ITK python itkMeshF3_Pointer

Beginner Questions
1

Hi,

One of the module interface method I’m working on takes an itk::SmartPointer<itk::Mesh<float, 3>>
as parameter. In python, this translates to itkMeshF3_Pointer. I tries to convert the output of itk.MeshFileReader to itkMeshF3_Pointer but the type seems unknown by default. Do I have to wrap it as part of my module?

Thanks for your help!

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2

Hi @cg2,

You may want to try the ITK 5.1.0 Python packages, which have support for both itk.Mesh.F3 and itk.Mesh.D3 – note that this can be found with:

import itk
itk.MeshFileReader.GetTypes()

And the convenient way to load files in ITK 5.1.0 without type specification is:

mesh = itk.meshread('mesh_filename.off')
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3

@matt.mccormick Thanks for your help.

Here the result of itk.MeshFileReader.GetTypes() :

6:   [<itkCType double>, 2]
6:   [<itkCType double>, 3]
6:   [<itkCType float>, 2]
6:   [<itkCType float>, 3]
6:   [<itkCType signed short>, 2]
6:   [<itkCType signed short>, 3]
6:   [<itkCType unsigned char>, 2]
6:   [<itkCType unsigned char>, 3]

When trying to read a mesh, I got the following error:

>>> mesh = itk.meshread(fixed_filename)
...
6:   File "ITK-build/Wrapping/Generators/Python/itkExtras.py", line 767, in meshread
6:     reader = TemplateReaderType.New(**kwargs)
6:   File "ITK-build/Wrapping/Generators/Python/itkTemplate.py", line 473, in New
6:     return self._NewMeshReader(itk.MeshFileReader, *args, **kwargs)
6:   File "ITK-build/Wrapping/Generators/Python/itkTemplate.py", line 633, in _NewMeshReader
6:     PixelType = itkTemplate._pixelTypeFromIO(pixel, component, numberOfComponents)
6:   File "ITK-build/Wrapping/Generators/Python/itkTemplate.py", line 666, in _pixelTypeFromIO
6:     raise RuntimeError("Unknown pixel type: %s." % pixel)

Even if I manage to get rid of this error, would I be able to do something like

mesh_ptr = itkMeshF3_Pointer(itk.meshread(fixed_filename))

given that my generated interface seems to expect itkMeshF3_Pointer?

Thanks again,

Charles

4

Hi Charles,

The detected type of the files may not be what is supported, so you can cast to a desired type, e.g. a float type makes sense for many cases, like this:

mesh = itk.meshread(fixed_filename, itk.F)
5

This works, thanks. Though, I’m still not able to convert it to itkMeshF3_Pointer :confused:

6

That is the equivalent of the result – pointers are not handled directly in Python.

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7

Indeed… Updating my interface to take pointer instead of smart pointer fixes the issue.

Thanks for your help!

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