[vtkusers] Question to use the vtkStreamTracer

[kenichiro yoshimi]

Hi,

You need to call setActivectors on the point data:
reader.GetOutput().GetPointData().SetActiveVectors('velocity')

Regards
2018年10月30日(火) 7:27 Yu Zhou <zhouyu at live.com>:
>
> Hello,
>
>
> I have a problem with vtkStreamTracer.
>
> Here is the code:
>
>
> ```
>
> def generate_streamline(source_file, dest_file, axis, resolution=1):
>     reader = vtk.vtkXMLImageDataReader()
>     reader.SetFileName(source_file)
>     reader.GetPointDataArraySelection().DisableArray('density')
>     reader.Update()
>     extent = reader.GetOutput().GetExtent()
>     center = [np.mean(extent[0:2]), np.mean(extent[2:4]), np.mean(extent[4:6])]
>
>     seeds = vtk.vtkPointSource()
>     seeds.SetCenter(center)
>     seeds.SetRadius(10.5)
>     seeds.SetNumberOfPoints(100)
>     seeds.Update()
>
>     streamTracer = vtk.vtkStreamTracer()
>     streamTracer.SetInterpolatorTypeToDataSetPointLocator()
>     streamTracer.SetInputData(reader.GetOutputDataObject(0))
>     streamTracer.SetSourceData(seeds.GetOutputDataObject(0))
>     streamTracer.SetIntegratorTypeToRungeKutta45()
>     streamTracer.SetMaximumPropagation(104)
>     streamTracer.SetInitialIntegrationStep(0.2)
>     streamTracer.SetMaximumIntegrationStep(0.5)
>     streamTracer.SetIntegrationDirectionToBoth()
>     streamTracer.SetStartPosition(center)
>     streamTracer.SurfaceStreamlinesOn()
>     streamTracer.Update()
>
>     print(streamTracer.GetOutputDataObject(0))
>
> ```
>
> The output is:
> ```
>
> vtkPolyData (0x273ece0)
>   Debug: Off
>   Modified Time: 2638
>   Reference Count: 2
>   Registered Events: (none)
>   Information: 0x2ccb540
>   Data Released: False
>   Global Release Data: Off
>   UpdateTime: 2680
>   Field Data:
>     Debug: Off
>     Modified Time: 2628
>     Reference Count: 1
>     Registered Events: (none)
>     Number Of Arrays: 0
>     Number Of Components: 0
>     Number Of Tuples: 0
>   Number Of Points: 0
>   Number Of Cells: 0
>   Cell Data:
>     Debug: Off
>     Modified Time: 2636
>     Reference Count: 1
>     Registered Events:
>       Registered Observers:
>         vtkObserver (0x2ccc370)
>           Event: 33
>           EventName: ModifiedEvent
>           Command: 0x2ccb880
>           Priority: 0
>           Tag: 1
>     Number Of Arrays: 0
>     Number Of Components: 0
>     Number Of Tuples: 0
>     Copy Tuple Flags: ( 1 1 1 1 1 0 1 1 )
>     Interpolate Flags: ( 1 1 1 1 1 0 0 1 )
>     Pass Through Flags: ( 1 1 1 1 1 1 1 1 )
>     Scalars: (none)
>     Vectors: (none)
>     Normals: (none)
>     TCoords: (none)
>     Tensors: (none)
>     GlobalIds: (none)
>     PedigreeIds: (none)
>     EdgeFlag: (none)
>   Point Data:
>     Debug: Off
>     Modified Time: 2638
>     Reference Count: 1
>     Registered Events:
>       Registered Observers:
>         vtkObserver (0x2ccc210)
>           Event: 33
>           EventName: ModifiedEvent
>           Command: 0x2ccb880
>           Priority: 0
>           Tag: 1
>     Number Of Arrays: 0
>     Number Of Components: 0
>     Number Of Tuples: 0
>     Copy Tuple Flags: ( 1 1 1 1 1 0 1 1 )
>     Interpolate Flags: ( 1 1 1 1 1 0 0 1 )
>     Pass Through Flags: ( 1 1 1 1 1 1 1 1 )
>     Scalars: (none)
>     Vectors: (none)
>     Normals: (none)
>     TCoords: (none)
>     Tensors: (none)
>     GlobalIds: (none)
>     PedigreeIds: (none)
>     EdgeFlag: (none)
>   Bounds:
>     Xmin,Xmax: (1, -1)
>     Ymin,Ymax: (1, -1)
>     Zmin,Zmax: (1, -1)
>   Compute Time: 2692
>   Number Of Points: 0
>   Point Coordinates: 0
>   Locator: 0
>   Number Of Vertices: 0
>   Number Of Lines: 0
>   Number Of Polygons: 0
>   Number Of Triangle Strips: 0
>   Number Of Pieces: 1
>   Piece: 0
>   Ghost Level: 0
> ```
>
> And I get an empty vtkPolyData without any streamline in it.
>
> Attached please find the testing dataset.
>
>
> Please help me.
>
>
> Thanks,
>
>
> Joey
>
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