"The matte painting would virtually 'stick' to the 3D model"

"When the chunks were hit by Blaster, they would carry the texture with them" click image to see full size

"Traditionally people use 2D mattes to integrate CG with footage, but in this case, neither the fire or the building could be matted this way" click image to see full size

Texturing: Because the model was made of literally thousands of individual groups, conventional texture mapping was not an option. In fact, nothing in the scene was textured by any standard means. Instead, the matte painting (described earlier) was projected onto the geometry. Basically this means that the matte painting would virtually 'stick' to the 3D model. And even when the chunks were hit by Blaster, they would carry the texture with them. Multiple layers of the matte painting were used to texture separate layers of the scene. In the end there were 6 layers: sky, background buildings, sky scraper, main building, forground wall.

Smoke & Fire: When the explosion was originally composed, it was only dealing with fire. When the time came to create the smoke, there were a couple options: 2D particles, 3D particles, or footage. All of these seemed to be daunting tasks. However, I discovered the Artbeats Cloud Tank series. With a combination of 2D particles and the cloud tank footage, I managed to tightly integrate smoke with the explosive fire element. This was done by choosing smoke clips that had similar motion to that of the explosions. The footage was heavily manipulated using time stretching and many filter effects to achieve the integration. FE Particle World was also used to add a finer layer of smoke. Perhaps the most elusive and difficult aspect was creating the transition from fire to smoke; smoke does not 'fade on'.

Compositing: With the smoke and fire complete and the building animated, there still remained the marrying of the two. Traditionally people use 2D mattes to integrate CG with footage, but in this case, neither the fire or the building could be matted this way. Instead I needed some sort of 3D representation that would interact with the building. To accomplish this, I used volumetric fog lights. These were animated in 3D, generalizing the shape and movement of the fire and smoke as clusters of spheres. The result of this process was a completely volumetric matte that could then be used to stencil the building around the fire.

The final scene was composed in AfterEffects. As I do with all my work, the scene was rendered in many passes so I could control different shading aspects in 2D. These render passes separated shadow, light, and specular highlights.

"Multiple layers of the matte painting were used to texture separate layers of the scene" click image to see full size
"In the end there 6 layers: sky, background buildings, sky scraper, main building, forground wall" click imageto see QuickTime final composite

Steven's work can be found at www.walkersj.com.

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