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<div class="moz-cite-prefix">Hi Andrey,<br>
<br>
As I understand your need, you want to put something in
essentially the backdrop of the scene. This needs to be far enough
away that it will never have parallax and the user cannot zoom in
to anything that might be displayed. This would normally be down
with the X3D node "Background", but that requires six total
images, when all that is visible is one ("Front") and part of
another two ("Up" and "Down"). In the case of really wide-angle
lenses, there might be portions of "Left" and "Right" that show up
too. <br>
<br>
Would it be possible to construct template images that is
lens-dependent that marks out the visible areas and those portions
of the scene that are too far away (10km in your description) just
be painted into the background image. The "Back" image can always
be a transparent PNG as would the regions of the other background
images that are outside of the lens' field-of-view.<br>
<br>
Leonard Daly<br>
<br>
<br>
<br>
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<blockquote type="cite"
cite="mid:161a0255fff.108e42d0b43291.5548363524029565940@elphel.com">
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<div
style="font-size:10pt;font-family:Verdana,Arial,Helvetica,sans-serif;">We
are using x3d models to present long-range 3d scenes captured by
a quad stereo camera. And really far objects do not have the
distance resolved, so they should be treated as at infinity. We
first tried to use background node for such images, but it is
not very convenient - we had to provide all 6 images (only one
is real), and extend the camera image to match the stereo angle
to 1/6 of the full sphere. The rest of the models consist of
multiple surfaces as IndexedFaceSet (the viewer is here: <a
class="moz-txt-link-freetext"
href="https://community.elphel.com/3d+map">https://community.elphel.com/3d+map</a>,
just the models: <a class="moz-txt-link-freetext"
href="https://community.elphel.com/3d+map/models/">https://community.elphel.com/3d+map/models/</a>).
So we ended up with just a very far (at 10,000 m with the rest
of the objects closer than 1000m) IndexedFaceSet instead of the
background.<br>
<br>
Can it make sense to extend IndexedFaceSet (and possibly some
other nodes) to use ideal points (x,y,z,0) without increasing
number of the point coordinates?<br>
For our particular application just a single boolean would do,
but other applications might benefit from a mixture of the
finite and and ideal points by providing a per-vertex boolean
array. This can make more uniform representation to replace
background and suggest a straightforward way to export the model
to the systems that do not support objects at infinity.<br>
<br>
</div>
<br>
<br>
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<br>
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</blockquote>
<p><br>
</p>
<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 Past Chair<br>
President, Daly Realism - <i>Creating the Future</i> </font></div>
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