3D Camera Merges Depth and Spectral Data

Rice University, Houston, Texas

The compact Hyperspectral Stripe Projector (HSP) combines the HSP, a monochrome sensor array, and sophisticated programming to give users a more complete picture of an object’s shape and composition. It captures four-dimensional information from an image — three spatial and one spectral — in real time.

HSP takes a cue from portable 3D imaging techniques — such as face ID systems in smartphones and body trackers in gaming systems — and adds a way to pull broad spectral data from every pixel captured. This compressed data is reconstructed into a 3D map with spectral information that can incorporate hundreds of colors and be used to reveal not only the shape of an object but also its material composition.

Regular RGB (red, green, blue) cameras provide three spectral channels; however, a hyperspectral camera provides spectra in many channels. HSP simultaneously encodes the depth and hyperspectral measurements, allowing the use of a monochrome camera instead of an expensive hyperspectral camera as typically used in similar systems.

HSP uses an off-the-shelf digital micromirror device (DMD) to project patterned stripes that look something like colorful bar codes onto a surface. Sending the white-light projection through a diffraction grating separates the overlapping patterns into colors. Each color is reflected back to the monochrome camera, which assigns a numerical grey level to that pixel. Each pixel can have multiple levels, one for every color stripe it reflects. These are recombined into an overall spectral value for that part of the object.

The finely tuned spectra can reach beyond visible light. What they reflect back to the sensor as multiplexed fine-band spectra can be used to identify the material’s chemical composition. At the same time, distortions in the pattern are reconstructed into 3D point clouds, essentially a picture of the target but with a lot more data than a plain snapshot could provide.

For more information, contact Mike Williams at This email address is being protected from spambots. You need JavaScript enabled to view it.; 713-348-6728.