"Wolfgang Wieser" <wwi### [at] gmxde> wrote in message
news:3f20353c@news.povray.org...
> Fernando Gonzalez del Cueto wrote:
>
> > Are the heights on a real scale? I saw Africa-Europe image and it seems
to
> > me that the elevations are exagerated, but perhaps I have a wrong
> > intuition.
> >
> As explained in the text above the images, the height (and the atmosphere)
> is scaled by a factor of 30.

Only 30?  Looks something more like 10,000 to me.  They say the earth, if
shrunken down, would be more smooth than any common man-made sphere.

>
> Otherwise Earth would be boringly flat ;)

I agree, and you do have artistic license for scaling, including your
extremely thick atmosphere.

>
> Wolfgang
>

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Machiavelli wrote:
> "Wolfgang Wieser" <wwi### [at] gmxde> wrote in message
> news:3f20353c@news.povray.org...
>> As explained in the text above the images, the height (and the
>> atmosphere) is scaled by a factor of 30.
> 
> Only 30?  Looks something more like 10,000 to me.  They say the earth, if
> shrunken down, would be more smooth than any common man-made sphere.
> 
Look: The atmosphere is 20km, scaled by factor 30 yields to 600km. 
Earth has a radius of 6368km (don't mind the last digit) which is 
about 1/10th of the atmosphere. Looking at the image that seems 
plausible...

> I agree, and you do have artistic license for scaling, including your
> extremely thick atmosphere.
> 
Ok, then I'll use my "license" :)

Wolfgang

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> Only 30?  Looks something more like 10,000 to me.

10000?? A mountain, only 1.3 km high, scaled by this factor, would then
be higher than the earth's equatorial diameter!

> They say the earth, if
> shrunken down, would be more smooth than any common man-made sphere.

This shrunken earth would then be a very tiny sphere:
   Diameter of earth = 12756 km
   Height of Mt. Everest = 8.850 km
   Depth of Marianas trench = 10.924 km

Thickness of the traces of a standard printed circuit board = 0.035 mm
These traces are man-made and are *easily* felt with the fingertips.
Shrinking the earth by approx. 1/253000000 gives
   Diameter of earth = 5 cm (2")
   Height of Mt. Everest = 0.035 mm
   Depth of Marianas trench = 0.043 mm

Shrinking the earth by approx. 1/312000000 gives
   Diameter of earth = 4.1 cm
   Height of Mt. Everest = 0.028 mm
   Depth of Marianas trench = 0.035 mm

Although neither Mt. Everest nor Marianas trench have vertical walls,
even a 5-cm-earth would have a feelable Mt. Everest and Mariana trench.
But 35 micrometers are far from the smoothest man-made sphere; the
most accurate sphere probably is this:
http://www.tip.csiro.au/IMP/Optical/spheres.htm

Enlarging this to earth-size, we get
   Diameter =    9.4 cm -> 12756 km
   Total error =  50 nm -> 6.79 m (not km!)
   Roughness   = 0.2 nm -> 37.6 cm

Or the other way:
   Diameter of earth = 0.032 mm (!)
   Height of Mt. Everest + Depth of Marianas trench = 50 nm

So "more smooth than any man-made sphere" is wrong by two to three
orders of magnitude (depending on the diameter, of course).

   Sputnik

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High!

Wolfgang Wieser schrieb:

  The large volvano is Olympus Mons -- said to be the highest volcano in
  the solar system: it is 24km high and measures 550km across.

  The large canyon system is called Vallis Marineris: it extends
  over 4000km and is up to 7km deep.

No, the latter is not true - there are some areas in the large southern
impact basin Hellas Planitia which are even about 8,000
metres below average elevation!

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Yadgar

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> Wolfgang Wieser schrieb:
>   The large canyon system is called Vallis Marineris: it extends
>   over 4000km and is up to 7km deep.
> 
> No, the latter is not true - there are some areas in the large southern
> impact basin Hellas Planitia which are even about 8,000
> metres below average elevation!
> 
If I understand you correctly, then you just explained that there 
is a region on Mars called "Hellas Planitia" which is 8 km "deep" (?)

That's interesting... maybe you know the longnitude and latitude?

BTW, I don't see why my above statement is "not true". 

A close-up rendering of Vallis Marineris is available here: 
http://www.cip.physik.uni-muenchen.de/~wwieser/render/img/mars/

Wolfgang

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Wolfgang Wieser wrote:

> Unfornunately, the link is dead and half an hour searching the net
> did not reveal it...

2min searching the ftp server revealed:
ftp://ltpftp.gsfc.nasa.gov/projects/tharsis/MOLA/GRIDS


   Matthias

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Matthias Wieser wrote:
> Wolfgang Wieser wrote:
>> Unfornunately, the link is dead and half an hour searching the net
>> did not reveal it...
> 
> 2min searching the ftp server revealed:
> ftp://ltpftp.gsfc.nasa.gov/projects/tharsis/MOLA/GRIDS
> 
Yeah... because that IS the dead link I mentioned. 

Fortunately, it seems that the host was only temporarily down 
because I was able to get that file today. 

Thanks for pointing that out. 

Wolfgang

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