BigStar shot the slow motion footage of the raven on green screen using a Phantom camera, then composited the bird into its various environments. 

"HBO’s idea was to juxtapose this ancient character into the modern world in a way that felt organic and not forced,” explains Norton. “Representing the entire globe though our series of environments, we chose different types of architecture, from classic structures such as cathedrals and statuaries, to modern skyscrapers. Here, the challenge was compositing the raven with the right orientation to make it look realistic and feel seamless transitioning between scenes.”

BigStar constantly considered visual cues such as "weather" (warm and cold mornings) and “time of day,” evoking dusk and dawn to set the tone for each scene.

“Time of day is ultimately what holds these shots together more so than anything else,” Norton says.” “One shot, for example, was inspired by the Manhattan sunset, that magical hour on the Westside when thousands of windows capture the sunlight.”

Intrinsic to the visual narrative also included conveying a sense of population without actually showing people.

"Keeping the viewer focused on the raven while conveying an eerie sense of stillness in places you’d normally see life teeming was crucial,” Norton elaborates. 

The promo’s music was ultimately the x-factor tying it all together. With a library of music that HBO provided from previous seasons, BigStar sought a track that would inform the emotion and concept behind the promo.

“The track we chose, ‘Rains over Castamere,’ has a beautiful melody and poetic prose,” remarks Norton. “The minute we put it to picture, we knew it was the right choice. It really helps drive the narrative and, above all, defines the whole piece as distinctively ‘Game of Thrones.’”

“The collaborative process with HBO was quite unique and inspiring,” concludes Katie Tricot, Executive Producer, BigStar. “With a great story and a solid concept, we embraced the opportunity to visually execute it all.”

Source: BigStar