"Aliens" style motion scanner

[Bitter Ashes]

I think nearly everyone in the Western world has seen the film Aliens, so hopefully you'll know what I mean.

You know those things that the marines had that detected motion and put it on a nice display complete with a satisfying beeping noise to signal range. Do these things actually exist in a portable system? I'm guessing that they'd use either radar or sonar doppler effect or something, so I was thinking that they'd be pretty easy to build perhaps (the main issue being the display and processing algorithms I reckon).

Just curious really, although now I think on it, the psychological impact of seeing crusty anarchists running around with sci-fi style equipment could be worthwhile perhaps.

[Sasha]

You know those things that the marines had that detected motion and put it on a nice display complete with a satisfying beeping noise to signal range. Do these things actually exist in a portable system? I'm guessing that they'd use either radar or sonar doppler effect or something, so I was thinking that they'd be pretty easy to build perhaps (the main issue being the display and processing algorithms I reckon).

pretty sure you could build them from an amped up parking sensor or something but i dont really see what use they would be besides parameter protection of your base.



Just curious really, although now I think on it, the psychological impact of seeing crusty anarchists running around with sci-fi style equipment could be worthwhile perhaps.

our greek comrades are working on that:
http://www.laserpointersafety.com/news/files/pic-2011-02-15-at-9.19.40-am.jpg
http://i.dailymail.co.uk/i/pix/2011/02/09/article-1355132-0D18166D000005DC-935_634x397.jpg

they use laser pointers not only to blind the cops but also to point out which one everybody should throw their bricks and mollys on.
an multiple angle attack on an individual cop and then together move to the next is way more effective than everybody throwing at their own copper.

[Bitter Ashes]

Well, I'm kinda thinking now if maybe just being able to demonstrate that a collective not part of the capitalist system is capable of matching, or even surpassing, capitalism's R&D capabilities.

We've had the idea recently to build a stirling engine that is powered by the sun focussed by a parabolic mirror and using it to power a cassette player or something. Then dropping it off at the local paper with a note to say something like "put me in sunlight" and then it starts playing the tape which explains what the machine is, how it works, how it was developed and includes free plans on how to make your own for electricity generation, or pumping, or whatever and how it can be made out of junk.

Open source technology I suppose.

[Psy]

I think nearly everyone in the Western world has seen the film Aliens, so hopefully you'll know what I mean.

You know those things that the marines had that detected motion and put it on a nice display complete with a satisfying beeping noise to signal range. Do these things actually exist in a portable system? I'm guessing that they'd use either radar or sonar doppler effect or something, so I was thinking that they'd be pretty easy to build perhaps (the main issue being the display and processing algorithms I reckon).

It is tricky even for stationary motion detector to figure out relevant motion so what most do now is uses a camera and only have a relevant area that the computer looks for motion like in front of a door on a video feed.

With a portable system everything will move so the system will just keep seeing movement as it moves as everything moves relative to it. Thus you can't get the computer to look for movement on a video feed.

[Bitter Ashes]

Well, wouldn't you be able to come up with a solution with something like a broadcasting radio signal that could be triangulated from static transceivers to determine if the scanner unit has moved. A simpler method, more mobile version, could be to use tilt switches perhaps to determine if the scanner is in motion and in what direction.


distance and direction of scanner moved = current co-ordinates of scanner - previous co-ordinates of scanner

You then use that to elimate objects that have changed in distance relative to the scanner as a result of the scanner being moved.


Object has moved if
distance/direction of object moved =/= distance and direction of scanner moved

It does create a blind spot though if the object is moving at the same speed and direction as the scanner. Not sure how to counter that yet.

[Psy]

Well, wouldn't you be able to come up with a solution with something like a broadcasting radio signal that could be triangulated from static transceivers to determine if the scanner unit has moved. A simpler method, more mobile version, could be to use tilt switches perhaps to determine if the scanner is in motion and in what direction.


distance and direction of scanner moved = current co-ordinates of scanner - previous co-ordinates of scannerYou then use that to elimate objects that have changed in distance relative to the scanner as a result of the scanner being moved.


Object has moved if
distance/direction of object moved =/= distance and direction of scanner movedIt does create a blind spot though if the object is moving at the same speed and direction as the scanner. Not sure how to counter that yet.

Right that would work but even then ground clutter will give back false movement for example even a tree moving in the wind will be seen as movement to radar and a camera will see lots of movement just from shadows (static camera based motion detectors control the level of light in the area it is looking for motion in).

[Bitter Ashes]

Well, you wouldn't do it with light. You'd have it giving off IR, or radio (radar), or sound (sonar) and be reading that part of the EM spectrum rather than light which can have multiple sources. That'd sort out the shadows.

As for the background clutter, I'm not sure. Even in the film they were being set off by a couple of hamsters running around in a wheel if I remember right. Maybe you could put some kind of threshold on the velocity of an object before it's flagged up? That way, a flag lightly fluttering in the wind wouldn't set it off because the fabric will only be moving a little in any one direction at any one time, but if it were flying in the wind it'd be covering a lot of distance in a short time and would be flagged.

Maybe you could also have a feature on there to manually flag/de-flag objects on there as a backup?

[Psy]

Well, you wouldn't do it with light. You'd have it giving off IR, or radio (radar), or sound (sonar) and be reading that part of the EM spectrum rather than light which can have multiple sources. That'd sort out the shadows.

As for the background clutter, I'm not sure. Even in the film they were being set off by a couple of hamsters running around in a wheel if I remember right. Maybe you could put some kind of threshold on the velocity of an object before it's flagged up? That way, a flag lightly fluttering in the wind wouldn't set it off because the fabric will only be moving a little in any one direction at any one time, but if it were flying in the wind it'd be covering a lot of distance in a short time and would be flagged.

Maybe you could also have a feature on there to manually flag/de-flag objects on there as a backup?

How fast does infantry move when trying to avoid detection? What you could do is have the computer look at the contacts and see if the movements follow a pattern that would resemble infantry in some kind of formation since armed forces only have finite number of formations thus example it would look see contacts moving on the side of a wall and see that it resembles a formation for stacking up to prepare for entry of a room (that would also be nice information for the user).

[Dr Mindbender]

I think nearly everyone in the Western world has seen the film Aliens, so hopefully you'll know what I mean.

You know those things that the marines had that detected motion and put it on a nice display complete with a satisfying beeping noise to signal range. Do these things actually exist in a portable system? I'm guessing that they'd use either radar or sonar doppler effect or something, so I was thinking that they'd be pretty easy to build perhaps (the main issue being the display and processing algorithms I reckon).

Just curious really, although now I think on it, the psychological impact of seeing crusty anarchists running around with sci-fi style equipment could be worthwhile perhaps.

I think the closest thing in real life would be the CAT scan that they use in hospitals.

[Dr Mindbender]

pretty sure you could build them from an amped up parking sensor or something but i dont really see what use they would be besides parameter protection of your base.



our greek comrades are working on that:
http://www.laserpointersafety.com/news/files/pic-2011-02-15-at-9.19.40-am.jpg
http://i.dailymail.co.uk/i/pix/2011/02/09/article-1355132-0D18166D000005DC-935_634x397.jpg

they use laser pointers not only to blind the cops but also to point out which one everybody should throw their bricks and mollys on.
an multiple angle attack on an individual cop and then together move to the next is way more effective than everybody throwing at their own copper.


Blue lasers would be better for this job.

http://www.youtube.com/watch?v=E0oM66jfaJ4&NR=1

http://www.youtube.com/watch?v=H-SduY4A2kE&feature=related

http://www.youtube.com/watch?v=4Rl3w8nG1kU&NR=1