What would Celestia look like if it had cloud shadows!

General discussion about Celestia that doesn't fit into other forums.
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Don. Edwards
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What would Celestia look like if it had cloud shadows!

Post #1by Don. Edwards » 19.12.2003, 08:43

This is going to be complex so I will try and make it as simple as I can.
A couple of weeks ago I was planning on releasing a demo texture of what the new 16k Earth texture and the new Northern Summer cloudmap would look like together. My intention was to simply give everyone that wanted to, a way of seeing what the coloring and cloudmap would like. This is what I originally came up with.

Image

I then took a specmap of the same size and added a reversed version of my cloudmap and then layered that on top and came up with this.

Image

I then used the old trick of plugging in the specmap into the alpha channel. That way all anyone would have to do was simply plug in the texture all by itself and you would get specular reflections only on the water. But when I went and tested the texture I saw something that allot of us have been waiting for in Celestia for along time now. The clouds had shadows but only over the water. Well this got me thinking and I started to create a bunch of different specmaps in and attempt to make this possibly work better and of course the test texture never got released.
The end result was quite startling and amazing. Have a look at what Celestia would like with real drop shadows under the cloudmap.

Image Image

In these pictures the results are of course subtle but they are really there. Here are the same shots with the clouds turned off.

Image Image

As everyone can see there are cloud shadows on the water. Of course this is very, very far from perfect. You don't get any cloud shadows over the land unless you use a specmap with no continents. But it gave me the initial idea of just how close Celestia really is to being able to implement this feature. As I see it there are two ways it can work.
1. A second specmap with the clouds only that does not interfere somehow with the main specmap. As far as I can see this isn't the best way of doing it. Although this was the way I found out it worked.
2. The better choice would be to have a second cloud layer entry that can be set to zero height so that it appears under the main cloudmap. This probably could be done and I understand some users have had multiple cloud layers work in the past. I do not remember how it was done. But if Chris could just tweak the code a little more we can finally have those shadows under the clouds that they have in Star Strider and Orbiter. :wink:

Don. Edwards

P.S.
If anyone wants to try this out themselves they can click on the above texture samples and get the 2k demo texture and specmap respectively and give it try. It will not be very pretty at that resolution but it will give you the main feel of what I saw the first time I tried it. It is kind of shocking to see those drop shadows on the water. But it does make things a little more interesting. 8O
I am officially a retired member.
I might answer a PM or a post if its relevant to something.

Ah, never say never!!
Past texture releases, Hmm let me think about it

Thanks for your understanding.

john71
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Post #2by john71 » 21.12.2016, 21:05

Wait a minute, does Celestia have a cloud shadow feature in 2016? What happened? :eek:

Added after 12 minutes 45 seconds:
I mean I see the option but I cannot see the graphic result...

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John Van Vliet
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Post #3by John Van Vliet » 21.12.2016, 22:21

you are aware that this thread is 13 years OLD

shadows are part of the current version
BUT
they require that part of the clouds be 100% alpha

most cloud maps do not have HARD lines for the shadows

john71
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Post #4by john71 » 21.12.2016, 22:30

Yes, I know, that's why I was a little bit surprised...I use the 32k Earth cloud map for every earth-like planet and I cannot see any shadows... :cry:

Added after 3 minutes:
This is the best cloud map ever http://www.celestiamotherlode.net/catalog/show_addon_details.php?addon_id=406

Topic author
Don. Edwards
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Post #5by Don. Edwards » 22.12.2016, 01:22

Back in the day when I was in the Celestia scene I had 16K cloudmaps that did cast shadows pretty darn good. They were based on the same data set as the ones you linked, but they had the missing polar data. There are a few ways to get the clouds to do what you want. It involves editing them in Photoshop or GIMP and basically doubling up the clouds. The issue it that the clouds are about 50 to 60% transparent and that's why they don't cast shadows, as it was already pointed out. Unfortunately most of my texture work is long gone from the Celestia forums and servers. I do have archives on DVD, but I just don't have the time to dig them up for such an old app and one that really has no support anymore. OH, and another reason I stopped releasing textures is that they were being stolen by those Hollywood types and used without permission in TV movies. If yo look around in the past forum entries you may find my post on the subject minus the images of course.
It is possible that if enough people asked I might throw my textures up on Dropbox, but I would need to really get nagged a bit for it. Or hear from one of the bigger Celestia archives that they want them.
I am officially a retired member.
I might answer a PM or a post if its relevant to something.

Ah, never say never!!
Past texture releases, Hmm let me think about it

Thanks for your understanding.

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John M. Dollan
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Post #6by John M. Dollan » 22.12.2016, 06:57

Ah, Don, how I miss your Celestia creations. I only ever had the Ice Age Earth (which I'm sure I have on my archive drive SOMEWHERE), but even if I was never able to get your others, I loved their value as beautiful eye candy....

john71
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Post #7by john71 » 22.12.2016, 11:07

Don Edwards, thanks for your reply! It is nice to see that you can get a reply for a 13 years old thread. This is kinda very cool. :clap:
And yes, I really beg you for your 16k cloud map... :help:
In my opinion this is not an old app, this is the best app in astronomy. I hope the 64 bit conversion will succeed and future generations can enjoy this wonder too.

Added after 12 minutes 21 seconds:
I think the file name was: 8k-CloudShadowMap.zip

http://www.professores.uff.br/hjbortol/arquivo/2006.1/applets/textures/The%20Celestia%20Motherlode_%20Earth%20Surface%20Maps_files/www.celestiamotherlode.net/catalog/earthcloud.html

Added after 4 minutes 28 seconds:
I really like digital archaeology. :twisted:

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Goofy
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Post #8by Goofy » 22.12.2016, 13:54

Hi Don, welcome back!
I'd like to see your shadowing clouds so, please, make those available somewhere.
Thanks a lot.
Goofy :smile:
"Something is always better than nothing!"
ASUS G75VX4007H- Intel i7 3630QM, 2.4 GHz-SSD 250GB+SSD 1TB, SATA 3-32GB DDR3 1600 MHz- Nvidia GeForce GTX 780MX 3 GB

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FarGetaNik M
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Post #9by FarGetaNik » 22.12.2016, 21:56

john71 wrote:I use the 32k Earth cloud map for every earth-like planet and I cannot see any shadows... :cry:

I assume you are using a virtual texture. I noticed that virtual textures don't support cloud shadows. This feature isn't that great to be honest, it conflicts with other texture effects and renders some worlds black (or at least dark, depending on the intensity defined by the ssc).

Don. Edwards wrote:OH, and another reason I stopped releasing textures is that they were being stolen by those Hollywood types and used without permission in TV movies

I would consider this both an honor and an insult. I can understand your reason, but I would be amazed if that happened to my creations! I don't really mind if anybody used my stuff, but credit would be nice sometimes. Space Engine features my Miranda bump map but they didn't credit me...

scalbers
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Post #10by scalbers » 01.01.2017, 19:13

FYI - some related discussion can be found in these threads:

viewtopic.php?f=10&t=17571

viewtopic.php?f=30&t=17578&p=135492#p135492
http://stevealbers.net

scalbers
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Post #11by scalbers » 16.01.2017, 20:24

Here we look at the subtle shadows of some crepuscular rays from space with my rendering package:

3.jpg


4.jpg


The ground location under the observer has the sun just below the horizon. Observer altitude is labeled in the images. Here are animated versions:

http://stevealbers.net/outerspace/animated_polar.gif

http://stevealbers.net/outerspace/animated_cyl.gif
http://stevealbers.net

john71
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Post #12by john71 » 21.01.2017, 14:52

Looks very real! It should be integrated into Celestia....

scalbers
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With us: 14 years 2 months

Post #13by scalbers » 21.01.2017, 17:37

Thanks john71. I'm continuing to refine this as for example there's a stepwise gradient in the terminator that I think can be smoothed out. I've been working in FORTRAN code, though it could be translated or emulated if we can figure out how to modularize things. This also depends on the path Celestia takes with volumetric rendering and ray marching capabilities. Though as we were saying the simple bump map could be a start.
http://stevealbers.net


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