[Solved] Why does POP3D hate corners and straight lines?

I’ve spent the last two weekends trying to scan the inside of a sheet metal object. Everything in there was formed with a press brake, and–aside from some ragged, rusty holes–it’s made up of crisp, clean lines and sharp angles.

I’m getting good scans–plenty of points, plenty of data–but when I download it and try to stitch them together, none of the angles are right and all the straight lines are now nice and wavy. 90-degree corners are anywhere between 85 and 110 degrees, and straight lines turn out to actually have a radius.

How do I resolve this? POP was supposed to make my life easier, not more complicated.

Hi @Rusty

Could you please send us the files? Please send it to forum@revopoint3d.com.

Btw, may I know which mode did you use? When scanning parts, we suggest users to use the Marker Mode.

Best Regards

I sent you a dropbox link to a folder containing the most recent batch of individual scans, as well as what they look like when merged together.

I’ve tried every mode except Marker, because you can’t use that with an iPhone, and it’s not particularly feasible to get in there with my laptop anyway.

Here’s a for-instance of the issue with capturing straight lines. In the picture, you can see the red line (the X-axis). That part edge should be following straight along it, rather than being a radius.

(incidentally, most of the holes you see in that mesh are where I had tracking dots applied, before I discovered that the iPhone doesn’t do marker mode.)

Hi @Rusty

Could you please send us the picture of scanned object? We will try to re-merge it.

Btw, after checking the files you sent, we think the straight lines became wavy is because some parts are wrongly scanned.

or did you use the body or face mode when scanning this part? if you choose the body or face mode, since they’re designed for scan human, so it may cause the appear non-rigid registration.

Best Regards

All the parts were scanned with Feature mode, not face or body.

When you say “wrongly scanned,” I mean, there’s not really a lot of options to use…

I’ll see what I have available for pictures. I’m out of town for the next couple days but I might have something on my iPad, or at a minimum I can mark up some screenshots of the scans and show you where the edges are supposed to meet.

This is about the best I can do for you right now as far as pictures go- one of them is a photo before the hole in the middle was opened up quite so far, and the other three are screenshots from a LIDAR scan from my iPad. The LIDAR scan is obviously not that great, but it’s enough for you to see how everything is supposed to fit together.

Also- the colors in the photograph aren’t correct anymore. After being unable to scan at all with the original black paint and rust, I tried painting (and scanning) again with flat white, satin finish light blue, and satin finish charcoal gray. The gray gave the best results, which is the file set I sent you. I have a whole bunch of other files as well, which didn’t turn out very well at all. The LIDAR scan was done when there was a splotchy, streaky bit of white paint over the rust and dirt.

Bump… still looking for some guidance on this.

For anyone else who’s following along, here’s some visuals. In the middle, we’ve got a point cloud that shows all the merged scans. Around the outside, we have the individual scanned pieces that were merged to create it.

(In case anyone was curious, it’s the trunk of a car. I’m scanning it so that I can model up replacement steel parts that will just drop in rather than needing a ton of hand-fitting.)

This first corner is the front left. All the flat surfaces appear flat, and the corners appear to be 90 degrees… but they’re not.

Here’s the second corner- front right. Still looks pretty good. We’ve got plenty of scan data, there’s a little bit of noise, but you can see that most of the stuff that looks like noise is the same in all the scans. It’s rust, built up dirt, bubbling paint, etc. We’ve got plenty of overlap in the scans, and it looks like they merged just fine.

Again, the corners look like they’re 90 degrees, but they’re not… and that’s adding up.

Third corner. Right rear. Great detail- you can clearly see the texture on the strips of sound absorbent rubber that were glued to the floor panels. The sides of the hex nuts on the hardware look good. There’s even some places where I can see spot welds in the scan that are difficult to see in person with the naked eye. The detail is great.

The corners look nice and crisp… but again, they’re bigger than they’re supposed to be, and that error is adding up.

And here we are now at corner 4… and corner 5.

Those errors in the previous corners added up, and this is where we came out. All four sides of the trunk should be largely parallel to each other, and when merged, the two corners that you see here should only be one corner.

Here’s a top view with an orthographic projection. You can clearly see here that things which are supposed to be straight are very much not straight, and that angles which should be square are not.


@Revopoint-Cassie - haven’t heard anything back on this in a while. Any updates?

Hi @Rusty

For this issue, I invited our product director Vivian reply you directly. Sorry for the delay, she is very busy.

Best Regards

Thank you! I will be patient.

Thank you for your kind understanding. I had pushed her just now. We will try our best to reply you today or tomorrow.

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Hi @Rusty

Could you please provide more photos of the scanned objects? Thank you.

Best Regards

It’ll be tomorrow, but yes- I’ll get you some more pictures.


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Thank you so much for your cooperation.

I’ve emailed a dropbox link as before. This one has pictures as well as the results of a LIDAR scan from iPad.

Bump… @Revopoint-Cassie, any updates yet? I sent the stuff over about 4 days ago.

Bump… @Revopoint-Cassie, still looking for answers / help. It’s been over 2 weeks now.

Hi @Rusty

Sorry so much for the delay. Since I don’t know how to deal with this issue, I transfer it to our product director, but she is too busy to reply this post.

I will push her again.

Best Regards

Thank you! I’m really hoping to start getting usable results soon.

Hi @Rusty,

How are you?

I sent you a PM and an email, but no reply.

Please let me know your shipping information as soon as possible. We prefer to resend you a new POP, then call this one back to investigate. Thank you.

Best Regards