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Is there a way to mask parts of sky in planetarium software?

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#1 Nebulous1

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Posted 22 June 2021 - 07:07 PM

Hi all! I have a lot of my home sky blocked by trees and am looking for observing software that would let me set parts of the sky I cannot see. Something I can set permanently for a defined site, so I can more easily plan my observing session.

Do any of you know if this is a feature on any of the popular programs?

I'm using Starry Night 6 Pro, and it says you can set your own horizon from a 360 degree panorama pic, but don't know if that would do what I'm looking for.

Thanks in advance!

#2 kathyastro

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Posted 22 June 2021 - 07:31 PM

In Stellarium, you can define your own landscape image, including all your own local trees and obstructions.  Assembling an accurate panorama image takes some care, but the result is exactly what you are looking for.

 

It sounds like Starry Nights has the same feature.


Edited by kathyastro, 22 June 2021 - 07:31 PM.

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#3 Older Padawan

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Posted 22 June 2021 - 07:35 PM

I haven't figured out how to do it but I've seen the guys at San Diego Astronomy Assn. do it on their You Tube videos. Gary has his CDC set up showing his limited sky from his back yard. You might go to SDAA web site and see if you can leave a message for them or find him on CN and ask how it's done


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#4 Dynan

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Posted 22 June 2021 - 08:22 PM

This is my Stellarium Sky after mapping it with ALT readings from my CEM60. (I edited the 'Zero Horizon' text file with my readings and saved is as a new 'Zero Horizon' file.)

 

STELLARIUM_SKY.jpg

 

 


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#5 Nebulous1

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Posted 22 June 2021 - 08:46 PM

In Stellarium, you can define your own landscape image, including all your own local trees and obstructions.  Assembling an accurate panorama image takes some care, but the result is exactly what you are looking for.

 

It sounds like Starry Nights has the same feature.

Thanks kathyastro!  I did see where Starry Nights had a way to drag trees/bushes into the horizon, and could resize them but wouldn't let me make them large enough (yes, it's that bad at my site!).  I'll definitely look into Stellarium, as even taking some time to set it up accurately would be worth the effort.  I just got my first quality mount (a Losmandy G8 with Gemini 2) and even doing a multi star alignment is difficult with limited sky views, so knowing ahead of time what I'll be able to see would really help.



#6 Nebulous1

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Posted 22 June 2021 - 08:51 PM

I haven't figured out how to do it but I've seen the guys at San Diego Astronomy Assn. do it on their You Tube videos. Gary has his CDC set up showing his limited sky from his back yard. You might go to SDAA web site and see if you can leave a message for them or find him on CN and ask how it's done

Thanks Older Padawan!  I see that SDAA has ~37 videos uploaded, so If you happen to recall the name of one where you saw this, please let me know, I'd like to see how it looks when they have their sky shown limited.   Would give me some ideas maybe.  Would that I had the time to watch them all!



#7 Nebulous1

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Posted 22 June 2021 - 09:10 PM

This is my Stellarium Sky after mapping it with ALT readings from my CEM60. (I edited the 'Zero Horizon' text file with my readings and saved is as a new 'Zero Horizon' file.)

 

attachicon.gifSTELLARIUM_SKY.jpg

Thanks Dynan!  That's interesting.  Good idea to use the ALT readings from your mount.  I hadn't thought of it, but makes much more sense than standing in my yard trying to estimate the altitude angles of my obstructions.  My thinking is I can use about three spots in my yard, and maybe set up a different horizon model for each "site". 

 

I forgot I had an older version of Stellarium installed, and see the Zero Horizon. I'll need to look into how that can be edited (or how difficult it is to edit).  I changed to the "Trees" horizon view and it's about what I'm dealing with, but with different locations. :)


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#8 DJL

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Posted 22 June 2021 - 09:20 PM

https://www.youtube....h?v=wv_Fpvf06Bw - Martin's Astrophotography explains how to do this in Stellarium, which is free on Mac and Windows, also available for a few $ on iOS at least. Check out the rest of his channel, it's very helpful.


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#9 lphilpot

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Posted 22 June 2021 - 09:20 PM

It's a few years old (as is SNP 6) but here's another discussion on the same question. Maybe there's some help here?

 

https://www.cloudyni...plus-6-horizon/

 

There's talk of using an existing panoramic horizon as an example. Unfortunately the couple of links I looked at were dead ends, but maybe some of the other info could be of use?



#10 Older Padawan

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Posted 22 June 2021 - 10:27 PM

Thanks Older Padawan!  I see that SDAA has ~37 videos uploaded, so If you happen to recall the name of one where you saw this, please let me know, I'd like to see how it looks when they have their sky shown limited.   Would give me some ideas maybe.  Would that I had the time to watch them all!

Sorry Nebulous1 I went back to try and find the video but I've watched so many of them I couldn't find the one I was referring too. If I run across it at a later time I will send you the link.



#11 Dynan

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Posted 22 June 2021 - 11:29 PM

Thanks Dynan!  That's interesting.  Good idea to use the ALT readings from your mount.  I hadn't thought of it, but makes much more sense than standing in my yard trying to estimate the altitude angles of my obstructions.  My thinking is I can use about three spots in my yard, and maybe set up a different horizon model for each "site". 

 

I forgot I had an older version of Stellarium installed, and see the Zero Horizon. I'll need to look into how that can be edited (or how difficult it is to edit).  I changed to the "Trees" horizon view and it's about what I'm dealing with, but with different locations. smile.gif

The Zero Landscape file is in C: Program Files > Stellarium > landscapes > zero

 

It's just a text file so you can easily edit in Notepad. Save a copy of the original and have at the file. Save as zero_horizon.txt. Then point to it in the landscapes in Stellarium. 

 

It REALLY helps when you have an accurate sky map. I can plan almost down to the minute, when I have the scope and sensor info entered in the Image Sensor Frame chosen in the upper right.

 

Here is my full zero_horizon.txt file, shown here to point out that you need to leave the cardinal points (0°, 90°, 180°, and 270°) as they are with the line before and after each one so it'll work correctly. (Mentioned in the text in the zero_horizon.txt file.)

 

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

# Trivial zero-line horizon for Stellarium
# avoid spurious vertical lines/triangles by small offset from north/south!
# The cardinal directions are marked by low spikes for technical reasons. 
# Note that we should start the horizon line at 90 degrees - this indicates a polygon bug!

90.1 40
115 27
140 24
150 25
179.9 21
180 0.01
180.1 21
190 26
210 30
220 34
225 42
250 25
260 20
269.9 20
270.0 0.01
270.1 20
285 15
300 23
315 21
340 28
359.9 18
0.0 0.01
0.1 18
020 10
050 32
89.9 40
90 0.01

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 

(See the 0.01 entries at 0, 90, 180, 270? Gotta leave them there... You can put the proper reading 0.1 before and after each cardinal point.)

 

Easy peasy...


Edited by Dynan, 22 June 2021 - 11:38 PM.


#12 Der_Pit

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Posted 23 June 2021 - 07:41 AM

KStars has two similar features.  You can either define a horizon line, or use an equirectangular panorama view.

See here.

 

The terrain is visual only.  Work is ongoing to have the scheduler use the horizon line for planning...



#13 airscottdenning

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Posted 23 June 2021 - 08:46 AM

What Pit said about KStars. TheSkyX has the "defined polygon" custom horizon. SkySafari has the ability to import a custom photograph of your site as a super realistic local horizon, just like Kstars.


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#14 MattZ40

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Posted 23 June 2021 - 09:02 AM

I have major obstruction issues and solved the planning challenge using Stellarium and making a custom landscape. My obstruction horizon is wildly varied so trying to measure it would be more work than creating the landscape. It wasn't hard and was a good learning experience. Now I can tell exactly when an object goes behind or comes out from behind a tree or house.

I followed this video here: https://www.youtube....h?v=6rxzah27I1I

I took a 3-row, 360 degree panorama with a point and shoot camera on a tripod from the exact spot where I put my scope. Stitched it together with Microsoft Image Composite Editor (which was free). Used Photoshop to create transparent areas, resized with Irfanview, and used trial and error to get resizing and alignment correct. To get those as accurate as possible I took a picture at night from the same spot with the same camera when the moon sat right at the point of the ridge of the house. Then time travel Stellarium to the exact date and time of that picture, pause tracking, and adjust size and rotation of the landscape to exactly match the picture. It sounds like more work than it turned out to be. I even made one for winter (no leaves) and summer (leaves galore).

Here's a screenshot of the finished product:

Stellarium Landscape Screenshot

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#15 lphilpot

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Posted 23 June 2021 - 09:31 AM

Your backyard "horizon" looks kinda like mine. This is a vertical pano so it's a little distorted (the tree really doesn't bend) but the top is right at 80 degrees elevation, almost overhead There's more to the left and right, out of frame. Oh yeah, the overcast is apparently a feature of my backyard sky, too.  Grrr... smile.gif

 

Why someone years ago would leave -- or even worse, plant -- two sweet gum trees between houses ~12 feet apart is a totally different question. Probably the same person who planted the (now gone) pampas grass around them...

 

K7eceCD.jpg


Edited by lphilpot, 23 June 2021 - 09:33 AM.

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#16 obrazell

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Posted 23 June 2021 - 10:12 AM

SkyTools also allows you to define a elevated horizon so that it can tell when an object rises. Of cousre it is not free.


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#17 MattZ40

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Posted 23 June 2021 - 03:18 PM

Your backyard "horizon" looks kinda like mine. This is a vertical pano so it's a little distorted (the tree really doesn't bend) but the top is right at 80 degrees elevation, almost overhead There's more to the left and right, out of frame. Oh yeah, the overcast is apparently a feature of my backyard sky, too.  Grrr... smile.gif

 

Why someone years ago would leave -- or even worse, plant -- two sweet gum trees between houses ~12 feet apart is a totally different question. Probably the same person who planted the (now gone) pampas grass around them...

 

 

Yes the perspective on panoramics makes trees look smaller and further away, although that doesn't seem to compromise the accuracy of when objects appear and disappear. The oak in the center of my screenshot is hanging almost halfway across my yard, and my new neighbor is kind enough to shine a spotlight up into it every single night, just in case I forget where it is.

Sweet gums are the gift that keeps on giving. Cut them down and they start sending up volunteers everywhere.



#18 Dynan

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Posted 23 June 2021 - 03:33 PM

I forgot to mention (in post#11) that I used Stellarium to 'goto' each azimuth's (AZ) elevation (ALT) to find the actual clear view of the sky. (Up a little more? Racafratz pakalumer! I went the wrong way! lol.gif)

 

Even with comfortable familiarity with an EQ mount, it was quite frustrating point to the exact spot I needed to log for the zero_horizon.txt file. So I clicked on the spot (after pressing 'A' in Stellarium to give a night sky) and hit [Ctrl]+[1] and it easily found the new spot. No trees? Down a little bit. Got trees? Up until the view was full cleared of treetops. Mark it!


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#19 Nebulous1

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Posted 23 June 2021 - 08:09 PM

https://www.youtube....h?v=wv_Fpvf06Bw - Martin's Astrophotography explains how to do this in Stellarium, which is free on Mac and Windows, also available for a few $ on iOS at least. Check out the rest of his channel, it's very helpful.

Thanks DJL, that is very cool, and I'll have to give this a try soon!



#20 Nebulous1

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Posted 23 June 2021 - 08:12 PM

The Zero Landscape file is in C: Program Files > Stellarium > landscapes > zero

 

It's just a text file so you can easily edit in Notepad. Save a copy of the original and have at the file. Save as zero_horizon.txt. Then point to it in the landscapes in Stellarium. 

 

It REALLY helps when you have an accurate sky map. I can plan almost down to the minute, when I have the scope and sensor info entered in the Image Sensor Frame chosen in the upper right.

 

Here is my full zero_horizon.txt file, shown here to point out that you need to leave the cardinal points (0°, 90°, 180°, and 270°) as they are with the line before and after each one so it'll work correctly. (Mentioned in the text in the zero_horizon.txt file.)

 

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

# Trivial zero-line horizon for Stellarium
# avoid spurious vertical lines/triangles by small offset from north/south!
# The cardinal directions are marked by low spikes for technical reasons. 
# Note that we should start the horizon line at 90 degrees - this indicates a polygon bug!

90.1 40
115 27
140 24
150 25
179.9 21
180 0.01
180.1 21
190 26
210 30
220 34
225 42
250 25
260 20
269.9 20
270.0 0.01
270.1 20
285 15
300 23
315 21
340 28
359.9 18
0.0 0.01
0.1 18
020 10
050 32
89.9 40
90 0.01

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 

(See the 0.01 entries at 0, 90, 180, 270? Gotta leave them there... You can put the proper reading 0.1 before and after each cardinal point.)

 

Easy peasy...

Thanks Dynan, I did a roughing in of my obstacles, just using a compass and estimating the altitude from my back patio (the worst of my three spots).  And, wow.  I really need to think about removing a tree or two!

Attached Thumbnails

  • Rough Zero Horizon for back porch.png

Edited by Nebulous1, 23 June 2021 - 09:28 PM.


#21 Nebulous1

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Posted 23 June 2021 - 08:22 PM

KStars has two similar features.  You can either define a horizon line, or use an equirectangular panorama view.

See here.

 

The terrain is visual only.  Work is ongoing to have the scheduler use the horizon line for planning...

Thanks Der_Pit.  I hadn't looked into KStars, but those horizon features look nice!  

 

BTW for all that have replied, I am overwhelmed with how many have pitched in with responses!  CloudyNights has a great community! I tried many web searches for this feature, but always came up empty, yet one ask on CN, and tons of great useful answers!


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#22 Nebulous1

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Posted 23 June 2021 - 08:26 PM

What Pit said about KStars. TheSkyX has the "defined polygon" custom horizon. SkySafari has the ability to import a custom photograph of your site as a super realistic local horizon, just like Kstars.

Thanks airscotdenning, so many new features/astronomy software packages to check out.  This will take some time to look into it all and see which package I go with.  It may come down to telescope control, and of course the free user supported software is a bonus too.



#23 Nebulous1

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Posted 23 June 2021 - 08:33 PM

I have major obstruction issues and solved the planning challenge using Stellarium and making a custom landscape. My obstruction horizon is wildly varied so trying to measure it would be more work than creating the landscape. It wasn't hard and was a good learning experience. Now I can tell exactly when an object goes behind or comes out from behind a tree or house.

I followed this video here: https://www.youtube....h?v=6rxzah27I1I

I took a 3-row, 360 degree panorama with a point and shoot camera on a tripod from the exact spot where I put my scope. Stitched it together with Microsoft Image Composite Editor (which was free). Used Photoshop to create transparent areas, resized with Irfanview, and used trial and error to get resizing and alignment correct. To get those as accurate as possible I took a picture at night from the same spot with the same camera when the moon sat right at the point of the ridge of the house. Then time travel Stellarium to the exact date and time of that picture, pause tracking, and adjust size and rotation of the landscape to exactly match the picture. It sounds like more work than it turned out to be. I even made one for winter (no leaves) and summer (leaves galore).

Here's a screenshot of the finished product:

MattZ40, that looks a lot like the kind of major obstructions I have.  I watched the Martin's Astrophotography video DJL posted above, and the one thing I didn't see was how you get the altitude of the obstructions correctly reflected in Stellarium.  I like your solution with matching a pic of the moon at a reference point in your site and then matching with the same time in Stellarium! 



#24 DJL

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Posted 23 June 2021 - 08:35 PM

Thanks DJL, that is very cool, and I'll have to give this a try soon!

I tweaked it a little as well. I made two layers in Photoshop of the panorama once I had it assembled. On the lower layer I removed the sky and trees. On the top layer I kept the trees but made it transparent. Result: I can see what is behind the trees and better predict when targets become visible.

 

I shot my panorama during daylight and lined up the sun in the photo with the sun in Stellarium for the same date and time.


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#25 Nebulous1

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Posted 23 June 2021 - 08:39 PM

Your backyard "horizon" looks kinda like mine. This is a vertical pano so it's a little distorted (the tree really doesn't bend) but the top is right at 80 degrees elevation, almost overhead There's more to the left and right, out of frame. Oh yeah, the overcast is apparently a feature of my backyard sky, too.  Grrr... smile.gif

 

Why someone years ago would leave -- or even worse, plant -- two sweet gum trees between houses ~12 feet apart is a totally different question. Probably the same person who planted the (now gone) pampas grass around them...

 

K7eceCD.jpg

Yes, I have a large Oak tree that goes up to 70-80 degrees and takes up ~100 degrees azimuth!  One tree takes a third of my view away.  I'm heartened that I'm not the only one, and that people are having success with planning around the obstacles using the custom horizons.  There's hope for trying to image from home. :)


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