[ITK-users] [ITK] streaming TileImageFilter for arbitrary number of inputs

[Grothausmann, Roman Dr.]

Many thanks Brad for Your detailed reply. I understand now the problems 
concerning streaming TileImageFilter.
However I still wonder why my non-streaming version also does not work any more 
after moving the creation of reader instances into the for-loop:
https://github.com/romangrothausmann/ITK-CLIs/blob/ebfc0aea37d28cbbf2bb22c3f56be52453cebde9/tile.cxx#L46-L50

Is this construct inappropriate for the TileImageFilter?
Why does it work for:
https://itk.org/Doxygen/html/SphinxExamples_2src_2Filtering_2ImageGrid_2AppendTwo3DVolumes_2Code_8cxx-example.html#_a2

On 21/07/16 15:41, Lowekamp, Bradley (NIH/NLM/LHC) [C] wrote:
> Hello,
>
> The TileImageFilter does not fully stream [1]. The filter also has some odd
> behavior, and other older implementation details. If you are going to work on
> a streaming pipelines it is best practice to examine the filters to determine
> how the Requested regions behave.
>
> However, there is no reason that the TileImageFilter algorithm couldn’t
> support streaming. It is just a matter of code and a bunch of testing. A
> contribution for this issue would be welcomed! Also this filter is in need a
> refactoring and bring it up to several other best practices. There are
> several issue with the current implementation that would cause it not to work
> correctly with a streaming pipeline, and cause excessive execution.
>
> You can also use the PipelieMoniotorImageFilter to record and print the
> pipeline interaction during Update [2]. This information helps with debugging
> and diagnosing problems, but if the pipeline is mis-behaving ( as the
> TileImageFilter may ), the information may not be correct.
>
> I have tried similar streaming with the JoinSeriesImageFilter. However I ran
> into many problems with having hundreds of ImageIO being utilized at the same
> time. There were problems with having too many files open at the same time
> along with ImageIO libraries that couldn’t handle single threaded access to
> multiple files.
>
> [1]
> https://github.com/InsightSoftwareConsortium/ITK/blob/master/Modules/Filtering/ImageGrid/include/itkTileImageFilter.hxx#L125-L136
>
>
[2] https://itk.org/Doxygen/html/classitk_1_1PipelineMonitorImageFilter.html
>
>> On Jul 21, 2016, at 6:41 AM, Grothausmann, Roman Dr.
>> <grothausmann.roman at mh-hannover.de> wrote:
>>
>> Dear mailing list members,
>>
>>
>> Based on the examples for TileImageFilter I've created a working CLI to
>> append an arbitrary number of inputs
>> (https://github.com/romangrothausmann/ITK-CLIs/blob/4fdf5778022598dcf83fb38e6002df72bd67bef3/tile.cxx).
>>
>>
As there is an example that does not apply Update and DisconnectPipeline on the 
readers 
(https://itk.org/Doxygen/html/SphinxExamples_2src_2Filtering_2ImageGrid_2AppendTwo3DVolumes_2Code_8cxx-example.html#_a2) 

>> I changed my code such that a reader instance is created for each input in
>> a for-loop:
>> https://github.com/romangrothausmann/ITK-CLIs/commit/ebfc0aea37d28cbbf2bb22c3f56be52453cebde9
>>
>>
>>
However, the update from the writer seems not to propagate to the readers 
whether streaming or not. Can the TileImageFilter not stream in such a case or 
are further modifications necessary?
>>
>> Thanks for any help or hints Roman
>>
>>
>> On 18/08/14 17:01, Michka Popoff wrote:
>>> Hi
>>>
>>> Going the way described in the CreateVolume example is the way to go.
>>>
>>> Why did you uncomment the DisconnectPipeline() call and Update() call in
>>> the for loop ? They need to stay there, else you will always use the last
>>> image. That’s why you see the same image, the single update call will be
>>> triggered at the end of the script and read only one image.
>>>
>>> You don’t need to call tileFilter->Update(), you can remove this line.
>>> The writer->Update() will take care of the pipeline update. As a bonus,
>>> you may wrap your writer->Update() call, to fetch errors at the end of
>>> the pipeline:
>>>
>>> try { writer->Update(); } catch( itk::ExceptionObject & error ) {
>>> std::cerr << "Error: " << error << std::endl; return EXIT_FAILURE; }
>>>
>>> I made a little Python prototype, the syntax is a little bit different
>>> than in C++ but it gives you the main idea.
>>>
>>> Michka
>>>
>>
>> -- Dr. Roman Grothausmann
>>
>> Tomographie und Digitale Bildverarbeitung Tomography and Digital Image
>> Analysis
>>
>> Institut für Funktionelle und Angewandte Anatomie, OE 4120 Medizinische
>> Hochschule Hannover Carl-Neuberg-Str. 1 D-30625 Hannover
>>
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-- 
Dr. Roman Grothausmann

Tomographie und Digitale Bildverarbeitung
Tomography and Digital Image Analysis

Institut für Funktionelle und Angewandte Anatomie, OE 4120
Medizinische Hochschule Hannover
Carl-Neuberg-Str. 1
D-30625 Hannover

Tel. +49 511 532-2900