Extract Topography

class PVGeo.grids.subset.ExtractTopography(op='underneath', tolerance=0.001, offset=0.0, invert=False, remove=False)[source]

Bases: FilterBase

This filter takes two inputs: any mesh dataset and a set of points for a topography source. This will add a boolean data array to the cell data of the input grid on whether that cell should be active (under topographic layer). A user can also choose to directly extract the data rather than appending a boolean scalar array via the remove argument.

  • op (str, int, or callable) – The operation as a string key, int index, or callable method

  • tolerance (float) – buffer around the topography surface to include as part of the decision boundary

  • offset (float) – static value to shift the reference topography surface

  • ivert (bool) – optional to invert the extraction.

  • remove (bool) – Optional parameter to apply a thresholding filter and return a vtkUnstructuredGrid object with only the extracted cells. The remove option is only available in Python environments (not available in ParaView). The remove flag must be set at the time of instantiation of this algorithm. This does not actually update the algorithm’s output data object but applies a PyVista threshold filter to pass a new data object after calling apply.


This currently ignores time varying inputs. We can implement time variance but need to think about how we would like to do that. Should the topography surface be static and the volumetric data have time variance?

FillInputPortInformation(port, info)[source]

This simply makes sure the user selects the correct inputs

RequestData(request, inInfo, outInfo)[source]

Used by pipeline to generate output

RequestDataObject(request, inInfo, outInfo)[source]

Constructs the output data object based on the input data object

static _intersection(topo_points, data_points, tolerance)[source]

Extract cells intersecting the topography surface

static _query(topo_points, data_points)[source]

Queries the data points for their closest point on the topography surface

static _underneath(topo_points, data_points, tolerance)[source]

Extract cells underneath the topography surface

apply(data, points)[source]

Run the algorithm on the input data using the topography points

static get_operation(idx)[source]

Gets a extraction operation based on an index in the keys


the operation method

Return type:


static get_operation_names()[source]

Gets a list of the extraction operation keys


the keys for getting the operations

Return type:


static get_operations()[source]

Returns the extraction operation methods as callable objects in a dictionary


Get the tolerance threshold for the querry


Sets the boolean flag on whether to invert the extraction.


Sets how far off (in Z dir) to slice the data


Set the type of extraction to perform.


op (str, int, or callable) – The operation as a string key, int index, or callable method


This can accept a callable method to set a custom operation as long as its signature is <callable>(self, topo_points, data_points) and it strictly produces an integer array of zeros and ones.


Set the tolerance threshold for the querry