![]() What is important to the stereo matchmover is that the convergence, i/o and focal length of the original photography must be determined so that when visual effects are added to the plates, the stereo depth of the CGI elements closely match the live action elements. This is controversial and subjective process, with different artistic camps. Imax films typically maintain the left and right cameras as parallel to one another, but many other stereo systems "toe in" the cameras. Convergence is the pan angle between the two stereo cameras. The stereo effect would be lost and the viewers eyes would physically hurt. But if the effect is too strong, the human eye will not be able to fuse the binocular images together and painful eyestrain will result. The greaterthe (tx) distance between the two eyes, the stronger the stereo effect. ![]() In humans, this distance is typically 2.5 inches, but artistic and eyes train considerations mean that the photographed i/o may be set atmany unusual values and might even animate during the shot. Interocular (i/o) is the distance between the left and right eyes. The rounding down of the focal length value (no fractions, just whole numbers) caused minor problems and probably will be fixed in later versions of the Pacestereo encoding software. On JCE, Pace meta data, the i/o and convergence was floating point and the focal length was truncated to an integer. dpx header and inthe EXIF section of our. A separate ASCII file can be used, or in our case, stereo meta data was placed in the. ![]() ![]() Various "singlesystem" and " double system" techniques can be used for synchronizing this stereo meta data to the image. The animated focal length, convergence and interocular values are recorded every frame and then embedded in the 1920x1080 video image. On any stereo show, the critical stereoscopic settings are interocular and convergence, which can be changed dynamically during actual photography. The Pace stereo camera is typically fitted with matching, synchronized zoom lenses on the two stereo camera heads. Although beam splitter stereorigs are somewhat silly looking and "Rube Goldbergish", they are oftenconsidered the most artistically flexible rig type. By using compact "film look" video cameras, the stereoscopic rig was brought down to a relatively small size. Traditional 35mm or 65mm stereo cameras using an outboard beam splitter can be very large, especially in the case of the twin 65mm Showscan/Panavision cameras that we used for Cameron's T2-3D. A standard camcorder contains an integral recorder, but in our application, only the camera was on stage and the MPEG4 recorders were far away, in a high tech video village. These video cameras are relatively compact, since they consist only of a lens/image sensor and no tape, disc or other recording device. The Pace design utilizes two Sony HiDef 24P cameras looking into a beam splitter. JCE was photographed with the Pace stereo camera, the design of which was commissioned by James Cameron. Ant Bully was pure CGI animation and so the stereoscopic problems were very different than a live action visual effects film like JCE. Previously, I had worked on other stereoscopic films, including the 65mm productions The Ant Bully - 3D (Imax) and T2-3D (5-perf). Other important vfx studios also did considerable work on JCE. The overall vfx supervisor was Chris Townsend and the vfx Supervisor for Meteor Studios was Bret St. Principal photography and visual effects work was primarily produced in Montreal. JCE (Journey Center Earth) was produced by Walden Media, directed by Eric Brevig, photographed by Chuck Shuman and stars Brendan Fraser.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |