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Check out our YouTube Tutorial on How to 3D Scan Mechanical Parts with Polycam!
Preparing Small Objects for Scanning
Polycam is a tool, and just like any tool, you can be more or less skilled at using it. And the more skilled you are at it, the more difficult things you can capture with it. First, let's learn how to scan small objects. Place the object on a flat, evenly colored surface that's a different color from the object itself, and then make sure you can rotate the object three hundred and sixty degrees. You can scan an object anywhere, but it will work best if the lighting is diffuse, not direct.
Capturing Small Objects With Polycam
Once you've found the place where you're gonna scan your object, take out your phone and open the Polycam app. Tap the purple plus button in the bottom right, and then tap Object. If your object is small and your phone will be closer than about twenty centimeters to it, then click the flower button, which will turn on your phone's macro mode if you have it. Tap the white circle to start recording.
Capturing All Angles of the Object
Slowly move the phone up and down to capture all sides of the object. You can feel a slight buzz whenever a photo has been taken. Make sure each photo that you take has at least a fifty percent overlap with the previous photo. If you don't feel a buzz after you've moved the phone, go back and make sure a photo is taken there.
Rotating the Object During Capture
After you've moved the phone up and down, then rotate the object on its base slightly and repeat until you've turned the object fully three hundred and sixty degrees.
Closing the Capture Loop
When you get back to the place you started, go a little further just to close the loop so that some of your photos at the end repeat some of those photos that you captured at the beginning. This will help the algorithm stitch the photos together accurately.
Capturing the Bottom of the Object
If you need to turn the object over in order to capture the bottom, do it now, and repeat the same steps for the bottom of the object. Then click Done.
Scanning Large Mechanical Objects
For bigger objects, you'll walk around the object instead of rotating it. Here, I'm walking around an engine in a busy conference hall. Just move around the object fully three hundred and sixty degrees, raising and lowering your phone while keeping it pointed at the center of the object. Again, the more photos you take, the better, and you can feel that a photo is being taken whenever your phone buzzes. If any part of the object blocks another part or occludes it, make sure you capture all the angles around and behind anything that it's blocking.
Processing the Capture
When you finish taking these photos, upload them all as a mesh or a Gaussian splat. We recommend starting by uploading them as a photogrammetry mesh, but you can always reprocess them later as splats. If you turned over your object when you were recording it, then click the Isolate button so that our algorithm knows that you turned it over. Your capture will be ready after a few minutes.
Troubleshooting Scan Failures
If your scan fails, that's okay. There are a few other things you can always try. The first thing to try is changing the background. So here, I'm moving the part over to a wooden base, which should help Polycam's algorithm understand the geometry. Even though the wood isn't going to be included in our scan, the algorithm will notice the wood patterns, and it'll be able to align each photo better.
Understanding Geometry Misalignment
Now, notice that this scan actually came out with a misalignment in the geometry of the part. This is probably because not enough of the wood was in focus because I used macro mode, and I probably had the phone too close to the object.
Avoiding Blurry Backgrounds
Now, when the phone is too close, parts of each photo become blurry. Even if those parts are the background, that's a problem because for photogrammetry to work properly, everything has to be in focus.
Recommended Capture Settings
The scanning process that ended up working the best for this little part was using a white background, diffuse lighting, and holding the phone twenty centimeters from the part as I slowly rotated it.
Reprocessing Captures as Gaussian Splats
If you wanna reprocess your capture as a splat later, then you can open it, click the three little dots in the corner to duplicate it, and this will create a copy of your capture. Now open the copy and click Process. Tap Gaussian Splat, and then re-upload your photos to start the process.
Editing and Organizing Captures
There are lots of things you can do with these meshes to clean them up all within the Polycam app. You can crop your captures to get rid of anything that you don't need to have in your scan. You can rotate them to face in the right direction. You can save the thumbnail image so it's easy for you and your team to tell what the capture is of later. And you can send them to your colleagues or download the three-d files yourself. Thanks for using Polycam, and happy scanning.