Hi,

A little update, nobody can explain me the simplifier in details ?

Thanks.

Regards,
  Vincent

Vincent Bourdier a écrit :
Hi,

I do an update on this topic, because I would like to understand well the osgUtil::simlifier. This implementation seems to be very complex and powerful, but I don't know how to manage it better.

/For that I would like to know what do the following methods and how to set the values to have the expected result :/

           void setSampleRatio(float sampleRatio) { _sampleRatio =
   sampleRatio; }


           /** Set the maximum point error that all point removals must
   be less than to permit removal of a point.
* Note, Only used when down sampling. i.e. sampleRatio < 1.0*/
           void setMaximumError(float error) { _maximumError = error; }


           /** Set the maximum length target that all edges must be
   shorted than.
             * Note, Only used when up sampling i.e. sampleRatio > 1.0.*/

Maybe this is a noob question, but I think it can help/inform other osg users to know precisely how to configure the Simplifier...

I set the Sample ratio to values < 1, and this seems to do some good job on my model, but not enough... I am looking at a way to destruct a mesh from 800 Mbyte (.ive) to 100Mbyte (.ive) (for LOD usage mainly) I know the size of the ive file is not a good reference, but it is important for my application. And I know that if a file is lesser, the mesh will be lighter too...
Relative to that,
/What can make an ive file heavy// or light ?/ (example : 20M triangles in a 850Mbyts ive file, not proportional to 13M triangles in a 710Mbytes file)

Thanks for your help.

Regards,
  Vincent.

Vincent Bourdier a écrit :
Hi Andrew

Thanks for the tip on the simplifier, lower the sample ratio is, lower the vertex number is. (I get a crash under 0.6 but I'm not sure this is an osg crash) Concerning the optimiser, this do not reduce the vertex number but the inverse... on a 460k vertices model, the optimizer returns me a 480k vertices model ...

I'm looking for a destructive optimizer/simplifier for my model... Do you have any other tips or idea ?

Thanks.

Regards,
   Vincent.

2009/9/21 Andrew Burnett-Thompson <aburnettthomp...@googlemail.com <mailto:aburnettthomp...@googlemail.com>>

    Hi there,

    I've experimented with the simplifier, but am not using it.

    I found the setSampleRatio() method affects how coarse or fine a
    result you get. The simplification with a sample ratio less that
    1.0 appears to be destructive (i.e. Geometry out does not equal
    Geometry in). So far I've not found the right settings to be
    beneficial for my needs (which is reduction of memory consumption
    while keeping the mesh the same or similar).

    Another way of reducing the vertex count in your scene is to use
    the Optimizer. Here I have found that using the Optimizer with the
    options MERGE_GEOMETRY, CHECK_GEOMETRY and TRISTRIP_GEOMETRY can
    significantly reduce the number of vertices/primitives in each
    Geometry object, while giving you essentially the same mesh out.


    On Mon, Sep 21, 2009 at 10:10 AM, Vincent Bourdier
    <vincent.bourd...@gmail.com <mailto:vincent.bourd...@gmail.com>>
    wrote:

        Up ?

        No one does osg simplifications ?

        Thanks,
           Vincent.

        2009/9/17 Vincent Bourdier <vincent.bourd...@gmail.com
        <mailto:vincent.bourd...@gmail.com>>

            Hi all,

            Using the osg simplifier on a geometry, I'm just surprised
            to see that there is no way to set a level of
            simplification or something like that.
            Maybe I didn't saw it, but for the moment I just found

            _sm->setDoTriStrip(true);  //what for ? do triangle strip
            are more optimized ?
            _sm->setSampleRatio(?); //what does it mean ? what does it
            changes ?
            ...

            How can I control the simplification level ?
            Is this simplifier a destructive one ? (can deform the
            geometry)

            Thanks.

            Regards,
               Vincent.




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