Quick Advices to Work with the new SpectrophotometricColorCalibration tool

vicent_peris

vicent_peris

Administrator
Staff member
Hi,

I replied to a message in the official announcement thread the below text. Since I consider these three advices could be very useful for the users who want to experiment with SPCC, I'm posting them here as a sticky thread:
  • First, download Gaia DR3/SP database. If you don't want to download the big database (220 million stars), you can download the small one (30 million stars). To configure it, go to Process Explorer > Astrometry > Gaia. In the Preferences button of the Gaia tool (bottom right of its user interface), select the Gaia DR3/SP in the Data release dropdown; then, push the Select button to select the database files from your disk. Please note that the Gaia DR3 database is still needed for the plate solving, since it has 1.8 billion stars with their positions and proper motions.

  • Both PCC and SPCC are independent of the astrometric solving process. We decided to move this process to the preprocessing stage where it can be easily integrated and automated with WBPP. This means that in most cases you will be able to forget this work. If you want to apply PCC or SPCC to an image without an astrometric solution, just go to menu SCRIPT > Image Analysis > ImageSolver. Configure approximate coordinates of center, approximate date, focal length and pixel size (divide pixel size by 2 in case you used drizzle x2) and check the Distortion Correction checkbox.

  • Both PCC and SPCC will only work with linear images. Don't apply the process after stretching.

  • SPCC is not only a valid tool for the specific set of filters and cameras listed in the tool. In any case we advice you to use SPCC instead of PCC. Even in the case you select a different set of filters / sensors you are currently using, you will get always a better color calibration than in PCC/APASS. This is mostly thanks to the Gaia spectrophotometric catalog, which is game changer. Don't see you filters / camera listed? Open the Curve Explorer in SPCC and navigate the curve list to find which curves are more similar to the ones you're using.
We're are already developing new learning resources for you. Be patient, please, we're working hard to have it ready as soon as possible.

Enjoy. Best regards,

Vicent.
 
Where do you download Gaia DR3/SP . Went to Gaia website but there are so many different options
 
Looking at the documentation, I see there is an option to import filter data in the filter management dialog.

I use an Optolong L Extreme filter with my ASI2600MC pro camera, so I think I need to import the data for that in CSV format in order to get accurate color calibration using SPCC. Where can I find such data for my filter? (I looked on the Optolong website, but couldn't find it).

Here are my current settings in SPCC. Only the L Pro is currently showing, not the L Extreme
1669226838745.png
 
Hi Stuart,

The Altair Triband and Quadband and Skytech Light Pro are also no there. I'm not sure the information needed is generally available. I think we probably just have to wait and hope they are added at some stage.

Chees, Jim
 
JST200 said:
Hi Stuart,

The Altair Triband and Quadband and Skytech Light Pro are also no there. I'm not sure the information needed is generally available. I think we probably just have to wait and hope they are added at some stage.

Chees, Jim
Click to expand...
thanks. So does this mean my SPCC will not be accurate?
 
Hi Stuart,

Define accurate! ?

Just using the normal "Average Piral Galaxy", with no additional Filter selected will give an "accurate" result. But perhaps just not as accurate as it could be.

Just for info, using the default SPC and PCC settings, I have seen no pixel level difference between SPC and PCC. Perhaps something that we will change as we come to understand the power of SPC?

Cheers, Jim
 
Although the Optolong L-Pro is on the "Curve Explorer" (CE) list, it is not obvious (from the documentation) how to use it. Is this the correct process:
  • in CE, find and select the best match to your camera R filter
  • in CE, find and Ctrl-click the Optolong L-Pro ("PAN") filter
  • click on the
    1669232389356.png
    icon to combine and create and name a new combined R filter
  • repeat for G and B filters
  • select the combined filters from the R, G, B dropdowns
 
The .csv format is in the documentation (and the .xspd schema looks fairly self-explanatory - no sneaky embedded checksums or anything). So if you can find a filter curve anywhere you can import it quite easily yourself.
 
Is anyone having problems running SPCC just with WBPP? Says there is no astrometric solution. If I run ImageSolver on the same data, SPCC runs?

I am stacking separate RBG files in WBPP and creating the linear RGB with Channel Combo:

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

SpectrophotometricColorCalibration: Processing view: Image09

Writing swap files...

6937.735 MiB/s

*** Error: The image has no valid astrometric solution: Image09

Reading swap files...

11374.786 MiB/s

<* failed *>
 
jerryyyyy said:
Is anyone having problems running SPCC just with WBPP? Says there is no astrometric solution. If I run ImageSolver on the same data, SPCC runs?

I am stacking separate RBG files in WBPP and creating the linear RGB with Channel Combo:

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

SpectrophotometricColorCalibration: Processing view: Image09

Writing swap files...

6937.735 MiB/s

*** Error: The image has no valid astrometric solution: Image09

Reading swap files...

11374.786 MiB/s

<* failed *>
Click to expand...
Hy @jerryyyyy,
You've lost the astrometric solution somewhere in your initial processing steps since the image you're calibrating with SPCC does not contain an astrometric solution. Either run the ImageSolver script to regenerate it or ensure you've checked the Astrometric Solution checkbox in WBPP.

Looking at the image's id Image09, I guess that you've done some manual processing before applying SPCC; keep in mind that only channel combination and channel extraction preserve the astrometric solution; if you manually cropped the images or you've applied ABE/DBE generating a new image instead of replacing the master then you lose the astrometric solution that has to be regenerated.
 
I'm guessing for a dual narrowband like the L-Ultimate it's better to be in narrow band mode with the wavelengths and bandpasses set? Probably close enough I'd imagine.
 
robyx said:
Hy @jerryyyyy,
You've lost the astrometric solution somewhere in your initial processing steps since the image you're calibrating with SPCC does not contain an astrometric solution. Either run the ImageSolver script to regenerate it or ensure you've checked the Astrometric Solution checkbox in WBPP.

Looking at the image's id Image09, I guess that you've done some manual processing before applying SPCC; keep in mind that only channel combination and channel extraction preserve the astrometric solution; if you manually cropped the images or you've applied ABE/DBE generating a new image instead of replacing the master then you lose the astrometric solution that has to be regenerated.
Click to expand...
The main problem was solved, not checking the box, but there seems to be some problem with getting the astronomic solution when checked. I looked into this and it seems you call the ImageSoved in both WBPP and SPCC. ImageSolver seems to default to "Automatic limit Magnitude", which seems to be the cause of the iterations that never end... if I just set to 12, it works.

2022-11-25 23_08_52-PixInsight.jpg
 
Hi, all this is solved. Have been running the new WBPP and getting the plate solves on each master and then when combined into RGB, they are corrected with SPCC... seems tedious... but works.

I fixed all my dependencies to solve on the local machine correctly and to not automatically limit magnitude on SPCC.

I do have a complaint that WBPP does not seem to keep the check box for automatic image integration. Every time I re-open, have to re-check.
 
robyx said:
Hy @jerryyyyy,
You've lost the astrometric solution somewhere in your initial processing steps since the image you're calibrating with SPCC does not contain an astrometric solution. Either run the ImageSolver script to regenerate it or ensure you've checked the Astrometric Solution checkbox in WBPP.

Looking at the image's id Image09, I guess that you've done some manual processing before applying SPCC; keep in mind that only channel combination and channel extraction preserve the astrometric solution; if you manually cropped the images or you've applied ABE/DBE generating a new image instead of replacing the master then you lose the astrometric solution that has to be regenerated.
Click to expand...
I was getting the same thing. The Astrometry box in WBPP was definitely checked. I ran the Image Plate Solver script and it sees the correct RA & Dec and the Focal Length and Pixel Size are both correct. I clicked OK and then ran SCC again. This time I didn't get the "no astrometry data" error but got the the ones in the attached screen shot. I had already downloaded the small package of gdr3sp files and placed them in the same folder that holds the gedr3 and apass files.

I'm not sure what to do next.
 

Attachments

  • astrometry.png
    astrometry.png
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You should select the Local Database folder, but you have to define this in the GAIA process where the GAIA DR3 files are located.

Cheers
Tom
 
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