[Insight-users] platform dependent code in vtkPolyDataToitkMesh.cxx

[Georgi.Diakov at i-med.ac.at]

Dear Insight Users,

it seems that a line in the very handy and often used filter 
"vtkPolyDataToitkMesh" makes it platform dependent, which may cause 
unpredictable errors on some platforms. That line is:

t->SetPointIds( (unsigned long*)cellPoints );

This line sets the vertex indeces for the triangles in the mesh by 
copying the cell point ids from the polydata. t is from 
TriangleCellType. cellPoints is from vtkIdType, which is an integer and 
is declared in a platform independent manner in vtkIdType.h. The cast 
to unsigned long* type is platform dependent, which may lead to changed 
triangle vertex ids in the mesh. I experienced this under Fedora Linux 
on Pentium 4, where the mesh was distorted, something like drawing 
random lines between its points. I solved the problem by declaring a 
new variable of the type unsigned long* by:
unsigned long* meshids = new unsigned long[3];

and asigning the id values manually at each iteration:

meshids[0] = cellPoint[0]; and so on to [2].

Then:

t->SetPointIds(meshids);

This is probably not the most elegant way to modify the filter. I would 
suggest defining a platform independent id type for itk, similarly to 
vtkIdType.

Best regards,
Georgi