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Op 09/10/2019 om 20:06 schreef Bald Eagle:
>
> "angie866" <mde### [at] gmail com> wrote:
>
>> Is there a way to attach to the sphere a certain height to generate the real
>> height of the moon?
>> Or is there another way to do it? I have the data of the
>> digital elevation model from LOLA
>> Instrument in a .img file (from
>>
https://pds-geosciences.wustl.edu/lro/lro-l-lola-3-rdr-v1/lrolol_1xxx/data/lola_gdr/cylindrical/img/)
>>
>> Thank you to everybody who wants to help me.
>> Mauro
>
> Well, based on this
> https://www.loc.gov/preservation/digital/formats/fdd/fdd000420.shtml
>
> and
>
>
https://web.archive.org/web/20070801195300/http://home.gdal.org/projects/imagine/img2tif_src.zip
>
> You might have a shot at subdividing the sphere surface into a rectangular mesh,
> and using tif heightfields.
>
> But that would be a LOT of work, and use a lot of memory and parsing/rendering
> time.
>
> Maybe just find a bump map of the moon and uv-map the sphere, using the bump-map
> to create the normals.
>
> http://planetpixelemporium.com/earth.html
>
>
I absolutely second that. See for instance:
https://astrogeology.usgs.gov/search?pmi-target=moon
It has been 20 years since I last used dem data; I even must have a
couple of discs somewhere with the whole US on them ;-) The point is
that POV-Ray cannot use dem data directly in a height_field. You need to
convert them first to a tga image file and then use that as a spherical
height_field. The USGS used to provide a little utility just to do that
conversion with their data, called DEM2TGA.EXE, iirc. However, my
address to USGS seems to have gone dead so I cannot provide it immediately.
fwiw, see also: http://www.viewfinderpanoramas.org/dem3.html
--
Thomas
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