[osg-users] "Robust" Update of an osg::Image attached to a osg::camera ?

Erwan Bigorgne erwan.bigorgne at gmail.com
Mon Mar 9 06:46:23 PDT 2009


>How are you setting up your scene + viewer to
>render to the image?

basically :

mesh (readnodefile) -> PAT (internal)  -> PAT (external)
------------------>  Rootnode -> viewer
                                                                     |_____>
MyCam _____________|

|_____> Depth Map (osg::Image)


>Is your rendering just for the purpose of
>generating an osg::Image as output?

Actually, I just need a depth map, so the image is the only output for the
"osg part"

>How you are testing the results
>of the image?

my eyes (considering the next answer)

> What threading model have you used?
 no thread I think... this basic osg structure is "embedded" and called once
at each iteration :

something like :
mp_ExternalPAT->setPosition
mp_ExternalPAT->setAttitude
mp_Image->dirty();
m_Viewer.updateTraversal();
m_Viewer.frame();

---->access to the current Depth Map (osg::Image attached to the camera)


>As a general note, can you do the processing in shaders instead on the
>CPU?  Avoiding the readback from the GPU to main memory can be a big
>save in performance.

Although i handle a little Comp.Vision, I 'm really newborn in Comp Graph
area.
Are you telling me that if i'd define a chain camera -> texture -> image, my
depth map would be would be computed by the CPU?

If not, what I have to do ?

erwan





Robert.

On Mon, Mar 9, 2009 at 12:52 PM, Erwan Bigorgne

<erwan.bigor... at gmail.com> wrote:
> Hello,

> I'm currently using (and learning) osg in order to manage an implicite 3D-
> model in an computer vision task.
> for that purpose, i need to compute a reliable depth map, that i intend to
> update at each step of the algorithm.
> I've almost reach that goal, but sometimes, the generated osg::Image (i.e.
> the depth map) is either corrupt (two geometrical states of the model are
> partially rendered), or just not updated at all.
> osg::Image->dirty() makes things better but not perfect.
> Any Idea about what i should do next or about what  I should care?

> thanks,

> (btw, excuse my poor english)

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