Issue: Volume: 26 Issue: 7 (July 2003)

CG Superheroes: New Wrinkles


By Martin McEachern

Of all the digital superheroes dazzling moviegoers this year, none had to appear more "human" than Daredevil. That's because the title character of this summer's action film acquired his powers less from the assimilation of non-human abilities and more from the hyper-compensation of his remaining four human senses, after a childhood accident robbed the young Matt Murdoch of his sight.

With behind-the-scenes help from the effects group at Rhythm & Hues Studios, director Mark Steven Johnson achieved that goal, resulting in film critic Roger Ebert praising the digital double for transcending the look of an animated character and appearing more real and convincing than its contemporaries. Key to making the digital Daredevil look as human as possible were new character-animation techniques developed by Rhythm & Hues that realistically simulate the wrinkling of "tight" fabric. The procedural method, involving automatically generated displacement maps, was designed to replicate the unique creasing properties of the hero's crimson leather costume, which, unlike spandex, stretches and folds unpredictably with the extreme torsion from the hero's gymnastic style of locomotion.









Rhythm & Hues developed a new procedural wrinkling system that uses automatically generated displacement maps to show the detailed texture, grain, stitching, and realistic stretching of Daredevil's tight-fitting leather costume. All images ©2




Using a digital scan of actor Ben Affleck in full Daredevil regalia, the Rhythm & Hues artists obtained a high-resolution polygonal mesh, along with complete texture information of the leather outfit, which they imported into Side Effects Software's Houdini and Rhythm & Hues's proprietary Voodoo animation system. The group also assembled a library of reference material, including footage of a stuntman performing exaggerated motions that demonstrated the intricacies of the leather's deformation under the stresses of acrobatic movements.

To create an animatable model without losing the detail of the scanned data, the group worked on two separate Daredevil models at the same time. The first, containing the high-density polygonal mesh, was used only for texture mapping; the second, a less-dense version of the first, was fully rigged and used solely for animation. The team also created several versions of the animation model in different resolutions, incorporating both polygonal and subdivision surfaces, to meet the detail requirements of various shots.

















Prior to rendering, the artists had to restore the details of the initial model to the animation model by integrating three levels of displacement maps. For the first layer, the team developed a tool for determining the differences between corresponding points across the two versions within a series of maps, which the group then applied while rendering the animation model. The second level added the texture, grain, and stitching of the leather costume using high-resolution displacement surfaces that were hand-painted in Right Hemisphere's Deep Paint 3D and confined to select regions of the suit. This afforded a level of realism without massive amounts of surface data.

The actual wrinkling of the suit was accomplished in the third level using a Voodoo script that captured the squash and stretch transformations of every polygon in the texture map for each frame. The group then created a tool for use in its proprietary compositing software, Icy, that automatically integrated a hand-painted, animated wrinkle map corresponding to each polygon's "squash and stretch" map.

This procedural wrinkling system was put to the test during a complex scene in which Daredevil runs atop the front wheel of a charging motorcycle ridden by his nemesis, Bullseye, as the two perform simultaneous backflips framed in a slow, circular camera movement. Working in Voodoo, the artists animated the principal digital elements of the sequence, including the costumed Daredevil, the motorcycle, and Bullseye, whose billowing coat was driven by a cloth simulation in Alias|Wavefront's Maya. Following extensive matchmoving in Icy, the group composited the realistic animation into the live action.

Daredevil's outfit had to realistically react to the stresses and strains of the character's muscles as he performs a range of daring feats, such as diving headfirst from the top of a tall building.




Further complicating this sequence was the unique lighting, as the action occurs in the shadow of a tree that filters the light from a nearby street lamp. The lighting is additionally influenced by the flashing of the bike's headlights and the scattering of sparks as the cycle skids along the ground. This scenario, which necessitated advanced subsurface scattering shaders for the skin of both characters, also led to the innovation of Rhythm & Hues's new automated High Dynamic Range Image (HDRI) construction pipeline for mapping the position of onset lights. To create the HDRI maps, the artists combined multiple exposures of a smooth, reflective ball photographed on location, then employed custom software to extract the position of the lights.

Daredevil, the motorcycle, and Bullseye were animated in Voodoo, while Bullseye's coattails were driven by a cloth simulation in Maya.




The HDRI maps were crucial to upholding the dark and rainy atmosphere of the film. They also helped the artists accentuate details in the Daredevil model, such as muscle contours, without compromising the credibility of the lighting.

Many comic-book aficionados may argue that Daredevil is not the strongest or most powerful of the recent action heroes-turned-movie stars. But without question, the character's innovative costuming has him dressed to thrill.

Martin McEachern, a contributing editor of Computer Graphics World, can be reached at martin@globility.com.




Director Mark Steven Johnson's adaptation of the comic book Daredevil sought to uphold the tradition of dark realism forged by the Marvel title in the early 1980s. As a result, Daredevil had to look real while performing death-defying feats, while his way of "seeing" through sound had to be portrayed with a poetic beauty befitting the film's dark tenor.

Daredevil's ability to form images from sound demanded spectacular point-of-view shots of his auditory perceptions. This so-called "Shadow World" effect provided the company with a long-awaited opportunity to production-test its Virtual Cloud Tank, a set of tools for generating three-dimensional density fields in Houdini.

By using many of the familiar compositing operators, such as Plus, Minus, Inside, Outside, and Multiply, the artists could create volumes of almost infinite diversity—from soft-edged clouds, to thick fluids, to isometric surfaces encompassing the volumes. The density fields could then be rendered using a variety of iterative raytracers, including those designed for rendering dense volumes in high detail, casting localized blasts of internal light, or optimizing Houdini's native image3D volume file format. By the end of the project, the group had integrated 10 such interfaces into the tool set along with OpenGL-powered previsualization tools for viewing volume changes in real time.




Using this new Virtual Cloud Tank, along with its automatic displacement mapping procedure and other new or proven tools and techniques, the group at Rhythm & Hues generated more than 300 effects shots for the Daredevil movie, providing the gritty reality that is the hallmark of the original comic book series. —Martin McEachern




Alias|Wavefront www.aliaswavefront.com
Right Hemisphere www.righthemisphere.com
Side Effects Software www.sidefx.com
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