Tagged: photogrammetry

July 20, 2017

3D Modeling GSU Library Special Collections

Right now, on the eighth floor of Library South, you can visit Georgia State University Library’s Special Collection exhibit about Eastern Air Lines, a major airline that operated out of Atlanta from 1930 until 1991. Georgia State University Magazine included an article about Eastern in their December 2016 issue, complete with interviews and oral histories about the airline. The University Library holds an extensive collection of Eastern materials thanks to Carolyn Lee Wills, who donated her personal archive from her years working in public relations with Eastern. Wills graduated from Georgia State in 1959 with a Bachelor’s Degree in Business Administration.

Image of Carolyn Lee Wills, public relations officer for Eastern Air Lines — Carolyn Lee Wills in the 1980s

Part of the Library’s exhibit is our digital exhibit case, which allows you to see original artifacts and also interact with digital content from the Eastern collection, such as photographs, travel flyers, training manuals, and much more. Many of the items in the collection can be found in the Eastern digital collection, but some of the items are so unique that we chose to use photogrammetry to capture the object in 3D.

One example is a baseball that was given to Wills, presumably by the Atlanta Braves. As you can see in the picture below, the ball is covered with hand-written notes, each of which refers to a landmark in Georgia, such as Stone Mountain, Six Flags, Golden Isles, and Okefenokee Swamp.

Image of an Atlanta Braves baseball given to Carolyn Lee Wills — Atlanta Braves baseball given to Carolyn Lee Wills

When on display in the exhibit case, the baseball can only be viewed from one or two angles, but with a 3D model, visitors can turn the ball to see each of the locations. The high-quality model has 1.6 million individual polygons meshed together to create an accurate reproduction of the baseball. Just like a real baseball, the stitching and seams are raised to give (virtual) pitchers a better grip on the ball.

View on Sketchfab

We don’t know who signed the ball, but it was clearly someone associated with the Atlanta Braves who presented the ball to Wills. Eastern was known to promote the Atlanta Braves, and management members attended games in the 1970s and 80s.

Eastern Air Lines management attend an Atlanta Braves game in 1979. Some photos seem to be taken in the locker room.

Eastern Air Lines promoted the Atlanta Braves with posters such as this one from the 1980s

To view the baseball alongside other artifacts and documents from the Eastern Air Lines collection, and to check out our interactive digital exhibit case, visit Special Collections on the 8th floor of Library South!

Image of digital exhibit case with artifacts and 3D model — GSU Special Collections Digital Exhibit Case with Aircraft and Baseball Displayed with 3D Model of Baseball

June 13, 2017

Larger-scale Photogrammetry at CURVE

During the spring semester, I acquired a clay whisky jug from the Phoenix Lab, which contains artifacts recovered from the excavation of MARTA lines in the 1970s. Dr. Robin Wharton has worked with students in her multimodel composition course to scan and model objects from the collection, and discussed the process in Atlanta Studies. In this case, the purpose was to experiment with photogrammetry for larger objects, testing the equipment and software that the Library has acquired. The jug is roughly 8 inches high and 6 inches in diameter, with a circumference of 19 inches.

The jug wears the story of its life. The outside is worn and pitted, and carries a few kiln drips, where the kiln bricks melted and dripped on to the jug as it was fired. These drips show as dark splotches on the outside of the jug. Stamped on the top shoulder of the jug are two names: T.W. Cofield and E.C. Brown.

Whisky jug with stamp showing T.W. Cofield and E.C. Brown — Stamp showing T.W. Cofield and E.C. Brown

To capture the entire jug in detail, I took images of the jug at 15 degree intervals on three elevations. I used Agisoft Photoscan to assembled the images into point clouds, meshes, and then textured models. I then pinned the three partial sections together, which resulted in a full model of the jug.

In the finished 3D model, you can manipulate the jug to see its details and textures, including the stamped inscription with the two potters’ names.

Click here to see the Whisky Jug on SketchFab

Thomas William Cofield and Edward C. Brown were cousins who lived in the Howell’s Mills area in northwest Atlanta, near present-day Buckhead. Edward’s father was Bowling P. Brown, a potter. His grandfather was Bowling Brown, also a potter, who had moved the family from Jugtown (an unofficial name) on borders of Upson and Pike counties.

Bowling’s daughter (and B.P.’s sister) Mary Jane Brown married Thomas B. Cofield from North Carolina while they lived in Jugtown. Their son, Thomas W. Cofield, became a potter and worked alongside his cousin, E.C. Brown, to produce jugs for Atlanta’s businesses from the 1880s through the 1910s. [Note 1]

In his history of Georgia’s folk pottery, John A. Burrison suggests that Thomas and Edward worked together no later than 1911, after which Edward “became a gardener (and later foreman) at Grant Park.” Based on this suggestion, we can infer that the whisky jug is at least 106 years old. The jug is in remarkable shape for its age, but I still wouldn’t recommend drinking from it.

Notes

John A. Burrison, Brothers in Clay: The Story of Georgia Folk Pottery (Athens, GA: University of Georgia Press, 2008), pp. 71, 168, 191, 195, 199.
Ibid., p. 195.

[This article has been cross-posted from swroberts.ca]

February 27, 2017

Photogrammetry at CURVE

Photogrammetry, for the purpose of our work at Georgia State, refers to the use of software to combine, convert, and render 2D images into a 3D object. There are numerous methods for this practice, ranging from a single camera operated by a moving human to complex arrangements with multiple cameras and a movable object. The process can capture a range of objects from extremely large to fairly small. For instance, you might capture an ancient ruin by taking photographs as you walk around the structure. You might also capture a small figurine by taking photos with your camera or phone. The process changes depending on the size of object, the equipment available, and the software used.

In the spring semester, the library and CETL are prototyping a 3D scanning/modeling/printing course, in which students will learn how to fully digitize and replicate a material object in both digital and physical forms. To facilitate their learning, we have acquired a photogrammetry kit that will complement the other equipment we have available in the library.

The kit includes:

One Canon Rebel T5i DSLR camera, with standard 35mm lens
One basic tripod with multi-axis pan and tilt functions
One turntable, modified with degree markings
One wireless camera remote

To test the kit, I selected a small owl figurine. The object is roughly 1.5 x 1.25 x 1.125 inches. I placed the object in the center of the turntable, facing the 0 degree marker. I aimed the camera directly at the object on a level horizontal plane. Using portrait settings, the internal camera flash, and the wireless remote, I took photographs of the object at 15 degree increments, for a total of 24 images. I did not capture the top or bottom of the object for this test. Total time for capture: 20 minutes.

Using Agisoft Photoscan, which is available on four of CURVE‘s workstations, I aligned the photos, generated a cloud of points, created a mesh, and then textured the mesh. I removed some unnecessary details from the model, and then exported as an .obj model. I uploaded the model to SketchFab. Total time for model creation: 20 minutes.

Admittedly, the model lacks some features, such as a true representation of the bottom and top of the figurine. For a quick 40-minute test, however, the kit and software worked very well. For smaller objects, we may need to acquire a macro lens for the camera. The primary use of this equipment will be to train students, which will provide an additional benefit of helping to preserve archival objects and provide access to objects that are fragile or inaccessible.

Students interested in using this kit should contact me to arrange a meeting.

See below for a 3D rendering of the model and photos of the kit.