A Stealthy and Seamless War Horse
War Horse required a wide range of VFX work from Framestore (with previs supplied by The Third Floor), ranging from simple paint cleanups to full digital stunt horses. From the outset, the overriding goal was to be stealthy and seamless, ensuring that the viewer had no idea they had ever touched a shot. There were approximately 210 shots in all.
"Early in previs development Steven had decided to avoid showing graphic shots of riders and horses being gunned down leaving the audience to make their own connection between the earlier mounted charging cavalry and the now eerie shots of riderless horses jumping over the German gun positions," explains Ben Morris, Framestore's VFX supervisor and the onset supervisor. "In order to safely shoot this action [when the British Cavalry is gunned down by the Germans], we worked with the stunt team and horse trainers, devising a system of horse lanes made from posts and tape that looked, to the free-running horses, like electrical fencing. While it proved a highly effective deterrent to horses straying off course, it required many weeks of complex frame-by-frame paint work for the five to six shots in the sequence led by Marc Rice and Rob Garner. Another obvious safety factor was that the machine guns could not be fired during shots including real horses, so we added practical smoke and muzzle flashes using 2D elements we shot at the end of the schedule."
For the tank chase of Joey, they decided to use a CG horse with such a tight schedule and after the real horses proved unreliable. "Starting from a synchronized, multi-camera photogrammetry session and flat lit texture shoot, Scott Eaton built our CG horse model and Michael Borhi painted a texture set based on a combination of the two 'hero' horse actors playing Joey," Morris explains. "The complex cannon harness and tack worn by Joey was also modeled from photographic reference. The horse was then rigged by Matthieu Goutte and Mauro Giacomazzo in preparation for animation in Maya. A number of in-house tools were used to setup the underlying skin/muscle dynamics. Long hair and short fur was groomed on the model by Rachel Williams and it was then setup for lighting and rendering by Stephan Putz using our in-house PRMan shader library and fur system. Stuart Ellis animated the two shots involving the tank jump and Carl Bianco created the secondary simulation rigs for Joey's harnesses and tack."
Behind German lines and under a barrage attack from British forces we rejoin Joey in one of the most complex VFX shots in the film."The shot became known as the Trench Jump for obvious reasons and involved three separate real horse plates and two sections of CG horse animation," Morris elaborates."Starting with the Third Floor previs of the entire Joey in No Man's Land sequence, we immediately recognized that the action in the first shot of a horse failing to jump a trench, crashing into the far wall, falling to the ground and getting up to run away would require our CG horse in some form or other.