Death spirals, what is the gyro even for?

I am so incredibly frustrated by the Pop 2 and Revo Scan. Whenever there is any feature which has rotational symmetry the scanning tool chases it and spins the model out of control projecting points everywhere. This device has a gyro. The software has the data to estimate pose and compare that to gyro data. If they disagree the points should not be inserted into the model. Why is this not the case with the Revo Scan software. Even without the gyro you can tell the scanned object is not spinning at 200RPM. This shouldn’t be a problem for a tool with dedicated hardware.


That is the problem for most visual based scanners , how lower the accuracy and frame rate how more issues with this kind of objects when scanned without markers.
Some objects that I was not able to scan without marker mode with POP2, scanning perfectly with MINI in feature mode as the accuracy is so good it can use scanning spray surface as reference points .

Technically you are correct , but I don’t think the software take the whole advantage yet of the device’s hardware , but things improving as the time goes.

Until then I recommend to use additional feature references to break down the symmetry like placing additional object or marker mode .
You can also print out scanning plate with additional features or stick a simple fragment of a painter tape to break down the symmetry, there is lots of trick to avoid this situation successfully.

Make also sure you are using the last software build and last firmware version as the algorithms changed dramatically compared to the software from one month ago .

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Low frame rate itself is not a problem for scanning applications. You simply need to implement reasonable error metrics. When those error metrics are invalidated you make the user return to a point where you can robustly and for multiple frames determine pose. Applying optical flow as another cheap pose validation is also very easy. This is all stuff which was solved in public research papers over a decade ago and implemented in the commercial space shortly after.

ps. All up to date still having issues

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Example of something with a wiff of symmetry spinning off.

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You better show the picture of the object , it would be better to evaluate the situation and give you a tip .

This particular object isn’t even a very good example of the issues. It does seem to happen when there is any symmetrical subcomponent. But here is a photo

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You can avoid it by changing the mode to Face ,Head or Body, this object is particularly too big to be scanned in Feature mode what is for a very small objects , it needs 3D spray to keep the gain consistent since the gain is most important key here , It has lots of features to be scanned without huge issue .

Visual scanners are usually confused with symmetrical features , POP2 recognizes the same pattern and jump back and forth not because it don’t works correctly , it was designed to recognize the same pattern in case of losing tracking to be able to return back to the same position , so you got here a bitter-sweet situation that do not works with your object.

Changing the scanning angle may help , but if there is no way out , you need to use 3D spray as dark plastic and metal will be not captured correctly and also try markers . And if not needed , do not scan in color, it only drag down the whole process .

You can also scan partials and merge them together and not trying to scan everything at once as it going to be very difficult task .

Randomly realigning incorrectly is not working correctly. It’s an avoidable issue and the POP2 does not avoid it. If points were only inserted into the model when the pose was known with high confidence this would not happen.

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Sorry, that is all I can help you here with .
I have no issues with death spirals as you called it … I learned to avoid them .

It is what it is … you can’t have what is not there . The Gyro is not responsible for the tracking on this device , it uses it for the starting point to register the position of the begining of the scanned volume . Feature recognition and tracking algorithms are responsible for the rest , as with all scanners in the world , symmetrical features are a big troubles as are flat featureless areas and you can’t avoid them , that what markets are for.

In this case all you can do is practice and use the proper modes for your scanned objects .

And that is all I have to say on this subject, talking about will not fix your issue, practice will .

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I appreciate your desire to help and your suggestions. However there are clearly fundamental issues which could be addressed to make this easier for everyone. You can practice driving a half broken down car or you could fix the car. Obviously in this case we can’t fix it because it’s closed source.