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ISS (& Mercury) Transit Processing

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#1 Aaron Small

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Posted 13 November 2019 - 10:56 PM

I was lucky enough to capture an ISS Lunar Transit this week (13 images) and also many images of the Mercury transit.  

 

What does everyone use to create those images where the track of the transiting object is seen on one image of the background object?  I assume simply stacking would fill in the 'hole' but I know there is a way to do it without cutting and pasting.



#2 JDShoots

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Posted 13 November 2019 - 11:53 PM

I strong arm it in photoshop. 

I pick the best sun or moon shot and use that as my base shot.   I open the base shot in photoshop, and then I bring in all the others in the series as new layers.  

Then I just lasso select around the object (ISS or Mercury), select inverse and hit delete.   That leaves just the little object on top.   I do that for all of them except the base and there ya go.  It was super easy for the ISS on the sun, since I only got 4 frames with the ISS crossing the sun in 0.9 seconds.   I suspect your lunar ISS will similarly be easy.   How did you get 13 frames though?  With Mercury on the other hand I had the bright idea to take a picture every 10 minutes.   So I had about 33 images to cut out.   Also, since it was drawn out over 5 hours, I had alignment issues, frame to frame, that needed minor adjustments in  Photoshop on each layer to be right on top of the base.  And on top of that the changing atmospheric conditions caused a lot of exposure variations that needed to be corrected.  It took a little longer:)  

I hope someone laughs at this and tells us about some free software out there:)  


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#3 BQ Octantis

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Posted 14 November 2019 - 08:26 AM

In Photoshop CS5:

  • File → Scripts → Load Files into Stack…
  • Change the layer mode of all layers except the bottom layer to Darken

Screen Shot 2019-11-14 at 7.20.29 AM.png

 

This also works for meteor showers, lightning storms, and physics experiments to measure gravity…just change the layer mode to Lighten.

 

Cheers,

 

BQ



#4 DubbelDerp

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Posted 14 November 2019 - 10:05 AM

For my ISS transit image, I used the "non-stellar alignment" tool in Nebulisity 4 to align all the images and then stacked them to get a more contrasty image of the moon, plus it left a slight ghost image of the ISS across the frame. Then I loaded all the aligned images and the stacked image as layers in GIMP, left the stacked image as the bottom layer, and used layer masks on each individual top layer to only show the ISS above the background image.

 

Here's my attempt:

ISS Transit Oct 8, 2019

 

Note: The top 4 ISS images were clone-stamped from the bottom left, since I had a pretty small FOV in my SCT. I thought it made a better image. The others are real captures.


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#5 t_image

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Posted 14 November 2019 - 10:29 AM

BQ's method is great.

There are planetary imaging "lucky imaging" processing that one can also use to bring out more captured detail and eliminate seeing issues as this is the culprit that reduces surface details in Solar system objects.

I suggested using those with lots of continuous shots before the transit to give you data to use for detail then composite the authentic captured transiting object on top.

 

For alignment with mount drift in an Solar/Lunar eclipse/Mercury transit I prefer rotoscoping by hand but After Effects can also do well in helping to align(lots) by using the image stabilization/object tracking feature in reverse in a composition the size of your images and importing all your images as a sequence.

 

Maybe Dubbelderp can share whether Nebulosity can help align hundreds of Mercury transit images with mount drift issues....



#6 DubbelDerp

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Posted 14 November 2019 - 10:47 AM

Maybe Dubbelderp can share whether Nebulosity can help align hundreds of Mercury transit images with mount drift issues....

 

It probably could in theory, but I'm not sure how practical it would be. I've aligned and stacked maybe a couple dozen images, and it worked fine. But it took a loooooooong time. This was on a 2011-vintage mac and a newer workstation might handle it better, but it was pretty processor intensive. ~24 RAW files from my t3i took overnight to align, whereas it took maybe a half hour with a similar number of JPG files. It did align them well, though, and the stacked image was a significant improvement over the individual frames in both cases.



#7 Aaron Small

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Posted 14 November 2019 - 08:59 PM

I was worried that the brute force method was going to be the one.  I use GIMP instead of PS but it should work very much the same (in theory).

 

JD, I was able to get ~15 fps with my Canon T5I using BackyardEOS in planetary mode.  with a 0.91s transit, I got 13 frames.  It uses the liveview feature (JPEG only unfortunately) to create individual frames or avi files.  Only way to shoot raw would have been to break out the ZWO cameras but that would have been a lot more setup and I only decided to go for it a couple hours before.  It was cold out and I had other things to do, but since my daughter decided to go with me, we did it.  She actually saw it live when it crossed the laptop screen. 

 

I got about 6400 frames total so I may use some of the lucky imaging software to see if I can get a more refined base.  Transparency wasn't the best and it smudged the clarity.

 

Thank you all for the advice! 



#8 JDShoots

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Posted 14 November 2019 - 09:55 PM

Aaron,  Cool, I didn't think of shooting jpg.  And the transit here was .67.  But it was cold, over an hour away, and windy, I bagged on it.  I look forward to seeing what you come up with.  



#9 Aaron Small

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Posted 26 November 2019 - 10:28 PM

Here is what I came up with.  This is processed in PIPP by simple conversion to B&W, normalizing and stretching the white and black points. I stacked as an animated GIF with no alignment (wasn't really needed).  It looks slightly out of focus but that is caused by the low haze I was shooting through.  A few minutes before this, it was much clearer and sharper especially around the terminator.

 

My advice is if it is about 30 minutes away (an hour would have put me off too), do it.  Don't worry about the cold and wind (maybe).  You aren't out there that long anyway and the result was worth it.

Iss transit Tv140s 100iso 960x640 20191113 21h01m45s 004243 pipp

Edited by Aaron Small, 26 November 2019 - 10:28 PM.

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#10 BQ Octantis

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Posted 27 November 2019 - 12:00 AM

Great catch!



#11 JDShoots

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Posted 27 November 2019 - 12:05 PM

Here is what I came up with.  ....

My advice is if it is about 30 minutes away (an hour would have put me off too), do it.  Don't worry about the cold and wind (maybe).  You aren't out there that long anyway and the result was worth it.

This is great, nicely done.  

I keep watching for the next "good" crossing.   This one was rather ideal, nearly full moon and a large angular size on the station.   I hope another comes up soon near me.  



#12 Aaron Small

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Posted 05 December 2019 - 12:57 PM

BQ Octantis took my GIF and performed post processing on it.  This is the result using his process described above.  I am encouraged to spend some time on training and tutorials as BQ's experience truly shows.  Thanks, BQ!

 

Msg 273658 0 98893500 1574831120



#13 Ron359

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Posted 05 December 2019 - 10:16 PM

I captured this ISS transit back in Sept. 13, full moon.   I used Affinity Photo (Mac), Focus stacking feature to stack the 9 or 10 frames with the ISS.  I used a Canon 7D II shooting 10 fps.  

 

All you do is select and load the ten image files with the ISS and hit the enter and it takes less than 30sec. to stack, if I remember right, - it was very short anyway.  No layers, no other processing unless you want to sharpen or otherwise adjust exposure etc. Since a transit only takes about 1 sec. you don't have to worry about aligning the moon or sun in each frame.   Hoping to catch another transit in a few days if the weather cooperates.  

 

 

 

 

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  • ISS-MoonTransit-91319-small.jpg



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