Auto-Aligning AIA and HMI Data During Plotting#
This example shows how to auto-align two images with different reference frames during plotting.
Here we use the optional keyword
autoalign when calling Map’s
plot() method. The reference frames are defined by
the respective World Coordinate System (WCS) information.
See Aligning AIA and HMI Data with Reproject for an alternate approach to image alignment, where one of the maps is modified prior to plotting, and thus is available for purposes other than plotting.
import matplotlib.pyplot as plt
import astropy.units as u
We use the AIA image and HMI image from the sample data. For the HMI map, we use the special HMI color map, which expects the plotted range to be -1500 to 1500.
Plot both images side by side. Note that the HMI image is oriented “upside down” relative to the AIA image.
<matplotlib.image.AxesImage object at 0x7f5fa06c3b80>
autoalign=True allows plotting the HMI image onto axes
defined by the AIA reference frame. In contrast to the above code
block, we intentionally set the
projection for the axes to be
the AIA map instead of the HMI map. We also need to manually set
the plot limits because Matplotlib gets confused by the off-disk
parts of the image. The HMI image now has the same
orientation as the AIA image.
Note that off-disk HMI data are not retained by default because an
additional assumption is required to define the location of the HMI
emission in 3D space. We can use
retain the off-disk HMI data. See
Reprojecting Using a Spherical Screen
for more reference.
(-0.5, 1023.5, -0.5, 1023.5)
We can directly plot them over one another, by setting the transparency of the HMI plot.
Total running time of the script: (0 minutes 6.184 seconds)