Assembling a Meteor Shower Composite

Started Sep 7, 2015 | Discussions
RustierOne
RustierOne Veteran Member • Posts: 4,312
Assembling a Meteor Shower Composite
1

Assembling a Meteor Shower Composite

What follows is the method I have used to assemble a number of separate images containing meteors into a single composite image with all the meteors properly arranged. While this is likely elementary to those skilled in using the software, for those like myself who are unfamiliar with the process, I wanted to document the steps involved. I’m using an old copy of Photoshop Elements 2.0, but other similar photo editing programs with layers capability could be used. So here’s what to do:

Preprocessing

  1. Sort through all your images from a single meteor shower to find the ones containing meteors to be included in the composite.
  2. For each frame with a meteor, process to taste with your favorite photo editing program, endeavoring to have each image processed alike, particularly background sky darkness. I use Adobe Lightroom for preprocessing.

Assemble the Composite

  1. Choose your base image upon which all meteor images will be copied. This can even be an image without any meteors, that was shot with the lens stopped down for improved star images.
  2. In Photoshop open the base layer image.
  3. Open the next meteor-containing image in a separate window.
  4. Choose the Rectangle Marquee Tool from the palette of available tools, and select a portion of the image containing the meteor along with some key bright stars (to be used for aligning the layers).
  5. From the menu bar choose Edit then > Copy.
  6. Highlight the base layer window. Select Edit > Paste. The second image will show as another layer in the layers tab of the base image.
  7. In the layers tab, select the second layer, click opacity and set opacity to 50%.
  8. With the second layer still selected choose the Move Tool. Then move and rotate the second layer so that the stars in both layers are aligned over each other.
  9. When the stars in each layer are coincident, select the Lasso Tool. Using your mouse draw a line closely around the meteor, excluding as much of the sky and background stars as possible.
  10. In the Select Menu choose Inverse. This selects everything except the meteor you just Lassoed.
  11. Press the Delete Key to delete everything except the meteor.
  12. In the Select Menu choose Deselect to remove the Lasso line you had drawn.
  13. In the Layers Menu (not the layers tab) select Merge Down. This will combine the two layers into one, adding the meteor to the base image.
  14. Close (without saving) the separate window containing the meteor you just added, keeping the base layer window open.
  15. Repeat steps 3-14 for each additional meteor to be added to the base layer.
  16. When all meteors have been added to the base layer, save in a high quality format.

Post Processing

Process the composite image to taste, using your favorite image processing program.

So that's the process I use. Likely in more recent versions of Photoshop the process will be a bit different. But the same principals should apply. If any more experienced Photoshop users have some suggestions, they would be most welcome.

-- hide signature --

Best Regards,
Russ

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Rutgerbus Senior Member • Posts: 1,974
Re: Assembling a Meteor Shower Composite

very helpful information. Thanks for that. I assume that the images all have to be taken from the same part of sky to do a star-align and that it is not possible to make a panel of multiple parts of the night sky.

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RustierOne
OP RustierOne Veteran Member • Posts: 4,312
Re: Assembling a Meteor Shower Composite

Rutgerbus wrote:

very helpful information. Thanks for that. I assume that the images all have to be taken from the same part of sky to do a star-align and that it is not possible to make a panel of multiple parts of the night sky.

For the technique described there needs to be considerable overlap in all images for forming the composite.

But you've raised a good point about combining minimally overlapping images in a larger composite. I'm not sure of the utility of that unless using multiple cameras all shooting simultaneously. In that case you could use something like Microsoft ICE (Image Composite Editor) to combine the images with meteors in different parts of the sky.

I have used ICE, which works very quickly in producing a composite. Here are some examples from August 29, 2000, elevation ~8000 feet (2440 meters):

Milky Way from Perseus to Sagittarius

Here are a couple of crops from the above:

Milky Way from Perseus to Aquila

Milky Way from Cepheus to Scutum

No meteors in these. But they show the capabilities of ICE. All base images were made using Kodak PJ400 Ektapress film with a Mamiya-Sekor 55mm lens, f/1.4 @ f/2.8, 15-20 minute exposures.

-- hide signature --

Best Regards,
Russ

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rnclark Senior Member • Posts: 2,790
Re: Assembling a Meteor Shower Composite
1

This is very close to my work flow, with a couple of exceptions, below.

RustierOne wrote:

Assembling a Meteor Shower Composite

What follows is the method I have used to assemble a number of separate images containing meteors into a single composite image with all the meteors properly arranged. While this is likely elementary to those skilled in using the software, for those like myself who are unfamiliar with the process, I wanted to document the steps involved. I’m using an old copy of Photoshop Elements 2.0, but other similar photo editing programs with layers capability could be used. So here’s what to do:

Preprocessing

  1. Sort through all your images from a single meteor shower to find the ones containing meteors to be included in the composite.
  2. For each frame with a meteor, process to taste with your favorite photo editing program, endeavoring to have each image processed alike, particularly background sky darkness. I use Adobe Lightroom for preprocessing.

Assemble the Composite

  1. Choose your base image upon which all meteor images will be copied. This can even be an image without any meteors, that was shot with the lens stopped down for improved star images.
  2. In Photoshop open the base layer image.
  3. Open the next meteor-containing image in a separate window.
  4. Choose the Rectangle Marquee Tool from the palette of available tools, and select a portion of the image containing the meteor along with some key bright stars (to be used for aligning the layers).
  5. From the menu bar choose Edit then > Copy.
  6. Highlight the base layer window. Select Edit > Paste. The second image will show as another layer in the layers tab of the base image.
  7. In the layers tab, select the second layer, click opacity and set opacity to 50%.
  8. With the second layer still selected choose the Move Tool. Then move and rotate the second layer so that the stars in both layers are aligned over each other.
  9. When the stars in each layer are coincident, select the Lasso Tool. Using your mouse draw a line closely around the meteor, excluding as much of the sky and background stars as possible.

It is better to select just outside the meteor and feather the edge.

  1. In the Select Menu choose Inverse. This selects everything except the meteor you just Lassoed.
  2. Press the Delete Key to delete everything except the meteor.
  3. In the Select Menu choose Deselect to remove the Lasso line you had drawn.
  4. In the Layers Menu (not the layers tab) select Merge Down. This will combine the two layers into one, adding the meteor to the base image.

I prefer to keep the meteors on a separate later in case they need further adjustment to match intensities. By this I mean I put all meteors on a single meteor later.

You forgot an important step: change layer opacity back to 100%.

Then instead of using normal layer type, change the layer type to "lighten." If you keep the layer type normal, if the sky has changed between the 2 exposures, the lower intensities may not match well. If you have the layer type as lighten and with a feathered edge, then it it will blend nicely with the background.

Roger

  1. Close (without saving) the separate window containing the meteor you just added, keeping the base layer window open.
  2. Repeat steps 3-14 for each additional meteor to be added to the base layer.
  3. When all meteors have been added to the base layer, save in a high quality format.

Post Processing

Process the composite image to taste, using your favorite image processing program.

So that's the process I use. Likely in more recent versions of Photoshop the process will be a bit different. But the same principals should apply. If any more experienced Photoshop users have some suggestions, they would be most welcome.

-- hide signature --

Best Regards,
Russ

W5JCK
W5JCK Senior Member • Posts: 2,669
Re: Assembling a Meteor Shower Composite

That is similar to what I do Russ. If you have Photoshop, then you can use Adobe Camera Raw to open all the images containing a meteor into a single file and place each in its own layer. However, if the image files are large the newly created file will be exceptionally large, so there is a limit. I recommend PP the files first, then downsize them to a useful size. A full size 6000 x 4000 px file with dozens of layers will be pushing the limits of Photoshop. But if the files are downsized to 1920 x 1080 px then Photoshop, and your computer, can handle the job much easier.

I would like to use a tracking mount to keep the stars aligned in all of the images. This year I took my tracker along but clouds obscured Polaris when I was trying to set up, so I just went with a static mount instead. However, it is possible to use an alignment program like DSS or Nebulosity to align the images. No need to stack as they would likely filtered out the meteors. But at least with Nebulosity, and I assume DSS too, you can align the images and set it to save each one in the aligned position. Once you have that done, it is much easier to layer them together.

Here is a time lapse video I put together using the aligned and saved images (created in Nebulosity) from my static mount shoot. The stars are decently aligned, but as is expected the FOV changes with the earth's rotation. And this is the composite I made using the same images from the time lapse to layer in the aligned meteors.

Too bad we don't have many more meteor showers like the Perseids where we could practice these different techniques and ideas. I only get one or two showers of note to shoot per year, so not much practice time! I definitely need to find darker skies though as the location I've been using has gotten much brighter in the past year with the addition of over a dozen nearby natural gas wells that light up the sky.

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RustierOne
OP RustierOne Veteran Member • Posts: 4,312
Re: Assembling a Meteor Shower Composite

rnclark wrote:

This is very close to my work flow, with a couple of exceptions, below.

Thanks, Roger for taking the time and effort to look at my work flow and give a detailed reply. I was hoping that someone who knows how to do this would offer suggestions.

RustierOne wrote:

Assembling a Meteor Shower Composite

What follows is the method I have used to assemble a number of separate images containing meteors into a single composite image with all the meteors properly arranged. While this is likely elementary to those skilled in using the software, for those like myself who are unfamiliar with the process, I wanted to document the steps involved. I’m using an old copy of Photoshop Elements 2.0, but other similar photo editing programs with layers capability could be used. So here’s what to do:

Preprocessing

  1. Sort through all your images from a single meteor shower to find the ones containing meteors to be included in the composite.
  2. For each frame with a meteor, process to taste with your favorite photo editing program, endeavoring to have each image processed alike, particularly background sky darkness. I use Adobe Lightroom for preprocessing.

Assemble the Composite

  1. Choose your base image upon which all meteor images will be copied. This can even be an image without any meteors, that was shot with the lens stopped down for improved star images.
  2. In Photoshop open the base layer image.
  3. Open the next meteor-containing image in a separate window.
  4. Choose the Rectangle Marquee Tool from the palette of available tools, and select a portion of the image containing the meteor along with some key bright stars (to be used for aligning the layers).
  5. From the menu bar choose Edit then > Copy.
  6. Highlight the base layer window. Select Edit > Paste. The second image will show as another layer in the layers tab of the base image.
  7. In the layers tab, select the second layer, click opacity and set opacity to 50%.
  8. With the second layer still selected choose the Move Tool. Then move and rotate the second layer so that the stars in both layers are aligned over each other.
  9. When the stars in each layer are coincident, select the Lasso Tool. Using your mouse draw a line closely around the meteor, excluding as much of the sky and background stars as possible.

It is better to select just outside the meteor and feather the edge.

I noticed that there is a feathering option. So I'll look into how to include that in selecting the meteor. I would expect that feathering would make differences in background less noticeable.

Yesterday when making another try at my composite I noticed a better way to select the meteor via the Lasso Tool. Before I had been free-hand drawing a line with the mouse, something that is very hard to do. But the polygon option with the Lasso Tool allows snapping a straight line between points, right along the edge of the meteor - much cleaner. Live and learn.

  1. In the Select Menu choose Inverse. This selects everything except the meteor you just Lassoed.
  2. Press the Delete Key to delete everything except the meteor.
  3. In the Select Menu choose Deselect to remove the Lasso line you had drawn.
  4. In the Layers Menu (not the layers tab) select Merge Down. This will combine the two layers into one, adding the meteor to the base image.

I prefer to keep the meteors on a separate later in case they need further adjustment to match intensities. By this I mean I put all meteors on a single meteor later.

It looks like maybe the automatic spell correction struck again. By this do you mean that all meteors are copied onto a single layer? Or does each meteor reside on its own layer?

You forgot an important step: change layer opacity back to 100%.

Wow! Yes, an important step indeed. I wondered why the meteors looked so lackluster.

Then instead of using normal layer type, change the layer type to "lighten." If you keep the layer type normal, if the sky has changed between the 2 exposures, the lower intensities may not match well. If you have the layer type as lighten and with a feathered edge, then it it will blend nicely with the background.

So if I get this right, the meteor layer (with feathered meteors) is changed to a "lighten" type. At what stage do you merge all the layers down to the background layer? Is it preferable to "merge down" or "flatten"?

I hope my old Photoshop Elements 2.0 has the options you refer to. If not I may be getting a more modern version. I'm wanting to buy a scanner to scan some old medium format B/W negatives. I'm looking at an Epson V600 which comes with Photoshop Elements (for Windows and Mac). Right now I'm running PSE 2.0 on an old Windows XP laptop. It's one of my only Windows programs. So it will be nice getting PSE for the Mac. I do most of my post processing on the Mac with Lightroom 5.

This all shows how unskilled I am using layers in Photoshop.

Roger

Thanks again for the help Roger. You have added a lot to the forum. And it is appreciated.

  1. Close (without saving) the separate window containing the meteor you just added, keeping the base layer window open.
  2. Repeat steps 3-14 for each additional meteor to be added to the base layer.
  3. When all meteors have been added to the base layer, save in a high quality format.

Post Processing

Process the composite image to taste, using your favorite image processing program.

So that's the process I use. Likely in more recent versions of Photoshop the process will be a bit different. But the same principals should apply. If any more experienced Photoshop users have some suggestions, they would be most welcome.

-- hide signature --

Best Regards,
Russ

-- hide signature --

Best Regards,
Russ

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RustierOne
OP RustierOne Veteran Member • Posts: 4,312
Re: Assembling a Meteor Shower Composite

W5JCK wrote:

That is similar to what I do Russ. If you have Photoshop, then you can use Adobe Camera Raw to open all the images containing a meteor into a single file and place each in its own layer. However, if the image files are large the newly created file will be exceptionally large, so there is a limit. I recommend PP the files first, then downsize them to a useful size. A full size 6000 x 4000 px file with dozens of layers will be pushing the limits of Photoshop. But if the files are downsized to 1920 x 1080 px then Photoshop, and your computer, can handle the job much easier.

So is Adobe Camera Raw a separate program or part of Photoshop? Up to now I've been pre-processing in Lightroom and exporting as high quality JPEG. I don't think my old PS Elements 2.0 can handle RAWs. But I'll check into that. Thanks for the tips.

I would like to use a tracking mount to keep the stars aligned in all of the images. This year I took my tracker along but clouds obscured Polaris when I was trying to set up, so I just went with a static mount instead. However, it is possible to use an alignment program like DSS or Nebulosity to align the images. No need to stack as they would likely filtered out the meteors. But at least with Nebulosity, and I assume DSS too, you can align the images and set it to save each one in the aligned position. Once you have that done, it is much easier to layer them together.

Here is a time lapse video I put together using the aligned and saved images (created in Nebulosity) from my static mount shoot. The stars are decently aligned, but as is expected the FOV changes with the earth's rotation. And this is the composite I made using the same images from the time lapse to layer in the aligned meteors.

Too bad we don't have many more meteor showers like the Perseids where we could practice these different techniques and ideas. I only get one or two showers of note to shoot per year, so not much practice time! I definitely need to find darker skies though as the location I've been using has gotten much brighter in the past year with the addition of over a dozen nearby natural gas wells that light up the sky.

Yeah, I hear you regarding the few strong meteor showers. The only other one besides the Perseids is the Geminids in December. While that one is the strongest shower of the year, it happens during the time of year when weather almost always ruins the show. But it's worth a try if weather cooperates.

-- hide signature --

Best Regards,
Russ

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t_wade Contributing Member • Posts: 914
Re: Assembling a Meteor Shower Composite

Russ,

Excellent tutorial.  Just to add one more step to the excellent advice Roger gave, I use the rotate tool too.  Keep in mind the radiant moves through the night so the meteors orientation rotates with it.  I try to get the meteor as close as I can to the correct star-field, and then I rotate it to align with the radiant.  I use the background image for the current location of the radiant.  If the radiant is not visible in the background image, I use an off-screen point derived from several meteors to calculate where it should be.

The APOD on August 25 really annoys me because the author did not rotate the meteors to the actual Perseid radiant.  To me, it appears all these meteors are sporadics when in fact they are Perseids.  It would have been an exceptional image if the author had rotated the meteors to the actual Perseid radiant at the time of the background image.  I guess I'm just too hardcore.

Wade

rnclark Senior Member • Posts: 2,790
Re: Assembling a Meteor Shower Composite

RustierOne wrote:

rnclark wrote:

This is very close to my work flow, with a couple of exceptions, below.

Thanks, Roger for taking the time and effort to look at my work flow and give a detailed reply. I was hoping that someone who knows how to do this would offer suggestions.

RustierOne wrote:

Assembling a Meteor Shower Composite

What follows is the method I have used to assemble a number of separate images containing meteors into a single composite image with all the meteors properly arranged. While this is likely elementary to those skilled in using the software, for those like myself who are unfamiliar with the process, I wanted to document the steps involved. I’m using an old copy of Photoshop Elements 2.0, but other similar photo editing programs with layers capability could be used. So here’s what to do:

Preprocessing

  1. Sort through all your images from a single meteor shower to find the ones containing meteors to be included in the composite.
  2. For each frame with a meteor, process to taste with your favorite photo editing program, endeavoring to have each image processed alike, particularly background sky darkness. I use Adobe Lightroom for preprocessing.

Assemble the Composite

  1. Choose your base image upon which all meteor images will be copied. This can even be an image without any meteors, that was shot with the lens stopped down for improved star images.
  2. In Photoshop open the base layer image.
  3. Open the next meteor-containing image in a separate window.
  4. Choose the Rectangle Marquee Tool from the palette of available tools, and select a portion of the image containing the meteor along with some key bright stars (to be used for aligning the layers).
  5. From the menu bar choose Edit then > Copy.
  6. Highlight the base layer window. Select Edit > Paste. The second image will show as another layer in the layers tab of the base image.
  7. In the layers tab, select the second layer, click opacity and set opacity to 50%.
  8. With the second layer still selected choose the Move Tool. Then move and rotate the second layer so that the stars in both layers are aligned over each other.
  9. When the stars in each layer are coincident, select the Lasso Tool. Using your mouse draw a line closely around the meteor, excluding as much of the sky and background stars as possible.

It is better to select just outside the meteor and feather the edge.

I noticed that there is a feathering option. So I'll look into how to include that in selecting the meteor. I would expect that feathering would make differences in background less noticeable.

Yesterday when making another try at my composite I noticed a better way to select the meteor via the Lasso Tool. Before I had been free-hand drawing a line with the mouse, something that is very hard to do. But the polygon option with the Lasso Tool allows snapping a straight line between points, right along the edge of the meteor - much cleaner. Live and learn.

  1. In the Select Menu choose Inverse. This selects everything except the meteor you just Lassoed.
  2. Press the Delete Key to delete everything except the meteor.
  3. In the Select Menu choose Deselect to remove the Lasso line you had drawn.
  4. In the Layers Menu (not the layers tab) select Merge Down. This will combine the two layers into one, adding the meteor to the base image.

I prefer to keep the meteors on a separate later in case they need further adjustment to match intensities. By this I mean I put all meteors on a single meteor later.

It looks like maybe the automatic spell correction struck again. By this do you mean that all meteors are copied onto a single layer? Or does each meteor reside on its own layer?

I put all the meteors on one layer, but keep that layer separate from the sky layer. This way, in case there is a problem with merging, I can fix it easier.

You forgot an important step: change layer opacity back to 100%.

Wow! Yes, an important step indeed. I wondered why the meteors looked so lackluster.

Then instead of using normal layer type, change the layer type to "lighten." If you keep the layer type normal, if the sky has changed between the 2 exposures, the lower intensities may not match well. If you have the layer type as lighten and with a feathered edge, then it it will blend nicely with the background.

So if I get this right, the meteor layer (with feathered meteors) is changed to a "lighten" type. At what stage do you merge all the layers down to the background layer? Is it preferable to "merge down" or "flatten"?

I have learned to keep the layers in my nightscapes all the way to the final image. So in my Perseid nightscape image, I have 3 layers:
meteors, sky and land. I make 3 versions of the final image:
photoshop PSD with layers as the main file, a 16-bit flattened tiff, and an 8-bit flattened sRGB jpeg at highest quality. To make smaller versions, e.g. for print or web, I start with the 16-bit tiff. If I need to make a correction to a new version, I start with the psd and make a new psd file.

I hope my old Photoshop Elements 2.0 has the options you refer to. If not I may be getting a more modern version. I'm wanting to buy a scanner to scan some old medium format B/W negatives. I'm looking at an Epson V600 which comes with Photoshop Elements (for Windows and Mac). Right now I'm running PSE 2.0 on an old Windows XP laptop. It's one of my only Windows programs. So it will be nice getting PSE for the Mac. I do most of my post processing on the Mac with Lightroom 5.

My understanding is elements does not do 16-bits/channel editing. That is important when doing the big stretches with astrophotos.

Roger

rnclark Senior Member • Posts: 2,790
Re: Assembling a Meteor Shower Composite

RustierOne wrote:

W5JCK wrote:

So is Adobe Camera Raw a separate program or part of Photoshop? Up to now I've been pre-processing in Lightroom and exporting as high quality JPEG. I don't think my old PS Elements 2.0 can handle RAWs. But I'll check into that. Thanks for the tips.

Adobe Camera Raw is a separate program, but is bundled with photoshop and lightroom. You can't buy it separately (I wish you could).

rnclark Senior Member • Posts: 2,790
Re: Assembling a Meteor Shower Composite

t_wade wrote:

Excellent tutorial. Just to add one more step to the excellent advice Roger gave, I use the rotate tool too. Keep in mind the radiant moves through the night so the meteors orientation rotates with it. I try to get the meteor as close as I can to the correct star-field, and then I rotate it to align with the radiant. I use the background image for the current location of the radiant. If the radiant is not visible in the background image, I use an off-screen point derived from several meteors to calculate where it should be.

The radiant position among the stars moves very little from night to night, and thus within the few hours the radiant is up in early morning, it moves even less. This page lists the daily motion:
http://popastro.com/meteor/reference/meteorshowers/

The Perseid radiant moves only 5.6 RA minutes and 0.2 degrees in Dec per day. So in the 6 or so hours the radiant is up, it would move 1/4 those numbers.

Maybe you are seeing position projection differences due to curvature of the trajectory from the wide angle lens?

Roger

RustierOne
OP RustierOne Veteran Member • Posts: 4,312
Re: Assembling a Meteor Shower Composite

t_wade wrote:

Russ,

Excellent tutorial. Just to add one more step to the excellent advice Roger gave, I use the rotate tool too. Keep in mind the radiant moves through the night so the meteors orientation rotates with it. I try to get the meteor as close as I can to the correct star-field, and then I rotate it to align with the radiant. I use the background image for the current location of the radiant. If the radiant is not visible in the background image, I use an off-screen point derived from several meteors to calculate where it should be.

Thanks, Wade. I wasn't aware of having a separate rotate tool. But in my old PS Elements the Move tool allows for rotation as well. For my composite there was a lot of rotation to account for in the almost 4 hours of imaging. My sub-images were untracked, centered on the North Celestial Pole. I didn't try to rotate the meteors to project back to any radiant point. I just made the background stars in each meteor image match the stars in the base (background) layer. When that was done, the sporadic meteors were obvious. As for shower members, I don't believe that all of them come exactly from the radiant no matter how it moves from day to day. It would seem that even for Perseids there will be a bit of variation in radiant point. In my opinion (and I'm certainly no expert here) that if the background stars are made to match, that's the path the meteor actually took, regardless of the proper radiant point.

The APOD on August 25 really annoys me because the author did not rotate the meteors to the actual Perseid radiant. To me, it appears all these meteors are sporadics when in fact they are Perseids. It would have been an exceptional image if the author had rotated the meteors to the actual Perseid radiant at the time of the background image. I guess I'm just too hardcore.

Nothing hardcore there, Wade. We just want to get them all oriented correctly.

-- hide signature --

Best Regards,
Russ

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RustierOne
OP RustierOne Veteran Member • Posts: 4,312
Re: Assembling a Meteor Shower Composite

rnclark wrote:

RustierOne wrote:

rnclark wrote:

This is very close to my work flow, with a couple of exceptions, below.

[Some text omitted]

You forgot an important step: change layer opacity back to 100%.

Wow! Yes, an important step indeed. I wondered why the meteors looked so lackluster.

Then instead of using normal layer type, change the layer type to "lighten." If you keep the layer type normal, if the sky has changed between the 2 exposures, the lower intensities may not match well. If you have the layer type as lighten and with a feathered edge, then it it will blend nicely with the background.

So if I get this right, the meteor layer (with feathered meteors) is changed to a "lighten" type. At what stage do you merge all the layers down to the background layer? Is it preferable to "merge down" or "flatten"?

I have learned to keep the layers in my nightscapes all the way to the final image. So in my Perseid nightscape image, I have 3 layers:
meteors, sky and land. I make 3 versions of the final image:
photoshop PSD with layers as the main file, a 16-bit flattened tiff, and an 8-bit flattened sRGB jpeg at highest quality. To make smaller versions, e.g. for print or web, I start with the 16-bit tiff. If I need to make a correction to a new version, I start with the psd and make a new psd file.

I hope my old Photoshop Elements 2.0 has the options you refer to. If not I may be getting a more modern version. I'm wanting to buy a scanner to scan some old medium format B/W negatives. I'm looking at an Epson V600 which comes with Photoshop Elements (for Windows and Mac). Right now I'm running PSE 2.0 on an old Windows XP laptop. It's one of my only Windows programs. So it will be nice getting PSE for the Mac. I do most of my post processing on the Mac with Lightroom 5.

My understanding is elements does not do 16-bits/channel editing. That is important when doing the big stretches with astrophotos.

I seldom use Photoshop for any post processing of astrophotos, preferring to use Lightroom. But since the latter doesn't have layering capabilities needed for the meteor shower, I have reverted to PSE. I hope the lack of 16 bit stretches isn't too much of a problem with meteor showers.  For regular astrophotography I do have a commercial license for PixInsight which does work in 32-bit when called upon to do so.

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Russ

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W5JCK
W5JCK Senior Member • Posts: 2,669
Re: Assembling a Meteor Shower Composite

If you have PS and open a RAW file then ACR is the app wherein the initial window opens the RAW file and gives you a bunch of sliders to adjust the file. Since LR uses ACR also, though more covertly, it has much the same adjustments that can be made. Once you get through that initial open window for a RAW file, the file is shifted to and opened with PS. If you know how to use Adobe Bridge, which ships with PS, you can use it to open TIFFs and JPEGs where they too will initially pop up in ACR giving you the ability to do LR style adjustments before it opens in PS. Adobe Bridge also allows you to open multiple files as layers in a single PS document. I don't think PSE gives you direct access to Adobe Bridge or Adobe Camera RAW.

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W5JCK, amateur radio operator
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t_wade Contributing Member • Posts: 914
Re: Assembling a Meteor Shower Composite

Roger,

The Perseid radiant moves only 5.6 RA minutes and 0.2 degrees in Dec per day. So in the 6 or so hours the radiant is up, it would move 1/4 those numbers.

You are absolutely correct; however, just like any star in the sky, the radiant moves approximately 1 degree every 4 minutes. I have always had to adjust the rotation angle just a bit on every meteor except those within several minutes of the time of the background shot.

Maybe you are seeing position projection differences due to curvature of the trajectory from the wide angle lens?

This is likely the main cause. Perhaps, it also has to do with the radiant not being a point source too. Or perhaps it could be the mapping of a three dimensional object onto a flat CMOS sensor. I just like to tweak the meteors to coincide with the radiant. It just looks better.

Here's a prime example of what happens when you don't match the radiant's position relative to the time of the background image.

http://apod.nasa.gov/apod/ap150825.html

Although the true radiant is off-screen, it still is positioned slightly off to the left of the Milky Way about two or three screens up.  All Perseids should be emanating from this "point".  As it stands, the meteors look like sporadics.  I mean no disrespect to the author, but it would have been an outstanding composition if the meteors were lined up with the true Perseid radiant.

Wade

t_wade Contributing Member • Posts: 914
Re: Assembling a Meteor Shower Composite

Russ,

In my opinion (and I'm certainly no expert here) that if the background stars are made to match, that's the path the meteor actually took, regardless of the proper radiant point.

As usual, I'm having a hard time explaining visually what I mean.  What you are doing is fine when you have an all sky background.  The problem comes about when you have an Earth based foreground.  The position of the radiant is ONLY valid for that moment relative to Earth.  Since the Earth is rotating, we perceive this rotation as stars moving from east to west.  With an Earth based object in your foreground, such as a mountain, you have frozen the sky to that exact time.  Given the fact the Earth continues to rotate, the position of the radiant will continue to move along its path in the sky.   This gives a counter-clockwise rotational angle to the meteors as the night progress.  This is why I freeze my radiant to the background frame so I don't have a "lost radiant" look to my composites.  Yes, it's more work, but it definitely is more true to the time of the background image.

Wade

RustierOne
OP RustierOne Veteran Member • Posts: 4,312
Re: Assembling a Meteor Shower Composite

t_wade wrote:

Russ,

In my opinion (and I'm certainly no expert here) that if the background stars are made to match, that's the path the meteor actually took, regardless of the proper radiant point.

As usual, I'm having a hard time explaining visually what I mean. What you are doing is fine when you have an all sky background. The problem comes about when you have an Earth based foreground. The position of the radiant is ONLY valid for that moment relative to Earth. Since the Earth is rotating, we perceive this rotation as stars moving from east to west. With an Earth based object in your foreground, such as a mountain, you have frozen the sky to that exact time. Given the fact the Earth continues to rotate, the position of the radiant will continue to move along its path in the sky. This gives a counter-clockwise rotational angle to the meteors as the night progress. This is why I freeze my radiant to the background frame so I don't have a "lost radiant" look to my composites. Yes, it's more work, but it definitely is more true to the time of the background image.

It would seem that if one always aligns the meteor frame to the background stars, it wouldn't matter how the stars have rotated relative to the foreground earthly objects. That seems pretty basic. In essence one is de-rotating each later meteor frame back to the time of the base layer. That wasn't the position of the stars in the sky (relative to the foreground) when these later meteors occurred. But that's what is necessary to make a composite image from frames taken minutes or hours apart in time.

Does it seem like some photographers aren't bothering to align the meteor frames to the stars in the base layer? If so they aren't doing the obvious, which would be a problem.

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Best Regards,
Russ

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rnclark Senior Member • Posts: 2,790
Re: Assembling a Meteor Shower Composite

t_wade wrote:

Roger,

The Perseid radiant moves only 5.6 RA minutes and 0.2 degrees in Dec per day. So in the 6 or so hours the radiant is up, it would move 1/4 those numbers.

You are absolutely correct; however, just like any star in the sky, the radiant moves approximately 1 degree every 4 minutes. I have always had to adjust the rotation angle just a bit on every meteor except those within several minutes of the time of the background shot.

Maybe you are seeing position projection differences due to curvature of the trajectory from the wide angle lens?

This is likely the main cause. Perhaps, it also has to do with the radiant not being a point source too. Or perhaps it could be the mapping of a three dimensional object onto a flat CMOS sensor. I just like to tweak the meteors to coincide with the radiant. It just looks better.

Here's a prime example of what happens when you don't match the radiant's position relative to the time of the background image.

http://apod.nasa.gov/apod/ap150825.html

Although the true radiant is off-screen, it still is positioned slightly off to the left of the Milky Way about two or three screens up. All Perseids should be emanating from this "point". As it stands, the meteors look like sporadics. I mean no disrespect to the author, but it would have been an outstanding composition if the meteors were lined up with the true Perseid radiant.

Wade

Yes, I did email the Matthew about that and he agreed.  Matthew and I have been communicating for years.  He alignd the meteors to the frame edge.

rnclark Senior Member • Posts: 2,790
Re: Assembling a Meteor Shower Composite

RustierOne wrote:

t_wade wrote:

Russ,

In my opinion (and I'm certainly no expert here) that if the background stars are made to match, that's the path the meteor actually took, regardless of the proper radiant point.

As usual, I'm having a hard time explaining visually what I mean. What you are doing is fine when you have an all sky background. The problem comes about when you have an Earth based foreground. The position of the radiant is ONLY valid for that moment relative to Earth. Since the Earth is rotating, we perceive this rotation as stars moving from east to west. With an Earth based object in your foreground, such as a mountain, you have frozen the sky to that exact time. Given the fact the Earth continues to rotate, the position of the radiant will continue to move along its path in the sky. This gives a counter-clockwise rotational angle to the meteors as the night progress. This is why I freeze my radiant to the background frame so I don't have a "lost radiant" look to my composites. Yes, it's more work, but it definitely is more true to the time of the background image.

It would seem that if one always aligns the meteor frame to the background stars, it wouldn't matter how the stars have rotated relative to the foreground earthly objects. That seems pretty basic. In essence one is de-rotating each later meteor frame back to the time of the base layer. That wasn't the position of the stars in the sky (relative to the foreground) when these later meteors occurred. But that's what is necessary to make a composite image from frames taken minutes or hours apart in time.

Does it seem like some photographers aren't bothering to align the meteor frames to the stars in the base layer? If so they aren't doing the obvious, which would be a problem.

I have seen numerous images like that. In some cases the photographers are pasting meteors in randomly, not knowing how meteors showers work. In other cases they keep the alignment relative to the frame edge, and with a fixed tripod, the stars and origin are moving through the night.

Roger

Via Lactea Regular Member • Posts: 432
Re: Assembling a Meteor Shower Composite

RustierOne wrote:

Assembling a Meteor Shower Composite

What follows is the method I have used to assemble a number of separate images containing meteors into a single composite image with all the meteors properly arranged. While this is likely elementary to those skilled in using the software, for those like myself who are unfamiliar with the process, I wanted to document the steps involved. I’m using an old copy of Photoshop Elements 2.0, but other similar photo editing programs with layers capability could be used. So here’s what to do:

Preprocessing

  1. Sort through all your images from a single meteor shower to find the ones containing meteors to be included in the composite.
  2. For each frame with a meteor, process to taste with your favorite photo editing program, endeavoring to have each image processed alike, particularly background sky darkness. I use Adobe Lightroom for preprocessing.

Assemble the Composite

  1. Choose your base image upon which all meteor images will be copied. This can even be an image without any meteors, that was shot with the lens stopped down for improved star images.
  2. In Photoshop open the base layer image.
  3. Open the next meteor-containing image in a separate window.
  4. Choose the Rectangle Marquee Tool from the palette of available tools, and select a portion of the image containing the meteor along with some key bright stars (to be used for aligning the layers).
  5. From the menu bar choose Edit then > Copy.
  6. Highlight the base layer window. Select Edit > Paste. The second image will show as another layer in the layers tab of the base image.
  7. In the layers tab, select the second layer, click opacity and set opacity to 50%.
  8. With the second layer still selected choose the Move Tool. Then move and rotate the second layer so that the stars in both layers are aligned over each other.
  9. When the stars in each layer are coincident, select the Lasso Tool. Using your mouse draw a line closely around the meteor, excluding as much of the sky and background stars as possible.
  10. In the Select Menu choose Inverse. This selects everything except the meteor you just Lassoed.
  11. Press the Delete Key to delete everything except the meteor.
  12. In the Select Menu choose Deselect to remove the Lasso line you had drawn.
  13. In the Layers Menu (not the layers tab) select Merge Down. This will combine the two layers into one, adding the meteor to the base image.
  14. Close (without saving) the separate window containing the meteor you just added, keeping the base layer window open.
  15. Repeat steps 3-14 for each additional meteor to be added to the base layer.
  16. When all meteors have been added to the base layer, save in a high quality format.

Post Processing

Process the composite image to taste, using your favorite image processing program.

So that's the process I use. Likely in more recent versions of Photoshop the process will be a bit different. But the same principals should apply. If any more experienced Photoshop users have some suggestions, they would be most welcome.

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Best Regards,
Russ

Thanx for the info Russ,

maybe I should invest in Photoshop, I used to use version 4... long time ago...

bjorn

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Kind Regards,
Bjorn
like to see some timelapses of the Night skies have a go at
http://vimeo.com/bjornrvink
or
http://www.youtube.com/channel/UCcc5IhJozAPB1PeiJRyGSTQ

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