Point cloud of a dent in glossy car paint

What makes it hard

White glossy automotive paint is a typical specular surface. A projected pattern does not scatter back to the camera. It reflects away by the law of reflection, and highlight regions saturate the sensor. Body panel inspection therefore relied for a long time on human eyes and hands, or on developer spray. Developer spray requires cleaning after the inspection.

Dent detection is harder still. The target is not an absolute dimension but a subtle break in surface continuity. That needs dense depth across the whole region, not a few sample points.

What we measured

This is a complete capture of a body side panel. It covers the door, wheel arch and mirror. 786,432 raw points. About 11% of them were invalid depth pixels with no return. After we removed these pixels and the statistical outliers, about 670,000 points remain.

The dent in the middle of the door is clearly visible in the cloud. No annotation marks it. The break in surface continuity itself shows it.