For the opening of Jyosaien (城彩苑) in 2011, a Tokyo company with the cool name of Toppan Insatsu (凸版印刷 - “relief printing”) produced a virtual reality presentation of Kumamoto Castle called “Wakuwakuza” (湧々座), which is still on display there. Later, Kumamoto University Professor Koutaki Gou (上瀧剛助教 - another cool name) realized that this data could be useful for reconstruction. Toppan has provided some 40,000 highly detailed images of the pre-quake castle, and Prof. Koutaki has created a computer program that matches each stone to its original position. The method is still time-consuming as each stone awaiting restoration must be imaged for its location to be sourced (improvements are under investigation), but it is an important step which somehow makes this tremendous endeavor seem possible. - William
More about Wakuwakuza can be found here: http://9tabi.net/kumamoto/kumamoto00/kumamoto080.html and the Kumanichi article here: https://this.kiji.is/242830341186422269?c=92619697908483575
