Archive 2016 · Astro Pano landscapes - Basics for merging sky with land from panos

dereksurfs
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p.1 #1 · p.1 #1 · Astro Pano landscapes - Basics for merging sky with land from panos

Hi All,

Have you seen those beautiful astro pano shots showing a full Milky Way done with multiple frames? Some cover 180 degree field of view. Lonelyspec has a good article on his blog. That is what I am attempting to learn.

I am looking for guidance on merging sky from a mosaic pano with land including lessons learned. Also, if you know of any online articles or how-to guides it would be greatly appreciated.

I'm starting with the most basic astro mosaic and then hoping to branch out from there - more frames for sky, land, etc.... So, this initial exercise simply consists of:

* Three frame vertical pano (horizontal orientation) including land.

* One longer exposure frame for the foreground for greater detail and lower noise. This is identically aligned (initially) with the first frame of the pano:

https://photos.smugmug.com/Seascapes/Big-Sur-II/i-JHqBRkp/0/XL/05Sep16_2482c3-XL.jpg

I've combined the three frames in Photoshop using Photomerge. Once merged, the original images become somewhat skewed in the process. So, the initial challenges / questions are:

1. Where to select the best place to join the brighter land frame with the sky? The logical place would seem to be the land line (mountains, trees, rocks, etc...).

2. Alignment! These are never aligned after performing pano merges. See screenshot.

In my simple example the single land frame (rocks, stars) does not align with full pano mosaic after stitching - its skewed. I've attempted using the 'Transform' tool on the foreground in PS to manually align with the pano (same rock structures). However, it is far from precise and most likely not the best approach.

Before wasting countless hours on trial, error and guess work, I thought I would ask those 'in the know' with experience doing these sorts of merges. I've seen what some of you guys are doing with much more complex cases including merging many, many sky and land frames. For astro trackers with land blurring it becomes even more challenging/complex to merge with the static land frames. Hence, I want to start as simple as possible and then learn and grow from there.

3. Smooth, natural looking Transitions from land to sky. Normally, when I merge images together at differing exposures (bright land/dark sky), I feather transitions to look more natural. However, this cannot be done with stars since they are not perfectly aligned from one frame (land) to the next (starry sky).

https://photos.smugmug.com/Forums/Forum-2016/n-SdCg3Q/i-fXF8cx6/0/X2/i-fXF8cx6-X2.png

Any lessons learned from your own experiences and process are greatly appreciated.

Thanks in advance,

Derek

Edited on Sep 11, 2016 at 10:05 PM · View previous versions

Sep 10, 2016 at 02:23 PM

JimFox
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p.1 #2 · p.1 #2 · Astro Pano landscapes - Basics for merging sky with land from panos

Hey Derek,

2 quick thoughts.

First I don't use a pano creating tool usually for star shots. Usually I am just blending them in by hand.

I will start with the ground layer that looks best as my base layer, I will expand the canvas on it to make room on the top for more sky (stars)

Then I will lay in my star shot I took that had just a little land at the bottom, and blend it just above the horizon as you suggested. I like it because typically there is some haze there, and it makes it easy to blend in the sky. Since the angle of the camera changed, I will use the Warp tool to stretch the bottom of the star layer to match with the base layer.

Often that is all I will do. But if I decide to have gone with more stars, I simply do the same manual blend with the next set of stars. Using the warp tool and blend to fit it in and match it up.

Ideally, I am taking the majority of my star shots with just one shot. Using either light painting or timing the shot to use a weaker moon light to light up the ground.

Jim

Sep 10, 2016 at 09:12 PM

dereksurfs
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p.1 #3 · p.1 #3 · Astro Pano landscapes - Basics for merging sky with land from panos

Hey Jim,

Thanks for that explanation of your process. I like the idea of starting with base layer and then working up from there. I guess I was trying the reverse without as much luck. You definitely gave me good food for thought! So its back to the drawing board with hopefully a more workable approach.

Thanks again,
Derek

Sep 10, 2016 at 10:10 PM

jforkner
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p.1 #4 · p.1 #4 · Astro Pano landscapes - Basics for merging sky with land from panos

When you used Photomerge, which option did you choose? Auto? Perspective? Cylindrical? etc. Try cylindrical if you didn't already.

How much overlap of the merged frames are you allowing?

I assume you shot all the frames containing sky at about the same time (within a few minutes) and with the same aperture, ISO, & shutter speed?

Is it possible to post the frames in Dropbox or such so we can see them and/or try to create the image you’re after?

I seldom have alignment problems with Photomerge—only time was with 2 rows of 7 frames each. Not sure what to recommend without seeing the files. I've had a lot of success using Photomerge with 6-7-panel panos of the MW.

Jack

Sep 10, 2016 at 10:58 PM

dereksurfs
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p.1 #5 · p.1 #5 · Astro Pano landscapes - Basics for merging sky with land from panos

jforkner wrote:
When you used Photomerge, which option did you choose? Auto? Perspective? Cylindrical? etc. Try cylindrical if you didn't already.

How much overlap of the merged frames are you allowing?

I assume you shot all the frames containing sky at about the same time (within a few minutes) and with the same aperture, ISO, & shutter speed?

Is it possible to post the frames in Dropbox or such so we can see them and/or try to create the image you’re after?

I seldom have alignment problems with Photomerge—only time was with 2 rows of 7 frames each. Not sure what to recommend without seeing the...Show more →

Hi Jack,

Thanks for the reply. However, my primary question does not have to due with photomerge itself (overlapping files, etc...) but rather the inclusion of a single brighter foreground frame after the entire darker pano scene has already been created/merged successfully (three shots). So, if you look at the first image I posted above, that's the brighter foreground frame which I am attempting to 'overlay' on the vertical pano as the screenshot below it shows. Regarding the images, the bottom two bracketed frames are identical in every way except for exposure time and ISO, one being brighter. That's the one I am trying to include (post pano merge) to enhance the foreground of the darker overall pano scene.

In response to your other questions, yes, everything was the same in the three pano frames with the addition of the brighter (bracketed) foreground image. If you've ever shot a MW landscape with a foreground that was too dark which is almost always the case (unless light painting), the extra lighter bracketed frame is the one used to brighten the overall scene.

The challenge is bringing the two together - lighter foreground image (beach & rocks in this case) with starry background pano in a smooth, natural way. I don't know of any automated process that will do that well. Note that the stars go all the down to the edge of the foreground rocks. So its not a simple blending processing or basic pano merge. If they were somehow perfectly aligned (dark and light frame) it would be easier.

Because I am rather new to this type of astro pano shot, I know there is most likely an easier/better way to approach things. Since you asked, I have uploaded the original TIFF files (3 darks, 1 light) for anyone to give it go. Maybe it will be easier to see the challenges once you attempt to combine them. Thanks for any further input you can provide regarding your process.

Astro TIFF Files

Derek

Sep 11, 2016 at 06:43 PM

dgdg
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p.1 #6 · p.1 #6 · Astro Pano landscapes - Basics for merging sky with land from panos

I took a quick stab at it. The foreground and sky would need more processing, but I think it does blend.

Usually for seaside milky way, I would use a gradient mask to combine the two. The gradient mask preserves the atmospheric haze on the horizon. I think for the limited horizon, the gradient mask does not work as well.

Here is what I did for the example image below. I only used your first two images, the dark and light images which are identically composed. You can always add more sky.
Before you do any blending, process the sky exactly how you like it. Increase your image canvas and move over the other two sky images. Use a color picker at the boundaries to merge the seams. Once you finish your sky, the foreground adjustments are made relative to the finished sky portion.
I took the dark image and put a color picker 5x5 dropper on the darkest part of the sea on the right side. There is a darkish band slightly below the horizon.
I went to the light image and put a color picker in the same place. I used levels on each color channel separately to make that dark part of the ocean just below the horizon the same. Open the Info tab and watch the color picker channel levels. Now the light image looks dark again. That's ok.
I created a mask on the light image using the quick selection tool to catch just the foreground.
Now you have the dark sky with the light foreground. The foreground is too dark, but the data is there.
I created a duplicate layer of the light image and deleted it's quick selection mask. Instead I created a luminence mask and pushed it such that the rocks were all white, but the sea was a little grey in places. I used a curve adjustment on this layer (not the mask) to bring the rocks back up without affecting the sea as much.
I cleaned up the light image luminence mask using a brush in overlay mode since the luminence mask allowed the star trails to show through. Overlay mode won't affect pure black or white regions, but works well for removing grey.
There was a small dark band on the horizon in the sea which was exaggerated.
I fine tuned the light image horizon mask, mostly below the horizon, with 20% opacity 50% flow brush to smooth the exaggerated transition. It could still use a little tweaking to soften it further with cloning or partial opacity mask edits. I'd probably use a partial opacity clone stamp on a merged layer to smooth the sea horizon.
I didn't process the sky at all. Your example above looks very nice, but it does look slightly out of focus.
The long exposure of the foreground is creating some posterization effect in the water. Ideally you'd take the foreground shot during mid twilight for less noise.

Hope this gives you some other thoughts for pp.
Color pickers and the info tab to guide level adjustments.
Quick selection and luminence masks.
Partial opacity, partial flow brush tweaks to masks where transitions need a little softening.

David

http://davidsphotography.zenfolio.com/img/s7/v157/p51232258-5.jpg

A little brighter foreground
http://davidsphotography.zenfolio.com/img/s5/v131/p169850692-5.jpg

Edited on Sep 11, 2016 at 09:57 PM · View previous versions

Sep 11, 2016 at 09:32 PM

dereksurfs
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p.1 #7 · p.1 #7 · Astro Pano landscapes - Basics for merging sky with land from panos

dgdg wrote:
I did a quick stab at it. The foreground would need more processing, but I think it does blend.

Usually for seaside milky way, I would use a gradient mask to combine the two. The gradient mask preserves the atmospheric haze on the horizon. I think for the limited horizon, the gradient mask does not work as well.

Here is what I did for the example image below. I only used your first two images, the dark and light images which are identically composed. You can always add more sky.
Before you do any blending, process the sky exactly how you like it. The foreground adjustments are made relative to the finished sky portion.
I took the dark image and put a color picker 5x5 dropper on the darkest part of the sea on the right side. There is a darkish band slightly below the horizon.
I went to the light image and put a color picker in the same place. I used levels on each color channel separately to make that dark part of the ocean just below the horizon the same. Now the light image looks dark again. That's ok.
I created a mask on the light image using the quick selection tool to catch just the foreground.
Now you have the dark sky with the light foreground. The foreground is too dark, but the data is there.
I created a duplicate layer of the light image and deleted it's quick selection mask. Instead I created a luminence mask and pushed it such that the rocks were all white, but the sea was a little grey in places. I used a curve adjustment on this layer (not the mask) to bring the rocks back up without affecting the sea as much.
I cleaned up the light image mask using a brush in overlay mode since the luminence mask allowed the star trails to show through.
There was a small dark band on the horizon in the sea which is exaggerated.
I fine tuned the light image horizon mask with 20% opacity 50% flow brush to smooth the exaggerated transition. It could still use a little tweaking to soften it further with cloning or partial opacity mask edits. I'd probably use a partial opacity clone stamp on a merged later to smooth the sea horizon.
I didn't process the sky at all. Your example above looks very nice, but it does look slightly out of focus.
The long exposure of the foreground is creating some posterization effect in the water. Ideally you'd take the foreground shot during mid twilight for less noise.

Hope this gives you some other thoughts for pp.
Color pickers and the info tab to guide level adjustments.
Quick selection and luminence masks.
Partial opacity, partial flow brush tweaks to masks where transitions need a little softening.

David

http://davidsphotography.zenfolio.com/img/s7/v157/p51232258-5.jpg

A little brighter foreground
http://davidsphotography.zenfolio.com/img/s5/v131/p169850692-5.jpg...Show more →

Hi David,

I really like you've done with this for the lower land frame of the pano, especially in the brighter version.

Now, try to merge that frame with the sky frames. That is really what my primary question is all about: How to merge a brighter land frame with an astro Mosaic Pano (multiple frames above the land frame). I started with this simple example (3 vertical pano frames) as an exercise to focus on the process of merging with the lower land frame. I think my title may not have been clear enough. So, I added the word pano to it. Thanks for giving it a go.

Derek

Sep 11, 2016 at 09:56 PM

dgdg
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p.1 #8 · p.1 #8 · Astro Pano landscapes - Basics for merging sky with land from panos

I took two bright frames and merged the sky. You can still see a mild transition.

You would take identical border regions of sky and use color pickers.
Then use levels on one to match.
Move one image onto the other and increase canvas size.
With one create a mask and fill it black.
Then comes the endless tweaking to further blend the transition. You can partially opacify the mask edits. You can use a clone stamp with partial opacity too. Most of the transition is gone with a quick edit.
You can use dodge and burn tool too.
The seam on the right looks better since that is where I placed my color pickers. The seam on the right is still there some. I'd be tempted to split the image up and have more pickers on the right since the light is uneven.

You just have to keep fiddling with it. I have one image where I had to add a small strip of sky on the far left of the frame and it took me a while to smooth it well. I spent five minutes on this blend. On my image with the strip it probably took me an hour going back and forth.

Have you tried ptgui?
RobDickinson does a ton of multi image milky way pano shots. They are seamless. You may want to PM him.

http://davidsphotography.zenfolio.com/img/s5/v132/p912553443-5.jpg

Sep 11, 2016 at 10:26 PM

jforkner
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p.1 #9 · p.1 #9 · Astro Pano landscapes - Basics for merging sky with land from panos

Derek,

Here’s what I did:
1. Adjusted all images in ACR to bring-out as much detail as possible.
2. Blended images 82 & 83—masked off the sky from the foreground & used a layer mask to blend. Saved result as PSD-file.
3. Created pano from above PSD-file & image 85. Didn’t need image 84—that’s why I asked about overlap.
4. Used Dfine (Nik Plugin) for noise reduction.
5. Used control points in Viveza2 (Nik Plugin) to bring-out MW detail.
6. Used Macphun Intensify Pro to sharpen.
7. Used action to reduce star size.

Result is below. I did note the sky seemed OOF—rock & foreground were sharp. I like the composition—looks like volcano exploding.

Jack

PLEASE UNDERSTAND...THIS IS NOT MY PHOTOGRAPH! I MERELY REPROCESSED IT.

http://www.caltel.com/~jforkner/Untitled_Panorama1.jpg

Sep 12, 2016 at 10:58 AM

dereksurfs
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p.1 #10 · p.1 #10 · Astro Pano landscapes - Basics for merging sky with land from panos

jforkner wrote:
Derek,

Here’s what I did:
1. Adjusted all images in ACR to bring-out as much detail as possible.
2. Blended images 82 & 83—masked off the sky from the foreground & used a layer mask to blend. Saved result as PSD-file.
3. Created pano from above PSD-file & image 85. Didn’t need image 84—that’s why I asked about overlap.
4. Used Dfine (Nik Plugin) for noise reduction.
5. Used control points in Viveza2 (Nik Plugin) to bring-out MW detail.
6. Used Macphun Intensify Pro to sharpen.
7. Used action to reduce star size.

Result is below. I did note the sky seemed OOF—rock & foreground were sharp. I like the composition—looks like volcano exploding.

Jack

PLEASE UNDERSTAND...THIS IS...Show more →

Wow, Jack! Thanks so much. I'm really impressed with what you've done. Now I need to carefully review your process and figure how to do it myself.

In addition I love all the extra tweaks/adjustments including reducing star size. Gotta run to dinner for now. But I'll be back for further review of the steps.

Thanks again!

Derek

Sep 12, 2016 at 08:15 PM

Kane Engelbert
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p.1 #11 · p.1 #11 · Astro Pano landscapes - Basics for merging sky with land from panos

My astro workflow somewhat mirrors the instructions provided by Jim Fox. I always start with the Star image as my base layer and I usually add a bunch of canvas above and below so the next image can be placed and moved around to taste. Next i take the foreground subject exposure and place it on top of the star image and move to taste as noted earlier. you can play around with the opacity bar to ensure its placed well. Next I'll create another layer, then use the quick selection tool/refine edge to mask off the foreground, next Invert the selection tool, and hand blend in the background stars around the foreground object. Hand blending well is the key and may take some time . Next merge the images and crop excess canvas.

I noticed in your first post you were trying to use photo merge to merge two different sized images together? The star image is clearly larger vs the Seasick image. If you upsize your sea stack image to match your star image dimensions I bet it aligns well and stitches beautifully.

Sep 13, 2016 at 10:43 AM


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