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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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Use the minimum of image.nobjects and the number of objects available to be rendered. #463

Closed jchiang87 closed 4 months ago

jchiang87 commented 4 months ago

Mike's suggested fix seems to work. However, I don't know how to write an isolated unit test for this. The only way I can see to test it would be to run a full simulation and checking the outputs. Even running with just a couple of objects takes a long time. Suggestions welcome.

rmjarvis commented 4 months ago

I think you can use the truth catalog output to test. Case 1: instcat with say 10 objects, and output.nobjects=3 -> check that there are 3 items in the output truth catalog. Case 2: instcat with 3 objects and output.nobjects=10 -> check that there are again 3 items in the truth catalog. Case 3: instcat with 3 objects and no output.nobjects specified -> same output as case 2. And if the first 3 objects in case 1 are the same as the 3 in cases 2,3, all three output files should be identical. Both the truth catalog and image.

jchiang87 commented 4 months ago

Sure, but I think that still involves running full simulations. I was hoping there would be something that could be done to test the setting of LSST_ImageBuilder.nobjects directly for the different yaml inputs.

rmjarvis commented 4 months ago

There are ways to do that with mock, but I always prefer just running a full integration test if possible. You can make the fluxes quite small, so the run time could be very quick.