Work with experts to identify lack of realism in the sky images

[cwwalter]

As a long term goal and as we move into data taking, we would like to make produced images after ISR look as realistic as we can. We should work with experts in camera and survey data to identify important missing or simplified features. Many issues are already listed and I have a applied a "Realism" label to them.

We can track missing or too simple features here. Features now tracked via issue include:

• Add Clouds - Add capability for specifying clouds #12
• Sky Glow time structure - Enhance sky glow and other sky structure in the ESO model. #82
• Vary sky model over sensor - Add the ability to let the sky level vary over a sensor #152
• Allow the atmospheric transmission curves to vary by airmass - Allow the atmospheric transmission curves to vary by airmass #179
• Galactic Cirrus - Add galactic cirrus to images #135
• Object opacity - GalSim #550
• Intra-cluster light - Add intra-cluster light #204
• Artifacts - Satellites etc - Add satellites / other sky artifacts #205
• Galaxy Morpology with GANs - Add an input mode for galaxies that are produced by generative models. #134

Experts who have expressed interest in working consulting on this problem include @kadrlica. Add your name to the issue if you are also interested.

[kadrlica]

Here's my hot take: I think that the end game for imSim is as a tool for simulating objects that can be embed into real LSST data. Since the timeline for DC3 may overlap heavily with SV, I think that we should focus on object realism rather that survey or image realism. Based on a semi-arbitrary gauge of what people are worried about in DES, here is my ranked list of priorities. (Note that I am not considering the difficulty of the tasks.)

Object Realism

1. Galaxy Morphology
2. Intra-cluster light
3. Object opacity
4. Galactic Cirrus

Survey Realism

1. Add Clouds
2. Vary sky model over sensor
3. Sky Glow time structure
4. Artifacts - Satellites etc