[vtkusers] monitor progress of vol16Reader

[Sean McInerney]

Five times faster!?! A plausible reason is difficult to imagine ... 
except, perhaps ...

If you run your vtkImageReader-based app first, all data is read from 
disk (slow). If you subsequently run an app reading the same data, it is 
likely that the data has been partially or fully cached by the OS and 
will be accessed dramatically faster.

Otherwise ... what gives? I would not think that any two implementations 
of a volume reader could have a speed difference of this magnitude. 
There's not even a decompression scheme to consider. Can the rumors be 
true? ;-)

-Sean

Kate Kerekes wrote:
> Hello everyone,
>  
> I have looked at the messages regarding progress and update methods, but
> I still can't answer my question.  I am reading a large dataset (400 MB)
> and I need some sort of progress bar to update.  I was using
> vtkImageReader and the SetProgressMethod.  This worked as expected.
> Then I discovered that vtkVolume16Reader read in the data up to 5 times
> faster.  So I want to read my data with vtkVolume16Reader, but I need a
> way to set the progress method.  There are no "setProgress" methods in
> the vtkVolume16Reader class or any of its parents.  Does anyone know a
> trick to find out the current progress of the Volume16Reader?  Can
> someone explain why vtkImageReader is so much slower than
> vtkVolume16Reader?  Is there anything I can do to make vtkImageReader
> faster?
>  
> Thanks,
> Katherine Kerekes
>