[osg-users] about GIS Vector Overlay Problem

[Glenn Waldron]

Hi,
If you are using VIEW_DEPENDENT_WITH_ORTHOGRAPHIC_OVERLAY mode, the display
resolution of the overlay texture will depend on how much of the texture is
seen. For example, if you are looking out towards the horizon, the overlay
will appear blockier because it must render a larger piece of it within a
finite texture size. Google Earth overlays behave the same way.

You can adjust the texture size itself with
OverlayNode::setOverlayTextureSizeHint(). Try 2048 or 4096 if your video
card support it; it definitely helps -gw

-- 
Glenn Waldron : Pelican Mapping : http://pelicanmapping.com : 703-652-4791

On Jan 12, 2008 5:40 AM, 赵明伟 <david.zmw at gmail.com> wrote:

>     Hi, EveryOne.
>
>     I am using the VPB and osgGIS. My step as follows: first use the image
> and dem file of a small region to generate terrain models by VPB , and then
> use the shp file to generate vector shape models, finally, in my
> application, I set the vector shape models' root as overlay to the terrain
> models' root.
>
>     The final display effect has a problem that the generated texture of
> overlay cannot change it's resolution.So when I zoom in the viewer, the
> resampling effect is ugly.
>
>     And there is anthoer question that  I want the blend effect between
> overlay texture and the real terrain texture , but I can not find the
> interface in class osgSim::OverlayNode. If I don't use the OverlayNode and
> just blend the terrain models and the vector shape models, then the depth
> setting will be a question.
>
>     I'm waiting your reply, Thanks.
>
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