archaeological mapping
October 19, 2010 9:25 PM Subscribe
Could we see through walls?
with new deveolpments in archaeological mapping such Lidar and Gordion GPR and satellite data project, is there a technology being developed that could be passive yet accurate enough to identify an object?
with new deveolpments in archaeological mapping such Lidar and Gordion GPR and satellite data project, is there a technology being developed that could be passive yet accurate enough to identify an object?
2007: Engineers Develop Technology To See Through Walls
2010: Augmented Reality Makes Walls Transparent
And there was something a few years ago about bricks that transmitted the image of whatever was behind them, or something like that, but I can't dig up the right keywords to find it. I remember seeing a section of glassy-looking brick wall in something like a big garage...
posted by L'Estrange Fruit at 10:23 PM on October 19, 2010
2010: Augmented Reality Makes Walls Transparent
And there was something a few years ago about bricks that transmitted the image of whatever was behind them, or something like that, but I can't dig up the right keywords to find it. I remember seeing a section of glassy-looking brick wall in something like a big garage...
posted by L'Estrange Fruit at 10:23 PM on October 19, 2010
Response by poster: tenth of a mm.
In termal prospection, multispectral sensors can achieve this with-in 1 mil if not more but will not produce a more complete image of the area being surveyed, let alone what a small object is, say 30 ft or more underground.
posted by clavdivs at 10:39 PM on October 19, 2010
In termal prospection, multispectral sensors can achieve this with-in 1 mil if not more but will not produce a more complete image of the area being surveyed, let alone what a small object is, say 30 ft or more underground.
posted by clavdivs at 10:39 PM on October 19, 2010
One might nitpick that Lidar and GPR are more probing than seeing, where seeing to me is interpreting received light. As Burhanistan points out, you don't specify nondestructive. You can "see" through walls with a 50mm machine gun.
posted by StickyCarpet at 10:56 PM on October 19, 2010
posted by StickyCarpet at 10:56 PM on October 19, 2010
Response by poster: the 'see through walls' was bad mast head.
refer to more inside. but i like Lidar, GPR and this augmented reality.
As Burhanistan points out, you don't specify nondestructive. You can "see" through walls with a 50mm machine gun.
posted by StickyCarpet at 1:56 AM
...being developed that could be passive yet accurate enough to identify an object?
posted by clavdivs to technology..12:25 AM
try the time machine thread.
nice BIG GUN analogy.
transparent concrete is aleast akin to the science I'm trying to find out that might be/could about, needless i state my google-fu has run into bricks and high price journals. jeez, like some star trek characters at Wilton's Music Hall and Cmdr. Rikerstans' girdle is strangling his directional abilities.
posted by clavdivs at 11:37 PM on October 19, 2010
refer to more inside. but i like Lidar, GPR and this augmented reality.
As Burhanistan points out, you don't specify nondestructive. You can "see" through walls with a 50mm machine gun.
posted by StickyCarpet at 1:56 AM
...being developed that could be passive yet accurate enough to identify an object?
posted by clavdivs to technology..12:25 AM
try the time machine thread.
nice BIG GUN analogy.
transparent concrete is aleast akin to the science I'm trying to find out that might be/could about, needless i state my google-fu has run into bricks and high price journals. jeez, like some star trek characters at Wilton's Music Hall and Cmdr. Rikerstans' girdle is strangling his directional abilities.
posted by clavdivs at 11:37 PM on October 19, 2010
If you want something totally passive, I'm pretty sure the answer is no, except in certain cases.
To be completely passive, you could use only ambient light, which in most cases is approximately sunlight. Sunlight consists of the visible spectrum, which is redundant to our goal, plus the UV spectrum. Since UV is higher energy that visible light, in most cases that I can think of it is absorbed more easily in matter than visible light (for example, UV resistant sunglasses are clear to visible light, but absorb UV). UV is particularly easily absorbed by organic material, so anything like plastic or wood would be completely opaque.
Trying to use lower energy light, such as microwaves, will get you somewhere in that it'll pass through walls easily. But lower energy means longer wavelength, which means you lose the ability to resolve the shape of an object.
All that said, I don't know anything about archeological mapping, lidar, or GPR, so I may be talking out of my ass.
posted by auto-correct at 12:13 AM on October 20, 2010
To be completely passive, you could use only ambient light, which in most cases is approximately sunlight. Sunlight consists of the visible spectrum, which is redundant to our goal, plus the UV spectrum. Since UV is higher energy that visible light, in most cases that I can think of it is absorbed more easily in matter than visible light (for example, UV resistant sunglasses are clear to visible light, but absorb UV). UV is particularly easily absorbed by organic material, so anything like plastic or wood would be completely opaque.
Trying to use lower energy light, such as microwaves, will get you somewhere in that it'll pass through walls easily. But lower energy means longer wavelength, which means you lose the ability to resolve the shape of an object.
All that said, I don't know anything about archeological mapping, lidar, or GPR, so I may be talking out of my ass.
posted by auto-correct at 12:13 AM on October 20, 2010
Best answer: Radar is not exactly passive. In order for an electromagnetic wave to get pass a material (assuming you have a walled-off room with no windows), there are 2 ways. One is to use very short wavelength (ie x-ray/gamma-ray). The wavelength of these photons are smaller than the diameter of the atom so they don't get absorbed/reflected by the electrons (which is the main reason why most materials are opaque at longer wavelength). They may be scattered by the nucleus though; and they don't exist naturally, so you need a man-made source. Then there is a problem: what kind of material the object you want to detect need to be made out of, so that it scatter/absorb a photon that goes through a wall? In all likelihood, you will only be able to detect materials that are denser than the wall, i.e their nucleus are denser than your typical wall's elements (C, Si, Fe). If you try to detect Hydrogen or Oxygen (human body), any wavelength that is scattered by them will also be scattered by C,Si and Fe, thus unusable.
Method 2 is using long-wavelength (Ku-band). These wavelength are much longer than your typical molecular bond, thus they do not get absorbed by either the electron in an atom or the shared electron in the normal molecular bond. These can penetrate foliage and soil (to a certain degree), getting reflected off at material boundary. The problem with these wavelength is that they are long, thus you will get no return for small objects. In general, you are diffraction-limited to object the size of your wavelength, which is, tens of centimeter in the case of Ku band. They are also blocked by conductive materials (i.e. anything metal, sea-water) because these are equivalent to a sheet of electrons, reflecting the wave. To improve resolution, you may try exotic signal processing and/or wavefront detection, but these can be tough. Some French researcher recently did some interesting recreation of image behind an semi-translucent material, but they have to feed their signal processing algorithm with a lot of pre-condition to help it get to the image.
You may also try to do exotic method such as using one wavelength to penetrate the wall, then detect the fluorescent in a different wavelength. Typically though, the fluorescent wavelength is within the order of magnitude with the incoming wavelength, so you don't gain much in term of tuning your wavelengths around material properties.
In short, it's hard to look through wall (as it should be).
PS: I think transparent brick or augmented reality display is cheating. Of course if you get to decide what go into the wall you will be looking through, there are many ways to make it give off the information you need.
posted by curiousZ at 12:39 AM on October 20, 2010 [2 favorites]
Method 2 is using long-wavelength (Ku-band). These wavelength are much longer than your typical molecular bond, thus they do not get absorbed by either the electron in an atom or the shared electron in the normal molecular bond. These can penetrate foliage and soil (to a certain degree), getting reflected off at material boundary. The problem with these wavelength is that they are long, thus you will get no return for small objects. In general, you are diffraction-limited to object the size of your wavelength, which is, tens of centimeter in the case of Ku band. They are also blocked by conductive materials (i.e. anything metal, sea-water) because these are equivalent to a sheet of electrons, reflecting the wave. To improve resolution, you may try exotic signal processing and/or wavefront detection, but these can be tough. Some French researcher recently did some interesting recreation of image behind an semi-translucent material, but they have to feed their signal processing algorithm with a lot of pre-condition to help it get to the image.
You may also try to do exotic method such as using one wavelength to penetrate the wall, then detect the fluorescent in a different wavelength. Typically though, the fluorescent wavelength is within the order of magnitude with the incoming wavelength, so you don't gain much in term of tuning your wavelengths around material properties.
In short, it's hard to look through wall (as it should be).
PS: I think transparent brick or augmented reality display is cheating. Of course if you get to decide what go into the wall you will be looking through, there are many ways to make it give off the information you need.
posted by curiousZ at 12:39 AM on October 20, 2010 [2 favorites]
Response by poster: to be fair to Burhaistan, (I), from article I read, should have replied:
'Gamma Ray 0.03 nanometers Entirely absorbed by the Earth's atmosphere and not available for remote sensing.'
a good link and relative.
posted by clavdivs at 5:42 PM on October 21, 2010
'Gamma Ray 0.03 nanometers Entirely absorbed by the Earth's atmosphere and not available for remote sensing.'
a good link and relative.
posted by clavdivs at 5:42 PM on October 21, 2010
This thread is closed to new comments.
But how accurately do you want to identify something? You can already see the heat signatures of things through solid walls.
posted by inturnaround at 9:29 PM on October 19, 2010 [1 favorite]