[Insight-users] Pipeline question

[Miller, James V (Research)]

Paul,

Let me see if I understand the problem correctly.

You have a pipeline where near the end of the pipeline you have 3 separate
slice extraction filters.  When you call Update() on the slice extraction
filters in succession, the entire pipeline re-executes? Or just the slice
extraction filters re-execute?

Is the input image to the three slice extraction filters "big enough" to
support all three requests? If every filter before the slice extraction
filter that you are executing properly handles streaming, then filter before
the slice extraction filters would probably have only produced just enough
output to support the first slice extraction request.  When the second
request arrives, the pipeline would re-execute to generate the new requested
region.

One thing you might want to check is whether the BufferedRegion is changing
on the input to the slice extraction filters after each successive call to
Update() on the slice extraction filters. If it is changing, then it means
that when the filter before the slice extraction gets each request, it
thinks it needs to re-execute.  One thing you can try is to call
UpdateLargestPossibleRegion() on the filter before the slice extraction
filters so that all the output (to that point) is available.  Then the slice
extraction filters should never cause the filter before the slice extraction
filter to re-execute.

The last time I tested things like this explictly was a couple of months ago
when I added InPlace filters.  Here I exercised the pipeline quite a bit to
make sure branches of a pipeline properly executed.  But your issue may be
particular to the slice extraction filter.

But if the filter before the slice extraction filter is not re-executing but
the slice extraction filters are always re-executing, then that is a
different issue.  This could therefore be an MTime issue.

If you could whittle this down to a small test program that would certainly
help us out.



-----Original Message-----
From: Paul Yushkevich [mailto:pauly@cognitica.com]
Sent: Wednesday, May 14, 2003 5:02 PM
To: insight
Subject: [Insight-users] Pipeline question


Hi,

I have a small question about the pipeline.

I have a large image that is the input to three slice extraction filters 
that operate on different regions of the image.  Now, every time I call 
Update() on the outputs of these filters, the entire pipeline gets 
rerun, even though neither the input image nor the parameters of the 
filters had changed.

I traced this down to the fact that the input image is Modified() every 
time its requested region  changes.  As different RequestedRegions are 
propagated from the three different filters, the input image's MTime 
gets incremented, and the image appears as if it has changed, even 
though it really hadn't.

Is there any way around this issue?  I want to be able to call Update() 
frequently on the outputs of the three slice filters, but only have the 
filters run if the image or the filter parameters have changed.

Paul

-- 
--------------------------------
Paul A. Yushkevich, Ph.D.
President, Cognitica Corporation

17 Flemington Rd
Chapel Hill, NC 27517
Tel: 1-919-929-7652
--------------------------------


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