Texture map "flickering"

[Audrius Stundzia]

<x-flowed>Hi Ron,

Thanks for you explanation.

I'll second your request for the (very busy) developers to add
mipmaps to vtk.

Regards,

Audrius


>From: "Ron Inbar" <rinbar at netvision.net.il>
>To: <audrius at adv-biologic.com>, <vtkusers at gsao.med.ge.com>
>Subject: Re: Texture map "flickering"
>Date: Sat, 4 Dec 1999 22:56:17 +0200
>
>I believe your problem can be solved using mipmaps, but those are not yet
>supported by vtk, to the best of my knowledge (correct me if I'm wrong,
>anyone).  The flickering occurs because when several texels get mapped into
>a single pixel, just one (w/o interpolation) or four (with interpolation) 
>of
>them are used to color the pixel.  When the textured object moves even
>slightly, you different texels get mapped to the same pixel, resulting in
>flickering.  Mipmaps are smaller versions of the texture obtained by
>repeatedly replacing every four adjacent texels by their average.  During
>rendering, the rendering engine decides which mipmap to use depending on 
>the
>minification ratio.  Good 3D hardware supports this operation.
>
>So let me take this opportunity to request the developers of vtk to add
>support for mipmaps.
>
>Thanks in advance,
>
>Ron
>
>
>----- Original Message -----
>From: Audrius Stundzia <adv_biologic at hotmail.com>
>To: <vtkusers at gsao.med.ge.com>
>Sent: Wednesday, December 01, 1999 02:57
>Subject: Q: Texture map "flickering"
>
>
> > Dear fellow vtker's,
> >
> > I generate an orthogonal coordinate grid system as a 2D texture
> > map (it's overlayed on top of another texture map image).
> >
> > I find that as I zoom in and out (especially as the image gets
> > small) the horizontal and vertical grid line of the coordinate
> > grid appear and disappear ("flicker"). The InterpolateOn()
> > of vtkTexture reduces this flicker somewhat.
> >
> > I also have the swap buffers turned on (not that this seems to make
> > any difference)
> >
> > Why is this flickering occuring? Is this anything else I can due to 
>reduce
> > this unsightly effect?
> >
> > I'm running on a Ultra-60 with a Creator 3D graphics card.
> >
> > Any insight would be most appreciated. Thanks.
> >
> > Regards,
> >
> > Audrius
> >
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> > 
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</x-flowed>