3D Scanning for Everyone? Not Yet

Polycam is another app/service for reality capture that lets you scan items with your iPhone and delivers a 3D model of them. Polycam is similar to Canvas (see our review), but unlike Canvas, which limits itself to scanning the interiors of houses, it professes no such limit. This gave us great hope that it could quickly capture objects on the scale and with the detail that product design engineers work with, making it suited for reverse engineering.

We looked for confirmation in the scan examples shown on the Polycam site, which cover a broad spectrum of interests—to put it mildly. Every now and then, there is a building interior or a mechanically designed object. But you can find useful objects (such as the hand drill shown) using the search engine.

Polycam had relied on the built-in LiDAR of recent models of iPhones and iPads¹ for its scan but now adds a pure photography (photogrammetry) scanning option that allows it to be used on Android devices.

Polycam’s claimed accuracy of 2 percent is less than Canvas’ claimed accuracy (1%), so its use for accurate scans for reverse engineering is in doubt at the outset.

Using Polycam

Downloading the free Polycam app was a breeze and setting up an account requires no more than an email address and creating a password. Polycam will not ask for a credit card—at least not at first.

However, our first attempt to scan an object (a mini tripod) seemed to go smoothly. Using the LiDAR and the “OBJECT” mode on the iPhone app captured more of the office than the object, a mini tripod. But unlike other scanning applications we have seen (like SiteScape), Polycam includes an easy-to-use 3D cropping tool, with a cropping volume either rectangular or cylindrical, and its dimensions and orientation are easily modified using the touchscreen controls. The scanned model view orientation can also be similarly adjusted.

In less than a minute, the surrounding clutter of the office was gone, leaving only the tripod (though it had only two legs) and the surface it was resting on.

Once scanned, the object was uploaded to Polycam’s servers and an export of a video and a glTF file (an open standard format developed by the Khronos Group) was requested. Several other formats (mesh formats included OBJ and STL, and point cloud formats such as PLY) for those who subscribe (see How Much? below).

The Result

The 3D model of the tripod that was returned to us was missing parts (with only 2 of its 3 legs) and enough surfaces to make it useless as a 3D model for reverse engineering ... or anything else, in our judgment. Comparing our result to a few of the nice-looking models in the gallery made us feel rather inadequate—as if it was us that was at fault. We failed to view the missing leg, so how could the model have it?

We tried another scan and fared no better. This time the tripod was mysteriously absent. Were we too close? The object did look a little out of focus. We tried a third time—this time shooting from a greater distance. Again, Polycam did a great job of modeling the walls, the cluttered desk ... but again, ignored or seemed blind to the mini tripod.

Scanning the object, the camera view fills with busy triangles that are trying in vain to cover the details of the tripod. There is little help during the scanning process, such as providing alerts like “You’re too close,” or confirmation of areas that have been scanned—unlike Canvas, which paints the areas scanned to avoid duplication of coverage. Only once did we see “You are moving too fast.”

The time it took to process the image was less than the blink of an eye. But uploading the 3.7MB video file to a cloud drive or waiting for an email to arrive with the file attached took longer.... By the next day, neither had arrived. Nor had an email with a code to reset a lost password.

You can also publish whatever you have scanned—even two-legged tripods—to the company’s website. Polycam does not question or curate the objects. The company seems intent to show off any and all scans with a stated goal of becoming the leading library of 3D-scanned models. However, in its haste, the gallery looks more like an attic full of objects that are of no use but which their owner cannot bear to throw away.

Scans published are viewable in 3D measurable. There does not appear to be a way to download models uploaded by others or to delete your own.

How Much?

Though our model was not usable, we can’t complain about the cost. We only used the free plan.

Polycam’s generous free plan is more than enough to get you started and allow you to post your captures to the gallery. You can do 180 captures for free. However, if you want all the export formats (CAD or mesh formats), 150 captures a month, video with watermarks and the Building Plan Tool (for floor plans, which were not tested), you must get the Pro plan and pay a rather modest $7.99 a month or $59.99 for the year.

Conclusion

Polycam displays excellent technology and blinding speed in making models from video—an excellent first attempt. But to make it useful for anyone in need of accurate 3D models for reverse engineering or product-scale reality capture, it needs to do better at guiding the scan so that the object of interest is modeled.

Polycam’s claim of “3D capture for anyone” is writ large on the home page. It would be unfair to counter with “jack of all trades, master of none” to this new, exciting and inexpensive scanning service, as we did not try it for anything but reverse engineering. Polycam claims that it is “the best LiDAR scanning app for contractors, interior designers, and architects,” and although we did not test it for such a purpose, the inability to confirm (show a “painted” mesh) what has been scanned is enough to make it second to Canvas in our judgment.

When faced with scanning problems, such as missing surfaces, we went to the help section—and found it to be not too helpful. Two short videos called “getting started videos” did little to explain how to obtain a better scan.

Polycam was contacted for input into this article but did not respond.