Project Update – November 2020

Since the last post about this project, I have continued developing its digital archive of 3D models and have run several experiments related to them. Expanding the data involved in my project will be key to effective analysis in the future. So far I have successfully scanned two crucibles and an ingot mold. For each of these artifacts, several attempts and methods of scanning have been used and experimented with in order to develop a better, more efficient workflow.

This blog post will first document some of the experiments done recently, and then will move to a discussion of what I have learned and how the fellowship is going.

Field application experiments:
Different scale bars – this project tested less precise, makeshift scale bars to see if they could give accurate measurements. They ended up being precise to a tenth of a centimeter.

Phone camera – instead of the hundreds of precise, high quality photographs, this experiment used a cheap phone camera and 60 not very precise photographs. I was able to align these photos into a mostly complete inside and outside of a crucible. With more work this method can certainly be sustainable.

Photography experiments:

Depth of field/Camera Lens – We found that both the 50 and 25 mm lenses were able to create a strong depth of field. The 25 mm camera gives a greater DoF from less far away, however.

Lighting – This project has involved photographing both normal and slaggy forms of clay. For the more reflective slaggy portions, less light is necessary to avoid any glare. However, for more narrow insides of crucibles, a lot more light is needed.

Camera Angle – Over dozens of processing attempts, I found that taking 2-3 outside shots of the crucible is sufficient. After this, angling the camera towards the inside is necessary to get a properly aligned model.

Software Experiments

Recently I have been experimenting with alternate photogrammetry softwares, such as Meshroom and comparing the results to Agisoft. This has produced promising results. I have also been using a comparison software to show how these programs are different.

This video shows where the Meshroom and Agisoft models encounter the most differences. These are present around the base and spout of the crucible.

Lastly, I have also explored volumetric comparisons between both programs. There does not seem to be a significant difference as of now.

Discussion:

One of the key things that I have learned in the past month is to be flexible and always have different avenues to expand. I have had several attempts to gain access to other scanning equipment which have not been fruitful. However, instead of stalling this project, I have moved towards experimenting with different scanning software in more in depth ways. This expansion of my project has been interesting to me because involves exploring the technical and mathematical ways that photogrammetry software processes images. Thanks to the encouragement and advice of the Emerging Technologies team at University Libraries, I have been able to take this project is directions that I would have never thought about before.

The Digital Scholarship Fellowship has gone well so far. I have enjoyed hearing about the other projects and have found the conferences that I have attended very insightful. In addition, I really appreciate the work that everyone involved does to help me out, from reviewing conference proposals to teaching me how to use new software.

The only downside of this experience has been being selected as an alternate presenter at an earlier conference I applied to. I think I can craft a very effective methods-based paper exploring photogrammetry and hope to get accepted to future conferences.

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