Question Why do some cameras record sides as curvy then?

[yelpisstupid1000]

There are some cameras, especially dash cameras, that when they record, the sides kind of bend, or curve, they get like a mirage, or wavy...............There is no one on the internet that writes about this, no one on youtube brings this up, no one seems to know about it, no one seems to know this......It has gotten to the point where I thought well maybe the camera was just setup differently or like maybe only.....but........its not true......some, not all, but some, especially dash cameras, when you record them, the sides of the video kind of get recorded as if they are curving, or waving, or in a mirage, like there not original.......because no one has written or posted videos on this, at first i thought well maybe its just the way the camera is setup.........so i bought a YI dash cam....and what do you know it records the sides as curvy or wavy........and before you say im imagingn things or no one else has the problem becuase it doesnt exist......when i recorded my room......it shows on the side, that the walls are curving and tilted........thats not how my walls are.....they are stright..........so now i know it is an issue with some cameras..........im just surprsied that no one has written about it, posted videos about it, explained this, or that no one seems to knwo about this.........you guys are experts...someone in toms hardware must know waters.

 

[Solandri]

i dont understand.......some dash cams have it...and some dont.....if some have dont have it, there must be a descirption as to which have it and which dont.....or...some numbers that which have it and which dont...so far ive had people telling me it comes with wide angles, and its usueless if its not wide angle and accusing me of argueing against physics then, and making it seem like you ge twhat you pay for, but its liek no one explains the common stuff!!!!!!

There are basically two types of lenses (ignoring minor distortions like barrel distortion).

Rectilinear lenses keep straight lines straight. The cost for this is that circles turn into ovals as they approach the top or sides of the frame, into teardrops as they approach the corners. This is a consequence of the playback medium though. If you're playing back rectilinear images on a flat screen, then these distortions will disappear if you sit close enough to the screen so that the screen field of view matches the recorded field of view.

Fisheye lenses keep circles round no matter where they show up in the image. The cost for this is that straight lines get curved as they approach the edges of the frame. This too is a consequence of the playback medium. If you could project a fisheye images onto a spherical screen, and viewed it from the center of the screen radius, the image would appear undistorted.

For security cameras, since consistency of the image is more important than undistorted projection, the fisheye view is preferred. It has the advantage in that an object that stays a constant distance from the camera will cover the same number of pixels no matter where it shows up in the recorded image. On a rectilinear lens, an object staying a constant distance covers more pixels towards the edges, fewest pixels towards the center.

Another problem with rectilinear views is that the distortion approaches infinity as you approach a 180 degrees field of view. You can see this if you imagine looking at a monitor. How close would you have to sit at the monitor for it to give you a 180 degree field of view? It would literally have to be right in front of your eye. Meaning that if you wanted to show two identical objects, one at the center and one at the edge, there would have to be an infinite amount of distortion between those two for them to appear identical.

Fisheye views OTOH can go all the way up to 360 degrees. They just look bad when viewed on a flat monitor. If you crop them so their angle of view matches the angle of view of the monitor, the distortion is minimal to nonexistent.

So the security and dash cams which use rectilinear lenses usually have a narrow field of view. As you move towards wide angle, fisheye lenses become more practical, yield a better image, and also happen to be cheaper to make.

 

[yelpisstupid1000]

ok im going to stop writing too much..and just keep it simple......some record with no fisheye...and some do.....if your saying all have to some extenct, fine, that must be some techincality becuase lots of videos onine DONT make the sides curve, or bend, or wavy, or like a mirage.....right?...do you agree with that much?...there are cameras that sometimes just record...i sent a link earlier ....here is a link of a recording i used with a non dash cam.....this recrding is fine...no fisheye....just regular.......https://www.youtube.com/watch?v=Uk8i-s3bshY&t=84s

 

[yelpisstupid1000]

There are basically two types of lenses (ignoring minor distortions like barrel distortion).

Rectilinear lenses keep straight lines straight. The cost for this is that circles turn into ovals as they approach the top or sides of the frame, into teardrops as they approach the corners. This is a consequence of the playback medium though. If you're playing back rectilinear images on a flat screen, then these distortions will disappear if you sit close enough to the screen so that the screen field of view matches the recorded field of view.

Fisheye lenses keep circles round no matter where they show up in the image. The cost for this is that straight lines get curved as they approach the edges of the frame. This too is a consequence of the playback medium. If you could project a fisheye images onto a spherical screen, and viewed it from the center of the screen radius, the image would appear undistorted.

For security cameras, since consistency of the image is more important than undistorted projection, the fisheye view is preferred. It has the advantage in that an object that stays a constant distance from the camera will cover the same number of pixels no matter where it shows up in the recorded image. On a rectilinear lens, an object staying a constant distance covers more pixels towards the edges, fewest pixels towards the center.

Another problem with rectilinear views is that the distortion approaches infinity as you approach a 180 degrees field of view. You can see this if you imagine looking at a monitor. How close would you have to sit at the monitor for it to give you a 180 degree field of view? It would literally have to be right in front of your eye. Meaning that if you wanted to show two identical objects, one at the center and one at the edge, there would have to be an infinite amount of distortion between those two for them to appear identical.

Fisheye views OTOH can go all the way up to 360 degrees. They just look bad when viewed on a flat monitor. If you crop them so their angle of view matches the angle of view of the monitor, the distortion is minimal to nonexistent.

So the security and dash cams which use rectilinear lenses usually have a narrow field of view. As you move towards wide angle, fisheye lenses become more practical, yield a better image, and also happen to be cheaper to make.

Ok so is there any dash cam that does not have the fisheye type of recording? Anything that records regularly? Anything means a good qulaity one. So i dont want bad quality obviously. A good quality that just records in a regular ways

 

[TJ Hooker]

Just curious, why does it matter if your dashcam has some distortion around the edges? I thought most people had dashcams for the sake of having video evidence in the case of an accident, wouldn't think some distortion would prevent the camera from working in this regard.

 

[hang-the-9]

s the sides curve.....i mean....some people are so picky about how there video, picture,, recording, or whatever film there putting together, and yet, no one cares about the sides of a video being a mirage or bending or being wavy?........this is surprising.....i want a dash cam that doesnt do that.....i had a camera that didnt do it, but it was not a dash cam.....i already put a link of that video.............there must be some dash cam that you can find when you shop around that doesnt do it then..............reviews dont have anything about that part........seems like the only way is to go by video....but....if this happens with any dash cam that has a wide range, then does that mean most have it?....because dont mo

i dont understand.......some dash cams have it...and some dont.....if some have dont have it, there must be a descirption as to which have it and which dont.....or...some numbers that which have it and which dont...so far ive had people telling me it comes with wide angles, and its usueless if its not wide angle and accusing me of argueing against physics then, and making it seem like you ge twhat you pay for, but its liek no one explains the common stuff!!!!!!....why do some have it and some dont?....if some have it and some dont , how do you figure it out OTHER then playing videos of people recordings then.......if 170 wide angle has it how come some 170 wide angles dont........if 170 wide angeles have it then what numbers wont have

If you don't want distorted images, get a normal camera and stick it on your dash to record. People are explaining things but you are not understanding the explanations. Read them fully. A dash cam would be pretty useless unless it had a wide field of view, since otherwise it will miss anything not happening right in front of it. To have a wide angle view there is no way to not have those curved and distorted sided in video, without using software to fix it after the recording. If you say some have it and some don't, link to some products you say don't have the distortion when using wide angle recordings. A dashcam or security camera to cover a wide area is not made for perfect video, it is made to record something happening in the area with enough detail to see what is needed. Meaning you can still see a car, a person, their face, the car license plate, who did what, etc.. with the wide angle view and image. If you want a perfect image, then don't use a camera designed for something else.

Car backup cams is another example, do you want a perfect picture or do you want to see what is needed so you don't back into something? Distorted image, shows a wide angle view to lens size especially.

f