Hello:

 I've been digging through forum messages and looking for this but I havent'
seen an exact hit.

 I'm trying to do a 'space elevator' animation from high orbit, down to the
ground in one shot.

 The curvature of the earth at the start point will be visible, but I want
to have a height field at lower elevations so that you can see the terrain
getting closer.

  I have some height fields that will work (large image maps from 3DEM), but
of course they are 'flat'.

  I could warp the height fields to be spherical I guess, but I"m worried
that the range of the grayscale TGA will cause a problem as the 'edge' dips
down.

  In a related issue, I was trying to wrap a heightfield around the inside
of a hollow cylinder to do an O'Neil colony.

  In both of these cases, I guess I could use an iso surface, but I'd have
to figure out the function, and a bigger issue is that I would have very
long rendering times.  For an animation this would kill me.

  Does anyone have any thoughts on something faster?

        == John ==

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In article <4065a9b0$1@news.povray.org>,
 "John D. Gwinner" <joh### [at] cornelledu> wrote:

>   In both of these cases, I guess I could use an iso surface, but I'd have
> to figure out the function, and a bigger issue is that I would have very
> long rendering times.  For an animation this would kill me.

Look at the spherical and cylinderical height field macros in 
shapes.inc. For the earth terrain, you will probably want to adapt the 
spherical version to only generate terrain for the area near the camera.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/

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If you do not mind generating new height fields, my program
planetGenesis generates height fields that can be map to spheres
by using POV's 'uv_mapping' option.

http://planetgenesis.sf.net

Dave

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