np.ndarray) -> float:
"""Estimate average crack width"""
# Create mask for contour
mask = np.zeros(gray_image.shape, dtype=np.uint8)
cv2.drawContours(mask, [contour], -1, 255, 1)
# Distance transform
dist = cv2.distanceTransform(mask, cv2.DIST_L2, 5)
# Get average distance (half-width)
nonzero = dist[dist > 0]
if len(nonzero) > 0:
return np.mean(nonzero) * 2
return 0
def _classify_crack(self, length_mm: float, width_mm: float,
contour: np.ndarray) -> str:
"""Classify crack type"""
# Fit line to get orientation
[vx, vy, x, y] = cv2.fitLine(contour, cv2.DIST_L2, 0, 0.01, 0.01)
angle = np.arctan2(vy, vx) * 180 / np.pi
if abs(angle) < 20 or abs(angle) > 160:
orientation = "horizontal"
elif 70 < abs(angle) < 110:
orientation = "vertical"
else:
orientation = "diagonal"
# Check for pattern (simplified)
if width_mm > 3:
return "structural_crack"
elif orientation == "horizontal" and length_mm > 100:
return "settlement_crack"
elif orientation == "diagonal":
return "shear_crack"
else:
return "shrinkage_crack"
def _get_crack_severity(self, width_mm: float, length_mm: float) -> str:
"""Determine crack severity based on dimensions"""
# Based on ACI 224R guidelines
if width_mm > 1.0:
return "critical"
elif width_mm > 0.4:
return "severe"
elif width_mm > 0.2:
return "moderate"
else:
return "minor"
def _get_crack_orientation(self, contour: np.ndarray) -> float:
"""Get crack orientation angle"""
[vx, vy, x, y] = cv2.fitLine(contour, cv2.DIST_L2, 0, 0.01, 0.01)
return float(np.arctan2(vy, vx) * 180 / np.pi)
def generate_crack_report(self, cracks: List[Dict]) -> Dict:
"""Generate summary report of detected cracks"""
if not cracks:
return {'message': 'No cracks detected'}
total_length = sum(c['length_mm'] for c in cracks)
max_width = max(c['width_mm'] for c in cracks)
severity_counts = {}
for c in cracks:
sev = c['severity']
severity_counts[sev] = severity_counts.get(sev, 0) + 1
return {
'total_cracks': len(cracks),
'total_length_mm': total_length,
'max_width_mm': max_width,
'avg_width_mm': sum(c['width_mm'] for c in cracks) / len(cracks),
'by_severity': severity_counts,
'by_type': self._group_by_type(cracks),
'most_severe': max(cracks, key=lambda c: c['width_mm'])
}
def _group_by_type(self, cracks: List[Dict]) -> Dict:
"""Group cracks by type"""
grouped = {}
for c in cracks:
t = c['type']
if t not in grouped:
grouped[t] = []
grouped[t].append(c['crack_id'])
return grouped
from datetime import datetime
import pandas as pd
class DefectInspectionSystem:
"""Complete defect inspection and reporting system"""
def __init__(self, detection_model: DefectDetectionModel):
self.model = detection_model
self.crack_analyzer = CrackAnalyzer()
self.inspections: List[InspectionResult] = []
def perform_inspection(self, image_path: str,
location: str,
element_type: str,
pixels_per_mm: float = None) -> InspectionResult:
"""Perform complete inspection on image"""
# Detect defects
defects = self.model.detect(image_path, pixels_per_mm=pixels_per_mm)
# Additional crack analysis for concrete
if element_type.lower() in ['concrete', 'slab', 'wall', 'column', 'beam']:
cracks = self.crack_analyzer.detect_cracks(image_path, pixels_per_mm or 1.0)
# Add detailed crack info to relevant defects
for defect in defects:
if defect.defect_type == DefectType.CRACK:
for crack in cracks:
# Check if crack overlaps with defect bbox
if self._boxes_overlap(defect.bounding_box, crack['bounding_box']):
defect.metadata['crack_details'] = crack
break
# Determine overall condition
overall_condition = self._assess_overall_condition(defects)
# Generate recommendations
recommendations = self._generate_recommendations(defects, element_type)
result = InspectionResult(
inspection_id=f"INS-{datetime.now().strftime('%Y%m%d%H%M%S')}",
image_path=image_path,
timestamp=datetime.now(),
location=location,
element_type=element_type,
defects=defects,
overall_condition=overall_condition,
recommended_actions=recommendations
)
self.inspections.append(result)
return result
def _boxes_overlap(self, box1: BoundingBox, box2: Tuple) -> bool:
"""Check if two bounding boxes overlap"""
x1_1, y1_1, x2_1, y2_1 = box1.x1, box1.y1, box1.x2, box1.y2
x1_2, y1_2, x2_2, y2_2 = box2
return not (x2_1 < x1_2 or x2_2 < x1_1 or y2_1 < y1_2 or y2_2 < y1_1)
def _assess_overall_condition(self, defects: List[DetectedDefect]) -> str:
"""Assess overall structural condition"""
if not defects:
return "Good"
severity_scores = {
SeverityLevel.MINOR: 1,
SeverityLevel.MODERATE: 2,
SeverityLevel.SEVERE: 3,
SeverityLevel.CRITICAL: 4
}
max_severity = max(severity_scores[d.severity] for d in defects)
total_defects = len(defects)
if max_severity >= 4 or total_defects > 10:
return "Critical - Immediate attention required"
elif max_severity >= 3 or total_defects > 5:
return "Poor - Repairs needed"
elif max_severity >= 2 or total_defects > 2:
return "Fair - Monitor and plan repairs"
else:
return "Good - Minor issues only"
def _generate_recommendations(self, defects: List[DetectedDefect],
element_type: str) -> List[str]:
"""Generate repair recommendations"""
recommendations = []
# Group defects by type
defect_groups = {}
for d in defects:
t = d.defect_type
if t not in defect_groups:
defect_groups[t] = []
defect_groups[t].append(d)
# Generate recommendations by defect type
for defect_type, group in defect_groups.items():
max_severity = max(d.severity for d in group)
if defect_type == DefectType.CRACK:
if max_severity in [SeverityLevel.CRITICAL, SeverityLevel.SEVERE]:
recommendations.append(
f"Structural engineer assessment required for {len(group)} crack(s). "
f"Consider epoxy injection or structural repair."
)
else:
recommendations.append(
f"Seal {len(group)} minor crack(s) with appropriate sealant."
)
elif defect_type == DefectType.SPALLING:
recommendations.append(
f"Remove loose concrete and apply repair mortar to {len(group)} spalling area(s). "
f"Check reinforcement for corrosion."
)
elif defect_type == DefectType.CORROSION:
recommendations.append(
f"Treat {len(group)} corrosion area(s). Clean rust, apply rust converter, "
f"and protective coating."
)
elif defect_type == DefectType.HONEYCOMBING:
recommendations.append(
f"Fill {len(group)} honeycomb area(s) with non-shrink grout. "
f"Investigate concrete placement procedures."
)
elif defect_type == DefectType.EFFLORESCENCE:
recommendations.append(
f"Clean efflorescence from {len(group)} area(s). "
f"Investigate and address moisture source."
)
if not recommendations:
recommendations.append("Continue regular inspection schedule.")
return recommendations
def export_inspection_report(self, inspection_id: str,
output_path: str) -> str:
"""Export inspection report to Excel"""
inspection = next(
(i for i in self.inspections if i.inspection_id == inspection_id),
None
)
if not inspection:
raise ValueError(f"Inspection {inspection_id} not found")
with pd.ExcelWriter(output_path, engine='openpyxl') as writer:
# Summary
summary = pd.DataFrame([{
'Inspection ID': inspection.inspection_id,
'Date': inspection.timestamp.strftime('%Y-%m-%d %H:%M'),
'Location': inspection.location,
'Element Type': inspection.element_type,
'Overall Condition': inspection.overall_condition,
'Total Defects': len(inspection.defects),
'Image': inspection.image_path
}])
summary.to_excel(writer, sheet_name='Summary', index=False)
# Defects
if inspection.defects:
defect_data = [{
'Defect ID': d.defect_id,
'Type': d.defect_type.value,
'Severity': d.severity.value,
'Confidence': f"{d.confidence:.1%}",
'Location (x,y)': f"({d.bounding_box.x1}, {d.bounding_box.y1})",
'Size (w×h)': f"{d.bounding_box.width}×{d.bounding_box.height}",
'Dimensions (mm)': d.dimensions_mm if d.dimensions_mm else 'N/A'
} for d in inspection.defects]
pd.DataFrame(defect_data).to_excel(writer, sheet_name='Defects', index=False)
# Recommendations
rec_data = [{'#': i+1, 'Recommendation': r}
for i, r in enumerate(inspection.recommended_actions)]
pd.DataFrame(rec_data).to_excel(writer, sheet_name='Recommendations', index=False)
return output_path
def get_defect_statistics(self, start_date: datetime = None,
end_date: datetime = None) -> Dict:
"""Get defect statistics across inspections"""
filtered = self.inspections
if start_date:
filtered = [i for i in filtered if i.timestamp >= start_date]
if end_date:
filtered = [i for i in filtered if i.timestamp <= end_date]
all_defects = []
for inspection in filtered:
all_defects.extend(inspection.defects)
if not all_defects:
return {'message': 'No defects found in period'}
# Statistics
by_type = {}
by_severity = {}
for d in all_defects:
t = d.defect_type.value
s = d.severity.value
by_type[t] = by_type.get(t, 0) + 1
by_severity[s] = by_severity.get(s, 0) + 1
return {
'period': {
'start': start_date.isoformat() if start_date else 'all',
'end': end_date.isoformat() if end_date else 'all'
},
'total_inspections': len(filtered),
'total_defects': len(all_defects),
'by_type': by_type,
'by_severity': by_severity,
'avg_defects_per_inspection': len(all_defects) / len(filtered) if filtered else 0
}
import torch
from torch.utils.data import Dataset, DataLoader
from torchvision import transforms
import os
from PIL import Image
class DefectDataset(Dataset):
"""Dataset for training defect detection model"""
def __init__(self, root_dir: str, annotations_file: str, transform=None):
self.root_dir = root_dir
self.annotations = self._load_annotations(annotations_file)
self.transform = transform or transforms.Compose([
transforms.Resize((800, 800)),
transforms.ToTensor()
])
def _load_annotations(self, path: str) -> List[Dict]:
"""Load COCO-format annotations"""
import json
with open(path, 'r') as f:
data = json.load(f)
return data['annotations']
def __len__(self):
return len(self.annotations)
def __getitem__(self, idx):
ann = self.annotations[idx]
image_path = os.path.join(self.root_dir, ann['image_file'])
image = Image.open(image_path).convert('RGB')
if self.transform:
image = self.transform(image)
# Prepare target
boxes = torch.tensor(ann['boxes'], dtype=torch.float32)
labels = torch.tensor(ann['labels'], dtype=torch.int64)
target = {
'boxes': boxes,
'labels': labels
}
return image, target
def train_defect_model(train_dataset: DefectDataset,
val_dataset: DefectDataset,
num_epochs: int = 10,
batch_size: int = 4,
learning_rate: float = 0.005):
"""Train defect detection model"""
device = torch.device('cuda' if torch.cuda.is_available() else 'cpu')
# Initialize model
model = fasterrcnn_resnet50_fpn(pretrained=True)
num_classes = 8 # 7 defect types + background
in_features = model.roi_heads.box_predictor.cls_score.in_features
model.roi_heads.box_predictor = FastRCNNPredictor(in_features, num_classes)
model.to(device)
# Data loaders
train_loader = DataLoader(train_dataset, batch_size=batch_size, shuffle=True,
collate_fn=lambda x: tuple(zip(*x)))
val_loader = DataLoader(val_dataset, batch_size=batch_size, shuffle=False,
collate_fn=lambda x: tuple(zip(*x)))
# Optimizer
optimizer = torch.optim.SGD(model.parameters(), lr=learning_rate,
momentum=0.9, weight_decay=0.0005)
# Training loop
for epoch in range(num_epochs):
model.train()
total_loss = 0
for images, targets in train_loader:
images = [img.to(device) for img in images]
targets = [{k: v.to(device) for k, v in t.items()} for t in targets]
loss_dict = model(images, targets)
losses = sum(loss for loss in loss_dict.values())
optimizer.zero_grad()
losses.backward()
optimizer.step()
total_loss += losses.item()
avg_loss = total_loss / len(train_loader)
print(f"Epoch {epoch+1}/{num_epochs}, Loss: {avg_loss:.4f}")
return model
| Defect Type | Detection Method | Typical Severity |
|---|---|---|
| Crack | Edge detection + CNN | Varies by width |
| Spalling | Object detection | Moderate-Severe |
| Corrosion | Color + texture analysis | Moderate-Critical |
| Honeycombing | Object detection | Severe |
| Efflorescence | Color analysis | Minor-Moderate |
| Width (mm) | Condition | Exposure |
|---|---|---|
| < 0.1 | Acceptable | Any |
| 0.1 - 0.2 | Acceptable | Dry |
| 0.2 - 0.4 | Repair recommended | Humid |
| > 0.4 | Repair required | Any |
| > 1.0 | Structural concern | Any |
progress-monitoring-cv for construction progress analysissafety-compliance-checker for safety defect integrationbim-validation-pipeline for model-based quality control