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how to find the visibility from a point on terrain.


 
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imran.livt (imran ahmed syed)
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Joined: 27 May 2011
Posts: 3

PostPosted: Thu Jun 09, 2011 4:30 am    Post subject:
how to find the visibility from a point on terrain.
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Hi,

i want to get the visibility from a point on terrain and change the color of the visible area.
To get the visibility I presume we have to calculate line of sight intersections in every direction. or is there any other procedure in osg?

Thank you!

Cheers,
imran
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robertosfield
OSG Project Lead


Joined: 18 Mar 2009
Posts: 12144

PostPosted: Thu Jun 09, 2011 8:23 am    Post subject:
how to find the visibility from a point on terrain.
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Hi Imran,

Have a look at the osginterstion example.

Robert.

On Thu, Jun 9, 2011 at 5:30 AM, imran ahmed syed <> wrote:
Quote:
Hi,

i want to get the visibility from a point on terrain and change the color of the visible area.
To get the visibility I presume we have to calculate line of sight intersections in every direction. or is there any other procedure in osg?

Thank you!

Cheers,
imran

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imran.livt (imran ahmed syed)
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Joined: 27 May 2011
Posts: 3

PostPosted: Thu Jun 09, 2011 9:25 am    Post subject:
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Hi Robert,

Thanks for the reply.

osgSim is taking a very long time to compute intersections. where as osg::LineIntersection produces quick results.
Is OsgSim more accurate ? ?
I am trying to find the terrain height by projecting a ray on to the terrain and getting the first intersection ( front) point.

Thank you!

Cheers,
Imran
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robertosfield
OSG Project Lead


Joined: 18 Mar 2009
Posts: 12144

PostPosted: Thu Jun 09, 2011 9:31 am    Post subject:
how to find the visibility from a point on terrain.
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Hi Imran,

On Thu, Jun 9, 2011 at 10:25 AM, imran ahmed syed <> wrote:
Quote:
osgSim is taking a very long time to compute intersections. where as osg::LineIntersection produces quick results.
Is OsgSim more accurate ? ?

The osgSim utilities use
osgUtil::IntersectionVistor/LineSegmentIntersection under the hood,
the only difference is that the osgSim utilities have support for
reading paged tiles from disk to make sure they get the highest level
of detail. Is it that you are using a paged database?


Robert.


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imran.livt (imran ahmed syed)
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Joined: 27 May 2011
Posts: 3

PostPosted: Thu Jun 09, 2011 11:18 am    Post subject:
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Hi,

Yeah. My terrain database is developed from VPB. It has more than one Levels.
I understand osgSim is taking more time as it goes to highest level of detail.

Thank you for the explanation.

Cheers,
imran[/list]
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