the "Bypass" feature in imaging

[John Biddiscombe]

Lisa,

>should be that new filters will be easier to write - and writing a graphics 
>filter won't be too much different than writing an imaging filter.

I'm pleased to say I've been experimenting with the multi-threading aspects
in Image filters and I like it lots. I'm hoping that you'll extend the
information idea to polydata (or any cell based data) so that graphics
filters can be parallelized easily by simply sending the data to N threads
- each with cell ID's as extents - and hey presto, lots of stuff will
instantly work threaded. Just override Execute(....) and
ExecuteInformation, ComputeRequiredUpdateExtents etc etc and away you go.


>This leads to my question - how many people out there are using the Bypass 
>feature in the imaging filter? And, if you are, how awful would it be if it 
>goes away? Here are the pros and cons:

>From my (albeit brief) experiments with the imaging classes I'd say,
"remove bypass" and make the execute rock solid. It takes minimal effort to
bypass a filter by simply setting oneFilter->SetInput(anotherFilter); which
is no harder than doing a Midfilter->SetByPassOn(); etc etc

It seems you've got two possible execute methods running side by side with
the streaming. One for single thread operation and one for multiple
threads. If the bypass feature is interfering with this then there's a good
reason for removing it.


John B

PS. vtkImageToStructuredPoints is still well knackered. :( I daren't
mention it really because I'm sure you're all fed up with it.



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