Max Therry shared some thoughts about some of the hardware you can use for photogrammetry experiments.
Max Therry shared some thoughts about some of the hardware you can use for photogrammetry experiments. Make sure to check out the blog photogeeky.com for more photo insights.
If you’re into creating high-quality game assets, you probably know that not everything can be done easily or efficiently with 3D sculpting software. That’s where photogrammetry comes in. Photogrammetry is the process of taking multiple photos of a real-world object and using software to generate the mesh and texture data. When done well and with the right objects (rocks, pine cones, trees, etc.), the end result will provide an extremely detailed 3D asset in much less time than it would take to create it from scratch.
Assets created with the Unity Photogrammetry workflow
So what camera should you use to get started? Here’s a quick run-down.
Photogrammetry is very forgiving camera-wise—you can get acceptable results with just about any decent camera, including a smartphone or a compact camera. The key word here is ‘acceptable.’ Your end results won’t be a good as if taken with a DSLR and you might forfeit any gains in time with having to take more photos (to compensate for lack of quality) and having to do more image processing in general. Your best results will come from a camera that allows for manual control, shoots in Raw has an in-camera histogram, and ideally has interchangeable lenses. In short, a mirrorless camera or a DSLR will be your best bet for most projects, yet there will be times when a GoPro or even a drone will come in handy.
The Full Frame Camera
By default, you’ll be taking a large number of photos to get a fully detailed asset, and the better the camera you use, the fewer you’ll have to take. A full frame (FX) camera like the Canon 6D or the Nikon D750 will give you the highest quality output in the least amount of photos. (Both of these are often used for photogrammetry.) Sony also makes some great full frame cameras, but the lenses are pretty pricey, so if you’re looking for the lower end of things, you’ll be better off with a Canon or Nikon.
The DX DSLR or the Mirrorless Camera
Both of these are good options if you’re looking for full control at a (somewhat) lower price point. Which one you choose will really come down to what type of camera you’re into, but the primary benefit of the mirrorless camera is that it’s small and light. As far as cropped-sensor DSLRs are concerned, folks are using a wide variety of DX cameras—none really seem to stand out. In the mirrorless department though, the Sony Alpha a6500 is quite popular in the photogrammetry world. If budget isn’t so much of an issue, the Sony A7RII is also a top pick, as is the Olympus OM-D EM-5 Mark II.
While GoPros are not ideal as your primary camera for photogrammetry (overly sensitive to high lighting conditions, usually do not have manual controls for ISO and aperture, and often contain blur due to hand-shake), they can play an important role as your backup camera. For example, once you’re finished taking the stills with your primary camera, take a quick 4k video of the object with the GoPro, following the same path. In so doing, you’ll have a ready-made backup for any areas you might have missed with your main camera or any undersampled or badly reconstructed areas. (Honestly, this simple back up can save you many days of reconstruction correction.) Just make sure that you use a color checker with the video so you can manage the white balance.
Another benefit to bringing a GoPro with you is that it can reach areas difficult for larger cameras and you can get much closer to the object than with larger cameras.
The DJI drone Phantom 4 RTF works great in this application
If you’re photographing a very large object (i.e. a building, a cliff, a canyon, etc.) you’ll need a drone to get to the upper regions. In this case, it’ll be significantly easier to use video. Depending on your software, you should be able to mix the shots taken with the drone with shots taken by hand much closer to the object.
As always, the better the glass, the better the image. So try not to skimp in this department. You can buy a stellar camera, but if your lens is only so you won’t get stellar results. In most photogrammetry applications you’ll want to choose a prime lens with next to no distortion. Not only will this give you the sharpest results, but photogrammetry software will not work with zoom lenses. However, in the field, a zoom is sometimes necessary. Whichever you choose (and it’s easy to have one of each), make sure the lens has as little distortion as possible. (Standard lens correction software can’t be used in this process.)
Popular Photogrammetry Lenses
For full frame Nikons, both the AF‐S FX NIKKOR 50mm f/1.8G and the Nikon 20 mm f/2.8D come highly recommended. The Nikon 20 mm f/2.8 AIS works on both FX/DX cameras and outperforms the Nikon 20 mm f/2.8D, but has no autofocus. So if manual focus is your thing, his is probably the best affordable prime lens to work with. As far as DX-only lenses go, the 40mm f/2.8 “Micro” comes highly recommended. (It’s often used for reproduction jobs.) If you want stellar edge-to-edge sharpness and you’re shooting smaller objects, the 105mm 2.8 Macro is a good option, depending on the amount of working space you need.
For a full-frame Canon, the Canon 20 mm f/2.8 has superb performance. For cropped-sensor, the EF-S 10-22mm and EF-S 10-18 IS STM comes highly recommended. The Sigma 18-35mm f/1.8 DC HSM Art Lens is also a favorite. Standard all-purpose prime lenses like the Sigma 85mm and 50mm 1.4 Art lenses also work great.
When you’re out shopping for a camera, keep these qualities in mind:
- Able to shoot in Raw
- Has a fairly high frames-per-second ability (in Raw)
- Long battery life (remember, you’ll be taking lots of photos)
- Exceptional low noise performance with a native ISO of 100 or lower
- Will this camera be dedicated to photogrammetry or will you be using it for other applications?
In the end, the main considerations will obviously be your project requirements and your budget. If you’re a beginner just looking to try it out, don’t let the specs get in the way. The best camera to use is the one you have with you, so if you want to try it out on your smartphone, by all means, do so. There are plenty of tutorials out there. But once you become more serious, you’ll definitely want to consider the cameras and considerations listed above.