I suppose it depends on the crack sizes, small ones will be hard to detect unless high res image data is used.
Most AI vision stuff in real time is around 300x300 pixels.
Could a florescence spray help, it would tend to collect in the cracks and shows up under UV LED spotlights.
Very easy to detect that, pretty much a standard practice.
Spray cans on drones next to walls, "Officer, I am just checking for cracks"
UV graffiti? A new art form?
Those Highlighter pens are pretty good, cut them open and squeeze out the goop into water
Yellow ones are best
I have used Ximea Hyperspectal USB cameras with Pi's but not for fluorescence, yet.
I'm dancing on Rainbows.
Raspberries are not Apples or Oranges