Changing Faces
A very resourceful character, Bob is able to transform his appearance into any other likeness. This particular effect is achieved by continuing Bob’s fire nature. He burns away the old self like paper, revealing the new character underneath. “We wanted to have an effect that looked like paper turning to ash, or a burning cigarette,” Cranford explains. “We knew that this effect would be reoccurring quite often, throughout the series, and we didn’t want to hinder the extremely tight six day filming production schedule by putting up a green screen each time for this effect. So, we decided to shoot with locked off cameras. Technically, we would shoot the first actor while filming with a DV camera that was supported by a video switcher that director of photography Alwyn Kumst carried. We would then remove actor #1, replace him with actor #2, line the body up with the switcher and record. Then, artist Zac Campbell made selections that grow while following the contours of the actor’s body. These are then filled to reveal the other actor underneath. As the effect grows, we create a heat distortion and crumple the first body to give it a decaying look as it dies away. The advantage of this technique is that two people generally don’t line up perfectly, even with the use of a switcher. We then painstakingly paint the burning glow over the two people frame-by-frame. This is then enhanced by a ‘God’s ray’ element to give Bob his ethereal quality.”

Keyframe did use greenscreen to turn a live-action character into a full-on 3D werewolf. The actress was replaced with a werewolf model built in Cinema 4D and then refined in ZBrush.

In one of the later episodes, Keyframe was faced with a tough challenge: turning a live-action character into a full-on 3D werewolf. The first step in creating the transformation was to shoot the actress on green screen with a locked off camera. She then stepped out and the crew removed the greenscreen to grab the plate. The green screen was set up directly on stage to take advantage of the actual light from the set, thus allowing for a better composite later. The werewolf model was built in Cinema 4D by Belgrave, and then refined in ZBrush. Normal maps were created from the model to use on a lower resolution version, once converted to 3ds Max.

Texture mapping was created from the same info. Textures for the werewolf were gathered from the practical puppet that was used for some silhouette shots. “We also went as far as to photograph a large dog, especially the head as reference and for additional textures,” Cranford recalls. “Hair was added to the model using 3ds Max standard plug-ins. Our 3ds Max rigger, Paul Neale, created a swap character rig, so that we could quickly animate the bones, then swap that out for the high- resolution werewolf, once we were ready to articulate the face. We originally planned on using morph targets for the face, but decided a face rig would give us a broader facial range. The last stage was to match move the werewolf to the actress’ motion, and light it appropriately. To create the transition between the two characters, artist Simon Park used Combustion 4 morph tools. Once blended properly, it was composited in the background plate.”

The same process was used to create the 3D demons that often confront Dresden. The main difference was that demons were created via CG face replacements, while the werewolves were entirely CG. “The faces are matched in 3ds Max with a loose ‘eyeball’ track,” Cranford notes. “At this point, we are mainly concerned with the rotation, so we delete the position keys. We bring the rotation tracked head into Combustion, and use its tracker.”

Keyframe is used to last minute vfx effects requests and are ready to tackle anything on short notice. Each week the script introduces a whole new set of challenges in terms of characters and effects. Above, Bob passes through a wall.

Challenges on a Weekly Basis
Some of the more demanding shots involve complex 3D tracking. The network requested one shot, in particular, after the entire show had been filmed. It required adding a set of 3D wings to a raven man character. “The performer was behind glass doors with a lot of reflections,” Green says. “Also, the shot was not locked off, and another character overlaps the effect. Did I mention that the glass had wire mesh in it? It took a week to do, but we were very proud of it afterwards!”

The idea was to have wings and feathers morph back into appropriate body positions on the were-raven character until he was human again. The plate was never intended to be a CG shot. “What we received was a plate that was moving, out of focus in the foreground, and the raven man character that was semi-silhouetted behind a security (meshed) glass with reflections,” Cranford adds. “We rigged the wings with all the lead feathers attached to the skin of the mesh. That way, the base mesh deformed with the skeleton, but the feathers would fan out nicely. These were then animated and tracked to the actor. Combustion was then used to morph and color-match the pieces onto the body. The glass had as much reflection and mesh removed as we could. Then, we replaced it with our own reflections and newly tracked mesh. Lastly, the foreground character was rotoscoped out. One week later, and voilá! Two glorious seconds of raven man transformation!”

Such last minute calls happen more often than not on a television show, and visual effects vendor have to be ready to tackle just about anything on short notice. “Besides time, our main issue with the show is the unknown,” Green concludes. “Each script introduces a whole new set of challenges in terms of characters and effects. Besides the signature effects that are in almost every episode, each new script introduces new vfx concepts. Although this presents challenges, it also keeps the artists excited about the show!”

Alain Bielik is the founder and editor of renowned effects magazine S.F.X, published in France since 1991. He also contributes to various French publications and occasionally to Cinefex. In 2004, he organized a major special effects exhibition at the Musée International de la Miniature in Lyon, France.