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Hello,
I am trying to make a picture of the Earth and the Moon. One POV unit
equals one mile. The Moon is something like 250000 miles from the
origin and it is nothing but a tiny, gray speck. When the camera is
near the Moon, the Earth looks small too. Is there a limit on how far
apart objects can be? I might have one POV unit equal to 100 or 1000
miles.
Brendan Ryan
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There is a limit, but 250,000 units should be well within that limit. You might
have the simensions of the objects wrong. I too have had the problem you
describe, the Moon seeming too small at correct distance & size, but 'a tiny
gray speck' seems a bit extreme. Unless you have a very large camera angle.
Do you absolutely _need_ to have the correct dimensions?
Margus
Andrea Ryan wrote:
>
> Hello,
> I am trying to make a picture of the Earth and the Moon. One POV unit
> equals one mile. The Moon is something like 250000 miles from the
> origin and it is nothing but a tiny, gray speck. When the camera is
> near the Moon, the Earth looks small too. Is there a limit on how far
> apart objects can be? I might have one POV unit equal to 100 or 1000
> miles.
> Brendan Ryan
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Everytime I make them the right size and distance I get the same problem. I
think it is because even a large monitor is not as large as the sky and so
you have to divide the apparent size of the moon by the same factor that
your screen divides the sky.
"Andrea Ryan" <ary### [at] global2000 net> wrote in message
news:38794C56.4F454654@global2000.net...
> Hello,
> I am trying to make a picture of the Earth and the Moon. One POV unit
> equals one mile. The Moon is something like 250000 miles from the
> origin and it is nothing but a tiny, gray speck. When the camera is
> near the Moon, the Earth looks small too. Is there a limit on how far
> apart objects can be? I might have one POV unit equal to 100 or 1000
> miles.
> Brendan Ryan
>
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Wow sounds complicated...
Bill DeWitt wrote:
> Everytime I make them the right size and distance I get the same problem. I
> think it is because even a large monitor is not as large as the sky and so
> you have to divide the apparent size of the moon by the same factor that
> your screen divides the sky.
>
> "Andrea Ryan" <ary### [at] global2000net> wrote in message
> news:38794C56.4F454654@global2000.net...
> > Hello,
> > I am trying to make a picture of the Earth and the Moon. One POV unit
> > equals one mile. The Moon is something like 250000 miles from the
> > origin and it is nothing but a tiny, gray speck. When the camera is
> > near the Moon, the Earth looks small too. Is there a limit on how far
> > apart objects can be? I might have one POV unit equal to 100 or 1000
> > miles.
> > Brendan Ryan
> >
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Wasn't it Andrea Ryan who wrote:
>Hello,
>I am trying to make a picture of the Earth and the Moon. One POV unit
>equals one mile. The Moon is something like 250000 miles from the
>origin and it is nothing but a tiny, gray speck. When the camera is
>near the Moon, the Earth looks small too. Is there a limit on how far
>apart objects can be? I might have one POV unit equal to 100 or 1000
>miles.
There's a sort of optical illusion that makes the Moon seem to be much
larger than it is. If you take a photo that includes the moon with, say,
a 50mm lens, the picture looks like this:-
+-------------------------------------------+
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+-------------------------------------------+
A POVray image that uses the default camera angle will look similar. To
get a decent looking photo of the Moon you need to use quite a long
telephoto lens, so in POVray, that would mean setting your camera to
something like this.
camera {location < 0, 0, -250000>look_at <0,0,0> angle 2}
--
Mike Williams + #
Gentleman of Leisure
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I checked this stuff out since you brought it up and found that I had to use a
camera located 20 million miles away having an 'angle 0.05'. The Earth and Moon
were proportionally correct at about 8000 miles and 2100 miles diameters (Moon
placed almost directly behind the Earth, really no difference if in front at
this field of view) and of course the Moon being 240,000 miles from the Earth.
Problem was that the image mapping becomes distorted at angle 1 or less, perhaps
other small angles distort things too depending upong the objects and/or
textures. Like Mike W. has pointed out, in photography the same sort of thing
becomes apparent. The usual viewpoint of a person never matches too well. In
fact I've come to think of this as a somewhat macro-view to tele-view aspect of
human vision (to sound scientific). If you look at the Moon (or anything)
directly as opposed to indirectly there's a sense of zooming in closer. The
typical gaze upon a landscape however for example is wide field and were the
Moon looked at while also taking in the entire surrounding sky or horizon then
it shrinks from sight more. If you pick anything out of your vision area, such
as a unavoidably noticeable Moon in this case, then it immediately seems larger.
Take notice next time you stare at one object and see how everything else blends
away into the background (or foreground). Look at the same thing while also
taking in the surroundings and it can seem smaller than when looked at directly.
Anyhow, that's my theorizing about it.
Bob
"Andrea Ryan" <ary### [at] global2000net> wrote in message
news:38794C56.4F454654@global2000.net...
> Hello,
> I am trying to make a picture of the Earth and the Moon. One POV unit
> equals one mile. The Moon is something like 250000 miles from the
> origin and it is nothing but a tiny, gray speck. When the camera is
> near the Moon, the Earth looks small too. Is there a limit on how far
> apart objects can be? I might have one POV unit equal to 100 or 1000
> miles.
> Brendan Ryan
>
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I seem to remember reading something about this effect - basically our
brains visually resize large distant objects. The eye is not a camera. We do
funny things with colours as well. We can look at a colour under different
lighting conditions and see the same colour. Try that with a camera. I
believe we use surrounding colours as a kind of gauge.
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Remember that the moon is pretty small in the night sky. If you face due
north, then follow a line throught the zenith (directly above you) and
back down to due south, you've coverd 180 degrees of sky. The moon is
about one quarter of one degree across. That aint very big. Remember the
"bigger, brighter moon" last December? It was technically bigger, but not
so the human eye could detect
Andrea Ryan wrote:
> Hello,
> I am trying to make a picture of the Earth and the Moon. One POV unit
> equals one mile. The Moon is something like 250000 miles from the
> origin and it is nothing but a tiny, gray speck. When the camera is
> near the Moon, the Earth looks small too. Is there a limit on how far
> apart objects can be? I might have one POV unit equal to 100 or 1000
> miles.
> Brendan Ryan
--
Josh English
eng### [at] spiritonecom
ICQ: 1946299
"Stress is when you wake up screaming and realize you haven't fallen
asleep yet."
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> funny things with colours as well. We can look at a colour under different
> lighting conditions and see the same colour.
Definitely. At the moment the only light source in the room is red neon,
everything else is black, and yet I can see things in their original colors.
--
Lance.
The Zone - http://come.to/the.zone
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Andrea Ryan wrote:
>
> Hello,
> I am trying to make a picture of the Earth and the Moon. One POV unit
> equals one mile. The Moon is something like 250000 miles from the
> origin and it is nothing but a tiny, gray speck. When the camera is
> near the Moon, the Earth looks small too. Is there a limit on how far
> apart objects can be? I might have one POV unit equal to 100 or 1000
> miles.
> Brendan Ryan
About a year ago we were discussing the same with other astronomical
things, and the conclusin was that it was harder to get them scaled
correctly, correct lens data and cheats with eye and perception than it
was to cheat and make the moon look apperantly correct. Sorry to say
this, but use the artistic licence(TM) to get the best results.
--
//Spider -- [ spider@bahnhof.se ]-[ http://darkmere.wanfear.com/ ]
And the devil in black dress watches over
My guardian angel walks away
Life is short and love is always over in the morning
Black wind come carry me far away
--"Sisters of Mercy" -- "Temple Of Love"
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