5 ms·

Turning Corners into Cameras: Principles and Methods

87 points by yamaneko 9y ago

yamaneko 9y ago
Paper is available here: http://people.csail.mit.edu/klbouman/pw/papers_and_presentations/cornercam_iccv2017.pdf http://people.csail.mit.edu/klbouman/pw/papers_and_presentat... Abstract: We show that walls, and other obstructions with edges, can be exploited as naturally-occurring “cameras” that reveal the hidden scenes beyond them. In particular, we demonstrate methods for using the subtle spatio-temporal radiance variations that arise on the ground at the base of a wall’s edge to construct a one-dimensional video of the hidden scene behind the wall. The resulting technique can be used for a variety of applications in diverse physical settings. From standard RGB video recordings, we use edge cameras to recover 1-D videos that reveal the number and trajectories of people moving in an occluded scene. We further show that adjacent wall edges, such as those that arise in the case of an open doorway, yield a stereo camera from which the 2-D location of hidden, moving objects can be recovered. We demonstrate our technique in a number of indoor and outdoor environments involving varied floor surfaces and illumination conditions.
- taneq 9y ago
  > methods for using the subtle spatio-temporal radiance variations that arise on the ground at the base of a wall’s edge to construct a one-dimensional video of the hidden scene behind the wall Interesting. I realised a few years ago that I automatically look down any time I approach a blind corner (when walking through an office, for example). Once I noticed it took me a while longer to figure out that I was looking for the subtle diffuse shadowing that means you're about to walk into someone.
jake-low 9y ago
Fascinating and counter-intuitive that so much information is 'leaked' in light patterns that can't be discerned by the eye. There's a color-amplified visualization in the first embedded video of TFA (starts at 1:40) that shows this really well.
ge96 9y ago
Not related but I once saw this effect where your shades/curtain gap sometimes if the light goes through it correctly you see the image coming in from the window projected onto your wall... I think this is related to how pinhole cameras were discovered/made but anyway that's pretty sweet.
- homero 9y ago
  https://en.wikipedia.org/wiki/Camera_obscura https://en.wikipedia.org/wiki/Camera_obscura
  - ge96 9y ago
    Thanks
evanb 9y ago
This reminds me of dual photography, where one can recover hidden images from diffuse-diffuse light transfer. video: https://www.youtube.com/watch?v=p5_tpq5ejFQ https://www.youtube.com/watch?v=p5_tpq5ejFQ page: http://graphics.stanford.edu/papers/dual_photography/ http://graphics.stanford.edu/papers/dual_photography/
- anfractuosity 9y ago
  Wow the card reading experiment is really amazing! Also I'm not sure if this is similar or not but the following, seems like it might be related: https://www.cl.cam.ac.uk/~mgk25/ieee02-optical.pdf https://www.cl.cam.ac.uk/~mgk25/ieee02-optical.pdf "Optical Time-Domain Eavesdropping Risks of CRT Displays" Where he picks up an image from the diffuse light from a CRT on a wall.
vinchuco 9y ago
https://arxiv.org/pdf/1412.7884v1.pdf https://arxiv.org/pdf/1412.7884v1.pdf
chrischen 9y ago
Originally I thought they were detecting diffracted light around the edge of the wall but it turna out they are just annalzying the light on the floor, which seems to have been done before https://phys.org/news/2015-12-amazing-camera-corners-video.html https://phys.org/news/2015-12-amazing-camera-corners-video.h...
- tonyg 9y ago
  This present research cites the older work you link. The older work uses active illumination; the present work appears to be entirely based on passive recovery of information.
yathern 9y ago
Very cool! I'm always interested by clever uses of perception technology. I wonder if this can be combined with video magnification[1] to remove some of the noise? [1] (http://people.csail.mit.edu/mrub/vidmag/ http://people.csail.mit.edu/mrub/vidmag/)
tmaly 9y ago
This should be used to save people's lives. Many of the marines on the ground that have to go into buildings expect a 50% casualty rate.
- Zeebrommer 9y ago
  Since it's funded by DARPA this is most likely the envisioned application.

87 points by yamaneko 9y ago

Paper is available here: http://people.csail.mit.edu/klbouman/pw/papers_and_presentations/cornercam_iccv2017.pdf http://people.csail.mit.edu/klbouman/pw/papers_and_presentat... Abstract: We show that walls, and other obstructions with edges, can be exploited as naturally-occurring “cameras” that reveal the hidden scenes beyond them. In particular, we demonstrate methods for using the subtle spatio-temporal radiance variations that arise on the ground at the base of a wall’s edge to construct a one-dimensional video of the hidden scene behind the wall. The resulting technique can be used for a variety of applications in diverse physical settings. From standard RGB video recordings, we use edge cameras to recover 1-D videos that reveal the number and trajectories of people moving in an occluded scene. We further show that adjacent wall edges, such as those that arise in the case of an open doorway, yield a stereo camera from which the 2-D location of hidden, moving objects can be recovered. We demonstrate our technique in a number of indoor and outdoor environments involving varied floor surfaces and illumination conditions.

taneq 9y ago
> methods for using the subtle spatio-temporal radiance variations that arise on the ground at the base of a wall’s edge to construct a one-dimensional video of the hidden scene behind the wall Interesting. I realised a few years ago that I automatically look down any time I approach a blind corner (when walking through an office, for example). Once I noticed it took me a while longer to figure out that I was looking for the subtle diffuse shadowing that means you're about to walk into someone.

jake-low 9y ago

Fascinating and counter-intuitive that so much information is 'leaked' in light patterns that can't be discerned by the eye. There's a color-amplified visualization in the first embedded video of TFA (starts at 1:40) that shows this really well.

ge96 9y ago

Not related but I once saw this effect where your shades/curtain gap sometimes if the light goes through it correctly you see the image coming in from the window projected onto your wall... I think this is related to how pinhole cameras were discovered/made but anyway that's pretty sweet.

homero 9y ago
https://en.wikipedia.org/wiki/Camera_obscura https://en.wikipedia.org/wiki/Camera_obscura
- ge96 9y ago
  Thanks

evanb 9y ago

This reminds me of dual photography, where one can recover hidden images from diffuse-diffuse light transfer. video: https://www.youtube.com/watch?v=p5_tpq5ejFQ https://www.youtube.com/watch?v=p5_tpq5ejFQ page: http://graphics.stanford.edu/papers/dual_photography/ http://graphics.stanford.edu/papers/dual_photography/

anfractuosity 9y ago
Wow the card reading experiment is really amazing! Also I'm not sure if this is similar or not but the following, seems like it might be related: https://www.cl.cam.ac.uk/~mgk25/ieee02-optical.pdf https://www.cl.cam.ac.uk/~mgk25/ieee02-optical.pdf "Optical Time-Domain Eavesdropping Risks of CRT Displays" Where he picks up an image from the diffuse light from a CRT on a wall.

vinchuco 9y ago

https://arxiv.org/pdf/1412.7884v1.pdf https://arxiv.org/pdf/1412.7884v1.pdf

chrischen 9y ago

Originally I thought they were detecting diffracted light around the edge of the wall but it turna out they are just annalzying the light on the floor, which seems to have been done before https://phys.org/news/2015-12-amazing-camera-corners-video.html https://phys.org/news/2015-12-amazing-camera-corners-video.h...

tonyg 9y ago
This present research cites the older work you link. The older work uses active illumination; the present work appears to be entirely based on passive recovery of information.

yathern 9y ago

Very cool! I'm always interested by clever uses of perception technology. I wonder if this can be combined with video magnification[1] to remove some of the noise? [1] (http://people.csail.mit.edu/mrub/vidmag/ http://people.csail.mit.edu/mrub/vidmag/)

tmaly 9y ago

This should be used to save people's lives. Many of the marines on the ground that have to go into buildings expect a 50% casualty rate.

Zeebrommer 9y ago
Since it's funded by DARPA this is most likely the envisioned application.