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<p>I'll echo Leonard's comments about previously developing
standards. Let's not reinvent the wheel. WebVR, OSVR, OpenXR are
all dealing with multiple hardware vendors/configurations and have
figured out the reference model and nomenclature to cover all the
permutations. I would suggest getting as much as possible from
those initiatives as they are all open and will likely be the
defacto standards.<br>
</p>
<br>
<div class="moz-cite-prefix">On 7/9/17 10:01 AM, Leonard Daly wrote:<br>
</div>
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<div class="moz-cite-prefix">OK. I really think this is a very BAD
IDEA. I've tried to explain why below. It's also toned down a
lot from my first effort.<br>
<br>
<br>
Having a separate node that provide for duplicate control for
certain scene assets (e.g., cameras) is a mistake. If UserInfo
defined a stereo camera and the Viewpoint used an orthographic
camera you would get vision disorientation. Stereo vision needs
the two view frustas to converge. There is no convergence with
orthographic projection.<br>
<br>
When viewing a scene in a headset, it is generally accepted that
certain features need to remain fixed (e.g., world-up). <br>
<br>
There is already a node for the camera. It should handle all
aspects of the camera (perspective, ortho, stereo, etc.). That
node is called Viewpoint (there is really no need for
OrthoViewpoint). Introducing another, perhaps contradictory
means for that would just add confusion.<br>
<br>
There is a developing standard for VR on the Web by the W3C. It
is called WebVR. It does not control how you present certain
information to the user, but how code needs to interact with the
browser in order to have the proper VR experience. WebVR also
includes some standardization of the various user-interface
devices. A misalignment with WebVR would just cause more
confusion. More confusion leads to a lower adoption rate.<br>
<br>
The spec needs to keep related things together. Viewpoint should
be how the scene is presented to the user. It needs to cover all
aspects of the camera, camera type, FOV, interpupillary
distance. NavigationInfo covers how the user navigates from the
current viewing position. Audio node(s) would indicate whether
the sound is mono, spatialized, or stereo (plus). <br>
<br>
If a browser wishes to build in a set of user-configurable
options (perhaps for disability access or some other reason),
then that is fine; but would not be part of the spec.<br>
<br>
The discussion of multi-user is irrelevant. Each user has their
own copy of the scene (at least for rendering purposes). What
one person sees is independent of another in the same scene at
the same time. Multi-user support is more for passing high-level
information from one viewer to another. Presenting a
"birds-eyes" view of a scene in headset mode is not a good idea.
Of course it can be done, but the results will be bad and very
disturbing (as in cognitive dissonance). (Think of a web page
with every word on a blink tag with different rates. That is
just beginning to go down the disturbing path.)<br>
<br>
<br>
Leonard Daly<br>
<br>
<br>
<br>
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<div class="WordSection1">
<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">At a recent X3D working group meeting we
proposed some possible new nodes to provide support for VR
displays within X3D. Here is an extract from the minutes:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<ul style="margin-top:0cm" type="disc">
<li class="MsoNormal" style="color:#0070C0;mso-list:l0
level1 lfo1">VR<o:p></o:p></li>
<ul style="margin-top:0cm" type="circle">
<li class="MsoNormal" style="color:#0070C0;mso-list:l0
level2 lfo1">Stereo viewpoint, which needs two cameras.
The X3D specification only allows one camera, e.g.
Viewpoint, which is a bindable node. Contrast here the
Viewpoint/OrthoViewpoint nodes, which are perspective
and orthographic renderings, respectively.<o:p></o:p></li>
<li class="MsoNormal" style="color:#0070C0;mso-list:l0
level2 lfo1">Input interfaces, possibly from multiple
buttons. For example, TouchSensor, may need to be
expanded to permit more types of input.<o:p></o:p></li>
<li class="MsoNormal" style="color:#0070C0;mso-list:l0
level2 lfo1">Audio – is it good enough. There is no
left, right ear dependence, i.e. stereo audio.<o:p></o:p></li>
<li class="MsoNormal" style="color:#0070C0;mso-list:l0
level2 lfo1">Viewpoint switching – alternative methods
of animating viewpoint changes are required. For
example, Viewpoint node currently has a <i>jump</i>
field, but Fade out/Fade in might be needed.<o:p></o:p></li>
</ul>
</ul>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">After that meeting Don and I were talking
about this, and came up with an alternative suggestion. This
was for the following node:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<ul style="margin-top:0cm" type="disc">
<li class="MsoListParagraph"
style="margin-left:36.0pt;mso-list:l0 level1 lfo1">UserInfo<o:p></o:p></li>
<ul style="margin-top:0cm" type="circle">
<li class="MsoListParagraph"
style="margin-left:36.0pt;mso-list:l0 level2 lfo1">Should
this be a bindable node, with its own binding stack, so
that only one was active at a time? Then, what about
multiple users interacting with the same scene?<o:p></o:p></li>
<li class="MsoListParagraph"
style="margin-left:36.0pt;mso-list:l0 level2 lfo1">It
could indicate if the user was needed a stereo
rendering, and have attributes for stereo parameters.<o:p></o:p></li>
<li class="MsoListParagraph"
style="margin-left:36.0pt;mso-list:l0 level2 lfo1">It
could indicate if the user required stereo audio, having
appropriate attributes.<o:p></o:p></li>
<li class="MsoListParagraph"
style="margin-left:36.0pt;mso-list:l0 level2 lfo1">It
could have attributes relating to FOV – currently in
Viewpoint.<o:p></o:p></li>
</ul>
</ul>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">This node would not have to be included
in a scene. It could be added by the implementation (or
modified if present) using SAI techniques. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The node could be added to the Navigation
component, perhaps at support level 2, to fit into the
immersive profile.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">An example:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<ul style="margin-top:0cm" type="disc">
<li class="MsoListParagraph"
style="margin-left:36.0pt;mso-list:l0 level1 lfo1">Let’s
imagine a garden scene. We would like to be able to render
it in stereo, from the perspective of two different users.
The first is human. The second is a bird. The saved scene
need not have a UserInfo node, and so could be independent
of the user. The implementation would then insert the
appropriate UserInfo node into the scene at run time,
permitting the scene to be rendered with the desired user
properties.<o:p></o:p></li>
</ul>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">What do you think? Good idea? Bad idea?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">All comments welcome.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">All the best,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Roy<o:p></o:p></p>
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<div class="moz-signature">-- <br>
<font class="tahoma,arial,helvetica san serif" color="#333366">
<font size="+1"><b>Leonard Daly</b></font><br>
3D Systems & Cloud Consultant<br>
LA ACM SIGGRAPH Chair<br>
President, Daly Realism - <i>Creating the Future</i> </font></div>
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