[osg-users] vpb - libmini - opinion

Cedric Pinson mornifle at plopbyte.net
Sun Sep 14 07:51:09 PDT 2008


Thanks Robert
i will contact people on vtp

Cedric

Robert Osfield wrote:
> Hi Cedric,
>
> I'm not a CLOD expert, so I'd recommend asking some like Ben Discoe,
> or others from the VirtualTerrainProject community, as VTP has plenty
> of CLOD implementations to choose from so have lots of first hand
> experience.
>
> In terms of osgTerrain integration, the part you'd need to implement
> would be a custom osgTerrain::TerrainTechnique that build/renders a
> single TerrainTile according to the Elevation and Colour Layers
> attached to it.
>
> Right now VirtualPlanetBuilder assigns a GeometryTechnique to each
> TerrainTile, but at runtime you can replace this with your own
> technique via a Registry::ReadCallback that traverses loaded subgraphs
> and does the replace.   Longer term, possible in the OSG-2.8 time
> frame, my plan is to have the osgTerrain::Terrain node, that can be
> used to decorate a subgraph containing TerrainTile, to provide the
> default TerrainTechnique to use, this way you wouldn't need to have
> the ReadCallback, you could just set the terrain technique on the
> Terrain, and all its children would then use it.
>
> Robert.
>
> On Sat, Sep 13, 2008 at 4:55 PM, Cedric Pinson <mornifle at plopbyte.net> wrote:
>   
>> Hi Robert,
>> I think to implement a clod technique for osg, i did not check all clod
>> technique yet. My first candidate to evaluate is libmini. Would you have
>> some advise about clod technique to use ? Ideally i would like to plug it to
>> osgTerrain.
>>
>> Cheers,
>> Cedric
>>
>> Cedric Pinson wrote:
>>     
>>> Thank you Robert for those informations.
>>>
>>> Cedric
>>>
>>> Robert Osfield wrote:
>>>       
>>>> Hi Cedric,
>>>>
>>>> VPB/osgTerrain doesn't yet have any blending between LOD levels so
>>>> "popping" is still apparent.  The effect is less apparent now when
>>>> using the --terrain option in VPB, as it creates tiles of higher
>>>> resolution so the pixel errors associated with moving between LOD
>>>> levels is lower.
>>>>
>>>> W.r.t libmini, the author of this library, Stefan Roettger,  was
>>>> planning on writing an OSG NodeKit to interface the library with the
>>>> OSG.  This was last year, but haven't had an update recently from
>>>> Stephan so I don't know the status of this work.
>>>>
>>>> With the development of osgTerrain I designed it so we could implement
>>>> new TerrainTechnique implementations, just now we just have a crude
>>>> brute force GeometryTechnique implementation, but the path is
>>>> available to integrate CLOD techniques as custom TerrainTechnique
>>>> implementations, this would allow one to integrate external techniques
>>>> but reuise the osgTerrain::TerrainTile data structure, so even in
>>>> theory allow you to use VPB generated database with a tool like
>>>> libmini.
>>>>
>>>> Robert.
>>>>
>>>> On Tue, Aug 19, 2008 at 8:11 PM, Cedric Pinson <mornifle at plopbyte.net>
>>>> wrote:
>>>>
>>>>         
>>>>> Hi all,
>>>>>
>>>>> Is there someone that has already try this library
>>>>> (http://www.stereofx.org/terrain.html) in production ? On the example it
>>>>> seems a little slow,  i would just want feedback compared to vpb osg.
>>>>> Then i
>>>>> have a second question, i did not try a recent version of vpb but i
>>>>> remember
>>>>> last time i used it there was some little popup when switching lod
>>>>> level. Is
>>>>> there something new to attenuate this effect ?
>>>>> Then my last question, do you think that it would be useful to use new
>>>>> algorithms that works with data in live like libmini ? I guess it
>>>>> depends
>>>>> the needed of the application, but i would like different opinions
>>>>>
>>>>> Cheers,
>>>>> Cedric
>>>>>
>>>>> --
>>>>> +33 (0) 6 63 20 03 56  Cedric Pinson mailto:mornifle at plopbyte.net
>>>>> http://www.plopbyte.net
>>>>>
>>>>>
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>>>>>
>>>>>           
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>>>>         
>> --
>> +33 (0) 6 63 20 03 56  Cedric Pinson mailto:mornifle at plopbyte.net
>> http://www.plopbyte.net
>>
>>
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-- 
+33 (0) 6 63 20 03 56  Cedric Pinson mailto:mornifle at plopbyte.net http://www.plopbyte.net





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