Case Study · Model Training & Fine-Tuning

Custom Computer Vision Model for Vehicle Damage Inspection

A custom-trained detection model that finds and grades dents, scratches and panel damage from walk-around photos, so trade-in inspections are faster, more consistent and easier to defend with customers.

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Client
Used-vehicle and trade-in operation
Industry
Automotive
Delivers
Consistent, photo-based damage grading

The problem

Trade-in and used-vehicle inspections depend on the individual inspector. Two people can grade the same car differently, reconditioning estimates vary, and customers dispute valuations that aren't backed by clear evidence.

How the model was trained

Data collection

Gather walk-around photos from past inspections across vehicle types, colours, lighting and weather.

Annotation

Label damage type (dent, scratch, crack, chip, paint mismatch), panel location and severity, using an annotation guide agreed with senior inspectors.

Transfer learning

Start from a pretrained detection and segmentation backbone and train it on the labelled automotive data.

Robustness

Augment for reflections, glare, dirt and camera angles, and rebalance so rare damage types are still learned reliably.

Evaluation

Measure mean average precision (mAP) by damage type, recall by panel, and agreement with a panel of experienced inspectors, and review where the model and experts disagree.

Deployment

Export an optimised, quantised model that runs in the inspection app on the device. Results flow into the dealer management system with an annotated photo report.

Feedback loop

Inspector corrections are captured and added to the training set, so the model improves with every inspection.

KPIs we design for

Inspection time per vehicle
Guided capture and automatic detection
Grading consistency
One standard across inspectors and sites
Reconditioning estimates
Built from detected damage, not memory
Valuation disputes
Photo evidence for every finding

Technology

PyTorchYOLO / Mask R-CNN-class modelsCVAT / Label StudioONNX RuntimeFastAPIMobile inspection app

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