On 13-10-2013 8:11, posfan12 wrote:
> Here's a render from 1 mile above the surface. Lots of stuff are messed up.
> There should be clouds and an atmosphere above my head. The ground texture cuts
> out as it starts curving upward. Yuck!
>
> I'll post the scene file in povray.text.scene-files.
>

The problem your are now meeting is the epsilon issue in POV-Ray. Bill 
Pragnell and I we have met this before with this type of configuration 
of the Ringworld. In short, you cannot really see the Ringworld 
correctly because of the huge size range of the object and POV-Ray is 
unable to render that correctly when the camera is put close to its 
surface. Our solution is to use the Ringworld itself as a background for 
a currently flat landscape scene using height_fields or isosurfaces and 
a sphere simulating the local sky. The Ringworld is then seen through 
this sphere like we see the Moon in our day lit sky on Earth. To achieve 
this use a semi-transparent sphere for the sky with the sky colours as 
inside_texture and space black for the outside. Like the following code:

#declare BlueSkySphere =
texture {
   pigment {
     gradient y
     pigment_map {
       [0.0 srgb < 0.8235294,  0.8901961,  0.9254902 >*1.5 transmit 0.5]
       [1.0 srgb < 0.3843137,  0.6156863,  0.7411765 >*1.5 transmit 0.5]
     }
   }
   finish {
     emission 1
     diffuse 0.0
   }
}

#declare CosmosSkySphere =
texture {
   pigment {
     color rgbt <0,0,0,1>
   }
   finish {
     ambient 0.0
     diffuse 0.0
   }
}

#declare SkyDummy =
sphere {
   <0, 0, 0>, 1
   texture {CosmosSkySphere} //using inverse puts the inside of the 
sphere outside
   interior_texture {BlueSkySphere}
   no_shadow
   no_reflection
   hollow
   scale <100*10e3, 1*10e3, 100*10e3>
   translate <CamLoc.x, -2.0, CamLoc.z>
}

object {SkyDummy}


This correctly shows what the Ringworld would look like from its surface 
as the distances are so huge that it would look flat near the camera, 
like we see the surface of the Earth.

Thomas

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