Spanish researchers claim that they can avoid the use of ground control to register mobile lidar data scans using sign reflectivity. Here is a portion of their abstract.
Mobile light detection and ranging (LiDAR) is currently one of the most used instruments in road inspections to collect geometric and radiometric data. Different strips of the same area are common and bring problems in data registration related to the inaccuracies of global navigation satellite systems.
This paper shows a methodology for automatic and robust data registration. It is based on segmentation of highly reflective data (i.e., road signs) and avoids the use of control points manually marked, typically used in the traditional techniques. The data set must be acquired under favorable climatological conditions. Root-mean-square errors in registration show values around 2 cm, while if the high-reflectivity segmentation is not used values higher than 8 cm are obtained.
Sounds promising, but what about rural areas where there are very few signs?