One of the core lessons any physics student will come to realize is that the more you know about physics, the less intuitive it seems. Take the nature of light, for example. Is it a wave? A particle? Both? Neither? Whatever the answer to the question, scientists are at least able to exploit some of its characteristics, like its ability to bend and bounce off of obstacles. This camera, for example, is able to image a room without a direct light-of-sight as a result.
The process works by pointing a camera through an opening in the room and then strobing a laser at the exposed wall. The laser light bounces off of the wall, into the room, off of the objects on the hidden side of the room, and then back to the camera. This concept isn’t new, but the interesting thing that this group has done is lift the curtain on the image processing underpinnings. Before, the process required a research team and often the backing of the university, but this project shows off the technique using just a few lines of code.
This project’s page documents everything extensively, including all of the algorithms used for reconstructing an image of the room. And by the way, it’s not a simple 2D image, but a 3D model that the camera can capture. So there should be some good information for anyone working in the 3D modeling world as well.
Thanks to [Chris] for the tip!
This appears to be using Helmholtz Reciprocity – a well-known concept in computer vision circles.
My own research showed that using a large silver mirror instead of just a wall will give even better images.
A lot better.
Beggars can’t always be choosers.
This seems remotely related to one of the amazing properties of the “French Curve” drafting tool.
The curve is designed such that, no matter how you hold it, the bottom of the curve will always be parallel to the ground.
The bottom of any smooth convex curve is parallel to the ground. So is the top. (More strictly speaking, a line tangent to the bottom of a smooth convex curve is parallel to the ground, where the ground is assumed to be a plane perpendicular to the gravity vector through the “bottom” of the curve and “bottom” is the point on the curve where the distance to the ground plane is minimized.) (I assume an expert in geometry or trigonometry can express this better and more completely.) (I’m assuming Euclidean space.)
a circle would fit that criteria. The bottom of a circle is always parallel to the ground too. :-)
I believe this was covered already in slightly more detail here https://hackaday.com/2019/08/22/looking-around-corners-with-f-k-migration/
Looks like this is a blog post about the same publication.
Seems awfully similar to the recent https://hackaday.com/2019/08/22/looking-around-corners-with-f-k-migration/
Uses the same images and dataset too. But this author (Rutkowski] didn’t simply repackage and re-present Lindell’s Stanford work — he builds on it and re-explains it, in what I think is a more accessible way.