VFXhack

Just finished this little write-up for the work that I did for the series finale of Jericho. The whole show was a blast to work on and many talented people poured a lot of hours and hard work into this baby. Hope you enjoy.

The Mission

Jericho tells story of small town struggling to survive in the landscape of a post apocalyptic America. In the final episode of the show’s second season, the creators wanted to give the fans something special. The VFX team worked with production to give the audience a glimpse at what the rebuilt capitol of drastically altered capital city would look like and a stunning climax that pitted the shows main character, Jake against the might of the Cheyenne air force in a dramatic aerial battle. The challenge to the VFX team was to make these important story points completely realistic. The VFX was not to detract from the story but enhance it by delivering seamless effects.

The Approach

The reveal of the capitol building under construction in the new Capitol of Cheyenne was not to be your run of the mill matte paining. The story called for a city under drastic expansion and rapid construction. Reference photography of the current city of Cheyenne could be used as a base, but new buildings as well as construction cranes, vehicles, pedestrians and construction workers would have to be added after the fact. The show’s most difficult sequence came in the form of the final aerial battle. Knowing that it would be impossible to tell the story through the use of stock or custom shot aerial photography, the visual effects team settled on a mostly CG approach. The scene called for a variety of different aircraft and many camera angles to cover the action. There was dialog between Jake and the pilots of both the Cheyenne and later the Texas planes, so plates of the actors would need to shot on green screen and combined with the CG planes and backgrounds. At one point in the battle, two of the planes are blown out of the sky by air-to-air missiles. Knowing that a photo-real explosion would be difficult to achieve by using CG alone, it was decided that scale models were to be built based on the CG planes and animatics and blown up using traditional special effects methods. Later these elements would be composited with the CG planes.

Shot Elements

Once the methodology was decided upon, the wheels were set in motion to gather all the practical elements that needed to be shot. These fell into several categories. First HDRI 360° photography of the first unit location for the reveal of the Cheyenne Capital. The HDRIs captured on set were used as a basis for the background buildings and were used as a lighting basis for the 3d elements in the matte painting. The raw photos for the panoramas composed of 38 different camera positions with nine exposures for each position.

The final shot was to be from the perspective of a hotel room 12 stories above the street so the HDRIs were taken from atop a 40 foot platform. Many elements were also gathered to create the feeling of activity in the scene. A camera was again placed on a platform to match the high vantage point of the final shot. Many passes of ground activities of civilians, military, construction workers and their vehicles were taken. To create the illusion of more extras costumes were changed multiple times and movement patterns were varied from take to take.

The aerial battle plates consisted of two main parts, the green screen photography of the actors for inside the plane cockpits and the explosion plates of the jets. The green screens were filmed on a high definition video camera with Jake (the main character) sitting inside a cut out portion of a real plane cockpit that was a close match to the model that was shot on first unit.

The glass on the cockpit windows was left in on most shots so any of the actors reflections could be lifted and used in the final composite. The pilots of the F-15 and F-16 fighter jets were also filmed against green with the intention of modeling a digital cockpit for those shots. Pivotal to the success of the green screen shoot was the animatic that was created by the VFX team and cut by Jericho editorial. This animatic was worked on with the creators of the show so that all the major action of the scene was represented in a rough 3d form. This gave the actors an excellent idea of what was happening in the scene and helped them achieve the proper eye-lines and emotional impact rather than just acting against a void.

When it came to shooting the plane explosions, great care was put into the planning and preparation of the shoot. The animatic was again used to determine the detail and placement of the plane models. A VFX shoot team was assembled consisting of a DP and his crew, a pyrotechnics team and few model makers and painters. The plane that was to be destroyed was an F-15 fighter and the fiberglass shell from a remote control plane kit was used as the base model. Four shells with a wingspan of a little over 5 feet were prepped and painted to match the markings and textures of the CG models exactly. On the day of the shoot the model planes were packed with explosive and lifted onto a 30 foot armature. Three cameras were placed at different heights that lined up to several shots in the animatic, a live switcher was used to line up the video feeds from the camera to the animatics. The three cameras rolled simultaneously on each explosion at 120 fps. The higher frame rate was used to compensate for the smaller scale of the models. All together 3 models were blown up for the shoot.

3d Techniques

Before any modeling or texturing of the 3d assets was started, an exhausting search for reference was begun. The new Capitol building under construction in Cheyenne began as model from a stock library. Pieces of the substructure and framing of the building were then created using the stock model as a guide. Then pieces of the original model were stripped away to reveal the unfinished skeleton. The construction cranes for the 3d matte painting were modeled using photo reference, along with other street props. The hero buildings were generic models that were placed in the scene with projected textures of the building matte paintings used to enhance the details.

The aerial battle sequence started with the creation of a detailed animatic which served as a master template for animation, camera movement and lighting. After editing, the stand-in planes were replaced with hi-resolution versions. Careful attention was taken to make sure that the planes were authentic. The Cessna Citation that Jake flies in the scene not only had to look real in the CG shots but be a perfect match to an aircraft shot by production taxiing on the runway in the previous scenes. Many photographs were taken of the markings and logos on the plane to make sure the match was seamless. The F-15s and F-16s also had to be extremely detailed as they were seen close-up from nearly every angle. The cockpit and pilot seat of each plane also had to be rendered and textured to accommodate the green screen footage of the pilots. A lot of photographic reference both still and moving was used ensure that the shading and behavior of light across the planes surface was highly realistic. The flags and markings of the new Air Force in the Jericho story line also had to be created and applied to the planes.

2d Techniques

Many of the compositing shots in this show made use of the tight integration between the 3d and 2d working environments. For the Cheyenne Capitol shot, a 3d track was created for the scene. 3d elements were rendered with basic lighting using the track data, then the same track data was used in the compositing software. This allowed the compositor to place elements in the scene on 3d cards and have them track perfectly with the rendered elements. It gave the artists the flexibility to paint detail directly onto the parts of the image that needed it without having to request another element to be rendered in 3d. This technique was used to great effect when building the sky environment for the aerial battle scene. The shot began with the camera created during the 3d animation process. A basic sky dome and rough 3d landscape was added to each shot and rendered. The compositors than painted over the rough landscape using stock aerial photography to add detail while maintaining the basic lighting and depth from the 3d render. The 3d camera move was also brought into compositing for the addition of photographic cloud elements placed at different distances from the camera to create the illusion of volume and depth.

To create the photographic look of the planes, a multi-pass pipeline was used. Each component of the 3d render (reflection, color, specularity, etc.) was rendered as a separate element and combined in composite to achieve the final look. Using this method, the compositors had an extreme amount of control in how the subtle lighting effects played across the surface of the ships. Perhaps the most convincing of composite effects done for the show was the explosion of the two F-15s. Since the line-up of the shot footage of the planes exploding from the VFX shoot lined up perfectly, a quick dissolve from the CG plane to model footage was all that was needed. In fact the explosion proved so effective that close-up shots of the explosion from the VFX shoot were added to the edit towards the end of the editing process. The clean-up of the explosions involved removing the rig from each shot and pulling keys from the sky behind the model.

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Conclusion

It is rare to get to work on a Visual Effects sequence for a television show that i so pivotal to the storytelling of the episode. In the case of Jericho Episode 207, the story and visual effects were intertwined in such a way that one could not have happened without the other. Because of the tight integration between story and effects, all of the work done on the show had to be seamless. Anything out of place would distract the viewer from the emotional impact of the action. An imaginative combination of techniques both old and new were used to create scenes with an amazing degree of authenticity. The VFX team for this show worked tirelessly to make sure that the fans of the Jericho series would not be disappointed.

This entry was posted on Thursday, May 29th, 2008 at 8:16 pm and is filed under 3d, compositing, howto, techniques, tips, vfx, visual effects. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.