GalSim-developers/GalSim — pull request #87 by rmjarvis (2012-04-07 09:53:05+00:00)
Title: #27 Demo scripts

I think the scripts in examples/Demo.py are pretty good for the purpose of the milestone. There are three scripts. If you just do `Demo.py` (in the `examples` directory), it will run all three scripts. You can also run just the first script with `Demo.py 1`. Likewise for the other two.

The first script is intended to be about as simple as you can get. It's a circular Gaussian galaxy convolved with a circular Gaussian PSF, with a small amount of Gaussian noise.

The second script is a bit more complicated, and resembles something that we would do for testing a shear measurement pipeline. It uses an exponential profile for the galaxy, sheared a significant amount (0.1, 0.2), and convolved with a Moffat PSF. The image then adds in a sky value, adds Poisson noise, then subtracts the sky back off.

The third script includes pretty much all the effects that are in play for a real telescope. It has both atmospheric and optical components to the PSF. The galaxy is a generic Sersic profile. It has both Poisson sky noise and Gaussian read noise. And the pixels are even slightly distorted.

All three scripts make the image, write it to disk, and then run Rachel's measure_moments program on the output file. The outputs all look reasonable.

There are a few remaining issues that came up while writing the scripts that warrant further work. I've made new issues for each of them, so I think we can close out this issue now and merge the branch.