Showing posts with label Thermographic camera. Show all posts
Showing posts with label Thermographic camera. Show all posts

Friday, November 28, 2014

Thermal and Night Vision Tracking: Info for Writers with Deputy Jay Korza


English: Soldier wearing night vision goggles.
 (Photo credit: Wikipedia)
Fiona - 
ThrillWriting is happy to host author Deputy Jay Korza who works as a first responder with fourteen years of experience as a deputy as well as military experience under his belt. 

Jay, I'm writing a scene where the good guys (and gals) are using night vision goggles. I've asked around and no will let me play with them. Boo. So I'd like to ask you some questions to make my scene believable, please.

First up, what is the biggest mistake you see writers and filmmakers making, so I can bypass that mine field.

Jay - 
I have a lot of experience and training with thermal imaging. That is THE MOST messed up thing you see in movies and TV. Thermal imaging does NOT do what they portray it to do.

It can not see through walls.

Thermal imagers detect the temperature of the surface of whatever you are pointing it at except glass.

For instance, if you were looking at the hood of a car with the engine running, the hood would be hot. Now, take a piece of ordinary scotch tape and place it on the hood of the car. That scotch tape will show up in the imager because it's surface is a different temperature than the surrounding metal. Eventually, maybe even only several seconds, that tape will heat up to match the temperature of the surrounding metal and it may disappear in the image. But if that tape is even one-tenth of a degree different in temperature, you will still see it on the hood of the car. So, if the imager can't see through a fraction of a millimeter of tape, do you think it can see through a wall? Nope.

Also, thermal imaging is relative in what it shows. If I had two ice cubes sitting on a frozen plate of metal and the metal was 20 degrees and the ice cubes were 25, the ice cubs would be blazing "hot" in comparison.

It will see through smoke though. I can see through bushes, sort of. If a bad guy is behind a bush, his heat goes through the spaces in the leaves and branches and comes out the other side and forms an image for you to view.

Glass and most kinds of plastic reflect heat. So you can't see through glass at all with thermal. You see whatever is on your side of the glass, usually yourself.

A lot of things retain heat from the day so at night, you get a lot of, "Holy shit, there's someone over there. Oh, nope, it's a barrel cactus."

But what's funny is, when you see a person, you NEVER mistake it for anything else, and you know that. But barrel cactuses will still get you excited even though you know that people are obvious. At least at ground-level handheld imaging. Planes and ariel images are less obvious because of distance.

Fiona - 
How does this differ from green spectrum night-vision goggles?

Wikipidia public domain

Jay - 
Night vision goggles are infrared viewers. To be totally accurate, thermal imaging is also infrared viewing. But the two are in different infrared spectrums. So it's easier to separate them and call them NVG (night vision goggles) or Thermal to distinguish between the two.

Fiona - 
Which do you feel is the more accurate when you use them for work?

Jay - 
NVG takes a certain portion of the IR spectrum that is usually invisible to us, and enhances it. Or it takes low-light images and makes them brighter for us. That's the basic answer, though I'm sure an engineer who builds NVGs would pull his hair out at the oversimplicity of my description.

Fiona - I have an engineer ex- I would say much of what I said made him pull his hair out - poor bald fellow, LOL (kidding.)

Jay - 

Thermal is way more accurate. But it's also WAY more expensive. There are pros and cons to each. That's why for the last five years they have been working on blending the technology into combined imagers. I had a $19k imager that I used for a couple of years, and I loved it! It was NVG with thermal overlay. Or you could use either one independently. I tended to go with thermal only. Though one night during training, I was on point in a desert operation, we were searching for the "bad guys". I took a knee to look around, and I heard a distinctive rattle. I looked around to find the snake, and I couldn't. I turned from thermal to NVG, and he was about eight inches from my leg. He didn't show up on thermal because he was cold blooded and took on the temperature of his surroundings - he blended in on thermal.

Fiona -
YIPES! awesome detail!

Jay - 
Check out this article on the recent flaw found in USB stuff. I read a similar one the other day and it goes along with your security questions. HERE

Here is a thermal imager that we have on SWAT. It's an older one but it works. It's not a dual overlay. HERE

Fiona - 

Last quick question, which do you prefer for water searches thermal or NVG? How is water affected by thermal?

Jay - 
Water reflects heat. So when you look at water it usually shows as extremely cold no matter what its temperature is because it's reflecting the temperature of the upper atmosphere which is cold. So searching for a person in water with thermal is easy because their little head shows up as REALLY hot compared to the water around them.

Video Quick Study - (1:01) Watch this thermal vs NVG video. 
Video Quick Study - (2:01)  Anti-nightvision camouflage (I'd definitely want to be the "ghost"!

Hey ThrillWriting readers, Jay has a new book out.

2.99 on Amazon
Sebastian Giustina has a rare talent. Scientists call it hyperosmia, but other officers vying for the top spot in the NYPD Homicide Detectives' rankings call it an unfair advantage. Sebastian has a nose for crime - with a heightened sense of smell and a photographic scent memory, Sebastian can detect evidence at crime scenes that would otherwise go unobserved.

When a female serial killer crosses the U.S. to target her prey in New York City, she unwittingly leaves evidence that only Sebastian can uncover. It's a race against time and a match of wit and will for Sebastian and his partner to save the next person on the murderer's list from becoming yet another victim.

Thank you so much for stopping by. And thank you for your support. When you buy my books, you make it possible for me to continue to bring you helpful articles and keep ThrillWriting free and accessible to all.