An indoor surveying apparatus comprises a light source, a color imaging system, a memory storing calibration coefficients, and a computing device for determining coordinates of 3D intersection points of the emitted light with objects using calibration coefficients and images captured by the imaging system. The power transmission mechanism includes a first power transmission unit interlocked with the drive unit, and a second power transmission unit interlocked with the working unit and capable of being detachably connected to the first power transmission unit. The method further includes formulating at least one subsetting rule based on the profile; and selecting a subset of data records from the plurality of data records based on the at least one subsetting rule. The transient current carrying path presents a substantially open circuit during normal operation. Unlike prior art vapor barriers, the present invention provides membranes having good crack-bridging and non-water-absorption characteristics.