How to create Animations

Section author: Florian Zill (Helmholtz Centre for Environmental Research GmbH - UFZ)

To demonstrate the creation of an animated plot we use a component transport example from the ogs benchmark gallery (https://www.opengeosys.org/docs/benchmarks/hydro-component/elder/).

import matplotlib.pyplot as plt
import numpy as np

import ogstools as ogs
from ogstools import examples

mesh_series = examples.load_meshseries_CT_2D_XDMF()

To read your own data as a mesh series you can do:

from ogstools.meshlib import MeshSeries
mesh_series = MeshSeries("filepath/filename_pvd_or_xdmf")

You can also use a variable from the available presets instead of needing to create your own: Variable presets and data transformation

Let’s use fixed scale limits to prevent rescaling during the animation.

ogs.plot.setup.vmin = 0
ogs.plot.setup.vmax = 100
ogs.plot.setup.dpi = 50

You can choose which timesteps to render by passing either an int array corresponding to the indices, or a float array corresponding to the timevalues to render. If a requested timevalue is not part of the timeseries it will be interpolated. In this case every second frame will be interpolated.

timevalues = np.linspace(
    mesh_series.timevalues()[0], mesh_series.timevalues()[-1], num=25
)

Now, let’s animate the saturation solution. A timescale at the top indicates existing timesteps and the position of the current timevalue. Note that rendering many frames in conjunction with large meshes might take a really long time. We can pass two functions to animate: mesh_func which transforms the mesh and plot_func which can apply custom formatting and / or plotting.

def mesh_func(mesh: ogs.Mesh) -> ogs.Mesh:
    "Clip the left half of the mesh."
    return mesh.clip("-x", [0, 0, 0])


def plot_func(ax: plt.Axes, timevalue: float) -> None:
    "Add the time to the title."
    ax.set_title(f"{timevalue/(365.25*86400):.1f} yrs", loc="center")

anim = mesh_series.animate(
    ogs.variables.saturation,
    timevalues,
    mesh_func=mesh_func,
    plot_func=plot_func,
)

Once Loop Reflect