RawImageGuess module


(Murat Maga) #1

This project is potentially useful for our user base to facilitate raw image import from microCT scanners without having to create nhdr header to define them. I have tried with a sample data that I have in https://blogs.uw.edu/maga/2018/09/importing-microct-data-from-scanco-into-slicer/

But encountered some issues. Specifically, I can’t seem to enter a header size bigger than 2500, I can’t type specific values in the image dimension boxes.

Can one of the developers tell me who we can contribute?


(Steve Pieper) #2

@nagy.attila this one’s for you!


(Attila Nagy) #3

Hi all,

sorry for getting a little bit late here :slight_smile:

Actually there are no restrictions in the code, at least none that I explicitly put there. I checked, and really, no data can be entered that is beyond 2500 header and 5000x2500 (X x Y dimensions) - even worse, if I move the slider for Z up to 1567, then Slicer catches an exception, saying Bad Allocation.

Generic Warning: In D:\D\S\Slicer-4101-build\VTK\IO\Image\vtkImageReader2.cxx, line 757
File operation failed. row = 0, Read = 5000, FilePos = -1

Unable to allocate 19550000000 elements of size 1 bytes.

“Slicer has caught an internal error.\n\nYou may be able to continue from this point, but results are undefined.\n\nSuggested action is to save your work and restart.\n\nIf you have a repeatable sequence of steps that causes this message, please report the issue following instructions available at http://slicer.org\n\n\nThe message detail is:\n\nException thrown in event: bad allocation”

19550000000 indeed equals 5000 x 2500 x 1564.

This equals around 18GB of data if we take an 8bit pixel color depth, if I calculated correctly.

This part is beyond me, so we still might need someone else to chime in!

As for the header, I will look into this. Also downloading your data right now.


(Attila Nagy) #4

Okay, too long time passed to edit my previous post

So there were restrictions and they were arbitrary. But not in the code but in the UI file…
I edited it and checked in the changes into master.
Also checked in a slightly newer version of the python file.


(Steve Pieper) #5

Thanks @nagy.attila :+1:

The memory allocation error is not unexpected. The machines are finite, so we may as well let people push up to the limits.


(Murat Maga) #6

Thanks @nagy.attila. I will give a try.
As for the limits, I think it might be useful to precalculate the datasize as you did above, and give a warning about its consequences.

I think in general, we need a consistent way of resampling the stack without needing to load the entire stack into the Slicer. This will come in handy for datasets from high-resolution mCT as well as microscopy to load into computer with limited resources. @smrolfe started one sometime ago, so there might be some synergy there…