{"id":1588,"date":"2017-04-28T14:23:22","date_gmt":"2017-04-28T14:23:22","guid":{"rendered":"https:\/\/libapps.libraries.uc.edu\/thepreservationlab\/?p=1588"},"modified":"2017-04-28T14:23:22","modified_gmt":"2017-04-28T14:23:22","slug":"fun-with-photodoc-rti-edition-5","status":"publish","type":"post","link":"https:\/\/libapps.libraries.uc.edu\/thepreservationlab\/2017\/04\/fun-with-photodoc-rti-edition-5","title":{"rendered":"Fun with PhotoDoc – RTI (Edition 5)"},"content":{"rendered":"

At the beginning of April I was lucky enough to attend a RTI (Reflectance Transformation Imaging) workshop offered by Cultural Heritage Imaging<\/a> (CHI) at Yale University. \u00a0CHI is a non-profit organization \u00a0that shares and teaches RTI and Photogrammetry technology with cultural heritage institutions around the world. \u00a0The class I attended was a 4-day NEH grant sponsored course taught by three RTI experts from CHI, and it was amazing!
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\"Fun<\/a>

This is a composite image of all the highlight points from one RTI section. The software uses these highlight points to map the surface shape and color of your object.<\/p><\/div>
\nSo, what is RTI? \u00a0CHI describes it on their website as “a computational photographic method that captures a subject\u2019s surface shape and color and enables the interactive re-lighting of the subject from any direction”. \u00a0For highlight RTI, which is the least expensive and most accessible method for most institutions and what I was taught in the class, you basically take a series of 36 to 48 images of an object where everything is constant (settings and position of objects, camera and spheres) except for the light position. \u00a0With a reflective black sphere (or 2) set up next to your object, you move you light source around the object at varying angles. \u00a0Then, you take that set of images and plug them into the free RTI software provided by CHI and the algorithm detects the sphere(s) and the highlight points (from your light) captured on the sphere(s) and voila!…you have an fun and interactive way to look at your object’s surface texture.
\nBefore I attended this fantastic training opportunity, our conservator and I knew right away what the subject of our first capture would be when I returned…a 16th century German Reformation text by Martin Luther with a highly decorated cover that is practically invisible under normal illumination.
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\nHere’s a time lapse video of our first (and second) capture in the Lab…