使用vtk给定一组点创建多条折线 [英] create multiple polylines given a set of points using vtk

问题描述

我需要使用vtk和paraview显示50个粒子的空间中的轨迹。目前，我的数据是 pos（x，y，t，n），其中n是第n个粒子的标签。我已将所有数据保存在一个vtk文件中，该文件的组织方式为：

I need to display the trajectories in space of 50 particles using vtk and paraview. Currently my data is pos(x,y,t,n) where n is the label of the n-th particle. I have saved all my data in a vtk file which is organized as:

# vtk DataFile Version 3.0
VTK from Matlab
BINARY

DATASET POLYDATA
POINTS 199250 double
[PROPERLY ORGANIZED BINARY COORDINATES OF THE 199250 POINTS]

以上文件可以正确导入ParaView，乍一看，我可以应用以下programmagle过滤器

The above file can be imported correctly into ParaView, and at a first glance I can apply the following programmagle filter

pdi = self.GetPolyDataInput()
pdo =  self.GetPolyDataOutput()
newPoints = vtk.vtkPoints()
numPoints = pdi.GetNumberOfPoints()

for i in range(0, numPoints):
    coord = pdi.GetPoint(i)
    x, y, z = coord[:3]
    x = x * 0.03
    y = y * 0.03
    z = z * 2
    newPoints.InsertPoint(i, x, y, z)

pdo.SetPoints(newPoints)
aPolyLine = vtk.vtkPolyLine()
aPolyLine.GetPointIds().SetNumberOfIds(numPoints)

for i in range(0,numPoints):
 aPolyLine.GetPointIds().SetId(i, i)

pdo.Allocate(1, 1)
pdo.InsertNextCell(aPolyLine.GetCellType(), aPolyLine.GetPointIds())

创建以下图形

过滤器基本上会创建一条连接其他所有点的线，但在在这种情况下，它将一个粒子轨迹的最后一个点连接到以下轨迹的第一个点。

The filter basically creates a line connecting every other point, but in my case it connects the last point of one particle trajectory to the first one of the following trajectory.

我想为每个粒子创建一个不同的多数据对象，所以我可以甚至分别给它们贴标签或上色（并消除全连接问题）。我对类似过滤器的首次猜测是

I would like to create a different polydata object for every particle, so I could even label or color them separately (and eliminate the "all-connected" issue). My first guess for a similar Filter would be

pdi = self.GetPolyDataInput()
pdo =  self.GetPolyDataOutput()
nParts = 50
newPoints = vtk.vtkPoints()
numPoints = pdi.GetNumberOfPoints()
numPointsPart = int(numPoints/nParts)

for i in range(0, numPoints):
    coord = pdi.GetPoint(i)
    x, y, z = coord[:3]
    x = x * 0.03
    y = y * 0.03
    z = z * 2
    newPoints.InsertPoint(i, x, y, z)

pdo.SetPoints(newPoints)
pdo.Allocate(nParts, 1)

for i in range(0,nParts):
  aPolyLine = vtk.vtkPolyLine()
  aPolyLine.GetPointIds().SetNumberOfIds(numPointsPart)
  indStart=int(i*numPointsPart)
  indEnd=int((i+1)*numPointsPart)
  for i in range(indStart,indEnd):
    aPolyLine.GetPointIds().SetId(i, i)
  pdo.InsertNextCell(aPolyLine.GetCellType(), aPolyLine.GetPointIds())

但是，当我运行它时，ParaView只是关闭由于段错误。奖励：代码编写正确：如果将nParts设置为1，则将获得与上述相同的图形。

However, when I run this, ParaView just closes due to segfault. Bonus: the code is written correctly: if I set nParts to 1, I get the same graph as above.

编辑：可以找到数据集此处

EDIT : the dataset can be found here

推荐答案

问题出在迭代逻辑中：

for i in range(indStart, indEnd):
    aPolyLine.GetPointIds().SetId(i, i)

更改为以下内容：

for i in range(indStart, indEnd):
    aPolyLine.GetPointIds().SetId(i - indStart, i)

原始代码调用了 SetId 具有错误的索引。另外，请注意带阴影的变量 i 。尽管这不是问题的根源，但如果在第二个 for 循环之后使用 i ，则结果可能不是您会期望的。

The original code was calling SetId with an incorrect index. Also, note the shadowed variable i. Although that's not what's causing the issue, if you use i after the second for loop, the result may not be what you'd be expecting.

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