[vtkusers] Simple 2D unstructured grid

[Andrea Gavana]

Hi Andras,


On Wed, 26 Sep 2018 at 19.00, Andras Lasso <lasso at queensu.ca> wrote:

> Your script works well in Paraview’s embedded Python interpreter, too.
>
>
>
> It seems that something is wrong in your Python/VTK environment. To
> confirm, you can check if other VTK Python examples
> <https://lorensen.github.io/VTKExamples/site/> crash, too.
>


It appears that the issue is due to my laptop Intel’s integrated graphics
card (!). I have tried on another, more serious machine with a NVidia
graphics card and the script works flawlessly...

I understand that my laptop may not be super duper (it’s fairly new though)
in terms of GPU processing but I was not trying to visualize millions of
polyhedrons, just 6 polygons... I wonder why VTK bombs out like that...

Thank you again for investigating and for your suggestions.

Andrea.



>
> Andras
>
>
>
> *From:* Andrea Gavana <andrea.gavana at gmail.com>
> *Sent:* Wednesday, September 26, 2018 11:53 AM
> *To:* Andras Lasso <lasso at queensu.ca>
> *Cc:* vtkusers at public.kitware.com
> *Subject:* Re: [vtkusers] Simple 2D unstructured grid
>
>
>
> Hi Andras,
>
> On Wed, 26 Sep 2018 at 17:37, Andras Lasso <lasso at queensu.ca> wrote:
>
> Works well for me in 3D Slicer’s embedded Python 2.7 64 bit, both with
> latest VTK master and VTK 7.1.0.
>
>
>
>
>
> Thank you for trying it out. I have upgraded VTK to 7.1.1 from Gohlke's
> site but the program still crashes Python hard. Does anyone know what might
> be going on?
>
>
>
> Andrea.
>
>
>
>
>
>
>
> Andras
>
>
>
> *From:* vtkusers <vtkusers-bounces at public.kitware.com> *On Behalf Of *Andrea
> Gavana
> *Sent:* Wednesday, September 26, 2018 10:23 AM
> *To:* vtkusers at public.kitware.com
> *Subject:* [vtkusers] Simple 2D unstructured grid
>
>
>
> Hello list,
>
>
>
>     I m trying to create a very, very simple 2D unstructured grid but
> every time I run my script - no matter what modifications I do - Python
> crashes hard with a Windows message "Python has stopped working...".
>
>
>
> A simplified version of my grid is in the picture below (done in Excel,
> sorry...):
>
>
>
> [image: image.png]
>
>
>
> I attach a copy of my script below. Could anyone offer some suggestions on
> what I am doing wrong? I am using VTK 7.1.0 on Windows 7 64 bit, Python 2.7
> 64 bit - VTK comes from Christophe Gohlke very useful Python binary wheels.
>
>
>
> Thank you in advance for your help.
>
>
>
> Andrea.
>
>
>
>
>
> # -- BEGIN CODE -- #
>
>
>
> import numpy
>
> import vtk
>
>
>
> import vtk.util.numpy_support as numpy_support
>
>
>
> # X, Y coordinates of a simple grid - Z is zero
>
>
>
> X = [600.4957421, 600.5, 600.5, 600.4957421, 600.4913048, 600.5,
>
>      600.5, 600.4957421, 600.4913048, 600.4868674, 600.5, 600.5,
>
>      600.4913048, 600.4868674, 600.4824301, 600.5, 600.5, 600.4868674,
>
>      600.4824301, 600.4779928, 600.5, 600.5, 600.4824301, 600.4779928,
>
>      600.4735554, 600.5, 600.5, 600.4779928, 600.4735554]
>
>
>
> Y = [2940.5, 2940.5, 2940.404044, 2940.5, 2940.6, 2940.6, 2940.5,
>
>      2940.5, 2940.6, 2940.7, 2940.7, 2940.6, 2940.6, 2940.7, 2940.8,
>
>      2940.8, 2940.7, 2940.7, 2940.8, 2940.9, 2940.9, 2940.8, 2940.8,
>
>      2940.9, 2941, 2941, 2940.9, 2940.9, 2941]
>
>
>
> # First face is triangular, everything else is a 4-sided polygon
>
> IDS = [range(4)]
>
> IDS += numpy.split(numpy.arange(4, len(X)), 5)
>
>
>
> npoints = len(X)
>
> matrix = numpy.zeros((npoints, 3), numpy.float32)
>
>
>
> matrix[:, 0] = X
>
> matrix[:, 1] = Y
>
>
>
> # Create the grid points
>
> vtk_pts = vtk.vtkPoints()
>
> vtk_pts.SetData(numpy_support.numpy_to_vtk(matrix, deep=1))
>
>
>
> # Create the unstructured grid
>
> grid = vtk.vtkUnstructuredGrid()
>
> grid.SetPoints(vtk_pts)
>
>
>
> # Allocate space for the cells in the grid
>
> nc = len(IDS)
>
> grid.Allocate(nc)
>
>
>
> # Loop through all cells
>
> for i in xrange(nc):
>
>     cell_ids = IDS[i]
>
>     ncoords = len(cell_ids)
>
>     grid.InsertNextCell(vtk.VTK_POLYGON, ncoords, cell_ids)
>
>
>
> print grid.GetNumberOfCells(), nc
>
>
>
> mapper = vtk.vtkDataSetMapper()
>
> mapper.SetInputData(grid)
>
>
>
> actor = vtk.vtkActor()
>
> actor.SetMapper(mapper)
>
>
>
> ren = vtk.vtkRenderer()
>
> renWin = vtk.vtkRenderWindow()
>
> renWin.AddRenderer(ren)
>
> iren = vtk.vtkRenderWindowInteractor()
>
> iren.SetRenderWindow(renWin)
>
>
>
> # Add the actors to the renderer, set the background and size
>
> ren.AddActor(actor)
>
> ren.SetBackground(0, 0, 0)
>
>
>
> # This allows the interactor to initalize itself. It has to be
>
> # called before an event loop.
>
> iren.Initialize()
>
>
>
> ren.ResetCamera()
>
> renWin.Render()
>
>
>
> # Start the event loop.
>
> iren.Start()
>
>
>
>
>
>
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