3/23/2005 © Dr. Zachary Wartell 1 “Just Enough Reality: Comfortable 3-D Viewing via...

3/23/2005 © Dr. Zachary Wartell 1

“Just Enough Reality: Comfortable 3-D Viewing via Microstereopsis”

Mel Seigel and Shojiro Nagata

IEEE TCSVT, Vol 10., No. 3, April 2000, 387-397.

Presentation: Revision 1.0

Copywrite Zachary Wartell University of North Carolina at Charlotte 2006


Image Collection

• camera-to-scene distance: {132,48,30} cm(w/ lens focal length {50,20,12.5}mm)

• camera positions [-20,+20] mm from center-line at 1-mm intervals (41 positions total)

• 640 x 480 res.

{132,48,30} cm

[-20,+20] mm


Center-of-interest Correction

• Cross Lens Axis (CLA)• Parallel Axis

– image shift (display)– CCD shift (camera)


Center-of-interest – Crossed Lens Axis (CLA)

CCD

R“directmapping”

screen

L


COI: Parallel Camera – Image Shift

CCD

RL

“directmapping”

imageshift

screen

RL

RL

imageshift+

clipping


COI: Parallel Camera – CCD Shift

CCD

screen

RL

“directMapping”


CCD Shift: Multi-Axis Shift

CCD

screen

RL

“directmapping”

CCD shift in X and Yx

y


CCD Shift: X-Axis Shift + Inverted Telephoto

CCD

screen

RL

“directmapping”


Depth-Pair Ordering Experiment

• 80 pairs of stereo pictures– 1st 40: one picture has no stereo– 2nd 40: both have stereo– within each 40: 5 sequences of 8 pairs, each

sequence has mean m.e.s. in {4.5,3.5,2.5,1.5,0.5} mm

• sub’s indicates whether left, right, or neither stereo image has more ‘3D-ness’ than the other

• use wide-angle set of images (D=30cm)


left picture m.e.s. [0,10]mm

right

pic

ture

m.e

.s.

[0,1

0]m

m

0%

100%

Results


Results

• informally, 10 mm m.e.s. fusion time is effectively 0

• microstereopsis gives depth order information, but not absolutely correct depth:

“delivers ‘just enough reality’ for computer graphics, video news and entertainment, and enough for most eye-hand coordinated tasks, including teleoperation of mobile robots” -Question: Is this an overstatement? For which tasks?

• at smallest m.e.s., sub’s w/out stereo glasses ‘perceive’ only a slight blurring that is not distracting


Hypothesis on Future Displays

• with microstereopsis, “it should be possible to stimulate binocular stereopsis even in presence of substantial crosstalk”

• suggests stereo displays presenting microstereopic applications may allow for lots of crosstalk– might support new display technology


Crosstalk Experiment (Anecdotal)

• 3 sub’s• modify LCD shutter-glasses to control cross-talk• increase cross-talk until stereo animation with

20mm m.e.s. yields diplopia• reduce m.e.s. to 2mm• at 2mm, sub’s report perception of depth and no

perception of ghosting


Zoneless Autostereoscopic Display

• assuming microstereopsis applications, crosstalk may not be problem, so what kind of new displays are possible?

brighterto right eye

brighterto left eye

right eye image left eye image

60 Hz


Microstereopsis Summary

• for m.e.s. of 1-3 mm (out of 60-65mm)– disparity stimulate binocular stereopsis– cross-talk perceived as blur (depth-of-field)

rather than ghosting• non-veridical adjustment of image-shift alters

balance between negative & positive screen parallax which in microstereopsis condition appears to transfer blur to foreground or background

• problem: capturing left/right eye simultaneously using microstereopsis’s range of m.e.s. will require custom camera’s


Future Work

• more formal user studies• investigate new display technology


Comments & Questions?

• What does this mean to VR?– VR doesn’t require any extra work to get basic

“center-of-interest” correction—it is automatic; just use proper asymmetric view frustums as needed.

– experiment shows very small m.e.s. (1-3mm) can still yield binocular stereopsis. How much does this help in real tasks?

• undoubtedly task dependent (see prior work, etc.)

• What was viewer distance to display in exp. #1?– If view frustum not equivalent to CCD frustum,

displayed 3D image will be distorted. Could distortion exaggerate depth making stereopsis at 1-3mm m.e.s. discernable when it might not be under other distortions?


COI: Parallel Camera – CCD Shift

CCD

screen

RL

imageshift+

clipping


COI: Parallel Camera – Image Shift

CCD

L

R

“naïve stretch”

L

R correct!

screen

3/23/2005 © Dr. Zachary Wartell 1 “Just Enough Reality: Comfortable 3-D Viewing via...

Documents

Transcript of 3/23/2005 © Dr. Zachary Wartell 1 “Just Enough Reality: Comfortable 3-D Viewing via...