Re: [osg-users] Visualizing 3D-Points including standard deviation

2010-08-19 Thread Gerwin de Haan 
Hi Felix,

instead of using explicit 3D shapes, you could also use view-aligned
quads with a semi-transparent gauss-texture. These textures could be
pre-generated, I think the fountain example in OSG might also be
helpful with this. They could also be created on demand in shaders,
based on their Gauss attributes. We use a similar trick to draw lots
of nicely shaded particles with ellipsoidal or spherical appearance,
in this case for flow visualization and molecular visualization, e.g.
see http://graphics.tudelft.nl/Projects/AtmosphericViz (this was
OpenGL) and the first two images on http://graphics.tudelft.nl/VRVis
(these are OSG). If you're interested I can probably get some source
code your way, but I'd have to check with colleagues first.

cheers,
Gerwin


On Wed, Aug 18, 2010 at 11:19 AM, Felix Engelmann
efe+...@tu-chemnitz.eu wrote:
 Hi,
 I need to visualize points in 3D, whose positions are Gauss distributed. The 
 expected values and the standard deviations for each x, y and z coordinate 
 are given. So, how can I do that with OSG?
 I could draw a sphere (using osg::SphereDrawable) with a fixed radius at the 
 center and another transparent sphere around it for visualizing the standard 
 deviation. But that doesn't look nice...
 What I'm looking for is some kind of 3D-radial gradient. The transparency 
 should increase along the gradient accourding to the Gaussian distribution 
 function.
 Note, that the standard deviation can be different for each dimension.
 I'm a newbie in OSG and not an OpenGL expert. Some example code would be 
 really helpful.

 Thank you

 Sincerely,
 Felix

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Re: [osg-users] Visualizing 3D-Points including standard deviation

2010-08-19 Thread Felix Engelmann 
Thank you for the suggestions,

I think a billboard with a gaussian texture is right what I need. 
Either a view-aligned billboard, which requires to update the width/height of 
the billboard - or a static billboard with 2 (or 3) crossing quads.

A source code example would be great! Could you ask your colleagues, please? :)

Thanks again,
Felix

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[osg-users] Visualizing 3D-Points including standard deviation

2010-08-18 Thread Felix Engelmann 
Hi,
I need to visualize points in 3D, whose positions are Gauss distributed. The 
expected values and the standard deviations for each x, y and z coordinate are 
given. So, how can I do that with OSG?
I could draw a sphere (using osg::SphereDrawable) with a fixed radius at the 
center and another transparent sphere around it for visualizing the standard 
deviation. But that doesn't look nice...
What I'm looking for is some kind of 3D-radial gradient. The transparency 
should increase along the gradient accourding to the Gaussian distribution 
function.
Note, that the standard deviation can be different for each dimension.
I'm a newbie in OSG and not an OpenGL expert. Some example code would be really 
helpful.
 
Thank you

Sincerely,
Felix

--
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=30872#30872





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