Browsing by Author "Porter, Samantha T"
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Item Gigapixel macro photography of tree rings(2021-04-16) Griffin, Daniel; Porter, Samantha T; Trumper, Matthew L; Carlson, Kate E; Crawford, Daniel J; Schwalen, Daniel; McFadden, Colin H; griffin9@umn.edu; Griffin, Daniel; University of Minnesota Griffin Research Lab; University of Minnesota Advanced Imaging Service for Objects and SpacesHigh quality specimen digitization is becoming standard across the sciences, is relevant for curation of natural history collections, and must become a priority for dendrochronology. Here, ultra-high resolution images of tree-ring specimens are presented. Our gigapixel images of polished specimens have proven effective for digital analyses, archiving, and education, and we believe macro photography may prove a lower cost and more broadly accessible digitization alternative to microtomy and X-rays. We advocate for gigapixel macro photography as one accessible and adaptable paradigm to elevate reflected light imaging standards in dendrochronology.Item A Portable, Low-Cost, Open-Design Rig for Reflectance Transformation Imaging(2016-08-02) Porter, Samantha T; port0228@umn.edu; Porter, Samantha TThis simple and inexpensive rig is designed to assist researchers in capturing photographs for reflectance transformation imaging (RTI). It consists of 3D printed and laser cut parts, along with relatively easy to acquire hardware components. This project was presented as a poster at the 2016 meeting of the European Society for the Study of Human Evolution (ESHE) in Madrid, Spain, and can be cited separately as: "Porter, Samantha T. (2016, September). A Portable, Low-Cost, Open-Design Rig for Reflectance Transformation Imaging. Poster presented at the meeting of the European Society for the Study of Human Evolution, Madrid, Spain. Retrieved from the Data Repository for the University of Minnesota, http://doi.org/10.13020/D66C7Q"Item A Simple Photogrammetry Rig for the Reliable Creation of 3D Artifact Models in the Field: Lithic Examples from the Early Upper Paleolithic Sequence of Les Cottés (France)(2015-06-01) Porter, Samantha T; Roussel, Morgan; Soressi, Marie; port0228@umn.edu; Porter, Samantha T3D scanning is becoming an increasingly utilized tool in archaeology. In comparison with other methods of 3D registration close-range photogrammetry has the benefits of being relatively inexpensive, mobile, and extremely adaptable for use in field conditions. Here, 3D models of lithic cores from the Châtelperronian, Protoaurignacian, and Early Aurignacian levels of the site of Les Cottés (France) are presented as examples of the quality of model that can be produced using photographs taken with a simple and inexpensive photogrammetry rig.Item Three Dimensional Models and Two Dimensional Cross Sections of Châtelperronian and Protoaurignacian Lithic Cores from the Sites of Les Cottés and Roc de Combe(2018-05-29) Porter, Samantha T; Roussel, Morgan; Soressi, Marie; stporter@umn.edu; Porter, Samantha TThese data were generated as part of a study investigating the use of quantitative methods on three dimensional models of lithic artifacts. The majority of the data set is comprised of 3D scans of Châtelperronian and Protoaurignacian cores from the site of Les Cottés (France), which were generated using photogrammetry. Although cores from the site of Roc de Combe were also scanned for the associated study, we are not able to make them available here due to rights restrictions. The second part of the data set includes two dimensional representations of cross sections, which were from the 3D artifact models. These were used in two analyses, which are described in the associated publication in JCAA (see citation below).Item Three-Dimensional Models of Experimentally-Produced Lithic Artifacts Created using Expedient and Refined Photogrammetry Protocols(2016-05-16) Magnani, Matthew; Douglass, Matthew; Porter, Samantha T; port0228@umn.edu; Porter, Samantha TThe data set consists of three-dimensional (3D) models of experimentally produced lithic artifacts created using both expedient and refined photogrammetric setups and processing protocols. Source images for all models were captured using a 12.1 megapixel Canon PowerShot SX260 HS compact digital camera. In our expedient protocol, objects were placed on a wire stand. The photographer moved around the object, and captured photos using Auto mode. In our refined protocol, objects were placed on a rotating turntable under controlled lighting conditions. The camera was placed on a tripod. Shutter speed, f-stop, and ISO were set manually. This refined protocol is described in Porter, S. T., Roussel, M., & Soressi, M. (2016). A Simple Photogrammetry Rig for the Reliable Creation of 3D Artifact Models in the Field Lithic Examples from the Early Upper Paleolithic Sequence of Les Cottés (France). Advances in Archaeological Practice, 4(1), 71-86. The associated paper discusses the relative fidelity of the models produced using these different workflows. Models may also be viewed online (in browser) at: https://sketchfab.com/unlarchaeology/collections/magnani-et-al-2016.Item Two- and Three-Dimensional Representations of Thomas Bewick Woodblocks(2019-04-03) Hancher, Michael; Luce, Donald T; McFadden, Colin; Porter, Samantha T; stporter@umn.edu; mh@umn.edu; Porter, Samantha T; Hancher, Michael; Department of English, University of MinnesotaThe Bell Museum at the University of Minnesota owns fouteen wood blocks that were engraved in the workshop of Thomas Bewick to illustrate his History of British Birds, 2 vols. (Newcastle, 1797, 1804), as well as a block for a tail piece printed in The Fables of Aesop (Newcastle, 1818). This data set includes representations of these blocks captured using four digitization methods. 3D models were produced using structured light scanning and photogrammetry. Next, we used reflectance transformation imaging (RTI) to create interactive visualizations of the blocks' surfaces under variable lighting conditions. Finally, a high resolution two-dimensional image was generated for each block using a GIGAmacro device.