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Despite the fact that Canon has discontinued production of the 3-D lens for its
XL1 camera (see AC Aug. 2001), Jason Goodman of 21st Century 3D has moved
forward with stereoscopic video in developing a new system he calls "960p,"
based on dual Sony DXC-9000 cameras.
"It's a high definition stereoscopic format that takes its name from the HDTV
standards it is based on," says Goodman. "By utilizing two 720x480 progressive
(480p) video streams, we are able to produce high definition stereoscopic
images with low cost standard definition tools."
Goodman also notes that there are certain advantages of dual video recording over
the alternating field process used by the Canon XL1 3-D lens. "The XL1
3-D camera lens was unsuitable for blue- or greenscreen composite work,"
Goodman says. "The compressed video files, the 4:1:1 color space, and
sequential recording of the left and right eye images were all limitations."
By utilizing the built-in "feature" of NTSC video, sequential left and right
eye images were neatly stored on odd and even fields. "This is great for
telling the lens when to photograph each image and telling shutter glasses
when to open and shut," says Goodman. "but it can be bad for stereo photography.
Because the images are recorded sequentially, there is a 1/60-second time
differential between the capture of left and right eye
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images. In many cases, this causes stereo pairs to be mismatched. Photographing anything with a relatively
high degree of motion (the movement of fingers on a hand for example)
may exhibit temporal artifacts and a breakdown in stereoscopy. By switching
to a two channel system, this problem is eliminated."
The DXC-9000 camera uses three 1/2" CCDs. With progressive scan technology,
the camera can capture objects moving at high speeds and produces clear
images with high horizontal (720 TV lines) and vertical (480 TV lines)
resolution. A built-in frame memory provides three types of output signals,
including a non-interlaced signal.
"I got the DXC 9000s because they were the only camera that fit the qualifications
for progressive scan and broadcast quality," says Goodman. "They also
allow us to do component video uncompressed with 4:2:2 color space with
the option for 4:4:4"
While maintaining the benefits of progressive scan acquisition, the output signals
provide system compatibility with existing video equipment. The DXC-9000
uses square pixels for minimum distortion of the image and is ideal for
computerized image processing applications. The individual cameras weigh
in at 1.68 pounds each, and Goodman has assembled a system to record to
Beta SP.
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