Creating complexity with simplicity
It almost never fails that, when attempting to simplify, complexity always follows. As I mentioned in my most recent blog post, the project that I am undertaking as a CHI Fellow this year is to compose a “best practices” guide, of sorts, for what is to be a relatively simplified means of 3D data capture for archaeological skeletal material. When I say “relatively simplified” what I mean to say is that the process is somewhat easier to carry out than other options.
On the surface, photogrammetry seems simple enough: take a large quantity of overlapping photos, feed them into a program, and out pops a model. It is the “black box” logic: feed in data and out pops a result. Well, it is not so simple. As you may have surmised, the higher quality the model you wish to produce, the more photos you need and at higher resolutions. That, in and of itself complexifies matters. Storing hundreds of very high resolution photos eats up a lot of virtual space. Issue #1 to mitigate: storage of the raw image files. Simple enough: external hard drive (unless one wants to clutter an internal hard drive with all of these cumbersome photos…).
Now that the first hurdle is mitigated, we come to a second, and more difficult hurdle to surmount: creating the model. For this project, I will be using Agisoft’s PhotoscanPro. The product alone, for those of you who may be interested in purchasing a personal license, is not inexpensive. Cost notwithstanding, programs like PhotoScan are extremely memory-intensive. Take a look at the memory requirements listed for PhotoScan. Creating high quality, or ultra high quality models can with minimal photos can consume anywhere from 8GB-96GB of memory. This, of course, is dependent on multiple factors including photo resolution, overlap, and the number of photos. What does this all mean? If you don’t have a beast of a machine (read: workstation), producing high quality models is not possible. Lower quality could conceivably be achieved with an upgraded commercial computer, but higher quality models require more power than most average laptops and desktops are equipped to handle.
So, suddenly the “simple method” of creating 3D models becomes much more complex. Skeletal analysts expect high levels of detail, which translates into very high quality models, which in turn translates into the need to have the equipment to produce said models. Still, despite the hidden complexities of the process of photogrammetry modeling, it beats spending over $100,000 for a laser scanner and saves archaeologists the headache of lugging expensive equipment into the field (or more importantly, through airport security!).