Texture map "flickering"

[Ron Inbar]

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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