[osg-users] Large scale point clouds rendering with PagedLOD

[Chris Hanson]

>
> (1) I want to convert the EPT format, to the pagedlod format and saved as
> osgb file, is it possible for pagedlod that both parent and it's child are
> both drawn?
>

  Normally, no. OSG's underlying Group system allows only one LOD to be
drawn at a time, though lower LODs are actually retained in memory as
loaded.

  The way most OSG PagedLOD databases are built (the way VPB for example
builds databases) is that LOD 0 will be the low-res version and LOD 1 will
contain four sub-pieces at higher res, each of which is the LOD 0 of
another PagedLOD.

  You could either

1. Write a specialized variant of PagedLOD that displayed the lower LOD
automatically (not recommended)

2. Build your PagedLODs carefully so that PageLOD level 0 contains the
lowest detail point data, and LOD 1 contains that same data PLUS the four
child PagedLODs. I believe if you link things together properly, the two
copies of LOD 0 will only be stored in memory once and drawn once.

(2) The laz file also contains other attributes, such as lables (interger),
> return number (interger), I also want to implement shaders to render color
> by different attribute, is it possible to save these attribute in osgb and
> correctly bind the vertext buffer to the same program location?
>

  Yes. You can store these values as attributes and access them in a shader
to control rendering.


> Thank you!
> Cheers,
> Han
>

-- 
Chris 'Xenon' Hanson, omo sanza lettere. Xenon at AlphaPixel.com
http://www.alphapixel.com/
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