[vtkusers] Performance of 2DMapping

[David Gobbi]

Hi Janne,

This depends on the OpenGL drivers and the graphics card.
Some manufacturers' OpenGL drivers only use AGP for transferring
textures and geometry, but not 2D images.  Some graphics cards
don't provide an accelerated 2D image path at all.

So definitely use textures if you can, even for 2D viewing.
The only difficulty with textures is the 2^N limitation.

Looks like JB beat me to the punch, but I'm sending this
out anyway.

 - DG

P.S. Good to hear that someone is using vtkImageStencil!
Note that vtkImageBlend can do everything vtkImageStencil
can do, and then some.


On Thu, 17 Jul 2003, Hämäläinen Janne wrote:

> Hi,
>
> I've used combination of vtkImageMapper and vtkActor2D to present 2D images.
> Recently I tried presenting the same images using vtkImageActor, i.e., in
> effect putting them to 3D. I noticed that all the operations, e.g.,
> windowing and leveling of the gray level and swapping regions between images
> (as with vtkImageStencil) work much faster. In other words, the display
> updating is much smoother. Is my observation correct, and is this in general
> the case (or does it depend, e.g., on the used graphics card)? My first
> hunch would be that the 3D mode uses hardware acceleration and in 2D the
> processing would be done in software. Has anyone idea how things are
> working, and is there any reason to use 2D mapping?
>
> Thanks,
>
> Janne
>
>
>
> --
> Janne Hämäläinen
> Research Assistant
> Helsinki University Central Hospital
> X-ray Department
>
> email   janne.hamalainen at hus.fi
>
>
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