[vtkusers] performance of MIP mappers

[Mark Wyszomierski]

Ok I see. You mentioned that you think the 'internal' calculations are
off - do you know where this occurs? I could give it to a few people
to look at (if this internal part is part of the VTK source code?).

Thanks,
Mark

On 4/10/07, Michael Knopke <Michael.Knopke at gmx.de> wrote:
>
>
>
> Hi Mark,
>
> yes the mapper is resizing to max 256x256x256 for 1 component (I think it's
> not 128x256x256 as stated in the API doc). Anyway in both cases this is true
> if the ZDimension of the volume exceeds 256(128), otherwise it uses less
> planes. SampleDistance is fixed when not moving (to the value you have
> chosen), but will change to another fixed value while interacting. This
> fixed interactive value is calculated once depending on the size of the
> volume (so it's different with every volume you load). You can find this
> calculation in vtkVolumeMapper quite at the end.
>
> I think the only way (as a workaround of course) would be a function that
> shifts opacity depending on the number of planes.
>
>
>
> Regards
> Michael
>
> PS: I tried to find a general shift value myself but came to the above
> conclusion, it might be wrong though.
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