Having fun with Photogrammetry

For a previous project I worked on, I was tasked with exploring technologies that could be used to recreate hard to find parts for vintage cars. I started looking into 3D scanning techniques that didn’t rely too much on specialized hardware, when I discovered Photogrammetry.

What is Photogrammetry?

According to Wikipedia, Photogrammetry is the art and science of making measurements from photographs, especially for recovering the exact positions of surface points. In its simplest form, Photogrammetry can be used to measure the distance of two points on the image plane, if the scale of the image is already known. When reconstructing three-dimensional objects, photogrammetry is used to measure the distances between points on the surface of the object.

A 3D Scan of a skull. Photo © 2018 Cicero Moraes

Using my camera, I would be able to make detailed scans of real world objects. I kept thinking “This is a great way to preserve some of the older car models and collectibles I have!” In order to test out the technology, I downloaded an application called 3DFZephyr. This application specializes in generating scans from photo data and then creates a 3D model from the scans. I decided to test the whole thing out by taking photos of a model I have on a stool outdoors, and then processing the photos with the software. It took a few tries to get everything right, but the end result was pretty impressive:

Although the initial tests were promising, there were still issues with the scanning process. The fidelity of the scan was entirely dependent on lighting. Even the best scan still had gaps and mesh issues because of the shadows. The “complete” scan was just a result of getting lucky with the software settings and shooting on a cloudy day.

Learning on the go

After researching how to get better scans, I found that if I used a cake decorating table and a specialized lightbox, I could easily control the lighting and the positioning of the model.

A Photogrammetry setup similar to my own. Photo © 2019 Kelsea Weber, iFixit
A Photogrammetry setup similar to my own. Photo © 2019 Kelsea Weber, iFixit

I bought a photography lightbox on Amazon that was big enough to fit a cake decorating table, and did a test with a vintage matchbox car. The plan was to take a photo and then rotate the turntable a small amount, and then take another photo. I planned the amount of rotations beforehand, and figured out that I would get at least 20 photos by the time I fully rotated the turntable.

A simple animation showing the different angles I shot the Matchbox Car.

The end result was a fairly complete scan, with only a few errors in the mesh creation. But, the basic shape of the toy and certain details like the chips in the paint were preserved.

Photogrammetry for everyone?

At the end of my investigation I found it is easy get into photogrammetry. In most cases, you could easily create a scan using a smart phone and a decent lighting setup. However, because of the type of research I was doing, this proved to be in-viable compared to dedicated scanning solutions.

Still, this could be an interesting hobby once you get over the technical hurdles. I would highly recommend giving it a try if you’ve got a free weekend!

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