Author Topic: Stacking Milky Way Shots  (Read 519 times)

Offline Jkulin

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Stacking Milky Way Shots
« on: 2019 September 29 13:39:30 »
Hi All,

I was recently up in Scotland and captured with my Sony AR7III some Milky way Shots.

I also did my darks, flats and bias captures.

Using the batch processing script it processes everything excepts the Lights then reports "Cannot integrate less than three frames"

I've attached the log.

So I thought oh well I'll process just the one image and subtract the bias, darks and flats, nope it won't process one image, so I thought OK I'll process it all manually, nope it won't process one image.

So I am obviously doing something wrong, but can't figure out what, can anyone advise as I can see in the future when I am out doing widefield on the MW that processing a single image can be needed to remove the Bias, Darks and flats?

Many Thanks.

Offline bulrichl

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Re: Stacking Milky Way Shots
« Reply #1 on: 2019 September 30 03:36:50 »
The logfile shows that the light frames are successfully calibrated. As the image calibration (rightly) is performed on the CFA data, the calibrated files are in CFA format as well (see marked position):

[2019-09-29 20:29:09] Writing output file: F:/Captures/MW - Scotland 2019/Processed/calibrated/light/A7300222_c.xisf
[2019-09-29 20:29:09] Gaussian noise estimates:
[2019-09-29 20:29:09] s0 = 6.720e-03, n0 = 0.330 (MRS)
[2019-09-29 20:29:09] Writing image: w=7968 h=5320 n=1 Gray Float32   <===
[2019-09-29 20:29:09] 28 FITS keyword(s) embedded.
[2019-09-29 20:29:09] 8 image properties embedded.


Then StarAlignment is applied, and this cannot work: the files have to be debayered before registering!

Thus StarAlignment was not able to register the images:

*** Error:
*** Error: RANSAC: Unable to find a valid set of star pair matches.


and only one image (the reference image) is saved in the "registered" folder:

[2019-09-29 20:30:44] Writing output file: F:/Captures/MW - Scotland 2019/Processed/registered/A7300228_c_r.xisf

ImageIntegration then outputs the error message "Cannot integrate less than three frames".

As I don't use BPP I am not so familiar with it. However, there is a setting that the data will be debayered after image calibration. This must be turned on. Hope this helps.

Bernd

Offline Jkulin

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Re: Stacking Milky Way Shots
« Reply #2 on: 2019 September 30 04:08:55 »
Thanks Bernd,

I'll have a look at the debayering, as I normally use a CCD I missed that one.

Do you know a way to process just one light sub and use flats, darks and bias's?

Offline bulrichl

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Re: Stacking Milky Way Shots
« Reply #3 on: 2019 September 30 04:42:56 »
The calibration is already done and the calibrated files are saved. So just debayer the calibrated lights (*_c.xisf) in the folder   F:/Captures/MW - Scotland 2019/Processed/calibrated/light/   with the ColorSpaces/Debayer process. Bayer/Mosaic pattern is 'RGGB'. You have to 'Add files', set the Output directory and run the Debayer process by 'Apply Global'. Then you can view the debayered (*_c_d.xisf) files, if they are suitable, register them with the ImageRegistration/StarAlignment process and Integrate the registered (*_c_d_r.xisf) files with the ImageIntegration/ImageIntegration process.

Besides, it is not a good idea to use spaces in path names, that might lead to issues.

Bernd