Yea maybe I should have put more of the code up so you can get a better view of 
the whole thing. The issue is posting code on a public site like this requires 
approval from my boss (the Navy) - even though it's unclassified info, getting 
approval to show it can be a pain sometimes! 


robertosfield wrote:
> 1) Could it be z fighting?  The line is disappearing under the geometry?  Try 
> putting the scene in wireframe so that polygons won't obscure hidden lines.
> 
 
Yep, thought of that, I added that callback that uses the W that was used in 
the viewer example to toggle wireframe. No change!

Oh Yea, I forgot to add that I use two views, one for the terrain (the globe) 
and one for the elements in play. This is to avoid terrain clashing with other 
objects (like Terrain and the Overlays). This is necessary, because sometimes 
some of the elevations of objects in play are unreliable and would hide behind 
the terrain if I did think of a way to keep them visible. 

Both views are set up the same and use the same window (there like Photo Shop 
layers). except each added layer has background turned off (or you don't see 
the terrain in the first layer) and the cameras stay synced together. This make 
them appear like they are the same view, but they are not. 

FYI: In a Globe I sometimes use between two to six layers at a time. I call 
this thing Glass Onion! The only thing is that I have yet to add something to 
deliberately hide the objects as they go behind the global horizon. But that is 
not a problem for now! Actually it works very well – not counting this glitch!


robertosfield wrote:
> 2) Could it be a numerical precision issue?  VPB uses local MatrixTransform
> to place tiles with a local coordinate frame into ECEF to avoid precision 
> issues.
> 

You might have a point there; however, what I've done (and didn't show you) is 
that the data that I use is based on Lat/Long cords. I use the osg ellipsoid to 
calculate them into a matrix using the  
computeLocalToWorldTransformFromLatLongHeight  function. Then I can extract a 
transform from that to draw with an XYZ that is ECEF based (since all I need is 
a set of points on space). 

The Matrix is my friend, Neil! Grin! 

BTW: Everything in my map display projects is based on ECEF cords - .it’s just 
an easier way to draw things since most of the data I use is in that format! 


robertosfield wrote:
> 3) Near plan clipping?
> 


This is the most probable case since I had this problem with this before and my 
solutions have been hacks! 

Before then, I noticed that if I put up a model, I can zoom up to it and see it 
all. But, if I put a bigger model behind it, it is half cut off or disappears 
completely. This I figured is because some how the near plane clipping distance 
is being changed somehow. 

For example, when I would set a camera in the cockpit of a plane and look down 
the runway, the terrain would go to a point near the plane and the terrain 
disappear like it was cut off near my wheels. So I used 
"setNearFarRatio(0.000001f);" on the camera. That brought the terrain under my 
wheels, but then I noticed that at certain elevations in the air over the 
terrain that some of the textures seem to have a strange effect that looked 
like it was flapping in the breeze. So I fixed it so that above a certain point 
the camera would have the near far Ratio set at 0.000001 and above 11,000 m in 
elevation, I would set it to 0.0001 and that seamed to work.

I admit, I'm rather stupid in that area!  

Sigh!


D Glenn

------------------------
D Glenn (a.k.a David Glenn) - Join the Navy and See the World ... from your 
Desk!

------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=30007#30007





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