RE: [Dev] [3dweb] Multi-scopic displays

Hi,

Thank you for your feedback. It would be very helpful when we consider
auto-stereoscopic or multiscopic in the near future.

My comments are inline:

> -----Original Message-----
> From: Christophe de Dinechin [mailto:christophe@taodyne.com]
> Sent: Monday, March 04, 2013 4:45 PM
> To: Dong-Young Lee
> Cc: 'Christophe De Dinechin'; public-web-and-tv@w3.org;
> dev@nano.taodyne.com
> Subject: Re: [Dev] [3dweb] Multi-scopic displays
> 
> Hi,
> 
> 
> Here are a few very quick observations:
> 
> 1) Auto-steroscopic displays tend to require more than 2 pictures.
> Alioscopy for example requires 8, Tridelity usually 5. This is not true
> for mobile devices, where two pictures are usually sufficient because
> there is a single viewer and you are not trying to build parallax.
> 
> 2) There are two big philosophies on how to generate the many pictures.
> 
> 2a) The "pure" approach of Alioscopy or Tridelity is that you can send
> completely independent pictures.
> 
> 2b) The "generated" approach of Philips/Dimenco, Dolby or Toshiba is that
> you extrapolate the pictures from either a depth map and color map or a
> stereoscopic pair
> 
> 2c) The benefits of the pure approach is that it has no problem with
> transparency or parallax. It never needs to "invent" a pixel that is not
> there, whereas the "generated" approach does. With a depth map, you can
> only represent one depth, so no transparency either.
> 
> 2d) The benefits of the "generated" approach is that it works better with
> existing infrastructure. By contrast, a mixed Alioscopy frame needs to be
> pixel-perfect for a good 3D effect, and are built in such a way that
> compression won't work well, see
> http://pinterest.com/pin/218072806928832411/ for an example.
> 
> [Taodyne's approach is to have a device-independent representation, and
> render for a specific device at the last minute. For example, we may have
> 8 different images and mix them for Alioscopy, or take 5 out of 8 and mix
> them for Tridelity, or take 2 out of 8 and interlace them for a passive
TV,
> or 2 out of 8 and frame-sequence them for an active TV. This lets us
> leverage existing encodings and transports.]
> 
> 
> 
> Now specifically about the proposal at
> http://www.w3.org/2011/webtv/3dweb/3dweb_proposal_121130.html, and
> ignoring multiscopic displays:
> 
> 0) Does this apply to a contents or does it specify how it is rendered?
> For an image, you sometimes need to know its format, i.e. it's a JPG with
> side-by-side pictures. But for a rendered element, e.g. a text or some 3D
> object, you need is to describe how it will be rendered. Converting
> existing assets may be technically hard & expensive, but not always. So it
> makes sense to say "I have a side-by-side stereo image and I want to show
> it on an interlaced display", but not "I have a stereo-picture with a
> baseline of X and I want to show it with a baseline of Y"... unless this
> is a synthetic 3D picture (e.g. a .obj file)

As you know, there are two kinds of objects that can be rendered in
stereoscopic 3D on the web. One is transformable elements, such as <div>,
<img> etc., which use CSS 3D Transforms. The other is stereo 3D content,
such as stereo 3D images or videos, consisting of two views for each eye of
a user. The perspective-baseline property is only for elements styled by CSS
3D Transforms. On the other hand, stereo-* properties are to specify image
(or video) formats of stereo 3D content. So we don't need to say "I have a
stereo-picture with a baseline of X and I want to show it with a baseline of
Y" at the moment.

> 
> 1) perspective-baseline: The issue raised for perspective-baseline cannot
> really be answered without a camera / frustum model for what we are
> looking at. In addition to the baseline, we also need to know how the
> virtual eyes converge to some point (or to infinity).
> 

We have the same system model as [1] in mind. Let me know if you need
further clarification.

[1]
http://4.bp.blogspot.com/-M8y-ms1yjEo/TekJCDvKOwI/AAAAAAAAAbc/lYIkHAJ6cZY/s1
600/stereo_perspective_new.jpg

> 2) stereo-contents: What happens if you have a format that already
> specifies that? For JPG, you have JPS (2 pictures) and MPO (n pictures). I
> understand what a JPG with side-by-side stereo means, but what does a JPS
> with side-by-side stereo mean? How would I put a JPS or an MPO in a web
> page?
> 

If a browser can detect content formats of a 3D image file correctly, some
stereo-* properties might not be necessary.

> 3) stereo-render-option: Besides being hard to implement, I personally
> have no clue what "center" would mean precisely, unless there's already a
> center image (e.g. with a 5-pictures multiscopic format).
> 

Roughly speaking, it assumes that the perspective is in the middle of the
two perspectives of given two images. Although it's difficult to implement
with just two views, it would be meaningful with multiple images.

> 4) stereo-format: additional output formats include frame-sequential,
> checkerboard and anaglyph. For input, there are also formats that specify
> multiple pictures themselves. We could probably call that frame-sequential
> as well.

I agree that some additional output formats might be necessary. I guess
frame-sequential (for both input and output) is necessary for multiscopic,
right?

> 
> 
> 
> Just my two cents for today
> Best regards
> Christophe
> 
> On 26 févr. 2013, at 05:37, "Dong-Young Lee" <dongyoung.lee@lge.com>
wrote:
> 
> > Hi, Christophe,
> >
> > The spec proposal was written specifically "stereoscopic" 3D in mind,
> > since stereoscopic displays became quite popular these days (e.g.,
> > 3DTV).  I haven't thought much about autostereoscopy or multiscopy,
> > but there should be things to be considered for multiscopy at least.
> > I'm definitely interested in those topics and would welcome your input
> and participation.
> >
> > Best Regards,
> > Dong-Young Lee
> >
> >
> > -----Original Message-----
> > From: Christophe De Dinechin [mailto:christophe@taodyne.com]
> > Sent: Tuesday, February 26, 2013 3:18 AM
> > To: public-web-and-tv@w3.org
> > Cc: dev@nano.taodyne.com
> > Subject: [3dweb] Multi-scopic displays
> >
> > I've quickly browsed through the 3dweb proposal at
> > http://www.w3.org/2011/webtv/3dweb/3dweb_proposal_121130.html. I
> > wanted to know if any consideration had been given to
> > auto-stereoscopic and multiscopic displays (e.g. Alioscopy, Dimenco or
> > Tridelity)? I can't find anything by searching through the archive.
> >
> > Taodyne supports this kind of displays and the description of 3D
> > scenes (including mixing 3D movies and real-time 3D object rendering).
> > Here is an
> > example:
> > http://www.taodyne.com/shop/en/blog/63-integrating-3d-models-in-a-tao-
> > docume nts. 3D documents can be rendered on 2D or 3D displays,
> > including glasses-free displays. We can share our experience on this
> > list if there is any interest.
> >
> >
> > Best regards
> > Christophe de Dinechin
> >
> >
> >
> >
> >
> > _______________________________________________
> > Dev mailing list
> > Dev@nano.taodyne.com
> > http://nano.taodyne.com/mailman/listinfo/dev

Received on Friday, 15 March 2013 08:23:22 UTC