My Weird Phone Photo Collection

As a guess I would say that most people's phones are full of photos of various family members interspersed with nice scenic views. While mine does have the scenic pics on there the rest seems to mostly be the inside of walls or as in this case under the floorboards - all in the name of fining where wires go.

Here I'm looking for the red marker at the end to see how close to the joist a spotlight would be if I cut at this point.