# Paraview Sample Over Line
**URL:** https://discourse.paraview.org/t/paraview-sample-over-line/16587
**Category:** ParaView Support
**Created:** [May 8, 2025, 1:14pm UTC](https://discourse.paraview.org/t/paraview-sample-over-line/16587 "2025-05-08T13:14:15Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@Frankx9](https://discourse.paraview.org/u/Frankx9)
#### Post date: [May 8, 2025, 1:14pm UTC](https://discourse.paraview.org/t/paraview-sample-over-line/16587/1 "2025-05-08T13:14:16Z")
Hi,
what is the equivalent vtk class used in the Paraview sample over line GUI? I would like to replicate it in python with the vtk wrappers
Best
---
### Author:  [@Kenneth\_Moreland](https://discourse.paraview.org/u/Kenneth_Moreland)
#### Post date: [May 8, 2025, 1:30pm UTC](https://discourse.paraview.org/t/paraview-sample-over-line/16587/2 "2025-05-08T13:30:16Z")
Internally, ParaView is using the custom [`vtkPVProbeLineFilter`](https://gitlab.kitware.com/paraview/paraview/-/blob/master/VTKExtensions/FiltersParallelDIY2/vtkPVProbeLineFilter.h). I believe this is basically doing a [`vtkProbeFilter`](https://vtk.org/doc/nightly/html/classvtkProbeFilter.html) with a [`vtkLineSource`](https://vtk.org/doc/nightly/html/classvtkLineSource.html) but with _a lot_ of special sauce to make it work in parallel.
---
### Author:  [@Frankx9](https://discourse.paraview.org/u/Frankx9)
#### Post date: [May 8, 2025, 2:00pm UTC](https://discourse.paraview.org/t/paraview-sample-over-line/16587/3 "2025-05-08T14:00:02Z")
Thanks a lot!
It seems that I was able to find it but I am unable to locate the equivalent of `Sampling Pattern` in the vtk python wrapper where only the following methods are exposed
```auto
def CategoricalDataOff(self) -> None: ...
def CategoricalDataOn(self) -> None: ...
def ComputeToleranceOff(self) -> None: ...
def ComputeToleranceOn(self) -> None: ...
def GetCategoricalData(self) -> int: ...
def GetCellLocatorPrototype(self) -> 'vtkAbstractCellLocator': ...
def GetComputeTolerance(self) -> bool: ...
def GetFindCellStrategy(self) -> 'vtkFindCellStrategy': ...
def GetNumberOfGenerationsFromBase(self, type:str) -> int: ...
@staticmethod
def GetNumberOfGenerationsFromBaseType(type:str) -> int: ...
def GetPassCellArrays(self) -> int: ...
def GetPassFieldArrays(self) -> int: ...
def GetPassPointArrays(self) -> int: ...
def GetSnapToCellWithClosestPoint(self) -> bool: ...
def GetSource(self) -> 'vtkDataObject': ...
def GetSpatialMatch(self) -> int: ...
def GetTolerance(self) -> float: ...
def GetValidPointMaskArrayName(self) -> str: ...
def GetValidPoints(self) -> 'vtkIdTypeArray': ...
def IsA(self, type:str) -> int: ...
@staticmethod
def IsTypeOf(type:str) -> int: ...
def NewInstance(self) -> 'vtkProbeFilter': ...
def PassCellArraysOff(self) -> None: ...
def PassCellArraysOn(self) -> None: ...
def PassFieldArraysOff(self) -> None: ...
def PassFieldArraysOn(self) -> None: ...
def PassPointArraysOff(self) -> None: ...
def PassPointArraysOn(self) -> None: ...
@staticmethod
def SafeDownCast(o:'vtkObjectBase') -> 'vtkProbeFilter': ...
def SetCategoricalData(self, _arg:int) -> None: ...
def SetCellLocatorPrototype(self, __a:'vtkAbstractCellLocator') -> None: ...
def SetComputeTolerance(self, _arg:bool) -> None: ...
def SetFindCellStrategy(self, __a:'vtkFindCellStrategy') -> None: ...
def SetPassCellArrays(self, _arg:int) -> None: ...
def SetPassFieldArrays(self, _arg:int) -> None: ...
def SetPassPointArrays(self, _arg:int) -> None: ...
def SetSnapToCellWithClosestPoint(self, _arg:bool) -> None: ...
def SetSourceConnection(self, algOutput:'vtkAlgorithmOutput') -> None: ...
def SetSourceData(self, source:'vtkDataObject') -> None: ...
def SetSpatialMatch(self, _arg:int) -> None: ...
def SetTolerance(self, _arg:float) -> None: ...
def SetValidPointMaskArrayName(self, _arg:str) -> None: ...
def SnapToCellWithClosestPointOff(self) -> None: ...
def SnapToCellWithClosestPointOn(self) -> None: ...
def SpatialMatchOff(self) -> None: ...
def SpatialMatchOn(self) -> None: ...
```
Best
---
### Author:  [@Kenneth\_Moreland](https://discourse.paraview.org/u/Kenneth_Moreland)
#### Post date: [May 8, 2025, 2:35pm UTC](https://discourse.paraview.org/t/paraview-sample-over-line/16587/4 "2025-05-08T14:35:45Z")
Uh, weird. The class has `SetPoint1` and `SetPoint2` methods. I don’t know why those are not coming through in the python bindings. (They must work with the client/server bindings.)
Maybe someone who knows more about the wrapping could answer.
---
### Author:  [@Frankx9](https://discourse.paraview.org/u/Frankx9)
#### Post date: [May 9, 2025, 5:41am UTC](https://discourse.paraview.org/t/paraview-sample-over-line/16587/5 "2025-05-09T05:41:42Z")
> I believe this is basically doing a [`vtkProbeFilter`](https://vtk.org/doc/nightly/html/classvtkProbeFilter.html) with a [`vtkLineSource`](https://vtk.org/doc/nightly/html/classvtkLineSource.html) but with _a lot_ of special sauce to make it work in parallel.
After checking it is like that but I get different results when using the GUI in paraview and the vtk python bindings (Same starting and end point and same file)
GUI
python
Where the python bindings have been used as:
```auto
line = LineSource(pointa, pointb, resolution).output
alg = vtkProbeFilter() # Construct the ProbeFilter object
alg.SetInputData(line) # Set the Input data (actually the source i.e. where to sample from)
# Set the Source data (actually the target, i.e. where to sample to)
alg.SetSourceData(wrap(self._obj))
alg.SetPassCellArrays(True)
alg.SetPassPointArrays(True)
alg.SetPassFieldArrays(True)
if locator:
if isinstance(locator, str):
locator_map = {
'cell': vtkCellLocator(),
'cell_tree': vtkCellTreeLocator(),
'obb_tree': vtkOBBTree(),
'static_cell': vtkStaticCellLocator(),
}
try:
locator = locator_map[locator]
except KeyError as err:
msg = f'locator must be a string from {locator_map.keys()}, got {locator}'
raise ValueError(msg) from err
alg.SetCellLocatorPrototype(locator)
if tolerance is not None:
alg.SetComputeTolerance(False)
alg.SetTolerance(tolerance)
_update_alg(alg, progress_bar, 'Resampling array Data from a Passed Mesh onto Mesh')
return _get_output(alg), only_valid)
```
Vtk is installed as version
```auto
vtk 9.4.2
```
The issue appear to be very close to the wall region where the local resolution is higher.
Any idea?