QuickView

Using QuickView in Py-SPHViewer

QuickView is the simplest way to produce images with Py-SPHViewer. In this example, we’ll demonstrate its use.

We will create an image of a dark matter halo extracted from a cosmological simulation. Before starting the tutorial, please download this file.

You can read the file content using the h5py library:

import h5py

with h5py.File('dm_halo.h5py', 'r') as f:
    pos = f['Coordinates'][:]

The coordinates of the dark matter particles are in Mpc/h, tracing the density field of a collapsed dark matter halo from a cosmological simulation. Our goal is to visualize the projected density field.

Below is the xy projection of the particle distribution:

We can calculate (and visualize) the projected density field using QuickView:

from sphviewer.tools import QuickView
qv = QuickView(pos, r='infinity', plot=False)
qv.imshow()

The argument r='infinity' tells the camera to render the scene using a parallel (or orthographic) projection, as if viewed from infinity.

QuickView retrieves the active axis and places the image on it, while plot=False suppresses automatic plotting. The imshow method can be used to display the image. Valid **kwargs are the same as those accepted by matplotlib.pyplot.imshow. For instance, we can modify the colormap and vmax as shown:

qv.imshow(cmap="gist_stern", vmax=2)

You can also retrieve the image generated by QuickView:

img = qv.get_image()
extent = qv.get_extent()
fig = plt.figure(1, figsize=(7,7))
plt.imshow(img, extent=extent, cmap='gist_stern')