Ensuring consistent yaml configs for specifying the Camera to use

[jchiang87]

Currently, to switch from LsstCam to LsstComCamSim, (at least?) three entries in the yaml config need to be changed:

• The input camera to use for reading the focal plane geometry and per-amp parameters from obs_lsst:

  input.camera:  LsstComCamSim

• The tree rings file to use

  input.tree_rings.file_name: LsstComCamSim_tree_rings_2024-02-03.txt

• The optics model to use

  eval_variables.bIsComCam: True

  These can all be set independently to inconsistent values and simulations will run to completion without any warnings (though an info message regarding the tree rings file used will be emitted).

It would be great if all of this could be handled with a single config parameter, i.e.,

input.camera: LsstComCamSim

[jmeyers314]

Looking through imsim-config.yaml, I see:

output.camera: LsstCam

output.readout.bias_levels_file: LSSTCam_bias_levels_run_13421.json

input.vignetting.file_name: LSSTCam_vignetting_data.json

input.telescope.file_name: $f"LSST_{band}.yaml"

and potentially stuff like

output.nfiles: 189 # 9 for comcam

Some ideas on how to handle:

1

In galsim-config-language something like:

input.telescope.file_name: $ f"LSST_{band}.yaml" if @output.cameraName == 'LsstCam' else f"ComCam_{band}.yaml"

though that doesn't really scale past 2 cameras (maybe that's enough?).

2

Or, in imsim-config.yaml at least, shove all the camera-dependent stuff into various eval_variables and have one section uncommented for ComCam and another for LsstCam:

eval_variables:
    sband: r
    # For LSSTCam
    scameraName: LsstCam
    sopticsFileName: LSST_{band}.yaml
    inumdet: 189
    # # For ComCam
    # scameraName: LsstComCamSim
    # sopticsFileName: ComCam_{band}.yaml
    # inumdet: 9

That keeps everything related to the camera choice localized at least.

3

Or there's the approach in https://github.com/LSSTDESC/imSim/blob/main/devel-tools/vignetting/imsim-vignetting.yaml where I made a boolean config variable and used a bunch of $ ... if IsComCam else ... lower in the config. I think this makes for an uglier config, but does have the advantage that you can easily swap the camera on the command line, e.g.: galsim blah.yaml eval_variables.bIsComCam=True.

4

Haven't experimented, but you might be able to combine 2&3 with some kind of dictionary...

eval_variables:
    sband: r
    bIsComCam: False
    camera_vars: |
        dict( |
            cameraName='LsstCam', 
            opticsFileName=f'LSST_{band}.yaml', 
            numdet=189 | 
        ) if not IsComCam else |
        dict( |
            cameraName='LsstComCamSim', 
            opticsFileName=f'ComCam_{band}.yaml', 
            numdet=9 | 
        )

...
input:
    telescope:
        filename: $camera_vars['opticsFileName']

[jchiang87]

I was thinking we could have an Instrument class that serves a similar purpose as the OpsimData class in that all of the relevant info would be gathered in one place for other code to find what's needed. Doing this entirely with config-level manipulations seems confusing (to me at least) and error-prone.

[jchiang87]

A simpler approach would be to have per instrument yaml configs that just set the options relevant for each particular camera. One could then just include the config file for the desired camera, though it's not clear to me that the yaml-handling code we have is able to support this.

[jchiang87]

closed by #456