Lightning Artefacts on Video

robotriot

New Member
Hello everyone,

I stumbled upon this site today and find that whole debunking process you guys are involved in very interesting. I'm especially interested in explaining visual phenomena and I have something that I always wondered about. Maybe one of you can explain what exactly is going on here.

These are still images from a video of a thunderstorm I recorded with a cheap digital camera a couple of years ago. After taking a closer look at the lightning I recorded, I noticed that sometimes the lightning seems to be in front of trees and buildings, which means it would have struck about 100-150 meters from my window, several times. I don't know that it looks like when lightning actually strikes the ground and when observing the lightning, I always felt like the lightning struck much further away, behind the trees. So I was thinking it's probably some sort of visual artefact (like the frame in the middle row to the right, where the lightning is actually cut off entirely). Is it some form of double exposure? Can anyone explain what exactly is going on here technically?

lightning.jpg
 
in your last two photos.. what am i looking at? they are the exact same lightning bolt. ?

Yea, they are from the same lightning bolt. In the frame on the bottom left, it appears to be in front of the trees while in the second one, you can only see a short bit at the bottom that is cut off suddenly, and the rest of the bolt appears to be in the sky behind the trees.
 
and the rest of the bolt appears to be in the sky behind the trees.
theres a little bit in front of the trees on the bottom. i'm just guessing but if the camera was snapping that fast to catch a lightning bolt twice in the exact same position.. could it be something to do with the sensor not being able to reset fast enough?

eventually a "camera guy" will read this post and maybe be able to give you an explanation. :)
 
theres a little bit in front of the trees on the bottom. i'm just guessing but if the camera was snapping that fast to catch a lightning bolt twice in the exact same position.. could it be something to do with the sensor not being able to reset fast enough?

eventually a "camera guy" will read this post and maybe be able to give you an explanation. :)

I was hoping so :)

I've uploaded the video in its entirety for completeness sake to Youtube: (at the time I recorded a couple of minutes of the thunderstorm and just edited out all the non-lightning bolt footage).
 
I was hoping so :)

I've uploaded the video in its entirety for completeness sake to Youtube: (at the time I recorded a couple of minutes of the thunderstorm and just edited out all the non-lightning bolt footage).

nice vid. very cool. quick question.. so are those screen grabs from the video?
 
Nice video!

What camera is it? Could it possibly have a compression issue that's causing the bolt to be duplicated in picture 5, or were you behind glass?

Ray Von
 
Nice video!

What camera is it? Could it possibly have a compression issue that's causing the bolt to be duplicated in picture 5, or were you behind glass?

Ray Von
The camera model used was a Sanyo XACTI VPC-J2EX. The video was recorded from behind a closed window, yes.
 
What is the anomaly exactly? Lightning is known to discharge from the ground up, if that's what it is. Or is it the in front/behind thing happening?
 
This kinda sounds like the explanation (not that i can follow it really :) nice full article exxplanation though.

The 'ghost channel' artifact is simply an image of the first return stroke channel shifted downward to the bottom of the video frame. The return stroke occurs faster than the camera's shutter and 30 frames per second can resolve, causing the image of the channel to bleed across the lower section of the frame. The ghost channel's identity is given away by the fact that its shape matches that of the main lightning channel in the frames following it. The only difference is that its position on the screen is shifted vertically down from its true location, creating the illusion that it is striking something very close http://stormhighway.com/videoghost.php
Content from External Source

i noticed in one photo the bottom seems to match the top a bit too nicely... maybe this is the "ghost image" ?
purpleligtning.jpg


edit add.. and just for educational purposes, i googled "lightning photos purple artifacts", then "images" and clicked on teh first photo that looked like a purple artefact. basically i got lucky.
 
I think deirdre has it. Here's a sequence of the frames, just looking at the region on the right of the frame:


Notice the bolt at the bottom of frame 105 is basically the same as the bolt at the top of frame 110, clearly it's just an ghost image of the lighting in the sky.



It's a little confusing as the "ghost" image appears to happen before the real image. But that's just a result of the rolling shutter. In 105 the shutter had already got 3/4 of the way down the image before the lightning started.

Here's a boosted version of frame 105, which clearly shows the rolling shutter effect:


There's a lot more discussion of rolling shutter here:
https://www.metabunk.org/solved-str...ida-lightning-rolling-shutter-artifact.t3244/
With an example of how it can get a segment of the lighting bolt:
 
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More specifically, I download the video from YouTube using an OSX program called "Downie"
http://software.charliemonroe.net/downie/

I then use the Quicktime viewer to single-step through it using the arrow keys. I usually use the latest version, but sometimes use Quicktime Viewer 7, which lets you display the frame number
 
Thank you deirdre and Mick West for explaining the phenomenon! I was pretty sure it had to do something with the way video cameras worked, but the link that deirdre posted explains it perfectly. Good find!
 
Thank you deirdre and Mick West for explaining the phenomenon! I was pretty sure it had to do something with the way video cameras worked, but the link that deirdre posted explains it perfectly. Good find!
useful topic. :) plus i learned about grabbing video frames! dont know when i'll ever need them, but how cool is that?

sorry i mucked up your thread with my video/computer illiteracy.
 
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