Re:3D Scanning Systems That Can Render a Complete, Editable ...
by burntoutfire on Monday March 22, 2021 @03:27PM
(#26545534)
Do you know if purely vision based techniques have any advantages for inferring depth in these scenarios (close range object scanning) over lidars?
Re:3D Scanning Systems That Can Render a Complete, Editable ...
by nobbis on Monday March 22, 2021 @04:25PM
(#26546429)
Yes, different failure cases (purely vision can't tell the depth of a plain white wall) but there are orders of magnitude more pixels in regular cameras. Apple's LiDAR produces a 256x192 depth map, but its RGB cameras run at 1920x1440. You get much more detail, but passive stereo is orders of magnitude slower (ToF sensors are 60 Hz, photogrammetry takes minutes.)
They complement each other well, which is the basis of our approach at Abound: combine the detail of multi-view stereo for short-range with the robustness of ToF out to 5m.
It used structured light: project a static pattern of infrared dots and then measure parallax using an infrared camera a couple inches from the projector to calculate depth. It worked well, but can't be miniaturized as it relies on a large offset between projector and camera. Orbbec make similar cameras today, e.g. https://orbbec3d.com/product-astra-pro
Modern depth cameras, like the LiDAR Scanner in iPhones and iPads, use a different technique: time-of-flight (ToF), which shoots laser pulses and measures the time taken to reflect back to infer depth. Apple leads the field here, because they're the first to integrate a "direct" ToF sensor into mobile devices, which has a number of advantages over the "continuous wave" ToF found in Android phones.