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LSSTDESC / imSim

GalSim based Rubin Observatory image simulation package
https://lsstdesc.org/imSim
BSD 3-Clause "New" or "Revised" License
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Build a parameterized optical model with Batoid to use for fast simulations. #122

Open cwwalter opened 6 years ago

cwwalter commented 6 years ago

Currently the mapping between pupil coordinates and focal plane coordinates (Stored in obs_lsstSim?) is a fit to a grid of points simulated going through the optics with PhoSim. The result is a sum of Zernike polynomials fitted to PhoSim centroid files which apply a dx, dy shift on top of the naive solution. This info is taken from discussion with @danielsf so he should make any corrections.

Because of this, direct comparisons between PhoSim and imSim will not be completely independent when it comes to these features and we can't test them against each other. If we want to remove this commonality, we could redo the fit with the LSST Zemax model or use @jmeyers314 's "batoid" raytracing code which will eventually give us a optical ray trace model option in imSim (#10).

cwwalter commented 5 years ago

This issue (and AOS related response) should be handled with Batoid in #10.

cwwalter commented 4 years ago

I am re-titleing this rather old issue. We can use it to follow up on the discussion we began in the imSim technical meeting. With #10 will have a full raytraced optical model with Batoid.

However, we would still like to have a parameterized model for the cases where we would rather run more quickly and a parameterized model is fine. This likely includes fast tests of various pieces of our pipeline. When the old sims code is removed the old parameterization made by Scott will need to be replaced with a a model we build with Batoid.

We have started a technical discussion of how to best approach this

For example we could build WCS from Batoid (A good 6 month student project!)

[Note: if we go the WCS route this is also connected to other sky / FP transforms such as nutation/precession/proper motion/parallax etc. We need to consider where each of these pieces really best belong.]

Use this issue for further discussion.