mersenneforum.org  

Go Back   mersenneforum.org > New To GIMPS? Start Here! > Homework Help

Reply
 
Thread Tools
Old 2019-07-02, 00:28   #1
jasong
 
jasong's Avatar
 
"Jason Goatcher"
Mar 2005

5×701 Posts
Default maybe I don't know the right terms for a fisheye shape

https://www.bing.com/images/search?q...id&FORM=HDRSC2

I'm watching a lot of first amendment audit videos(US videos, free speech amendment) and sometimes people are accused of standing too close, which can be hard to determine with a fisheye video.

I'm looking for a picture that basically shows me mathematically, how far away stuff is. Optimally, I'd like to have a fisheye shape I could just put over a Youtube video, but I know that's a rainbows and unicorns type dream.

Have a nice day. :)
jasong is offline   Reply With Quote
Old 2019-07-02, 13:34   #2
Dr Sardonicus
 
Dr Sardonicus's Avatar
 
Feb 2017
Nowhere

2×1,901 Posts
Default

Quote:
Originally Posted by jasong View Post
I'm looking for a picture that basically shows me mathematically, how far away stuff is.
No can do. A camera renders a 3-D subject into a 2-D perspective image. This allows all sorts of mischief. As an example, I suggest you look up the Ames room.
Dr Sardonicus is offline   Reply With Quote
Old 2019-07-02, 13:49   #3
jasong
 
jasong's Avatar
 
"Jason Goatcher"
Mar 2005

5×701 Posts
Default

Quote:
Originally Posted by Dr Sardonicus View Post
No can do. A camera renders a 3-D subject into a 2-D perspective image. This allows all sorts of mischief. As an example, I suggest you look up the Ames room.
Are you claiming different cameras can fisheye differently?

The way I see it, and maybe I'm wrong, but if a camera says it does, say, 170 degrees, and it's a 16:9 image, I would think someone with the proper knowledge and software could simulate that. I don't have the knowledge for that,so I'm playing the role of a beggar. :)

It's not a huge deal for me, maybe it's harder than I think.

Tbh, I was hoping I was simply using the wrong Google terms. I've seen some of the images on Google, and I'm simply looking for one where the point of view is at the center of the ellipse(?) going out.
jasong is offline   Reply With Quote
Old 2019-07-02, 13:55   #4
Uncwilly
6809 > 6502
 
Uncwilly's Avatar
 
"""""""""""""""""""
Aug 2003
101×103 Posts

2·4,441 Posts
Default

Different cameras have different 'fisheye' lenses. The distortions are different. The angle covered by the lens is not a guarantee of the same representation on the image. Some lenses are more akin to a true panoramic, while others have a high drop-off on the sides. Also, they don't have to have the same rotational symmetry (up-down vs left-right can be different curves). Further, the sensor or film can be shaped to change the effect.
Uncwilly is online now   Reply With Quote
Old 2019-07-02, 13:57   #5
jasong
 
jasong's Avatar
 
"Jason Goatcher"
Mar 2005

DB116 Posts
Default

Quote:
Originally Posted by Dr Sardonicus View Post
No can do. A camera renders a 3-D subject into a 2-D perspective image. This allows all sorts of mischief. As an example, I suggest you look up the Ames room.
I'm certainly not an expert, but if you think about it, everything you see is a 2-d image, a spherical image that impinges on your eyeball.

I think most of the distortion would be going from a spherical image to a flat screen, so even regular tv is distorted.
jasong is offline   Reply With Quote
Old 2019-07-02, 14:44   #6
Dr Sardonicus
 
Dr Sardonicus's Avatar
 
Feb 2017
Nowhere

2×1,901 Posts
Default

Quote:
Originally Posted by jasong View Post
Are you claiming different cameras can fisheye differently
<snip>
No. I'm claiming that no camera (with a single aperture and focal plane) gives an image that can tell you how far away anything actually is. You need more information. If there's something in the image whose actual size is known, you can do stuff. Without that sort of information, the picture won't tell you if it's showing a tiny object nearby or a large object far away. An example of the mischief that can be caused by this ambiguity may be seen here.

If you are instead concerned with undoing the distortions caused by a lens, then as already indicated by other posters, it depends on the specific lens. I suggest a Google search with parameters

"fisheye lens correction"
Dr Sardonicus is offline   Reply With Quote
Old 2019-07-02, 15:40   #7
chris2be8
 
chris2be8's Avatar
 
Sep 2009

36308 Posts
Default

Quote:
Originally Posted by jasong View Post
I'm certainly not an expert, but if you think about it, everything you see is a 2-d image, a spherical image that impinges on your eyeball.
Most people have two eyes, and comparing the images lets you estimate how far away things are by parallax. And seeing how the image changes as you move relative to the scene lets you estimate 3D shapes as well.

A photograph is just one 2D image, so you have a lot more ambiguity to worry about.

Chris
chris2be8 is offline   Reply With Quote
Old 2019-07-02, 22:32   #8
Batalov
 
Batalov's Avatar
 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2

2×19×241 Posts
Default

An image, ha! Even a video is not going to tell you the truth:
Batalov is offline   Reply With Quote
Old 2019-07-02, 23:18   #9
a1call
 
a1call's Avatar
 
"Rashid Naimi"
Oct 2015
Remote to Here/There

29·67 Posts
Default

Another case and point.
ETA, sorry my video does not upload. I get the message it's invalid.

Last fiddled with by a1call on 2019-07-02 at 23:21
a1call is online now   Reply With Quote
Old 2019-07-02, 23:40   #10
Batalov
 
Batalov's Avatar
 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2

2·19·241 Posts
Default

Quote:
Originally Posted by a1call View Post
Another case and point.
ETA, sorry my video does not upload. I get the message it's invalid.
Different countries - different access. I also cannot view many of the videos that other people occasionally post.

Simply google for "The Mysterious Floating Orb" (add Yankovic if needed.
Batalov is offline   Reply With Quote
Old 2019-07-02, 23:47   #11
a1call
 
a1call's Avatar
 
"Rashid Naimi"
Oct 2015
Remote to Here/There

29·67 Posts
Default

I can see your video, no problem. I was trying to upload a video of the object created by the Japanese mathematician.
Here is an article about the object. The video is from the cylinders turning to diamond shape.

https://www.insider.com/optical-illu...atician-2018-5

a1call is online now   Reply With Quote
Reply

Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Can Mersenne composites share "shape"? jnml Miscellaneous Math 31 2018-01-01 01:55
3ds camera games:need help with search terms jasong jasong 0 2013-11-29 18:14
Shape of a CUDA lattice siever fivemack Programming 2 2012-12-16 01:07
Confusing terms/acronyms? Uncwilly Lounge 0 2010-12-29 01:27
We're #3 in terms of number of primes found! MooooMoo Twin Prime Search 35 2007-11-04 07:11

All times are UTC. The time now is 05:32.

Fri Nov 27 05:32:41 UTC 2020 up 78 days, 2:43, 4 users, load averages: 1.30, 1.23, 1.34

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.

This forum has received and complied with 0 (zero) government requests for information.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation.
A copy of the license is included in the FAQ.