pyvista.Plotter.add_volume

Plotter.add_volume(volume, scalars=None, clim=None, resolution=None, opacity='linear', n_colors=256, cmap=None, flip_scalars=False, reset_camera=None, name=None, ambient=None, categories=False, culling=False, multi_colors=False, blending='composite', mapper=None, scalar_bar_args=None, show_scalar_bar=None, annotations=None, pickable=True, preference='point', opacity_unit_distance=None, shade=False, diffuse=0.7, specular=0.2, specular_power=10.0, render=True, user_matrix=array([[1., 0., 0., 0.], [0., 1., 0., 0.], [0., 0., 1., 0.], [0., 0., 0., 1.]]), log_scale=False, **kwargs)

Add a volume, rendered using a smart mapper by default.

Requires a 3D data type like numpy.ndarray, pyvista.ImageData, pyvista.RectilinearGrid, or pyvista.UnstructuredGrid.

Parameters:

volume3D numpy.ndarray | pyvista.DataSet

The input volume to visualize. 3D numpy arrays are accepted.

Warning

If the input is not numpy.ndarray, pyvista.ImageData, or pyvista.RectilinearGrid, volume rendering will often have poor performance.

scalarsstr | numpy.ndarray, optional

Scalars used to “color” the mesh. Accepts a string name of an array that is present on the mesh or an array with length equal to the number of cells or the number of points in the mesh. If scalars is None, then the active scalars are used.

Scalars may be 1 dimensional or 2 dimensional. If 1 dimensional, the scalars will be mapped to the lookup table. If 2 dimensional the scalars will be directly mapped to RGBA values, array should be shaped (N, 4) where N is the number of points, and of datatype np.uint8.

Scalars may be 1 dimensional or 2 dimensional. If 1 dimensional, the scalars will be mapped to the lookup table. If 2 dimensional the scalars will be directly mapped to RGBA values, array should be shaped (N, 4) where N is the number of points, and of datatype np.uint8.

climsequence[float] | float, optional

Color bar range for scalars. For example: [-1, 2]. Defaults to minimum and maximum of scalars array if the scalars dtype is not np.uint8. rng is also an accepted alias for this parameter.

If the scalars datatype is np.uint8, this parameter defaults to [0, 256].

If a single value is given, the range [-clim, clim] is used.

resolutionlist, optional

Block resolution. For example [1, 1, 1]. Resolution must be non-negative. While VTK accepts negative spacing, this results in unexpected behavior. See: pyvista #1967.

opacitystr | numpy.ndarray, optional

Opacity mapping for the scalars array.

A string can also be specified to map the scalars range to a predefined opacity transfer function. Or you can pass a custom made transfer function that is an array either n_colors in length or array, or you can pass a string to select a built in transfer function. If a string, should be one of the following:

• 'linear' - Linear

• 'linear_r' - Linear except reversed

• 'geom' - Evenly spaced on the log scale

• 'geom_r' - Evenly spaced on the log scale except reversed

• 'sigmoid' - Linear map between -10.0 and 10.0

• 'sigmoid_1' - Linear map between -1.0 and 1.0

• 'sigmoid_2' - Linear map between -2.0 and 2.0

• 'sigmoid_3' - Linear map between -3.0 and 3.0

• 'sigmoid_4' - Linear map between -4.0 and 4.0

• 'sigmoid_5' - Linear map between -5.0 and 5.0

• 'sigmoid_6' - Linear map between -6.0 and 6.0

• 'sigmoid_7' - Linear map between -7.0 and 7.0

• 'sigmoid_8' - Linear map between -8.0 and 8.0

• 'sigmoid_9' - Linear map between -9.0 and 9.0

• 'sigmoid_10' - Linear map between -10.0 and 10.0

• 'foreground' - Transparent background and opaque foreground.

  Intended for use with segmentation labels. Assumes the smallest scalar value of the array is the background value (e.g. 0).

If RGBA scalars are provided, this parameter is set to 'linear' to ensure the opacity transfer function has no effect on the input opacity values.

n_colorsint, optional

Number of colors to use when displaying scalars. Defaults to 256. The scalar bar will also have this many colors.

cmapstr | list | pyvista.LookupTable, default: pyvista.plotting.themes.Theme.cmap

If a string, this is the name of the matplotlib colormap to use when mapping the scalars. See available Matplotlib colormaps. Only applicable for when displaying scalars. colormap is also an accepted alias for this. If colorcet or cmocean are installed, their colormaps can be specified by name.

You can also specify a list of colors to override an existing colormap with a custom one. For example, to create a three color colormap you might specify ['green', 'red', 'blue'].

This parameter also accepts a pyvista.LookupTable. If this is set, all parameters controlling the color map like n_colors will be ignored.

flip_scalarsbool, optional

Flip direction of cmap. Most colormaps allow *_r suffix to do this as well.

reset_camerabool, optional

Reset the camera after adding this mesh to the scene.

namestr, optional

The name for the added actor so that it can be easily updated. If an actor of this name already exists in the rendering window, it will be replaced by the new actor.

ambientfloat, optional

When lighting is enabled, this is the amount of light from 0 to 1 that reaches the actor when not directed at the light source emitted from the viewer. Default 0.0.

categoriesbool, optional

If set to True, then the number of unique values in the scalar array will be used as the n_colors argument.

cullingstr, optional

Does not render faces that are culled. Options are 'front' or 'back'. This can be helpful for dense surface meshes, especially when edges are visible, but can cause flat meshes to be partially displayed. Defaults False.

multi_colorsbool, optional

Whether or not to use multiple colors when plotting MultiBlock object. Blocks will be colored sequentially as ‘Reds’, ‘Greens’, ‘Blues’, and ‘Grays’.

blendingstr, optional

Blending mode for visualisation of the input object(s). Can be one of ‘additive’, ‘maximum’, ‘minimum’, ‘composite’, or ‘average’. Defaults to ‘composite’.

mapperstr, optional

Volume mapper to use given by name. Options include: 'fixed_point', 'gpu', 'open_gl', and 'smart'. If None the "volume_mapper" in the self._theme is used. If using 'fixed_point', only ImageData types can be used.

Note

If a pyvista.UnstructuredGrid is input, the ‘ugrid’ mapper (vtkUnstructuredGridVolumeRayCastMapper) will be used regardless.

Note

The 'smart' mapper chooses one of the other listed mappers based on rendering parameters and available hardware. Most of the time the 'smart' simply checks if a GPU is available and if so, uses the 'gpu' mapper, otherwise using the 'fixed_point' mapper.

Warning

The 'fixed_point' mapper is CPU-based and will have lower performance than the 'gpu' or 'open_gl' mappers.

scalar_bar_argsdict, optional

Dictionary of keyword arguments to pass when adding the scalar bar to the scene. For options, see pyvista.Plotter.add_scalar_bar().

show_scalar_barbool

If False, a scalar bar will not be added to the scene. Defaults to True.

annotationsdict, optional

Pass a dictionary of annotations. Keys are the float values in the scalars range to annotate on the scalar bar and the values are the string annotations.

pickablebool, optional

Set whether this mesh is pickable.

preferencestr, optional

When mesh.n_points == mesh.n_cells and setting scalars, this parameter sets how the scalars will be mapped to the mesh. Default 'point', causes the scalars will be associated with the mesh points. Can be either 'point' or 'cell'.

opacity_unit_distancefloat, optional

Set/Get the unit distance on which the scalar opacity transfer function is defined. Meaning that over that distance, a given opacity (from the transfer function) is accumulated. This is adjusted for the actual sampling distance during rendering. By default, this is the length of the diagonal of the bounding box of the volume divided by the dimensions.

shadebool, default: False

Default off. If shading is turned on, the mapper may perform shading calculations - in some cases shading does not apply (for example, in a maximum intensity projection) and therefore shading will not be performed even if this flag is on.

diffusefloat, default: 0.7

The diffuse lighting coefficient.

specularfloat, default: 0.2

The specular lighting coefficient.

specular_powerfloat, default: 10.0

The specular power. Between 0.0 and 128.0.

renderbool, default: True

Force a render when True.

user_matrixnp.ndarray | vtk.vtkMatrix4x4, default: np.eye(4)

Matrix passed to the Volume class before rendering. This affects the actor/rendering only, not the input volume itself. The user matrix is the last transformation applied to the actor before rendering. Defaults to the identity matrix.

log_scalebool, default: False

Use log scale when mapping data to colors. Scalars less than zero are mapped to the smallest representable positive float.

**kwargsdict, optional

Optional keyword arguments.

Returns:

pyvista.Actor

Actor of the volume.

Examples

Show a built-in volume example with the coolwarm colormap.

>>> from pyvista import examples
>>> import pyvista as pv
>>> bolt_nut = examples.download_bolt_nut()
>>> pl = pv.Plotter()
>>> _ = pl.add_volume(bolt_nut, cmap="coolwarm")
>>> pl.show()

Static Scene

Interactive Scene

Create a volume from scratch and plot it using single vector of scalars.

>>> import pyvista as pv
>>> grid = pv.ImageData(dimensions=(9, 9, 9))
>>> grid['scalars'] = -grid.x
>>> pl = pv.Plotter()
>>> _ = pl.add_volume(grid, opacity='linear')
>>> pl.show()

Static Scene

Interactive Scene

Plot a volume from scratch using RGBA scalars

>>> import pyvista as pv
>>> import numpy as np
>>> grid = pv.ImageData(dimensions=(5, 20, 20))
>>> scalars = grid.points - (grid.origin)
>>> scalars /= scalars.max()
>>> opacity = np.linalg.norm(
...     grid.points - grid.center, axis=1
... ).reshape(-1, 1)
>>> opacity /= opacity.max()
>>> scalars = np.hstack((scalars, opacity**3))
>>> scalars *= 255
>>> pl = pv.Plotter()
>>> vol = pl.add_volume(grid, scalars=scalars.astype(np.uint8))
>>> vol.prop.interpolation_type = 'linear'
>>> pl.show()

Static Scene

Interactive Scene

Plot an UnstructuredGrid.

>>> from pyvista import examples
>>> import pyvista as pv
>>> mesh = examples.download_letter_a()
>>> mesh['scalars'] = mesh.points[:, 1]
>>> pl = pv.Plotter()
>>> _ = pl.add_volume(mesh, opacity_unit_distance=0.1)
>>> pl.show()

Static Scene

Interactive Scene