A Crash Course on 3D Scanning and Photogrammetry With Your Phone


This is everything you need to know about using photogrammetry to create 3D scans on your phone and why you should be using Polycam.

Your smartphone is a camera, a GPS, and a music player; it does everything. But for VFX artists and video game developers, a smartphone is also a 3D scanner. With 3D scanning apps priced reasonably, anyone can capture 3D scans.

After scanning an object, you can upload it to a 3D-rendering software, such as Blender, and what you do with the scan once it’s in the software will depend on whether you’re an architect, video game developer, or visual effects artist. But before you start 3D scanning everything in your vicinity, you should know a few things about photogrammetry, the best 3D-scanning mobile apps, and best practices. 

What is 3D scanning?

The type of 3D scanning available on most phones is done via photogrammetry. This technique stitches photos taken from various angles and distances to create a complete image. Photographers employ photogrammetry with a technique known as focus stacking, which uses a large set of images to produce one tack-sharp image across the entire frame. It’s useful for product and landscape photography, but that’s not the kind of photogrammetry we’re interested in.

Photogrammetry isn’t a new concept. Video game developers, for example, have been using this 3D scanning technique to capture people’s faces or entire bodies, which are then used in-game. In a video game like FIFA, a football game made by EA, face scans of famous footballers are crucial to the gaming experience. This has led FIFA developers to create custom photogrammetry rigs for capturing players’ faces worldwide. Without player scans, the game wouldn’t feel as immersive. In the video below, the developers of EA’s Star Wars: Battlefront explain how they used photogrammetry in their game.

Aside from video games, photogrammetry is used for 3D printing, VFX, architecture, and even land surveys. The National Park Service uses photogrammetry to capture 3D scans of our protected lands and monuments. 

Photogrammetry has been out of reach for most people, however. Custom rigs made from a handful of DSLRs are not viable for most creators, and neither are aerial land surveys. But that’s no longer the case. Thanks to advancements made to the little computers we carry around everywhere, photogrammetry is now accessible to anyone with a smartphone. 

Why would you want to use a 3D scanning app? 

The power of a 3D scanner in your pocket is irresistible to visual creators such as video game developers or VFX artists. The app can turn real-world objects into digital ones that can be uploaded to 3D-rendering software. While the apps won’t create a perfect scan every time, it sure beats making an object from scratch within the software. Alternatively, if you own a 3D printer and know you’re way around 3D-rendering software, you can make prints of objects you’ve scanned. 

Creators aren’t the only ones that can enjoy a 3D-rendering app. You can still find uses for scans even if you don’t work in a 3D-rendering program. For example, illustrators and graphic designers can scan interesting objects to draw inspiration from. Or, you can scan an object just for the heck of it.

What’s the best 3D scanning app?

There are a lot of 3D-scanning apps out there, but Polycam is considered to be the best. I’ve been using the app for the past month, inventorying everything from condiment bottles to products I’m reviewing. I have fun scanning the most mundane objects. When I say that creating 3D scans of objects never gets boring, I mean it. 

Polycam is the best 3D-scanning app for a few reasons. For one, it works on both iOS and Android phones. That’s because the data is sent to be processed via the cloud, allowing older, less powerful phones to take advantage of mobile photogrammetry. As long as your phone has a camera, you should be fine. The simplicity of using Polycam is another plus, and the slick app design is easy to navigate.

Once the app starts, you can capture the object in two ways: the video mode takes photos of the thing as you move your phone, and the photo mode allows for manual shots. You can switch at any time. The object is ready for processing once the bar at the bottom is green, which takes a few dozen shots. But you’ll want to take the max 251 shots if you want the best possible scan. Before processing the data, you can select the file size, with larger files equaling higher-quality scans. After that, you’ll have a full 3D scan of your objects ready in a few minutes. 

The community also plays a significant role in Polycam. It’s one of my favorite aspects of using this app. The “explore” tab is an Instagram-like feed of 3D scans. With no comments section or direct messaging, it’s the least toxic social media platform I’ve encountered. It’s also wholly unhinged, but in a good way, placing scans of ancient dig sites and artifacts next to hamburgers and flip-flops. I love looking at others’ creations; I’ve also shared a few of my own. Even if you don’t plan on using the scanning feature often, I recommend looking at the explore section. You can even save the ones you like to a folder for later viewing. 

Why is the iPhone better for Polycam? 

Neither iOS nor Android phones are objectively better for Polycam’s photogrammetry feature. On compatible iPhones, you can use Polycam to take a full scan of a space, such as a living room, museum, or outdoor mural. But the Polycam app on iPhone has more features available thanks to the LiDAR sensor found on higher-end iPhones. 

This feature can significantly help interior designers, historians, VFX artists, and video game developers. That’s because the scans can be exported to 3D-rendering software, making it possible for someone, for example, to experience the space via a VR headset.

That’s not theoretical; it’s pretty easy to get this working, provided you have a VR headset. Historians and preservationists may also use the app to scan culturally-important places or objects so they may be experienced digitally. In the video below, photogrammetry was used to create 3D scans of ancient monuments.

On iPhones with LiDAR, you can also view 3D scans in AR. People like interior designers or engineers can use the app to view objects in a physical space. But this feature can also be helpful for everyday things like furniture shopping. You could go to IKEA, scan a couch, and then see it sitting in your living room, taking the guessing game out of the experience. 

Room mode is another iPhone-only feature recently launched at the tail-end of 2022. It also uses LiDAR to scan spaces, but it instead converts the data into floorplans. The uses for this feature are many. Professionally, architects and contractors get the most benefit with this tool, as would potential bank robbers casing the joint. But, nefarious intentions aside, there are many everyday uses for Room mode. For one, you would never have to write down measurements again when heading to Home Depot for a home renovation. But it’s also helpful when doing apartment or home hunting, allowing you to save and view floorplans later as you make your final decision.

How do you upload 3D scans to 3D rendering software? 

That will depend on the app you’re using and which program you will use for editing the scan. On Polycam, you can export scans to over a dozen file formats. But to make it easy, you can select which software you wish to use the scan with, which will recommend file types compatible with your chosen software. If you decide Blender, for example, you can select between OBJ, GLTF, FBX, DAE, STL, or PLY files. You can upload files directly to the cloud app of your choice or download them now from the web version. 

Best practices for 3D scanning 

I mentioned earlier that Polycam is simple but can be too simple. The app assumes you know how to do 3D scans, so it’s very light on guiding you. Polycam has made some tutorials covering the basics, but here’s what I learned after completing some 3D scans. 

  • Good lighting is everything. A softbox would be best, but use whatever you have. A flashlight, reflector, or camera-mounted LED light will be better than nothing.
  • Try to diffuse light as much as you can. Direct light can create harsh shadows and glare that will ruin the scan. In my case, I scanned an arcade stick with a reflective plexiglass cover, resulting in Polycam not processing spots with a lot of glare. I guess it assumed there was nothing there. 
  • Be thorough. If you’re not using all 251 images, you’re not being thorough enough. That may be overkill sometimes, but capturing an object from various heights, distances, and angles are best to guarantee a clear scan. Otherwise, you’ll end up with holes or blurry details on your scans. 
  • Turn on object masking if you move the object. The object should stay stationary while you’re scanning, but there may be times when you want to also scan the part of the object that is obscured because it’s resting on a surface. In that case, make sure to toggle on the object masking feature on the processing page. I didn’t do this at first because I didn’t know what it did, and I ended up with inverted scans that are the stuff of nightmares. 
  • As you’re moving the phone, you might accidentally go too fast and capture images that are either blurry. The good news is you can delete bad images on the processing page. 
  • Rescan and reprocess. Sometimes the scan doesn’t turn out well. You can either scan the object again or extend the scan by capturing additional images — click on the icon labeled “extend.” So long as you didn’t already max out the images, you can recapture the bad parts of the scan and reprocess the scan. This will delete the original scan, but it will likely result in a better one.
  • You can make several adjustments to a scan after it’s been processed. The cropping feature is particularly useful because you can eliminate unwanted elements that often appear in scans. I like that it lets me clean up the surface the object is sitting on since often it will appear like a rhombus. The “rotate” feature is also good, letting you adjust the object’s placement upon opening. 

Scan everything

While Polycam is the app I’m sticking to, it’s expensive if you’re not using it for projects, professional or otherwise. Other options are cheaper or plain free to use. Even if you don’t use 3D scans professionally, it’s a lot of fun to scan objects. I look at 3D scans the same as taking a photograph purely to capture the memory, except much more immersive and interactive.

Cover image by AC Drone

For more on 3D, check out these articles:

How to Integrate 3D Elements into Video Footage – Part I
How to Integrate 3D Elements into Video Footage – Part II
How to Integrate 3D Elements into Video Footage – Part III


Source link
Studionics The Best Media Production house in Coimbatore

Category: ,
%d bloggers like this: