When you have the requirement to capture huge amounts of detail in inaccessible locations, then laser scanning is your answer.
The least intrusive method of all, data can be captured from a position of safety, without the requirement for complicated isolations/possessions etc (depending on site constraints an scope)
Other benefits include the avoidance in assumptions and generalisations with the captured data as you will always have the original data set to refer back to.
Due to advances in technology, point clouds are now becoming hugely accurate with 3mm tolerances now the industry standard.
All registered data can be exported in a variety of formats and manageable chunks. General formats requested are IMP, PTX, PTS, POD files (Pointools)