Re: How can I plot a Hedgehog with programmatically-built data?

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Re: How can I plot a Hedgehog with programmatically-built data?

Andrew Maclean-3
The best way to get the data is to check out VTKExamples as detailed here.
Once you have done this the data files can be found in VTKExamples/src/Testing/Data.

If you are a Python user I have usually created a function: get_program_parameters(). This function tells you the data file used and any parameters needed.

In the case of the Cxx code you will usually find code like this:
  if (argc < 2)
  {
    std::cout << "Usage: " << argv[0] << " carotid.vtk" << std::endl;
    return EXIT_SUCCESS;
  }

Alternatively, look at the CMakeLists.txt file in the directory where the Cxx code lives. For the Cxx equivalent of the Python example you used, it is in  VTKExamples/Visualization. If you look at the CMakeLists.txt file there you will find a line:
------
add_test(${KIT}-ComplexV ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/${KIT}CxxTests
  TestComplexV ${DATA}/carotid.vtk)
------
Note that the paramters are also listed here e.g. in the case of  CorrectlyRenderTranslucentGeometry.cxx:
------
add_test(${KIT}-CorrectlyRenderTranslucentGeometry ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/${KIT}CxxTests
  TestCorrectlyRenderTranslucentGeometry 100 100 50 0.1 0 0)
------

Regards
   Andrew

---------- Forwarded message ----------
From:
​​
 Aron Helser <[hidden email]>
To: Jack Eiler <[hidden email]>
Cc: [hidden email]
Bcc: 
Date: Fri, 6 Jul 2018 10:21:55 -0400
Subject: Re: [vtkusers] How can I plot a Hedgehog with programmatically-built data? (Python)
If you build VTK, with testing or with examples, the data files end up in the build directory. It's a binary file ~2.5Mb, or I'd attach it.
The example uses  vtkStructuredPointsReader to read the file, then  vtkPolyDataMapper , tells you carotid is probably a PolyData, so you can look for examples of constructing that. The example of exchanging data with Numpy arrays might be helpful.
HTH,
Aron


On Fri, Jul 6, 2018 at 4:10 AM J. <[hidden email]> wrote:
I'd like to draw a Hedgehog plot in Python. I had a look at this example:


But unfortunately the data for the plot there is just read from a file, "carotid.vtk" (a file which, by the way, I can't find anywhere on the Internet - maybe a download a link could be added to the examples page?). Thus it's quite opaque exactly how this data needs to be presented. I've been trying to guess my way to success by looking at some C code I found, but I'm not getting any joy.

Say I have a 2-dimensional python array of python 3-tuples representing the values of a vector field at each point of a regular 3d grid. What steps do I take to plot that as a hedgehog?


--
___________________________________________
Andrew J. P. Maclean

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