"Daily, for about seven months, I found myself on a plane, train, taxi or driving myself between these four cities, often feeling like I was in a movie myself. With teething problems of small companies trying to grow, comes both frustration but also huge excitement, as artists realized that what they were doing was an important part of a much bigger picture. And, after about 800 shots, it's amazing how many in your face vfx shots there are, but equally incredible to see how many go unnoticed, the seamless invisible shots, which contribute greatly in making Ninja Assassin as visually slick as it is."

Blood simulation work was initially led by Pixomondo (done with RealFlow), and then also created at Trixter and Ghost FX using references from anime. The Pixomondo work was so good, in fact, that the simulations were used to generate libraries as the shot count grew higher.

"There's a lot of inspiration we took from anime and, particularly, Ninja Scroll, which we sent out as a reference to all of the vendors," Glass continues. "And it's got these super stylized battles in the forest, which is one of James' favorites. The clothes get torn to shreds and the blood travels in sheets that are very graphic and we designed it to have that feel but incorporating a physicality that you could almost believe except for the amount."

With about 7 liters of flying CG blood per ninja, Pixomondo definitely had its hands full.

Matte paintings were also essential, such as the cityscape provided by Pixomondo during the rooftop fight.

"Our work started with a huge matte painting for the preparation of the shooting in Berlin," recalls Bjørn Mayer, vfx supervisor at Pixomondo. "The 125k translite matte painting was wrapped around the set for the rooftop sequence after Raizo's first kill. The cityscape painting was printed 90m x 10m and lit from behind to serve as the environment for the rooftop fighting sequence.

"Together with Chas Jarrett, I was set-supervising 1st unit for the whole shooting starting in June 2008 for seven weeks. Early after principal photography, we received first plates to start with R&D on the blood squirts. Pixomondo worked overall on 185 shots that included a lot of blood and flying limbs but also all set extensions and matte paintings as well as the animation of Raizo's favorite chain weapon for some sequences.

"Our most complex shots were the head slicing sequence in the tattoo parlor in the beginning of the movie and the slow death of Raizo's nemesis. Although a lot of blood reference and blood elements were shot in front of greenscreen, we used none of them in our shots due to interaction with blood and other elements like jaws, heads, necks, hands, arms and much more. I think we were most successful with our blood simulations at the point when Dan asked us to reduce realism again because the MPAA would rate the movie NC-17, which was not intended by the studio.

"James had very special expectations for blood flying in the air, which were sometimes hard to meet because we had to bend a few laws of physics to match the shapes he had in mind. With the very dedicated work of our fx team, we were able to get all the arcs, discs and spirals of blood out of every limb or head flying in any direction as desired."

Bill Desowitz is senior editor of AWN & VFXWorld.