Artem vs. Predator • Hacker News Board

Re: Artem vs. Predator

#11

Post by yk » Fri, May 13, 2016, 8:26 AM UTC

taneq wrote: post #5

Great read! I'm curious about the last bit, saying you need liquid nitrogen cooling to detect the radiated heat from a human. I'd always thought some snakes have infrared-sensitive spots near their mouths that could sense mammals from a distance, are they just that much more sensitive than a photodiode? Or are they sensing something else?

No idea about snakes, but a sensor will glow itself at these wavelength, since it has room temperature which is basically the same temperature as body temperature. So to stop the sensor from blinding itself, you need to cool it significantly below the temperature you want to see.

Re: Artem vs. Predator

#12

Post by gregorkas » Fri, May 13, 2016, 8:27 AM UTC

You know those black and white photos? I thought Russia looked like that with regular cameras :P.

Just kidding, this has to be one of the coolest projects I've ever seen. To make all this by yourself is just ... awesome.

Re: Artem vs. Predator

#13

Post by aavotins » Fri, May 13, 2016, 8:38 AM UTC

Incredible dedication and a fantastic project. I wonder if a setup made from a FLiR Dev Kit, a Raspberry Pi and the Pi camera would produce similar result?

Re: Artem vs. Predator

#14

Post by adrianN » Fri, May 13, 2016, 8:53 AM UTC

venomsnake wrote: post #9

taneq wrote: post #5

Great read! I'm curious about the last bit, saying you need liquid nitrogen cooling to detect the radiated heat from a human. I'd always thought some snakes have infrared-sensitive spots near their mouths that could sense mammals from a distance, are they just that much more sensitive than a photodiode? Or are they sensing something else?

Snakes are seeing in the closest to visible specter IR IIRC. Also they have evolved a lot of other sensory mechanisms to detect pray - sounds, vibrations, taste

https://en.wikipedia.org/wiki/Infrared_sensing_in_snakes

They can sense radiation between 5 micrometers and 30 micrometers.

Re: Artem vs. Predator

#15

Post by sangnoir » Fri, May 13, 2016, 8:59 AM UTC

> But for our goal it’s important to remember, because infrared light does not pass through glass

I thought that was UV?! If that statement is true, how on earth am I able to busk in the heat of the sun behind a glass window, indoors?

Re: Artem vs. Predator

#16

Post by monk_e_boy » Fri, May 13, 2016, 9:11 AM UTC

I assume the distortions at the edge of the 'photos' is due to the X Y scanning rig. Moving the sensor around the edge of a sphere (on a curved X Y (and a little bit of Z) rig, the focal point being the center of the sphere) would sort that right out.

I expect the 3D printer could make a curved rail for the rig.

Or you could point the sensor at the center of the pin hole or lens using a mechanical linkage, then use some software to warp the resulting image.

Re: Artem vs. Predator

#17

Post by adrianN » Fri, May 13, 2016, 9:12 AM UTC

sangnoir wrote: post #15

> But for our goal it’s important to remember, because infrared light does not pass through glass I thought that was UV?! If that statement is true, how on earth am I able to busk in the heat of the sun behind a glass window, indoors?

The sun produces visible light as well.

Re: Artem vs. Predator

#18

Post by d--b » Fri, May 13, 2016, 10:05 AM UTC

monk_e_boy wrote: post #16

I assume the distortions at the edge of the 'photos' is due to the X Y scanning rig. Moving the sensor around the edge of a sphere (on a curved X Y (and a little bit of Z) rig, the focal point being the center of the sphere) would sort that right out. I expect the 3D printer could make a curved rail for the rig. Or you could point the sensor at the center of the pin hole or lens using a mechanical linkage, then use s…

No it's a property of pinhole diffraction: https://en.wikipedia.org/wiki/Airy_disk

Re: Artem vs. Predator

#19

Post by alphapapa » Fri, May 13, 2016, 10:08 AM UTC

david-given wrote: post #7

stared wrote: post #6

It is possible to see in near infrared - just use a IR filter (used for photography), and stick it to your eye. Everything should look dim and reddish, but what is characteristic (and different from a red filter) is that leaves are very bright. Also, many black t-shirts are not-dark. Also, it's fun to make such photos: http://migdal.zenfolio.com/ir-old

Just be really, really careful about sunlight! When you're using a filter like this your iris is wide open, and exposure to direct sunlight or reflected direct sunlight can damage your eyes.

Yes, probably the most comprehensive site about making and using IR goggles is here:

http://amasci.com/amateur/irgoggl.html

He has some very interesting photos taken with them. He also cautions about the iris being opened wide when wearing them, although he claims that he's suffered no ill effects after using them for years (avoiding looking at the sun, of course).

Re: Artem vs. Predator

#20

Post by alphapapa » Fri, May 13, 2016, 10:10 AM UTC

So is the future wavelength project something like radio waves? It would be fascinating to see an image lit by radio waves. Imagine a wifi router being lit up like a lightbulb, casting shadows around a room, or a room lit by FM radio passing through walls and windows, etc.