What is Photogrammetry?

Here's a Way to Start Your 3D Printing Models for 3D Printing

Photogrammetry, aka photo capture, for a 3D Printing Model. TJ McCue

During the 3DRV national road trip, I spent a lot of time capturing images of stationary objects with my digital camera (DSLR). Objects that I thought would make for terrific 3D prints, but objects that I did not want to draw or sketch from scratch, or from a blank screen.

I learned that it is possible to take multiple photographs of an object, at different vantage points, going around an object. By taking photos in this 360 degree fashion, you capture enough detail that advanced software can stitch these images back together for you, as a 3D model.  This method or process is known as photogrammetry. Some call it 3D photography.  

Here's what Wikipedia states (albeit a bit more complicated than my explanations, I believe):

Photogrammetry is the science of making measurements from photographs, especially for recovering the exact positions of surface points… [It] may employ high-speed imaging and remote sensing in order to detect, measure and record complex 2-D and 3-D motion fields (see also sonar,radar, lidar etc.). Photogrammetry feeds the measurements from remote sensing and the results of imagery analysis into computational models in an attempt to successively estimate, with increasing accuracy, the actual, 3-D relative motions within the researched field.

I prefer a much simpler explanation:  In order to use this definition, and process, let me explain what I understand and give kudos where it is due; Autodesk and the Reality Computing team have created the software to make all this easy and fast. The software is from Autodesk ReCap and there is also an app called 123D Catch that makes this possible with just a smartphone camera. The Autodesk ReCap team likes to summarize the idea of taking something of the physical world and making it digital as: Capture, Compute, Create. They do it with laser scanning and with photogrammetry, two different methods, but I’m focused on the latter in this post.

This is a rapidly developing part of 3D printing because it allows you to create from a series of photos, as I have mentioned, rather than a blank piece of paper or a digital screen. There are many apps that can so this or something like this. Two that I am working on reviewing further: Fyuse (app for iOS and for Android) and Project Tango from Google (which I have written about on Forbes as well. You can read that here.)

A Quick Overview of How It Works:

First, you can use a regular digital camera, a GoPro, or a smartphone to capture the photographs that software will allow you to stitch together into a 3D model. If you have ever used the panoramic function on a digital camera, you have a rough idea of how this will look.

Second, you take a bunch of photos of an object or person. There are many tips available that help you create the best 3D model, but the better your camera, the better the 3D result. You can capture most objects or even a person (if they hold very still) with this “reality capture” process.

Third, the software does the rest. You upload the photos to the ReCap service or 123D Catch and it will stitch those photos together so that you now see the photos in a full three dimensional perspective. It is similar to Google Street View where you can plan around an entire location – you make your own “street view” around the object. ReCap will allow you to do some or all of it manually -- to pick the actual locations or spots that overlap one another, but most of us will not do that and let the software do the heavy lifting. The free account allows up to 50 photographs, more than sufficient for consumer and small business usage.

Let’s briefly talk about “compute.” Data from the physical world captured via your camera is uploaded to the cloud (it takes a lot of computing power; more you’re your typical desktop/laptop can handle) and the ReCap Photo service does the work. The desktop version of ReCap handles laser scanning data, but you need the cloud for the intense work of matching and stitching photos, at least for now.  

Finally, for most uploads, you will get back the 3D model in less than an hour. That’s a pretty compelling reason not to draw or sketch from a blank page or screen. You can photo scan your way to a great model that you can modify, tweak, change, to speed up your design process. You can get to the “create” phase much faster this way.

Here are a few more resources for you:

Another version of this post first appeared in my 3DRV blog, originally entitled: What Is PhotogrammetryFull disclosure: Autodesk sponsored part of my 3DRV roadtrip in 2014.