3D Scanning: Technology on the Set
Professional Surveyor Magazine - June 2012
By Neil McLeod
His work has starred in such films as Harry Potter and the Half-Blood Prince, Hellboy II, The Dark Knight
, the remake of Total Recall, The Bourne Legacy
, the soon-to-be-released Man of Steel
, and the latest Ron Howard film, Rush
. But no one identifies Craig Crane on the street, which is appropriate, because he hopes his work in blockbuster films doesn’t stand out. It’s his job, in fact, to make sure his work goes unnoticed.
A 3D scanning consultant based in Portsmouth on England’s southern coast, Crane creates digital film sets and props using surveyors’ tools and skills. He captures physical sets through 3D scanning and then creates a precise 3D model—of a Gotham City hospital or police station, for example, or the Batmobile—the way the sets or props looked on the day of filming.
Crane’s 3D models may ultimately be used for a variety of purposes, including the rebuilding of a set and post-production editing. Of course, it’s crucial that the digital sets and props fit seamlessly into the whole picture.
Crane travels around the world to capture film sets in 3D. He usually waits until the crews and actors have completely cleared out to scan the elaborate sets built for many films today. These sets can be either studio-built constructions or real-world landscapes and buildings. And they can be large. For example, one set that Crane scanned and modeled
was the size of the famous Victorian-era Covent Garden Market buildings in central London. They can also be very intricate—such as the medieval Chichester Cross in the center of Chichester, England.
Cue the Technology
Crane uses Geomagic Studio
software in his quest for perfect on-screen assimilation. Geomagic Studio transforms the files he churns out with Leica HDS 6100 and Next Engine HD scanners into highly realistic digital models indistinguishable from the real thing. He tested this software on set for the first time in his recent work on a major Disney film (whose name he can’t divulge).
Before he scanned a single set for Disney, he looked into the numerous ways to turn the raw point-cloud data into accurate 3D polygon mesh models, which often have polygon counts in the tens of millions. After using the demo trial version of Geomagic Studio, Crane knew that he had found the solution for the most critical part of his pipeline—the scan data clean-up and meshing process.
“I had approached the job thinking that meshing was a dark art,” says Crane. “I had read papers on it from Siggraph [the Special Interest Group on Graphics and Interactive Techniques] and other sources, trying to find the best solution, and here was this software package … that just literally generated the mesh with the minimal amount of fuss or frustration. Job done. It’s so simple that within an hour I was able to start working with the software.”
Now Crane’s typical approach is to do point-cloud registration within Leica
Cyclone software, and then he exports files to Geomagic Studio for clean up, decimation, hole filling, and polygon meshing.
He says that certain meshing jobs that previously took him a full day with open-source software now take minutes with Geomagic Studio. He especially appreciates the software’s ability to remove unwanted data that often pops up from live scans of large sets. This unwanted data can be caused by a variety of sources, including scanner noise (reflective surfaces, deep dark blacks), people walking across the set, and natural phenomena beyond Crane’s control. “Weather often affects how I scan,” says Crane. “From rain to desert sandstorms, each on-location scan presents new challenges that have to be dealt with both on site and in post production.”
Crane is currently working with version 12 of the software, which he says is giving him the greater control he needs over processes such as edge sharpening and curve sampling. Curve sampling has been helpful in reducing file sizes by automatically removing polygons where they are not needed, such as large areas of a flat surface, without sacrificing detail. The smaller file sizes speed production and help his customers avoid system crashes when working with the files.
In some cases, the 3D digital sets produced by Crane have played key roles in film production. For example, where only a partial physical set is built—maybe the turrets on a castle don’t need to extend to their full height for filming—the set’s full size is digitally extended for the final scenes. Crane accomplishes this by creating a 3D surface mesh model in Geomagic Studio and then importing it into Autodesk Maya software, where he extends it.
The detailed digital models produced by Crane, combined with the designer’s working drawings and photographs, are often used for critical archiving as well, providing the only sub-millimeter reference of what the physical set looked like. The filming and photography of a set (or building, prop, or vehicle) invariably introduce distortions and occlusions, Crane notes.
Digital sets also can come in handy when a scene has to be redone because the physical sets are many times too costly to completely recreate.
In animated films, digitally modeled sets also provide an accurate ground reference for superimposing characters when they need to move through a given scene, including generating realistic shadows from digital computer graphics (CG) lighting. The digital set can also be dropped into shots from the initial shoot that have been camera-tracked (match-moved) to assess the quality of the new CG camera movement.
3D models such as Crane’s work may also be used for commercial purposes: the design and production of action figures and toys associated with a film.
While the Disney project is taking up most of Crane’s time at the moment, he is also in early production stages for a self-produced animated film that will require a lot of accurate and detailed 3D scanning and modeling.
Neil McLeod writes about the ways in which today’s 3D spatial data processing technologies help professionals in industry, commerce, the arts, and the public sector perform their day-to-day tasks.
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