Photogrammetry involves creating a 3D version of an object by collecting images which map out the object's position in space.
The Workshop/My Results
For this workshop, I utilized a flower which was from my Project 1 creation of a brain model using flowers and copper wire. This was ideal because it is small and non-reflective: two requirements for the software we were going to be using. Using my iPhone, I collected about 40 images from the flower- each from a different angle. Initially, these images were taken outdoors on a piece of paper with labeled measurements. Because I had issues working this software on my computer when trying to upload the pictures, I ended up just taking more pictures inside the classroom on my desk. I ended up using only about 20 pictures for time purposes. The result of this workshop is shown in the image below.
Reflection
Honestly, this was really hard. Maybe it was because of the software we used, or because of how draining it was to try to get the images uploaded onto the software (I really wish I had my mac to AirDrop the images), but I kept getting behind during the instruction. Because of this, I did not even have time to clean up the image, nor did I catch how to do that in the lesson.
In the above picture you can see my first try at this. I used about 40 pictures, as instructed, and I also used the given paper with dimensions. As you can tell, this looked nothing like my object. This also took WAY too long to get. The paper also got into the image which made those weird trapezoid-like shapes. Anyways, I did this again to get the nice image you saw previously, and my results were much better.
I had to do a lot of problem-solving on my own when it came to retaking images and finding new ways to upload them, but the resulting product is pretty satisfying. The table got into the image, but that is something that can be cleaned up later. There are also some holes in the object, but I know those can be filled with image processing.
I think it is super cool that we can do all of this for free without any fancy software or technology, but that definitely came at a price when it came to the ease of use and the quality of my final product. This is also another one of those things that I feel has a sharp learning curve. Once I knew how to do things once, it was easy to do it again. However, learning how to do that thing for the first time was difficult.
Applications
As a biomedical engineer, I'm always interested in finding ways to advance the current technology. Since I'm in a prosthetics-based club at Virginia Tech, I thought it was really cool to see that photogrammetry has applications in this field. I found an article titled, "A smartphone photogrammetry method for digitizing prosthetic socket interiors." (link: https://www.semanticscholar.org/paper/A-smartphone-photogrammetry-method-for-digitizing-Hern%C3%A1ndez-Lemaire/646c4924ba1f98c66f7bece7ee87e4099acd868c )
This figure from the article was particularly interesting to me:
In it, you can see 4 different digitized versions of the prosthetic socket joints. In reading the article, much of the variation between the physical and modeled versions were about 0.2 cm off, which isn't bad at all given that it was taken on a smartphone. If you were to utilize technology that is more advanced, the precision in these measurements would definitely increase. I think if you can obtain models of the patient's limbs with photogrammetry instead of creating molds, it would greatly speed up the process of making prosthetics. In our club we make 3D-printed prosthetics, therefore having a 3D version of the limb instead of a physical mold would be so beneficial. You could even design the prosthetic around the limb.
I also used to work in an organismal biomechanics lab where we used a bunch of Go-Pro cameras to track the movement of ducks as they landed on water. I would use the videos and a software called Argus to obtain the data points of the ducks in each frame. I also know that the Granata lab at VT uses a similar technology to track the movement of the human body as they do typical exercises.
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