Revopoint MINI Scan Challenges

[John-SL]

I received my evaluation unit of the MINI a couple of days ago. For some background, this is my first time using a 3D scanner, but I have have years of experience with 3D printers, CAD, and CNC machining. I assumed, incorrectly as it turned out, that it would work well for the applications I had in mind. So I immediately jumped into reverse engineering a part on my small lathe.

That resulted in a less than useful scan:

Some research later and I realized I needed to get something like the AESUB sprays (I have a can on order). I also decided I should start simpler and work my way up. I tried the bust that came with the scanner, and it worked perfectly. The results were great and fairly detailed.

Next I decided to try a model train box car. That didn’t go well at all. Since I haven’t received the AESUB spray (it will probably take about a week), I used foot powder spray and that certainly made a large difference. However, the results I’m getting are not of the quality I was expecting from this scanner:

I’m hoping it’s because I’m making one or more mistakes that can be correct. However, I’m concerned that it might be a mismatch between what I’m trying to do and the abilities of this scanner and software. For example, given the small size, it doesn’t seem to like marker mode (do I need to add more markers to the table?). And when I use feature mode, it easily loses tracking, which means I’m not able to perform multiple scans at different heights without it getting the alignment wrong.

Here is the setup to give you an idea of the scale (in inches):

Any suggestions?

Thanks,
– John
https://youtube.com/c/johnsl

[Revopoint]

Hello, for better analysis, could you provide the point cloud file about this model train box car to us?

[John-SL]

I sent a link to the file via email.

[Revopoint]

Hi, we have processed your point cloud file by Revo studio and we found something problem. So we can provide some advice to you to improve the scanning quality.

Before you start to scan an object, you may need to observe the characteristics of the object. Like if it’s an object with obvious geometric features, a face or a body, etc. You can tell that most parts of the object are regular which means you can choose the marker mode and add some marker to it. If you feel something wrong or unsatisfied with the object when you are scanning, you can also use the “undo” button in the Revo scan to adjust the scanning quality.

Just do more practice, we believe you can make it.

[John-SL]

I’m not sure I understand the suggestion. I used marker mode for the scan that I sent. Because the object is only 3 inches (75 mm) in the longest dimension, there isn’t room on the object to add markers without covering details of the model. Is the suggestion to add more markers to the turntable, or to have the scanner farther from the turntable so it can see more markers?

And if I understand marker mode correctly, this would also mean I can only move the scanner up and down to improve the scan, as it uses the markers, rather than the object, for alignment. Is that correct?

[PUTV]

You are correct , the object is small enough to have perfect scan results using MIN , how closer it is how sharper the details.
But you need to pay attention that to have all edges sharp you need to scan it from different angles as well and avoid overlapping the scanned areas , looking on your point cloud and meshing results , you overlapped the scan too much .
It would be better to scan it in vertical position , you can move up and down MINI to catch as much angles as possible .

When you scan in marker mode you can’t move the object on the sides to continue scanning multiple angles , marker mode is only to capture one side of the object meaning one 360 degrees rotation with 300-360 frames export and do another , then merge them both together in Revo Studio .

As good is your point cloud so will be your mesh .
Also remember that MINI can pick up powder and dust , what can result in noisy surface . Pay attention of the distance and do not go beyond 15-20 cm for best results .

@John-SL

And if I understand marker mode correctly, this would also mean I can only move the scanner up and down to improve the scan, as it uses the markers, rather than the object, for alignment. Is that correct?

Yes that is correct .
But your object is so detailed you can do that using feature mode at the distance between 15-20 cm .

Scanning straight corners is difficult, because if you do not scan all angles you will get rounded edges. So for the best result, scan multiple angles separately and merge them later .

Organic objects are easier to scan as you not dealing with sharp edges and since each detail has 3 sharp faces , scanning everything at once will not works so good
unless you have Dual Axis turntable, you will need to scan them separately.

But try to scan the track in vertical position in place of horizontal. You would be able to capture more surfaces at once , remember to keep your MINI at minimum 45 degree angle to the object . It will helps with the tracking in feature mode .

[John-SL]

Thank you. I decided to try a different approach. I had been using scans at 15-20 cm from the object, which resulted in what I originally posted. I just tried a different approach after reading what you wrote. I positioned the scanner about 10 cm from the part, which means it was too close to see a lot of markers at the same time. But instead of using the motor to move the turntable, I would move it by hand. Here is the approach I used. I would take a few frames and complete the scan. Then I’d move the turntable slightly and capture a few more frames, waiting until Revo Scan acquired tracking again. I’d stop and complete. I did this perhaps 10-20 times and here is the result I got:

As you can see, this has much better detail and is far smoother. I can see how this approach takes a lot more work and patience. It’s also clear that this object has details below what the MINI can capture. I’ll have to measure some of the details to see where that limit it.

[PUTV]

It looks much better indeed, I tested all possibilities with MINI already and it can capture volume details to 0.76mm and surface resolution details to 0.23mm still much more details than you got for the second time .

Keep your pitch point always at 0.02mm for finest details , any shifting in pitch point will lose the resolution of the surface.

Each scanned object needs a different approach to be scanned correctly , that include angles and speed while scanning , too fast scanning can result in vertical strips , too slow in overlapped points, capturing too many still frames can result in noisy surfaces .

Check my MINI thread, you may find there something for yourself to improve your results and see what it can do.

MINI- PUTV 3D Models Showcase Progress & Tips

KS link: https://www.kickstarter.com/projects/2125914059/revopoint-mini-3d-scanner-with-002mm-precison?ref=5pvnpf [Revopoint3D MINI | Unboxing & 3D Scans Samples by PUTV] Chapter 1 : UNBOXING As you already know I become a Beta tester for the new Revopoint’s 3d scanner MINI The package arrived very quick and as usual with the same accessories . In the box I got the MINI 3D scanner , 2 T-shirt , turntable ( same as the one that came with POP and a letter . [IMG_20220512_185229…

[John-SL]

Thanks. I’ve been “practicing” some more to see what works and doesn’t work. So far I haven’t been able to do better than my previous post after spending several hours trying. I’m wondering if the marker dots on the table are too large for the mini. The scanner seems to have a hard time picking these up really well, and often “jumps” away a little from these marks. It shows green, but it’s clear that the green section isn’t perfectly aligned with the previous blue sections. I often find I have to undo a set of frames and try again. It’s a pretty slow, error prone process. I should point out this happens mostly when I move the scanner down from where it’s at a 45 degree angle. In other words, when the dots are more oblong, because the scanner is lower, it has a much harder time tracking the marker dots.

How long do you estimate it would take you to scan this object? And I believe you suggested standing it on one end instead of the orientation I have. Right now that’s a little hard to do because I’m using foot powder spray, so it comes off very easily. I don’t have one of the better sprays yet (it’s on the way).

[JeffLindstrom]

After you press Stop, be sure to turn the automatic fuse switch OFF before you press Complete.

Then, verify that the Fuse Configuration (the little button to the left of the Fuse icon) is set to 0.02 before before performing the Fuse operation.

Do this every time.

[John-SL]

Yup, that’s what I’ve been doing.

[PUTV]

@John-SL

I’m wondering if the marker dots on the table are too large for the mini. The scanner seems to have a hard time picking these up really well, and often “jumps” away a little from these marks.

The scanning window is very small especially if you object is above 3 inches and you try to scan it on close up . There is just no place to make the markers visible all the time , that why you need to change the angle for the best position focusing on the markers when scanning in marker mode .
Smaller markets would works just fine as I tried all sizes . I would not recommend to using printed plates when Scanning with MINI as the enormous amount of data only slowing down all the process .

@John-SL

How long do you estimate it would take you to scan this object?

You should have scanned the whole object in less than 2 minutes, all parts of it .
Considering 30 sec per rotation .
And I mean here a Scanning time not fusing or processing .

@John-SL

And I believe you suggested standing it on one end instead of the orientation I have. Right now that’s a little hard to do because I’m using foot powder spray, so it comes off very easily. I don’t have one of the better sprays yet (it’s on the way).

I believe you could do faster keeping it vertically, you would scan too, sides and under so you would need 2 scan session for merging .
Using 3D spray is not smudge proof, you still need to use glove when touching as it is easy to remove it especially on smooth corners and surfaces .
I hope you got AESUB orange , it is much smoother and last much longer so you can finish your work without rush .
When using AESUB be careful not leaving it on copper or brass without cleaning it after even if disappeared already as there is something in that new formula that oxidate some not pure metals .

Also the reason I recommend the vertical position is to keep the object at the same distance from MINI while rotating , you also will avoid overlapping in the middle of the object while rotation .
Also I believe you will not need marker mode when scanning it in vertical position with distance of 10cm .

[John-SL]

Thanks. I tried standing it up and got this result (using 0.02 for the point pitch).

In some ways it has better detail. But it also has a lot more noise. I did this using feature mode with about 4 different heights of the scanner (I kept the same distance and same angle). This was meshed at excellent quality.

I also tried marker mode, but even the first scan at the top wouldn’t stay aligned.

Next I opened the file again and meshed it at the good level and got this:

And for good measure, here is it meshed using Standard level:

So the Good mesh setting produces the best results for me. I’m guessing this is about the limit for what the Mini can handle. This model has some pretty small details.

[JeffLindstrom]

@John-SL

So the Good mesh setting produces the best results for me.

I think you can do better. In Revo Studio, you can perform Overlap Detection on the Point Cloud. Personally, I’ve been running it at Near, Medium and Far multiple times until there are zero or a very small number of resulting points before continuing on to Mesh.

Also, sharp edges will be captured better if the two depth sensors are parallel to the edge. This model has a lot of rectangular features, so two passes (one at 90° to the other) are indicated.

Hint: The number of detected overlapping points is only displayed for a couple seconds at the lower left of the screen.

[John-SL]

I get worse results when I use Overlap Detection by removing all at Small, then all overlap at Medium, and then all overlap at Max. Here is the result with meshing set at Standard:

I will try another scan where I also change the angle of the scanner. For this scan, it was at about 45 degrees from horizontal for each pass. By 90 degrees, does that mean the scanner is horizontal?

[PUTV]

@John-SL

So the Good mesh setting produces the best results for me. I’m guessing this is about the limit for what the Mini can handle. This model has some pretty small details.

Yes it did , but that is not the max you can do using MINI , it is the max right now you can produce based on experiences with the device , and since you started with little more advanced model , you need to find your ways .

I see you overlapped you scan multiple time I can see that from your meshed object . It is hard if the model do not fits completely in depth cam preview and you need to move it or the MINI , but for having clear scan with hard edge model like the track , you need to capture one rotation save it and do next untill you captured everything and later merged it in Revo Studio all together .

Single rotation scan 300-360 frames will produce always the sharpest and smoothest scans .

I think you are on a good path , as results getting better and you gaining already some good knowledge how things working .
Now focus on mastering the capture of the point cloud , most important since everything else is dependent on that later , and you will be not able to do the model better than the original point cloud .

A good point cloud produces always good mesh no matter the value settings of meshing .
How to see your point cloud is ok ? It looks like meshed object from distance with smooth surface and sharp details . Point clouds are compact tight together , no noises or fussiness on the surface .

Remember you can edit point cloud in Revo Studio , smooth it out, remove everything including isolated points , but for hard edges I prefer the mesh the point cloud in Revo Scan , and later convert it to point cloud in Revo Studio for merging, the hardest work will be already done in Revo Scan and much better than manual edit.

There is many ways to one destination , just find the one way that works best for you .
Looking forward to see improvements … you can do better , remember MINI can capture details on your model to 0.23mm , and so far it looks like 0.1mm … did you measured the details ? What is the smallest details ?

I am going to see if my son still have small train tracks , since he is now into big train models , and if I find any I will make some scan for comparison to give you a better idea .

[PUTV]

@JeffLindstrom

Also, sharp edges will be captured better if the two depth sensors are parallel to the edge. This model has a lot of rectangular features, so two passes (one at 90° to the other) are indicated.

That is very important note when scanning this type of objects , but scanned models at 90 degrees actually will have more issues with tracking , since you going to miss the corners and the MINI will never see the edge , all it will see is flat surface based on the pattern . 30-45 degrees is still the best way and you need to scan two passes upper and lower and not at one of possible .

What we do with organic models while scanning is not what should be done while scanning hard edge models .

Look only in my DeWalt battery scanning video , look how sharp edges looks like when scanning just one pass at 45 degrees and look the other scan when 45 and 90 degrees was scanned using my dual axis turntable … the 90 degrees washed off the details , however it was not important for the merge since the other part had the sharper details already .

It is a fact not a theory, for this kind of models you need to use the industry standard workflow … not the one for organic models . 2 different animals

[John-SL]

Thanks. I tried a single rotation scan with the scanner horizontal and it’s getting there.

What’s interesting is that you can see that the B (photo below of the actual car) is slightly raised. That makes sense as it was printed onto the car body after it was painted. You can also clearly see that the foot powder is likely causing at least some of the noise. I have a can of AESUB Blue that’s supposed to arrive tomorrow and am looking forward to seeing how that improves the scans I can do.

For reference, the B is a little less than 1 inch wide. I need to head to work. But tonight I’ll get out my microscope and calipers so I can get an idea of the size of the smaller details.

And as you pointed out, next I need to learn how to combine multiple scans in Studio. It’s pretty clear that scanning isn’t something you can just start doing and get good results. I’m seeing now that it requires an investment in time to learn what works and doesn’t work.

[PUTV]

@John-SL

I tried a single rotation scan with the scanner horizontal and it’s getting there.

Yes looking already great , huge difference in the details . I can see already details smaller than 0.1mm what was exactly what I was talking about .

The printing layers are always visible in my scans , also the powder will clog small creases and details , even AESUB spray will do that if you spray too much , so less is better , not need to be all white , just slightly layer is already enough .

@John-SL

I’m seeing now that it requires an investment in time to learn what works and doesn’t work.

It is with everything , there is no one scanner in the world that do that with just a push of a button , I charge $75 per hour for my work or $300-$700 per scanning session so if that was so simple , I would be out of job

The scanner is simple forward , but what you need to learn is evaluation of your scanned object , how to process it best way and how to approach it . Proper angles , planning etc … skills you can’t get when purchasing 3D scanner as each object needs different approach, a little knowledge about 3D helps a lot .

Basic factors and tips can be put into manual to helps users out but not posible to cover everything .

Merging objects also depends on the scans you created so the whole process is linked into one chain of processing .

Check my YT for some video tips on merging in Revo Studio

PUTV3D

[JeffLindstrom]

@PUTV

That is very important note when scanning this type of objects , but scanned models at 90 degrees actually will have more issues with tracking

I did not mean 90° to the surface of the object (e.g. perpendicular); I meant what I said… the Depth Cameras should be parallel to the edge you want to capture. This can be done while still having a 30-45° angle from the edge you want to scan.