| Topic: |
Science > Physics |
| User: |
"" |
| Date: |
03 Oct 2006 03:28:09 AM |
| Object: |
Question about perspective |
This should be simple but I can't seem to find the answer. Consider the
parallel lines of a railway track perceived by a standing observer as
meeting at a distant point at the horizon. Now add two parallel laser
pointers on them and move them along the tracks. It seems to me that
the path of the laser beams and the angle they reach the eyes won't
change, but they should be perceived as getting closer, but how? Thanks
for your time.
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| User: "" |
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| Title: Re: Question about perspective |
03 Oct 2006 12:19:19 PM |
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wrote:
This should be simple but I can't seem to find the answer. Consider the
parallel lines of a railway track perceived by a standing observer as
meeting at a distant point at the horizon. Now add two parallel laser
pointers on them and move them along the tracks. It seems to me that
the path of the laser beams and the angle they reach the eyes won't
change, but they should be perceived as getting closer, but how? Thanks
for your time.
Here is the graph...
http://i95.photobucket.com/albums/l147/nobody1357/untitled2.gif
[IMG]http://i95.photobucket.com/albums/l147/nobody1357/untitled2.gif[/IMG]
In the second and third versions, the laser beams enter the eye at the
same angle, but how can they be percieved differently?
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| User: "Ben Rudiak-Gould" |
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| Title: Re: Question about perspective |
04 Oct 2006 04:32:07 AM |
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wrote:
http://i95.photobucket.com/albums/l147/nobody1357/untitled2.gif
First of all, as Jim Black said, in clear air you won't see the laser beams
at all unless they're pointed directly at your pupils, in which case they'll
appear as points, not line segments. If you add smoke to the air so that you
can see the beams, then as the laser pointers are moved towards you it's
just as though faraway parts of the beam are being erased, while nearby
parts of the beam are unchanged. So when the pointers are far away, the
perspective projection will show two yellow line segments meeting at the
same point as the railroad tracks, and when the pointers are closer it'll
show subsegments of those same line segments. None of these will be parallel
to the railroad tracks, contrary to your drawing.
-- Ben
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| User: "Jim Black" |
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| Title: Re: Question about perspective |
03 Oct 2006 02:20:17 PM |
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wrote:
This should be simple but I can't seem to find the answer. Consider the
parallel lines of a railway track perceived by a standing observer as
meeting at a distant point at the horizon. Now add two parallel laser
pointers on them and move them along the tracks. It seems to me that
the path of the laser beams and the angle they reach the eyes won't
change, but they should be perceived as getting closer, but how? Thanks
for your time.
In this setup, the laser beams won't enter the standing observer's eyes
at all.
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| User: "dedanoe" |
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| Title: Re: Question about perspective |
03 Oct 2006 08:41:22 AM |
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optics of lenses has the answer. the 3d-vector (x, y, z) viewed trough
the lense in your eye becomes 2d-vector (x', y') where
x'=3Dx*focus/(focus-z) and y'=3Dy*focus/(focus-z)
was that the answer you were looking for? the prove is for your
homework.
by the way i wanna show you how optics can be derived from the
lever-law. visit http://dedanoe.tripod.com and in section "the upcoming
age of levers" click "read more" and the thing is in the bottom of the
..pdf
nobody1357@operamail.com =D0=BD=D0=B0=D0=BF=D0=B8=D1=88=D0=B0:
This should be simple but I can't seem to find the answer. Consider the
parallel lines of a railway track perceived by a standing observer as
meeting at a distant point at the horizon. Now add two parallel laser
pointers on them and move them along the tracks. It seems to me that
the path of the laser beams and the angle they reach the eyes won't
change, but they should be perceived as getting closer, but how? Thanks
for your time.
.
|
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| User: "dedanoe" |
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| Title: Re: Question about perspective |
03 Oct 2006 08:42:53 AM |
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optics of lenses has the answer. the 3d-vector (x, y, z) viewed trough
the lense in your eye becomes 2d-vector (x', y') where
x'=3Dx*focus/(focus-z) and y'=3Dy*focus/(focus-z)
was that the answer you were looking for? the prove is for your
homework.
by the way i wanna show you how optics can be derived from the
lever-law. visit http://dedanoe.tripod.com and in section "the upcoming
age of levers" click "read more" and the thing is in the bottom of the
..pdf
nobody1357@operamail.com =D0=BD=D0=B0=D0=BF=D0=B8=D1=88=D0=B0:
This should be simple but I can't seem to find the answer. Consider the
parallel lines of a railway track perceived by a standing observer as
meeting at a distant point at the horizon. Now add two parallel laser
pointers on them and move them along the tracks. It seems to me that
the path of the laser beams and the angle they reach the eyes won't
change, but they should be perceived as getting closer, but how? Thanks
for your time.
.
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| User: "" |
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| Title: Re: Question about perspective |
03 Oct 2006 12:29:42 PM |
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dedanoe wrote:
optics of lenses has the answer. the 3d-vector (x, y, z) viewed trough
the lense in your eye becomes 2d-vector (x', y') where
x'=3Dx*focus/(focus-z) and y'=3Dy*focus/(focus-z)
Thanks, but please review this graph:
http://i95.photobucket.com/albums/l147/nobody1357/untitled2.gif
The angle that the laser beams enter the eyes cannot depend on distance
or z, they are the same for 2nd and 3rd versions, so how can you see
them differently?
was that the answer you were looking for? the prove is for your
homework.
by the way i wanna show you how optics can be derived from the
lever-law. visit http://dedanoe.tripod.com and in section "the upcoming
age of levers" click "read more" and the thing is in the bottom of the
.pdf
nobody1357@operamail.com =D0=BD=D0=B0=D0=BF=D0=B8=D1=88=D0=B0:
This should be simple but I can't seem to find the answer. Consider the
parallel lines of a railway track perceived by a standing observer as
meeting at a distant point at the horizon. Now add two parallel laser
pointers on them and move them along the tracks. It seems to me that
the path of the laser beams and the angle they reach the eyes won't
change, but they should be perceived as getting closer, but how? Thanks
for your time.
.
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