[Insight-developers] itkLargeImageWriteReadTest and large file

[Stephen R. Aylward]

Nice catch!

Can you add a metaio bug report to have it write in 1gig blocks?

Thanks!
s


-----Original Message-----
From: Bradley Lowekamp <blowekamp at mail.nih.gov>
Sent: Friday, July 24, 2009 9:16 AM
To: Insight Developers <Insight-developers at itk.org>
Cc: Luis Ibanez <luis.ibanez at kitware.com>
Subject: [Insight-developers] itkLargeImageWriteReadTest and large file

Hello,

The itkLargeImageWriteReadTests were added to test to see if itk::Image can deal with image greater then 2GB or 4GB. However, they fail on Mac OSX despite it being 64-bits with a 8-byte long. The apple OS is limited to only being able to read or write a maximum of 2GB at a time (regardless of 32 or 64-bit build). I don't know if this is the only OS with this limitation. The MetaIO library writes the files in one large block and therefore runs into this limitation. However the NRRD file format appears to read and write in smaller blocks, so by modifying the test to  use NRRD it passes on my system. An alternative is to use streamed reading and writing (actually I am not sure if that would work to get around this for writing, as I think the ImageFileWriter writes the whole image if it is available even if it was requested to stream).

The VisibleHumamStreamReadWriteTest is a very interesting test with regards to large images. Currently this is running only on my mini's, some are 64-bit, others are 32-bit. I did not realize it at the time, but this means that were are processing a 16GB image on a 32-bit machine. I am not saying that there are not issues related to this out of core processing, just that it is very cool we are already doing this :)

Currently I am running an experimental on "victoria", which should show up on the dashboard shortly.

Brad
========================================================
Bradley Lowekamp  
Lockheed Martin Contractor for
Office of High Performance Computing and Communications
National Library of Medicine 
blowekamp at mail.nih.gov

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