Algorithm NASA first applied to satellite imagery is now used to peer into antiquity <\/p>\n
High in\u00a0the central tower in the ancient Cambodian temple\u00a0of\u00a0Angkor Wat, paintings depict horseback riders and a traditional musical ensemble.\u00a0Thousands of visitors pass these images\u00a0daily\u00a0without noticing, because\u00a0they\u2019re\u00a0faded to the point of invisibility.\u00a0<\/p>\n
They were discovered\u00a0between 2010 and 2012, along with about 200 other paintings throughout the complex, by an\u00a0archaeologist using a method conceived at NASA\u2019s Jet Propulsion Laboratory in Southern California.\u00a0<\/p>\n
The technique, known as decorrelation stretch, heightens contrasts in digital imagery, making\u00a0features easier to spot.\u00a0It\u00a0is\u00a0especially\u00a0popular\u00a0for studying ancient rock art,\u00a0partly\u00a0due to the chance intersection of one man\u2019s hobby with his professional background.\u00a0<\/p>\n
Around 2005,\u00a0rock art enthusiast Jon Harman\u00a0saw\u00a0NASA\u00a0images depicting the Martian surface with and without the application of decorrelation stretch. Seeing how much detail the technique revealed,\u00a0Harman, now retired in Pacifica, California,\u00a0understood the implication for studying ancient, faded images.\u00a0<\/p>\n
He also worked\u00a0in medical imaging. \u201cI Googled it and found a NASA paper that explained how to do the algorithm,\u201d he said. \u201cI knew from my medical imaging experience that I could do it, so I did.\u201d\u00a0<\/p>\n
The paper was written in 1996 by Ronald Alley, a JPL employee developing\u00a0applications\u00a0for the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), a Japanese\u00a0imaging\u00a0instrument on NASA\u2019s Terra satellite.\u00a0One of\u00a0Alley\u2019s former supervisors\u00a0at JPL\u00a0had\u00a0coinvented decorrelation stretch, and Alley had recognized its potential for gleaning information from ASTER imagery.\u00a0\u00a0<\/p>\n
Harman made his plug-in for use with ImageJ,\u00a0an open-source program developed by the National Institutes of Health.\u00a0\u00a0<\/p>\n
He\u00a0said he\u00a0fulfills\u00a0about 200 requests\u00a0for\u00a0Dstretch\u00a0per year. Around 2010, he\u00a0also\u00a0created smartphone apps that use a shortcut to mimic decorrelation stretch. The apps have been downloaded thousands of times, and papers have been published describing Dstretch\u2019s usefulness in archaeology.\u00a0<\/p>\n
It has been used to spot and clarify imagery at ancient sites under a cliff in Norway, in an Egyptian tomb, at a park in Canada, and\u00a0in\u00a0many\u00a0other\u00a0locations.\u00a0It has also helped archaeologists find buried remains of ancient Greek buildings and examine tattoos on mummified human\u00a0remains, among its non-rock-art applications.\u00a0\u00a0<\/p>\n
Harman said he was not surprised Dstretch found wide use in the rock art community. \u201cBut\u00a0I\u2019ve\u00a0been surprised by a lot of the different applications people have found. So\u00a0that\u2019s\u00a0been cool.\u201d\u00a0\u00a0<\/p>\n","protected":false},"excerpt":{"rendered":"Algorithm NASA first applied to satellite imagery is now used to peer into antiquity High in\u00a0the central tower…\n","protected":false},"author":2,"featured_media":678797,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_share_on_mastodon":"0"},"categories":[270],"tags":[18,19,17,133,451,2454,2455,2456],"class_list":["post-678796","post","type-post","status-publish","format-standard","has-post-thumbnail","category-space","tag-eire","tag-ie","tag-ireland","tag-science","tag-space","tag-spinoffs","tag-technology-transfer","tag-technology-transfer-spinoffs"],"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@ie\/117236316960198698","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/678796","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/comments?post=678796"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/678796\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media\/678797"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media?parent=678796"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/categories?post=678796"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/tags?post=678796"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}