Only a small section of the ground floor of the shop front is built by production so the remainder of the store building has to be added as CGI. With the camera almost always in motion the 3D tracking of the set and the extraction of accurate lens distortion data becomes a priority to enable the CG and live action set to join seamlessly.
DNEG has spent many years perfecting the use of LIDAR (which records the precise dimensions of the location set using a huge number of measurements taken by a revolving Laser) and Lens grids (that determine how, for a specific lens, the image recorded is distorted with respect to it’s position on screen) within it’s tracking pipeline to make this process both accurate and fast. It proved invaluable in this instance and let production have an un-paralleled freedom to shoot with moving cameras throughout the series.
Aside from the store itself the team had to re-create Oxford Street with all its life and colour in 1914. Using historical photographs and maps the rest of the street was modelled and textured before being populated with CG cars and buses. Additional people were added using supporting artists specifically shot by DNEG TV on greenscreen to match the various camera angles used during the production.