Three historic sources were available for the reconstruction project:
- original plans by architect George
- Bähr, C19 and C20 measurement
- plans - historic photographs
- ruin pieces of the destroyed church,
- salvaged pieces

First analyses of those sources showed the complexity of the geometry of Frauenkirche. Problems arise due to the non-calibrated ell-based system of units that was in common use during the construction of Frauenkirche and existing but not dimensioned plans. Multi-arched surfaces of many vaults and the dome springer (the roof section that swings from the square ground plan to the rising external walls of the main dome), sub-arches, wall disks and vaults located on top of and crossing each other as well as interpenetrating rooms require 3-D design.