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(@mabula-admin)
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Joined: 6 years ago
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2nd step: 2nd degree LNC 3x (still scale 0,2x):

first test equirectangularProjection 2500stars 10pos 15neg 15pos mercator advNorm MBB50 lnc2 3x

Will now run it at scale 1.0x..

This post was modified 3 months ago by Mabula-Admin

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(@mikeabr)
Main Sequence Star Customer
Joined: 4 months ago
Posts: 36
Topic starter  

Hi Mabula,

 

Thank you for spending so much time on this, I truly appreciate it. 

So I just tried to completely replicate your settings but use (nearly) all the data I have from the other 2 nights and was greeted with this error: 

mabula settings error

Just for reference, the data was all shot at 85mm, but the first session was single 3 minute subs for each panel and similar coverage to the data you processed (I'm just trying to boost the SNR and not let that first night go to waste) and I loaded the data from that first night as individual mosaic panels just like you did in the data I provided. The only difference was I shot it on a lower MP camera, a7iii instead of A7IV. 

The second set of data I also tried to incorporate was shot on my a7iv also at 85mm just longer exposure time on the core. Again, loaded as 3 stacked and calibrated mosaic panels with a single fov. 

I used the beta version you mentioned in your comment, so aside from simply using more data than you had to work with, I changed absolutely nothing, even the reference frame is the bottom right corner like you used. 

 

Do I need to upload the additional data in order for you to troubleshoot this bug? Or am I doing something wrong? Same camera/optics is not checked.

 

EDIT: I restarted APP and it is working now, we shall see what happens!


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(@mabula-admin)
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Joined: 6 years ago
Posts: 3321
 

@mikeabr 

If you get that error, I think one of your mosaic panels has an issue and will not register to any of the other frames with those settings. Is there a panel with low star count  after star analysis?

This is the full scale result, no misalignment anywhere I think:

first test equirectangularProjection 2500stars 10pos 15neg 15pos mercator advNorm MBB50 lnc2 3x fullScale

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(@mikeabr)
Main Sequence Star Customer
Joined: 4 months ago
Posts: 36
Topic starter  

Gonna attempt to reshoot some flats to get better correction then will try stitching all of the data I have! Thank you so much for finding the optimal settings for this project, I can't wait to share the final result. 


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(@mikeabr)
Main Sequence Star Customer
Joined: 4 months ago
Posts: 36
Topic starter  

Update: I was able to correct the frames from my a7iv today decently well. Here's the result:

Before

image

After

image

 

Now I really need to be able to fix my a7iii lights. The flats I shot for that camera seem to overcorrect really badly and I get dark in the middle with bright edges. Since I no longer have that camera, I can't really reshoot them. I attempted to follow the sticky on creating an artificial flat but I can't get the tool to give me a good vignette removal... Any suggestions? I tried scaling down the a7iv master flat but APP will not allow it to be assigned to the a7iii files even with matching resolution. I can upload just a few flat frames and a light frame if that would be helpful.


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(@vincent-mod)
Universe Admin
Joined: 5 years ago
Posts: 5130
 

Did you follow the advice given below?

On all lights if you make an artificial master flat, select "create artificial flat". This will save the correction model as an artificial Master Flat. You can then use this Master Flat, just like an original master flat to correct the vignetting.

To get the most accurate result, first calibrate the lights with a master dark or master bias (create masters & assign to lights button, tab 2). Save these calibrated files (tab 2 all the way down). Then clear APP or reload APP and make the artificial flat using one of the calibrated frames (load in 1 of the calibrated lights). Then load in all the calibrated lights and add the artificial flat, calibrate again and see if that works.


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(@mikeabr)
Main Sequence Star Customer
Joined: 4 months ago
Posts: 36
Topic starter  

@vincent-mod That's exactly what I tried to do. When I try to use the tool for correcting the vignette, I do not get favorable results. I have watched tutorials on where to place the boxes (even mabula's) and just can't get a good correction. 

That aside, I am noticing that my masterflat is not being applied to my images often times. I recently shot 2 hours on cygnus with my 85mm lens, same exposure time and iso as the masterflat that I made for the mosaic project and it does not assign when I hit "re-assign masters to lights". 

 

image

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(@vincent-mod)
Universe Admin
Joined: 5 years ago
Posts: 5130
 

Mm, that must mean there is some mismatch between the masterflat and the lights. Could you share a few frames and the masterflat that shows this issue?


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(@mikeabr)
Main Sequence Star Customer
Joined: 4 months ago
Posts: 36
Topic starter  

Alright so something weird was happening, APP was not showing the proper resolution in the program for the lights. It should be 6000x4000, but Pixinsight showed 6024x4024, and APP was showing 6048x4024. Anyways, once I figured that out I resized my artificial flat (borrowed from my a7iv) and it worked quite well on some of my light frames.

I tried to correct frames from a previous session with the exact same setup and got the following errors: 

image

Does this mean my flat frame is mono for some reason? Not sure how that would have happened. I turned on debayering as suggested and it seemed to do the trick, but then...

image

I just have no clue what that means... my lights were fine, definitely not underexposed.

image

Appears to have corrected the data decently well, but when you zoom in:

image

Strange grid-like pattern. 

 

Any ideas? Seems like every time I solve a problem a new one pops up... the joys of our hobby!


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(@wvreeven)
Galaxy Admin
Joined: 4 years ago
Posts: 2035
 

@mikeabr The different sizes of the frames is because of the software you shot them with. DSLR cameras have dark strips next to the sensor which the camera software uses to determine the black spot. A sort of dark frame if you like. Some imaging software include those black strips and some don't. Let me therefore repeat an advice that we give a lot on this forum: ALWAYS take all frames (lights and calibration) with the same software!

The popup about the black and white flat possibly either originates from the image acquisition software not storing the bayer pattern in the exif data of the images or (more likely) is a result from resizing them. Forcing APP to debayer them indeed is the only solution.

The "serious data issue" popup happens because APP detects that some pixels clip after dark subtraction. This means that the signal value in those pixels in the lights have a (slightly) lower value than the corresponding pixels in the master dark. To the eye the lights may look exposed well enough but apparently there is a negative difference there between the lights and the master dark. This doesn't necessarily originate in the lights but may be caused by wrong darks/bias or a light leak (as explained in the popup). Once more, make sure to take ALL frames with the same software.

HTH, Wouter


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(@mikeabr)
Main Sequence Star Customer
Joined: 4 months ago
Posts: 36
Topic starter  

Hi,

 

I'm not sure what you mean by "Always take all frames with the same software". You mean generate all the calibration frames in the same software?

As I mentioned before, I am trying to create an artificial flat for my 6000x4000 resolution sensor from a flat I shot on my newer camera (bigger resolution). There is no way to downscale the flat (down to the exact pixel dimensions, that I'm aware of?) from within APP, which is why I was forced to resize it in PI, then PS. 

This time I resized it just in PI and didn't get any error messages but still got this: 

image

 

If there was a way to rescale in APP, I am sure this wouldn't be an issue.

 


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(@wvreeven)
Galaxy Admin
Joined: 4 years ago
Posts: 2035
 
Posted by: @mikeabr

I'm not sure what you mean by "Always take all frames with the same software". You mean generate all the calibration frames in the same software?

My bad. I didn't notice that you are using more than one camera.


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(@mikeabr)
Main Sequence Star Customer
Joined: 4 months ago
Posts: 36
Topic starter  

Any suggestions on how to resize the flat so that it works in APP without the grid issue?


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(@mikeabr)
Main Sequence Star Customer
Joined: 4 months ago
Posts: 36
Topic starter  

Any chance I can get an answer on this? All I need to finish this mosaic at this point is a way to correct my a7iii frames with an artificial flat (or figure out why my flats are overcorrecting). Sadly I no longer have that camera otherwise I'd just reshoot them.


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(@mikeabr)
Main Sequence Star Customer
Joined: 4 months ago
Posts: 36
Topic starter  

@vincent-mod @wouter-mod @mabula-admin

 

can you please let me know how I can create an artificial flat to correct this. I need to finish this project after many months. Using the built-in tool in APP doesn't correct anything at all but I am able to pretty successfully correct the lights artificially using a master flat from another camera aside from the strange grid effect after resizing. 


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(@vincent-mod)
Universe Admin
Joined: 5 years ago
Posts: 5130
 

Sorry for the delay Michael I've forwarded a request to Mabula for a good look as well


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(@mabula-admin)
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Joined: 6 years ago
Posts: 3321
 

Hi Michael @mikeabr,

The artificial flats must have the same dimension as the raw sensor dimensions since calibration is done on the whole sensor. which has dimensions of 6048x4024 in your case. For regular camera's like yours, always a raw border is removed to get the final dimensions of the image with good pixels which is then 6000x4000. That crop where the raw borders are removed is done after calibration of the data, therefor the master calibration frames must have a dimension of 6048x4024 to be able to work on your lights.

Scaling masters is never a solution to solve your issue.

I would recommend you to focus on making proper flats  instead of using an artifical flat. But if making good flats is not working at all with your camera, then the artificial flat is an option, but it will never be as good as proper flats.

Maybe the best solution for now is that you share a couple of lights, and a couple of bias or darks and I will show you how to make an artifical flat. You would a light frame with no clear object in the frame, it must contain only sky background otherwise it will be very hard to get things right.

Mabula


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(@mikeabr)
Main Sequence Star Customer
Joined: 4 months ago
Posts: 36
Topic starter  

@mabula-admin Thank you for taking the time to take a look. 

I understand that the scale must be 6048x4024, thanks for explaining that. I did rescale my master flat to that exact resolution but still get that artifact with the grid lines. Rescaling actually did still give me pretty decent results for vignette correction if it wasn't for that grid line artifact. You can see it here:

before/after

image
image

Unfortunately, I don't really have any lights without nebulosity, but you can take a look at the data as there's one shot in there without too much. 

I no longer have the camera, otherwise, I would not have to resort to any of this. At this point, I just need to do the best job of removing that vignetting as possible so I can proceed with the project. The above example should be an acceptable level of correction once everything gets stitched in the end, I just need to achieve that without the grid lines that come from importing the resized master flat.

Here are the light frames + calibration frames.

 


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(@vincent-mod)
Universe Admin
Joined: 5 years ago
Posts: 5130
 

Thanks Michael, I forwarded it to Mabula


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(@mikeabr)
Main Sequence Star Customer
Joined: 4 months ago
Posts: 36
Topic starter  

@vincent-mod @mabula-admin

I figured out how to remove the grid - I added a gaussian blur to the master flat in PS and it corrects the images just fine. Still not sure what was causing that issue but at this point it is resolved - if anyone is looking back at this thread with that issue, adding 10pixels of blur to the master flat solved it. 


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