PVGeo 離散點集連接成線

PVGeo.filters.AddCellConnToPoints用VTK_LINE 和VTK_POLYLINE把離散的點集聯通起來。可以按照點的索引順序連接也可以按照鄰近的距離。按照鄰近距離進行連接是最合理恰當的。

"""
Add Cell Connectivity To Points
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Example for :class:`PVGeo.filters.AddCellConnToPoints`

This filter will add **linear** cell connectivity between scattered points.
You have the option to add ``VTK_LINE`` or ``VTK_POLYLINE`` connectivity.
``VTK_LINE`` connectivity makes a straight line between the points in order
(either in the order by index or using a nearest neighbor calculation).
The ``VTK_POLYLINE`` adds polyline connectivity between all points as one
spline (either in the order by index or using a nearest neighbor calculation).

"""
import numpy as np
import pyvista
from PVGeo import points_to_poly_data
from PVGeo.filters import AddCellConnToPoints

# 首先，產生一些離散的點
def path1(y):
    """Equation: x = a(y-h)^2 + k"""
    a = - 110.0 / 160.0**2
    x = a*y**2 + 110.0
    idxs = np.argwhere(x>0)
    return x[idxs][:,0], y[idxs][:,0]

x, y = path1(np.arange(0.0, 200.0, 25.0))
zo = np.linspace(9.0, 11.0, num=len(y))
coords = np.vstack((x,y,zo)).T
# 打亂點集的順序
np.random.shuffle(coords)

# Make a VTK data object for the filter to use
vtkPoints = points_to_poly_data(coords)

###############################################################################
# Apply the Filter
# ++++++++++++++++
#
# Now that you have the points generated, lets go ahead and apply
# the **Add Cell Connectivity To Points** filter from
# *Filters->PVGeo: General Filters->Add Cell Connectivity To Points*.
# The output data should look really wacky and incorrectly built like the image
# below; this is good.
line = AddCellConnToPoints().apply(vtkPoints)

p = pyvista.Plotter()
p.add_mesh(line, line_width=5, point_size=10)
p.show()

按照索引順序連接，看起來雜亂無章。

# Use the filter: Here is vtkPolyData containing the connected line:
line_o = AddCellConnToPoints(nearest_nbr=True).apply(vtkPoints)
p = pyvista.Plotter()
p.add_mesh(line_o, line_width=5, point_size=10)
p.show()

按照點集的鄰近距離進行連通。