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{{Spaceflight}}
{{Spaceflight}}
=== Orbital Rendering:Earthview ===
=== Orbital Rendering: Earthview ===




{{FGCquote
By March 16th, 2012, Thorstem Renk managed to implement a scheme for orbital terrain rendering which he had cooked up a while ago.  
|1= I've managed to implement a scheme for orbital terrain rendering which I had cooked up a while ago.  
{{cite web
|2= {{cite web
   | url    = http://sourceforge.net/p/flightgear/mailman/message/28991398/
   | url    = http://sourceforge.net/p/flightgear/mailman/message/28991398/
   | title  = <nowiki>[Flightgear-devel] Earthview - Orbital terrain rendering in FG</nowiki>
   | title  = <nowiki>[Flightgear-devel] Earthview - Orbital terrain rendering in FG, 2012</nowiki>
  | author = <nowiki>Renk Thorsten</nowiki>
  | date  = Mar 16th, 2012
  | added  = Mar 16th, 2012
  | script_version = 0.23
   }}
   }}
}}


{{FGCquote
It was really low-tech and lived within the limitations of the current engine - just a textured sphere of 58 km diameter in the scene which was constantly repositioned using simple ray-optics to give the right impression and had a dedicated shader to never fog it and work around the high altitude light problem. The results using Celestia Level 3 texturing were quite compelling.
|1= this is really low-tech and lives within the limitations of the current engine - just a textured sphere of 58 km diameter in the scene which is constantly repositioned using simple ray-optics to give the right impression and has a dedicated shader to never fog it and work around the high altitude light problem (see below). The results using Celestia Level 3 texturing are quite compelling
{{cite web
|2= {{cite web
   | url    = http://sourceforge.net/p/flightgear/mailman/message/28991398/
   | url    = http://sourceforge.net/p/flightgear/mailman/message/28991398/
   | title  = <nowiki>[Flightgear-devel] Earthview - Orbital terrain rendering in FG</nowiki>
   | title  = <nowiki>[Flightgear-devel] Earthview - Orbital terrain rendering in FG - T Renk, 2012</nowiki>
  | author = <nowiki>Renk Thorsten</nowiki>
 
  | date  = Mar 16th, 2012
  | added  = Mar 16th, 2012
  | script_version = 0.23
   }}
   }}
}}


{{FGCquote
It took 7 hours to get it to this point, less than 100 lines of Nasal, some cut and paste with the shaders - most of the time was spent stitching and converting textures. It was really dumb - one could go to even higher resolution texturing by investing some smartness and introducing texture management (currently Earth is effectively covered by 4096x8192, the cloud layer adds the same amount).  
|1= It took me 7 hours to get it to this point, less than 100 lines of Nasal, some cut-past with the shaders - most of the time I spent stitching and converting textures. Right now it is really dumb - one can go to even higher resolution texturing by investing some smartness and introducing texture management (currently Earth is effectively covered by 4096x8192, the cloud layer adds the same amount).  
{{cite web
|2= {{cite web
   | url    = http://sourceforge.net/p/flightgear/mailman/message/28991398/
   | url    = http://sourceforge.net/p/flightgear/mailman/message/28991398/
   | title  = <nowiki>[Flightgear-devel] Earthview - Orbital terrain rendering in FG</nowiki>
   | title  = <nowiki>[Flightgear-devel] Earthview - Orbital terrain rendering in FG - T Renk, 201w</nowiki>
  | author = <nowiki>Renk Thorsten</nowiki>
  | date  = Mar 16th, 2012
  | added  = Mar 16th, 2012
  | script_version = 0.23
  }}
}}
}}


{{FGCquote
|1= the Earthview orbital rendering engine. The textures for the planet are based on the NASA Visible Earth collection http://visibleearth.nasa.gov
|2= {{cite web
  | url    = http://sourceforge.net/p/flightgear/mailman/message/32262904/
  | title  = <nowiki>[Flightgear-devel] Orbital rendering</nowiki>
  | author = <nowiki>Renk Thorsten</nowiki>
  | date  = Apr 24th, 2014
  | added  = Apr 24th, 2014
  | script_version = 0.23
  }}
}}






Textures are taken from the NASA Visible Earth project - at the highest resolution level, Earth can be rendered at 32768x65536 pixel (about 500 m per pixel) and clouds with half of that. Currently there is a much lower texture resolution distributed via GIT, a mode to make the GB-sized hires textures has yet to be determined.
Textures are taken from the NASA Visible Earth project - at the highest resolution level, Earth can be rendered at 32768x65536 pixel (about 500 m per pixel) and clouds with half of that. Currently there is a much lower texture resolution distributed via GIT; a mode to make the GB-sized hires textures has yet to be determined.


Combined with the [[atmospheric light scattering]] (ALS) shader to render the atmosphere, visuals are generally rather compelling.
Combined with the [[atmospheric light scattering]] (ALS) shader to render the atmosphere, visuals are generally rather compelling.
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   | title  = <nowiki>[Flightgear-devel] Mailing List, Apr 24 2014</nowiki>
   | title  = <nowiki>[Flightgear-devel] Mailing List, Apr 24 2014</nowiki>
   }}  
   }}  
}}




{{FGCquote
Earthview responds to the weather visibility setting and typically 80-140 km visibility work best (it won't affect any scenery loading because we're too far from the planet). Also, while rendering in ALS, manually tweaking Rayleigh and Mie constants gives a nice atmosphere effect. NASA provides textures in /much/ higher resolution - in the highest resolution texture set, Thorsten had the planet covered in 32768x16384 and the cloud layer in half of that. For such large textures, loading time is an issue (Earthview isn't excatly *cough* elegant) and pre-mipmapped compressed DDS is pretty much the only sane option - then that's 8 texture chunks at 176 MB each. It would be nice to make higher resolution versions available for download, but obviously that's quite a bandwidth hog - if there's sufficient interest and someone knows a server... the textures are there. Provided you have the texture memory, performance should actually be pretty high - there's just two textured spheres in the scene, and even on an old computer, some get a solid 60 fps.
|1= Earthview responds to the weather visibility setting and typically 80-140 km visibility work best (won't affect any scenery loading because we're too far from the planet). Also, rendering in ALS manually tweaking Rayleigh and Mie constants gives a nice atmosphere effect. NASA provides textures in /much/ higher resolution - in my highest resolution texture set I have the planet covered in 32768x16384 and the cloud layer in half of that. For such large textures, loading time is an issue (Earthview isn't excatly *cough* elegant) and pre-mipmapped compressed DDS is pretty much the only sane option - then that's 8 texture chunks a 176 MB each. It'd be nice to make higher resolution versions available for download, but I realie that's quite a bandwidth hog - if there's sufficient interest and someone knows a server... the textures are there. Provided you have the texture memory, performance should actually be pretty high - there's just two textured spheres in the scene, and even on my old computer I get a solid 60 fps.
{{cite web
|2= {{cite web
   | url    = http://sourceforge.net/p/flightgear/mailman/message/32262904/
   | url    = http://sourceforge.net/p/flightgear/mailman/message/32262904/
   | title  = <nowiki>[Flightgear-devel] Orbital rendering</nowiki>
   | title  = <nowiki>[Flightgear-devel] Orbital rendering - T. Renk</nowiki>
  | author = <nowiki>Renk Thorsten</nowiki>
 
  | date  = Apr 24th, 2014
  | added  = Apr 24th, 2014
  | script_version = 0.23
   }}
   }}
}}


== Requirements ==
== Requirements ==
Legoboyvdlp
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