The Gradient filter estimates the gradient vector at each point or cell. It operates on any type of vtkDataSet, and the output is of the same type as the input. For unstructured grids, the gradient is computed with the cell derivatives. For structured grids, the gradient is computed using central differencing, except on the boundary of the dataset where forward and backward differencing is used for the boundary elements. If the dataset is a vtkImageData, the gradient computation at the boundaries can also be done with central differencing using a duplication of the boundary values, smoothing out the result (see ‘Boundary Method’ property).

Data Descriptors¶

BoundaryMethod

Specify how to compute the gradient on the boundaries. ‘Smoothed’ uses central differencing by duplicating the boundary values to compute the gradient on the boundary elements (corresponds to the old ‘Gradient’ filter). ‘Non-Smoothed’ uses forward/backward differencing with the values of a boundary element and its neighbor to compute the gradient (corresponds to the old ‘Gradient Of Unstructured DataSet’ filter).

ComputeDivergence

If on, the divergence of a 3-component array is computed.

If on, the gradient of the input array is computed.

ComputeQCriterion

If on, the Q-criterion of a 3-component array is computed.

ComputeVorticity

If on, the vorticity/curl of a 3-component array is computed.

ContributingCellOption

Specify which dimensions of cells should be used when computing gradient quantities. Default is to use the dataset maximum cell dimension.

Dimensionality

Specify whether to compute the gradient in two or three dimensions. In two dimensions, the X and Y dimensions are used.

DivergenceArrayName

Provide a name for the output array containing the divergence vector.

ExtensiveComputation

Use the extensive ratio during the Hyper Tree Grid gradient computation. This property only work in UNLIMITED mode.

FasterApproximation

If on, the Gradient filter will provide a less accurate (but close) algorithm that performs fewer derivative calculations (and is therefore faster). The error contains some smoothing of the output data and some possible errors on the boundary. Has no effect when performing the gradient of cell data or when the input grid is not a vtkUnstructuredGrid.

HTGMode

Specify how to compute the gradient on a Hypertree Grid. ‘Unlimited’ handles the resolution change by virtually subdividing coarser cells and eventually applyging a ratio. ‘Unstructured’ operate like the AMR like if it was an unstructured mesh, which may give a higher weight to coarser cells.

Input

Specify the input to the Gradient filter.

QCriterionArrayName

Provide a name for the output array containing the Q criterion.

ReplacementValueOption

Specify what value to use when the gradient quantities at a point cannot be computed with the selected **ContributingCellOption**.

ResultArrayName

Provide a name for the output array containing the gradient vectors.

ScalarArray

Specify the name of the scalar array from which to compute the gradient.

VorticityArrayName

Provide a name for the output array containing the vorticity vector.

Data Descriptors inherited from Proxy¶

__dict__

dictionary for instance variables (if defined)

__weakref__

list of weak references to the object (if defined)

Methods¶

Initialize = aInitialize(self, connection=None, update=True)

Methods inherited from SourceProxy¶

FileNameChanged(self)

Called when the filename of a source proxy is changed.

GetCellDataInformation(self)

Returns the associated cell data information.

GetDataInformation(self, idx=None)

This method returns a DataInformation wrapper around a vtkPVDataInformation

GetFieldDataInformation(self)

Returns the associated cell data information.

GetPointDataInformation(self)

Returns the associated point data information.

UpdatePipeline(self, time=None)

This method updates the server-side VTK pipeline and the associated data information. Make sure to update a source to validate the output meta-data.

UpdatePipelineInformation(self)

This method updates the meta-data of the server-side VTK pipeline and the associated information properties

__getitem__(self, idx)

Given a slice, int or string, returns the corresponding output port

Methods inherited from Proxy¶

GetProperty(self, name)

Given a property name, returns the property object.

GetPropertyValue(self, name)

Returns a scalar for properties with 1 elements, the property itself for vectors.

InitializeFromProxy(self, aProxy, update=True)

Constructor. Assigns proxy to self.SMProxy, updates the server object as well as register the proxy in _pyproxies dictionary.

ListProperties(self)

Returns a list of all property names on this proxy.

SetPropertyWithName(self, pname, arg)

Generic method for setting the value of a property.

__del__(self)

Destructor. Cleans up all observers as well as remove the proxy from the _pyproxies dictionary

__eq__(self, other)

Returns true if the underlying SMProxies are the same.

__getattr__(self, name)

With the exception of a few overloaded methods, returns the SMProxy method

__hash__(self)

Return hash(self).

__init__(self, **args)

Default constructor. It can be used to initialize properties by passing keyword arguments where the key is the name of the property. In addition registrationGroup and registrationName (optional) can be specified (as keyword arguments) to automatically register the proxy with the proxy manager.

__iter__(self)

Creates an iterator for the properties.

__ne__(self, other)

Returns false if the underlying SMProxies are the same.

__setattr__(self, name, value)

Implement setattr(self, name, value).