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Mo-Capping Golfers for the USGA

Immersion Media creates 3D online rules guide By Frank Moldstad

To create an online demo illustrating the rules of golf, the United States Golf Association (USGA) could have opted to videotape actors on the golf course. But they wanted a variety of camera angles and zoom choices to be available for post-production to show the golf situations from multiple viewpoints, something that might require expensive reshoots if it was done on video.

So they turned to Immersion Media, a Fayetteville, NC-based company (with a production office in Kansas City) that specializes in motion capture and sports videos. Immersion Media outfitted two golf pros with body motion sensors in its studios to bring to life 25 of the most challenging golf scenarios. The resulting data was imported into 3ds max and assembled with multiple angles and commentary by broadcaster Roger Twibell. The results are posted on the USGA web site here.

In this Q&A, Meta Motion's Lee Dickholtz, who sold Immersion Media its mo-cap system, explains how the production was done and what equipment was used.

What was the process Immersion Media used to capture the golf animations for the USGA?

Immersion Media used an STT Jade Motion Captor optical motion capture system sold by Meta Motion to capture golfers' motions. Motion Captors stand-alone driver was used for all the captures. The resultant data sets were brought into 3ds max via Character Studios BVH importer. Meta Motion is the North American distributor for STT.

Immersion Media used Motion Captors BVH exporter to convert the Motion Captor optical data to BVH files. Motion Captor also has plugins that allow Maya, Softimage and XSI to import and re-target Motion Captors data onto characters in Maya, Softimage and XSI.

Motion Captor provides exceptional integration with Alias (Kaydara) Mocap. This allows the motion of one or two actors to be displayed on the actual 3D characters (from MAX, Maya, Softimage, XSI, Lightwave, Cinema 4D etc.) in real-time. Users can operate the entire system directly within Alias Mocap.

Motion Captor works well with Alias (Kaydara) MotionBuilder Professional as well. STT provides a plug-in that allows easy import of Motion Captor optical data into MotionBuilder for re-targeting to 3D characters.

Alias Mocap and MotionBuilder provide excellent tools for editing optical motion capture data and re-targeting the data to 3D characters for import by Lightwave, Maya, 3DS MAX, Softimage, XSI, Cinema 4D, etc.

STT also makes software specifically for golf swing analysis that works with the same hardware as used for the Motion Captor system.


What kind of mocap system was used, and how much does it cost?

The system used was a Jade (analog) Motion Captor system, by STT. Although Immersion Media owns a six-camera system, they were using it in a four-camera configuration due to the small size of the room they were working in.

The Jade Motion Captor system is the most cost-effective optical motion capture system available, and also the easiest to work with. When used in a six-camera configuration it excels in dual capture and provides very clean data thanks to automatic use of biomechanical tracking methods.

The Jade Motion Captor system is priced below $35,000 for a four-camera system. Immersion Media purchased a refurbished system that became available when another Meta Motion client upgraded their system to a Sapphire (digital) Motion Captor system. Although the studio had been considering purchasing a used magnetic system, they have been extremely pleased with the ease of use, flexibility and quality of output of their Motion Captor system.

Immersion Media self-installed its Jade Motion Captor system after just four hours of training. They were fully up-to-speed within a week after installation. This is in sharp contrast with other optical motion capture systems that have a learning curve of 6 to 12 months.


How many sensors were the actors wearing, and where were they placed?

Immersion Media used a 25-marker setup:

  • three for the head   (3)
  • three for the torso (3)
  • four per forearm, wrist and hand (8)
  • three for the pelvis (3)
  • four per lower leg, ankle and foot (8)

The Motion Captor system gets full functionality from a 25-marker set thanks to the systems automatic use of biomechanical tracking methods. Although the system ?sees markers, it detects it is tracking one or two persons. Since the system knows what human bodies can or cannot do, a lot of incorrect marker position solutions are eliminated in real-time. This automatic biomechanical approach greatly increases ease of use and lessens or eliminates many of the problems that commonly plague optical motion capture. Motion Captors biomechanical tracking methods provide much cleaner data more easily than competitive systems. Marker occlusion and swapping are greatly reduced. Data can often be used as-is, without further clean up. 

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Related Keywords:Immersion Media, USGA, Meta Motion, STT, Jade Motion Captor, motion capture, Lee Dickholtz


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