{"id":159355,"date":"2025-02-14T09:57:54","date_gmt":"2025-02-14T14:57:54","guid":{"rendered":"https:\/\/www.bu.edu\/eng\/?p=159355"},"modified":"2025-02-14T09:57:54","modified_gmt":"2025-02-14T14:57:54","slug":"using-the-light-we-cant-see","status":"publish","type":"post","link":"https:\/\/www.bu.edu\/eng\/2025\/02\/14\/using-the-light-we-cant-see\/","title":{"rendered":"Using the Light We Can’t See"},"content":{"rendered":"

Goyal team’s passive 3D imaging method can map distances, determine object materials, and more<\/strong><\/h3>\n

By Patrick L. Kennedy<\/strong><\/p>\n

When you look out your window at night, you expect to see objects\u2014a tree, a neighbor\u2019s house\u2014illuminated by street lamps or moonlight. If there were a power outage on a moonless night, you\u2019d see only darkness.<\/p>\n

That doesn\u2019t mean there\u2019s no light out there, though. \u201cThere is light,\u201d says Professor Vivek Goyal<\/a> (ECE<\/a>). \u201cIt\u2019s just at wavelengths that you can\u2019t see with the naked eye.\u201d<\/p>\n

With the aid of an ordinary thermal camera or night vision goggles, you could see something\u2014at least the outlines of nearby objects. But Goyal says a much richer sense of the surroundings can be gleaned from that invisible-to-us light, and his team is developing the more sophisticated data processing needed to do it. Someday, their 3D imaging technology\u2014which they recently reported in an IEEE journal<\/a>\u2014might be used for mapping and navigation for autonomous vehicles, among other applications.<\/p>\n

\"Vivek
Vivek Goyal (ECE)<\/em><\/figcaption><\/figure>\n

\u201cYou can infer distance,\u201d says Goyal. \u201cThe atmosphere is not only absorbing light but also emitting light, as a function of wavelength, and we can mathematically model that. There\u2019s different absorption at different wavelengths as light travels through the air, so light that\u2019s traveled a longer distance has a different spectrum than light that was emitted very close to you.\u201d<\/p>\n

Goyal and colleagues have begun successfully picking up distance cues by passively measuring thermal radiation at these various wavelengths that are too long for the naked eye. Their sensor technology is passive in the sense that it detects light, but doesn\u2019t emit light.<\/p>\n

\u201cThe work was initially funded by DARPA to support autonomous navigation in the dark while remaining stealthy,\u201d explains Goyal, who continued building upon the work for more general applications after completing the defense project. \u201cYou can put lidar [a laser imaging, detection, and ranging system] on an autonomous vehicle, but lidar is not stealthy\u2014it\u2019s emitting light all the time.\u201d<\/p>\n

For Goyal, the work of traditional thermal imaging is almost \u201ctoo easy,\u201d he says. \u201cA lot of the prior work was related to the Air Force, where they studied tracking a missile or an airplane\u2014something much hotter than the atmosphere. We want to be able to use this absorption principle to do ranging [determining distances] for scenes where the objects are not necessarily hotter than the air at all\u2014in fact, the objects could be colder than the air.\u201d<\/p>\n

In addition to mapping distances, Goyal\u2019s team believes their passive 3D sensing methods might also determine the materials of objects, air temperature, humidity, and gas concentrations\u2014all of which could aid in navigation.<\/p>\n

\u201cWe separate out the effects of material and temperature,\u201d Goyal says. \u201cSo if an autonomous vehicle is navigating at night, and an obstacle is just about the same temperature as the road, it would look the same to an ordinary thermal camera, whereas our sensor would discern the difference and be able to navigate around it.\u201d<\/p>\n

The students and postdocs in Goyal\u2019s lab hail from disciplines including computer science, materials science, electrical engineering, and computer engineering, and his colleagues include researchers at MIT, the National Institute of Standards and Technology, and the Jet Propulsion Laboratory.<\/p>\n

\u201cResearch is so social,\u201d says Goyal. \u201cA lot of it has to do with connecting with people with the same interests.\u201d<\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

The more sophisticated data processing the Goyal team is developing might be used for mapping and navigation for autonomous vehicles, among other applications.<\/p>\n","protected":false},"author":2662,"featured_media":159921,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[236,257,907,1067],"tags":[414],"_links":{"self":[{"href":"https:\/\/www.bu.edu\/eng\/wp-json\/wp\/v2\/posts\/159355"}],"collection":[{"href":"https:\/\/www.bu.edu\/eng\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bu.edu\/eng\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bu.edu\/eng\/wp-json\/wp\/v2\/users\/2662"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bu.edu\/eng\/wp-json\/wp\/v2\/comments?post=159355"}],"version-history":[{"count":5,"href":"https:\/\/www.bu.edu\/eng\/wp-json\/wp\/v2\/posts\/159355\/revisions"}],"predecessor-version":[{"id":159922,"href":"https:\/\/www.bu.edu\/eng\/wp-json\/wp\/v2\/posts\/159355\/revisions\/159922"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.bu.edu\/eng\/wp-json\/wp\/v2\/media\/159921"}],"wp:attachment":[{"href":"https:\/\/www.bu.edu\/eng\/wp-json\/wp\/v2\/media?parent=159355"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bu.edu\/eng\/wp-json\/wp\/v2\/categories?post=159355"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bu.edu\/eng\/wp-json\/wp\/v2\/tags?post=159355"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}