Wolfgang Wieser wrote:
> 
> > news://news.povray.org/3EC752E4.FCFDBF5D%40gmx.de
> > http://news.povray.org/povray.binaries.images/31675/225014/#225014
> >
> Nice images.
> Seems you found a color map of Mars somewhere...

It is very low resolution and includes shading which is difficult to
remove.  You can find this at various places, for example:

http://www.solarviews.com/cap/mars/marscyl1.htm

> IIRC, the 1/128 degree data did not include the poles at that time,
> to I decided to use the 1/64 degree data.

It only goes to 88 degrees but that's no reason not to use it (just fill
the rest with lower resolution).

There are some slight scanning structures in the data though (only visible
in extreme situations of course).

Christoph

-- 
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I am waiting with bated breath :)

It would be nice too if say a third of the earth was in shadow so you see
the topology coming into view as it breaks through the terminator.

Dave


"Wolfgang Wieser" <wwi### [at] gmxde> wrote in message
news:3f20f340@news.povray.org...
> > Animation, Animation, Animation :)
> >
> My next plan. Probably in a month or so...
> It'll render forever, though.
>
> Wolfgang
>

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Christoph Hormann wrote:
> It is very low resolution and includes shading which is difficult to
> remove.  You can find this at various places, for example:
> 
> http://www.solarviews.com/cap/mars/marscyl1.htm
> 
I never tried to use real color of Mars so far but thought I 
could search for a color map today. 

Unfortunately, the results were frustrating. 
It seems, there used to be a nice texture map on the net because 
I stepped over the following: 

Quote from: http://www.cherba.com/wcs/tutorials/vns/mola/
>The nice folks at NASA have made it easy to texture Mars. You'll find 
>the 7.4 Mb color.jpg in the same directory as the rest of the MOLA data.

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

Wolfgang

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"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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> 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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