The work you dont see! In the shot with the aborigines there is a tiny flock of seagulls. This is not a collection of blocks in the distance but a lovingly created set or modelled. textured rigged and animated flock of seagulls all animated to follow a distinct path. In the compositing stage the birds got smaller and smaller until they do look like blocks in the sky.
The other major challenge was to create a mongol horde. I built textured and rigged seven mongol soldiers, on seven different horses. They all had different weapons and flags. Each one was rigged an animated by me and then exported to Houdini where they were turned into a crowd of thousands or indeed a horde.
National Geographic