Google established designated scanning centers to which books were transported by trucks. The stations could digitize at the rate of 1,000 pages per hour. The books were placed in a custom-built mechanical cradle that adjusted the book spine in place for the scanning. An array of lights and optical instruments was used – including four cameras, two directed at each half of the book, and a range finder LIDAR that overlaid a three-dimensional laser grid on the book's surface to capture the curvature of the paper. A human operator would turn the pages by hand and operate the cameras through a foot pedal. The system was made efficient since there was no need to flatten the book pages or align them perfectly. The crude images were worked upon by de-warping algorithms that used the LIDAR data to process them. Optical character recognition (OCR) software was developed to process the raw images to text. Algorithms were also created to extract page numbers, footnotes, illustrations and diagrams.