[vtkusers] Tolerance of InsertNextPoint in python

[David Gobbi]

Hi Brett,

The default type of vtkPoints is "float".  If you need more precision,
then you can change the precision to "double":

vtk_points = vtk.vtkPoints()
vtk_points.SetDataTypeToDouble()

This is true in both C++ and Python.

 - David


On Tue, Apr 3, 2012 at 6:22 AM, Brett Tully <brett.tully at oxyntix.com> wrote:
> Dear all,
>
> I am finding that vtkPoints.InsertNextPoint when called from python does not
> return a point where I want it -- it seems to be out by ~1e-10 -- is there a
> way to set the tolerance of this function or improve its location to be more
> precise than 1e-10? Or is this due to python floats?
>
> Thanks,
> Brett.
>
> I.e. the following python:
>
> import vtk
> vtk_points = vtk.vtkPoints()
> e = [0.0, 0.0065, 0.0]
> e_id = vtk_points.InsertNextPoint(*e)
> p_e = vtk_points.GetPoint(e_id)
> print p_e, e
> print (e[0] - p_e[0]), (e[1] - p_e[1]), (e[2] - p_e[2])
>
> # gives
> # (0.0, 0.006500000134110451, 0.0) [0.0, 0.0065, 0.0]
> # 0.0 -1.34110451043e-10 0.0