Mesh merges for slightly asymmetric objects

I ran into an interesting problem with one of my scans the other day: I have an object that when laying on its “bottom” side is vertically symmetric but is only slightly symmetric about the horizontal axis. That is to say that there is a cross section of the object that contains a beveled rectangle but the top radii and the bottom radii are very slightly different. The first scan I did on this I used 3 scans with the object on its bottom, its side, and finally turned vertically. I found the final scan and print came out oddly but couldn’t quite tell why until I tried a 2 scan merge using only the top and bottom scans. It looks like RevoScan is merging the objects top and bottom faces instead of recognizing those slight radius differences on the beveled portions - essentially one scan is inverted 180 degrees about the horizontal axis. I originally tried a 2 scan solution figuring the software might handle that composition better but it didn’t. Has anyone run into a similar problem? I’m considering wrapping a piece of painters tape around a portion of the object that I intend to cut off in later modeling stages and having that essentially serve as an anchor for the software to hopefully align the scans correctly.

Yes you need to have at least 3 the same unique features on both scans for the software to recognize it , placing some fragment of the tape will create it but invest in something better , like print out some small cubes and stick them to avoid movements , tape can move while scanning , nit good replacement for merging features .

the best would be to stick color stickers like round color stickers and use color per vertex while merging for objects that lack features , right now this option is not available yet , but you can use Cloud Compare , if you can paint on the scanned object you can even use simple marker to paint couple of crosses around that later will guide you while merging with highest precision .

Don’t merge scans with just eyeballing the accuracy … a true registration need a little effort and time to be completed perfectly .

So using maybe a few of the 3d scanning stickers and coloring the centers different colors and then merging in CloudCompare would help produce an accurate merge?

Yes definitely, it depends of the size of your object of course , you can get yourself mini color stickers on Amazon for couple of dollars. Not expensive, don’t waste the good markers .

You can stick a little fragment of a white painter tape and paint a different color mini crosses , it will give you a better precision points for merging , remember to scan in color .

Later in Cloud Compare use it for registration and you should have perfect result .