I had this idea for Stellarium, and it's not bad....
My idea is to implement a generic layer manager that would let the user to either toggle or animate through several layers.
Each "layer" would consist of an alpha-blended sphere made of one or more textures that would be drawn across the Stellarium sky.
Each layer entry would hold the layer name such as one of the following:
layername="Cirrus Clouds"
layername="Aurora"
layername="W-Map Data"
Each layer would have a diameter, such as:
layerdiameter="32,000"
To achieve the correct drawing order, Following the name, an altitude would be given for the elevation from Earth the layer would appear, such as:
layeraltitude="6000" 'meters for cirrus clouds
Following the elevation, an option to pin or clamp it's position in space, . in orbit around the sun, clamp it's rotation, or give a unique x,y,z rotation velocity. Perhaps like one of these:
layerrotation="clampearth"
layerrotation="clampsol"
layerrortaion="clampspace"
layerrotation="-239,100,20" 'GPS satellite halo
The user would be able to download, add, or the layers to Stellarium. The user would also be able to select, page through, or animate several layers, from a list, such as this: Animate Cloud01 Cloud02 Cloud03 Cloud04 GPS
Lastly, and least an alphablend override would let the user alter the scale of the alphamaps in the textures, such as.
layeralpha=".5" 'textures are too bright, fix.
The textures for the layer would be stored in a folder under the name matching the layername. Stellarium would create an alphablended sphere at the given altitude and rotation, displaying it on the screen.
So, what can Stellarium gain from this?
1.) The foundation for real-time weather.
2.) Satellite halo visualization.
3.) Natural effect visualizations such as the Aurora Borealis.
4.) Real light-pollution visualization
5.) Custom grid and multi-culture visualization ability.
6.) Visualization for scientific data, such as W-Map data, how does it compare to the visible sky?
7.) Teaching and instructional capabilities.
Some present custom chunks of code for rendering such things as constellation art, and haze could be incorporated, or it's code could be used to create the layer manager.
The distant future:
Perhaps a drawing utility could also be added to draw notes that could be saved on a series of textures textures.
Thank You,
Brenda Make
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...The user could use page through the layers by using the "Page Up" and "Page Down" keys.
A real-time weather program could convert a photograph of the local cloud cover, and a program such as ImageMagic could insert that photo into a texture tile. I know that real clouds are a lofty idea, but it can give a person a subjective idea how large the Earth is.
I may do a mock-up of the clouds.
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The problem with real time satellite photos of cloud cover is resolution. Typical publicly available global cloud maps are 2048x1024, maybe up to 4096x4096. The entire area of sky visible to an observer at the surface would be a few pixels of cloud map. The feeds are also only updated every few hours, and are not super-reliable (I use xplanet with such cloud maps to render my desktop background;)
As such, "live" cloud maps would only really offer some measure of how overcast it is at a given location. To have anything which is visually appealing, it would be necessary to have some sort of cloud graphic generation program. This is certainly possible, but I think a good one would be hard to do with high FPS and good realism.
If all you want to do is drift some cloud images in front of the sky, it might be possible using scripting and some cunning use of images. There won't be good interaction between the images and the atmosphere however, so it could look weird. If you want to try this, search through the archives of this forum - a year or two back there was a post with an example script which simulates aurora. It was surprisingly good for something so simple.
There is also the question "why?" It would probably be a fun to do if you like graphics generation programs, but it's sort of out of line with Stellarium's goals. Who wants to postpone their use of a virtual planetarium because of cloudy weather?
Since the last release, a lot of work has been done to modularise Stellarium's code, and we are trying to define an API for writing third party modules. If you are a coder and wish to have a go at writing this sort of feature, please do. The module system is not yet complete, and there are as yet no publicly available example loadable modules. Plus the API isn't well define yet. But have a go maybe :)
Matthew
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While I did want to include information about clouds, I wanted a generic layer manager for the reasons outlined above. The point being: a generic sphere manager could show more than clouds, such as w-map data layer:
Stellarium already has some layering code (note grid lines do not draw in front of the landscape etc.). At the recent developer meeting they were discussed briefly with respect to changing the redering order for scripts, although I do not recall exactly what was decided, if anything. In short, there's a mechanism, but it may change.
On a slightly different note, I can see a good use for having layered rendering of planet texture maps as seen by an observer on another body. e.g. when viewing Earth from the Moon. At present this is not supported. I very much like the idea of an animated Jupiter texture. The danger here is that the animated texture file would loop at some point, leading to ugliness when re-starting the animation.
Matthew
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The w-map got me thinking. I wanted to see it.
I resized the w-map down to 512 square, I used it to replace the original milky way texture. http://www.brendamake.com/temp/w-map.jpg
I don't know if the milky way texture maps to the 90 degree view or if it scales correctly, but it was interesting to see. I am sure the texture is not rotated correctly, but the poles seem like though would be straight.
If the milky way does map all around the planet, then the w-map defiantly has enough detail. The w-map texture I have is a 2048 x 1024 cylindrical projection. Only 512 square is shown. i don't know what would happen if i used a larger texture.
[The textures appear to be palleted.]
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You see, as a human I see something like the w-map or a cloud on radar, and I want to be able to visualize how big it is. as I look at the w-map I still have no idea, or how it maps against our stars.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
I had this idea for Stellarium, and it's not bad....
My idea is to implement a generic layer manager that would let the user to either toggle or animate through several layers.
Each "layer" would consist of an alpha-blended sphere made of one or more textures that would be drawn across the Stellarium sky.
Each layer entry would hold the layer name such as one of the following:
layername="Cirrus Clouds"
layername="Aurora"
layername="W-Map Data"
Each layer would have a diameter, such as:
layerdiameter="32,000"
To achieve the correct drawing order, Following the name, an altitude would be given for the elevation from Earth the layer would appear, such as:
layeraltitude="6000" 'meters for cirrus clouds
Following the elevation, an option to pin or clamp it's position in space, . in orbit around the sun, clamp it's rotation, or give a unique x,y,z rotation velocity. Perhaps like one of these:
layerrotation="clampearth"
layerrotation="clampsol"
layerrortaion="clampspace"
layerrotation="-239,100,20" 'GPS satellite halo
The user would be able to download, add, or the layers to Stellarium. The user would also be able to select, page through, or animate several layers, from a list, such as this:
Animate
Cloud01
Cloud02
Cloud03
Cloud04
GPS
Lastly, and least an alphablend override would let the user alter the scale of the alphamaps in the textures, such as.
layeralpha=".5" 'textures are too bright, fix.
The textures for the layer would be stored in a folder under the name matching the layername. Stellarium would create an alphablended sphere at the given altitude and rotation, displaying it on the screen.
So, what can Stellarium gain from this?
1.) The foundation for real-time weather.
2.) Satellite halo visualization.
3.) Natural effect visualizations such as the Aurora Borealis.
4.) Real light-pollution visualization
5.) Custom grid and multi-culture visualization ability.
6.) Visualization for scientific data, such as W-Map data, how does it compare to the visible sky?
7.) Teaching and instructional capabilities.
Some present custom chunks of code for rendering such things as constellation art, and haze could be incorporated, or it's code could be used to create the layer manager.
The distant future:
Perhaps a drawing utility could also be added to draw notes that could be saved on a series of textures textures.
Thank You,
Brenda Make
Thanks for considering it : )
...The user could use page through the layers by using the "Page Up" and "Page Down" keys.
A real-time weather program could convert a photograph of the local cloud cover, and a program such as ImageMagic could insert that photo into a texture tile. I know that real clouds are a lofty idea, but it can give a person a subjective idea how large the Earth is.
I may do a mock-up of the clouds.
The problem with real time satellite photos of cloud cover is resolution. Typical publicly available global cloud maps are 2048x1024, maybe up to 4096x4096. The entire area of sky visible to an observer at the surface would be a few pixels of cloud map. The feeds are also only updated every few hours, and are not super-reliable (I use xplanet with such cloud maps to render my desktop background;)
As such, "live" cloud maps would only really offer some measure of how overcast it is at a given location. To have anything which is visually appealing, it would be necessary to have some sort of cloud graphic generation program. This is certainly possible, but I think a good one would be hard to do with high FPS and good realism.
If all you want to do is drift some cloud images in front of the sky, it might be possible using scripting and some cunning use of images. There won't be good interaction between the images and the atmosphere however, so it could look weird. If you want to try this, search through the archives of this forum - a year or two back there was a post with an example script which simulates aurora. It was surprisingly good for something so simple.
There is also the question "why?" It would probably be a fun to do if you like graphics generation programs, but it's sort of out of line with Stellarium's goals. Who wants to postpone their use of a virtual planetarium because of cloudy weather?
Since the last release, a lot of work has been done to modularise Stellarium's code, and we are trying to define an API for writing third party modules. If you are a coder and wish to have a go at writing this sort of feature, please do. The module system is not yet complete, and there are as yet no publicly available example loadable modules. Plus the API isn't well define yet. But have a go maybe :)
Matthew
While I did want to include information about clouds, I wanted a generic layer manager for the reasons outlined above. The point being: a generic sphere manager could show more than clouds, such as w-map data layer:
http://apod.nasa.gov/apod/ap031231.html
http://images.google.com/imgres?imgurl=http://laps.noaa.gov/albers/sos/universe/wmap/wmap_rgb_cyl_www.jpg&imgrefurl=http://laps.noaa.gov/albers/sos/sos.html&h=1024&w=2048&sz=570&hl=en&start=38&um=1&tbnid=frzKn0GzdRqDiM:&tbnh=75&tbnw=150&prev=/images%3Fq%3Dw-map%26start%3D21%26svnum%3D10%26um%3D1%26hl%3Den%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official%26sa%3DN
Stellarium already has some layering code (note grid lines do not draw in front of the landscape etc.). At the recent developer meeting they were discussed briefly with respect to changing the redering order for scripts, although I do not recall exactly what was decided, if anything. In short, there's a mechanism, but it may change.
On a slightly different note, I can see a good use for having layered rendering of planet texture maps as seen by an observer on another body. e.g. when viewing Earth from the Moon. At present this is not supported. I very much like the idea of an animated Jupiter texture. The danger here is that the animated texture file would loop at some point, leading to ugliness when re-starting the animation.
Matthew
The w-map got me thinking. I wanted to see it.
I resized the w-map down to 512 square, I used it to replace the original milky way texture.
http://www.brendamake.com/temp/w-map.jpg
I don't know if the milky way texture maps to the 90 degree view or if it scales correctly, but it was interesting to see. I am sure the texture is not rotated correctly, but the poles seem like though would be straight.
If the milky way does map all around the planet, then the w-map defiantly has enough detail. The w-map texture I have is a 2048 x 1024 cylindrical projection. Only 512 square is shown. i don't know what would happen if i used a larger texture.
[The textures appear to be palleted.]
You see, as a human I see something like the w-map or a cloud on radar, and I want to be able to visualize how big it is. as I look at the w-map I still have no idea, or how it maps against our stars.
I plan to add spherical images to the scripting facility, and improve the layer control for images. Just have not gotten to it.
OpenGL textures are limited by video cards, so 32,000 pixels would take some special work. We may need that anyway for some other things.
Rob