The Make editorial team tries out a lot more than fits into the magazine that appears every two months. That’s why we publish more test reports on our website at random.
Chinese manufacturer Revopoint crowdfunded the launch of its latest 3D scanner, called Revopoint Mini, on Kickstarter in July. The devices are on their way to the first supporters, for everyone else the 3D scanner can now be pre-ordered. However, Revopoint has already sent a copy to the Make editorial team for testing.
Blue light for depth
Like the manufacturer’s other devices, the Revopoint Mini is a structured light scanner: it has a projection system on board that throws a light pattern onto the surface of the object to be scanned. A stereo camera registers how the pattern is distorted by the object’s surface and uses this to calculate the 3D shape. The light pattern is visible on this scanner (infrared would have been an invisible alternative). Because of the flashing blue light on the Mini, the manufacturer warns against scanning people with it because it could damage their eyes.
In addition to the shape, an RGB camera records the colors and patterns of the surface so that textured 3D files can also be exported afterwards. The Mini is just 12 centimeters wide and is suitable for objects between one centimeter and half a meter in size. The optimal scanning distance to the surface is between 10 and 20 centimeters, the frame rate of the depth camera is 10 images per second. The manufacturer specifies the maximum achievable accuracy as 0.02 mm.
By hand or standing
Either you guide the Mini around the target object in your hand, which is more the procedure for larger objects. Or you can click the scanner onto the supplied mini tripod and install it next to a turntable on which the object rotates. How such scans are carried out and what comes out of it can be seen in the following video.
We slowed down the video by a factor of 10 from minute 3:39 so that you can see the cascade of blue stripe patterns that the scanner projects onto the surface. The procedure with such light patterns in itself is older. For example, we had it tried out on living editors at EuroMold 2013, with scanners from Artec and David. The mobile 3D scanner “Scan in a Box” also worked according to this principle, but in 2017 it also launched two industrial cameras and a projector, which first had to be assembled and adjusted by hand before scanning could begin.
Compared to these systems of the past, the Revopoint Mini costs just a quarter with its (still proud) 930 euros and works immediately after unpacking and installing the software – without time-consuming calibration. The software performs the automatic combination of different scan runs of the same object almost automatically. And it can also keep up with the resolution of the scans: In the test, the Mini reproduced the CE mark on the toy ram that we have been using as a test object for years – so far only the “Scan in a Box” has actually managed to do this in our tests “, but not the bigger (and cheaper) brother of Revopoint itself, the Pop 2, which we presented in detail in Make 3/22.
There is more on the subject in issue 3/22 of Make.
Who needs the Mini?
What is only a few centimeters in size but finely structured, the Mini captures excellently if you go to the fullest with the quality settings in the software (see video). But then you need a powerful (gaming) computer so that the processing of the point clouds, which may be several gigabytes in size, is eventually over. Prime disciplines for the Mini are, for example, the reproduction of tabletop miniatures and small spare parts, and jewelery designers and dental technicians could also benefit from this device.
If you want to scan larger objects with it, you have to reduce the resolution in the software, otherwise the mountains of data will grow over your head. If you want to capture larger objects more often and can live with a slightly lower resolution, you will probably be better off with the slightly cheaper Revopoint Pop 2. In the video, we recorded the same objects with both scanners and compared the results directly.
The projects from OpenScan.eu also remain as a cheaper alternative for do-it-yourselfers – we also presented the OpenScan Mini in Make issue 3/22. However, it works with the means of photogrammetry and needs finely structured surfaces. The test heads supplied with the Revopoint scanners would therefore have to be prepared for the OpenScan Mini using colored chalk spray in order to achieve the best possible result. The structured light devices, on the other hand, provide the necessary microstructure themselves via their light pattern.
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