Adjusting skymap produced by makeDiscreteSkyMap.py

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#1

Is there a way to adjust the skyMap produced by the lsstpipe task makeDiscreteSkyMap?

I’m running it through the command line task, with the usual TAN projection, and passing it a list of visit numbers as --id ccd=XX visit=YYYYYYY^ZZZZZZ etc. The input images are all of a single CCD, and nearly coaligned to the precision of the telescope tracking.

The task produces a single 2x2 patch map, with center equal to the image centre. This results in warps with mostly blank image bordering ~1/4 of the input image.

Each patch could easily fit a full CCD image. Is there a way to force makeDiscreteSkyMap to produce a 1x1 patch map instead of the 2x2 it defaults to?

Edit - the reason I want this is because for some footprints, the imageDifference task fails because it cannot find enough kernel sources in the small 1/4-ccd templates. I suspect this problem would not occur for a template containing the full ccd.

Thanks

#2

You could create a discrete skymap of your own design using makeSkyMap.py and a configuration file like the following:

config.skyMap["discrete"].raList = [1.234]  # degrees
config.skyMap["discrete"].decList = [-5.678]  # degrees
config.skyMap["discrete"].radiusList = [0.5]  # degrees
config.skyMap["discrete"].pixelScale = 0.168  # arcsec
config.skyMap.name = "discrete"
#3

Oh, and the size of the patches can be controlled via:

config.skyMap["discrete"].patchBuilder.patchInnerDimensions = (2000, 2000)  # pixels
#4

As noted by @erykoff on Slack, you could also run makeDiscreteSkyMap.py (that effectively sets the raList, decList and radiusList to cover the data) with adjusted patchInnerDimensions.

#5

Thanks for the tips @price .

I am getting the error:

makeSkyMap.py /arc/projects/NewHorizons/HSC_21_June-lsst/ --rerun /arc/projects/NewHorizons/HSC_21_June-lsst//rerun/03447_warpCompare_004 --clobber-config --configfile configs/testing_makeSkyMap_config.py

root INFO: Loading config overrride file '/opt/lsst/software/stack/stack/miniconda3-4.7.10-4d7b902/Linux64/obs_subaru/19.0.0+2/config/makeSkyMap.py'
root INFO: Loading config overrride file '/opt/lsst/software/stack/stack/miniconda3-4.7.10-4d7b902/Linux64/obs_subaru/19.0.0+2/config/hsc/makeSkyMap.py'
usage: makeSkyMap.py input [options]
makeSkyMap.py: error: cannot load config file 'configs/testing_makeSkyMap_config.py': 'DiscreteSkyMapConfig' object has no attribute 'patchBuilder'

know the solution?

#6

Will try this one out. Thanks!

#7

Oh, the patchBuilder part didn’t get added until after the 23.0 release. If you’re using LSST 23.0 then the spelling is config.skyMap["discrete"].patchInnerDimensions.

#8

Awesome. Thanks @price that got it working.

#9

I assume this is a gen2 butler and pipeline system then? In gen3 the equivalent is butler make-discrete-skymap.

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#10

Yep gen 2. We’ve avoided moving to gen 3 for the sake of maintaining consistency across the many years of this particular project.

#11

We have demonstrated parity between gen2 and gen3 pipelines.

You are likely locked into using v23 to keep gen2 support since we are currently removing chunks of gen2 functionality each week.

#12

Thanks @timj. I am aware of equivalency. I meant consistency of our codes. aka. Not having to reinvent the wheel mid-project.

#13

Hi. This method of setting the patch centres does not appear to work anymore? I get this error when setting my config up:

config.skyMap["discrete"].decList=[4.50]
config.skyMap["discrete"].radiusList=[0.0919]```
I get the error:
TypeError: 'BaseSkyMapConfig' object is not subscriptable

Which maybe indicates that the value of config.skyMap now referse to BaseSkyMapConfig setting when I attempt to run the command like so:

```butler --log-level VERBOSE make-discrete-skymap BUTLER HSC --collections F26FEB01_50_20260219 --skymap-id F26FEB01_50 --config-file makeSkyMap_config.py ```

What error am I making?   This is using pipeline version : `d_2025_10_22` 
Thanks,
JJ
#14

Hi @jjkavelaars , thank you for the question. Like you mentioned, the reason could be the version difference. I’m wondering if DM experts could help answer this? @timj @price
Also, could you try a standard release (perhaps an older one), rather than a daily/weekly release?

#15

I don’t know what butler make-discrete-skymap does, but here’s how I made a discrete skymap myself recently. I put in mySkyMap.py:

config.skyMap = "discrete"
config.skyMap["discrete"].raList=[123.456789]
config.skyMap["discrete"].decList=[87.654321]
config.skyMap["discrete"].radiusList=[0.123]

And ran:

butler register-skymap /path/to/butler -C mySkyMap.py -c name=mySkyMap
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