[osg-users] Using OsgSim Overlay

Glenn Waldron gwaldron at gmail.com
Thu Nov 19 05:22:24 PST 2009


Vaibhav,

The area covered by the projected texture changes based on your view angle.
As your angle of view gets less steep, the texture resolution appears to
descrease since it has to cover a larger area. Try
view-dependend-with-perspective-overlay, which helps with this issue. Also,
increase the texture size hint in the OverlayNode api.


Glenn Waldron : Pelican Mapping : http://pelicanmapping.com :
+1.703.652.4791


On Thu, Nov 19, 2009 at 7:29 AM, Vaibhav Bansal <vaibhav at darshan3d.com>wrote:

> Yes, this is what the overlay node does for me.
> But I am unable to understand, why the stretching occurs only 'at' some
> specific angles.
>
> Regards
> Vaibhav Bansal
>
> -----Original Message-----
> From: osg-users-bounces at lists.openscenegraph.org
> [mailto:osg-users-bounces at lists.openscenegraph.org] On Behalf Of J.P.
> Delport
> Sent: Thursday, November 19, 2009 3:47 PM
> To: OpenSceneGraph Users
> Subject: Re: [osg-users] Using OsgSim Overlay
>
> Hi,
>
> Vaibhav Bansal wrote:
> > Hello jp,
> >
> > Thanks for the quick reply.
> > How do I check if the 'resolution' of ovelay geometry is changing.
>
> imagine the following:
> You want to overlay a 1024x1024 checkerboard onto the earth and you have
> a 512x512 overlay texture. If you view the whole earth it obviously
> would not look good - too much detail to fit into the texture. What the
> view dependent modes try to do is this: When you zoom in, you only see a
> piece of the checkerboard, so now the 512x512 texture can contain only a
> piece of the checkerboard and so you see "more detail" of the overlayed
> geometry.
>
> I think this is the effect you are seeing when you are moving the view
> around.
>
> jp
>
> >
> > Regards
> > Vaibhav Bansal
> >
> > -----Original Message-----
> > From: osg-users-bounces at lists.openscenegraph.org
> > [mailto:osg-users-bounces at lists.openscenegraph.org] On Behalf Of J.P.
> > Delport
> > Sent: Thursday, November 19, 2009 2:41 PM
> > To: OpenSceneGraph Users
> > Subject: Re: [osg-users] Using OsgSim Overlay
> >
> > Hi Vaibhav,
> >
> > Vaibhav Bansal wrote:
> >> Hello,
> >>
> >> I have added a geometry as an overlay over another geometry.
> >> The overlay texture seems to distort(stretch) under certain viewing
> > angles.
> >> It seems the projected texture is generating incorrect texture
> > coordinates.
> >
> > The texture coordinates might be OK, but the resolution of your
> > overlayed geometry might change in the generated overlayed texture. What
> > happens in OBJECT_DEPENDENT_WITH_ORTHOGRAPHIC_OVERLAY? Does the
> > resolution/stretch stay the same?
> >
> > jp
> >
> >> The white area is the overlaySubgraph geometry, and the colored area is
> > the
> >> Overlay Node (base) geometry.
> >> The overlay mode is VIEW_DEPENDENT_WITH_ORTHOGRAPHIC_PROJECTION.
> >>
> >> Can anyone suggest where should I start troubleshooting.
> >>
> >> Thanks
> >> Vaibhav Bansal
> >>
> >>
> >> ------------------------------------------------------------------------
> >>
> >>
> >> ------------------------------------------------------------------------
> >>
> >>
> >> ------------------------------------------------------------------------
> >>
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> >> osg-users at lists.openscenegraph.org
> >>
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> >
>
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