3D scanning, I am confused...

[ajlelectronics]

I can get a passable image from the scanner, that's not a big issue. I then "mesh" it and fill holes etc but I am still left with a raggedy part that I can't do anything with apart from print it as it is.

What do I do with it from here? I need to clean it up and steepen the sides (reduce the width) and possibly further modify it, but of course it is a solid. It seems to me like the difference between a pixel image and a vector image. I have looked at Meshmixer and other programs, but again they seem not to be of much help.

Can someone explain in simple terms what scanning is all about and how to make use of it please?

 

[Bladevane]

I have not been involved with scanning for more than a decade so things will have progressed but my take is that the scanned model still requires the expert attention of someone who knows what they are looking at and can manipulate a CAD package. Scanning was not the simple answer of producing a manufacturable component direct from the scan. We re-engineered industrial gas turbine blades some years ago and had images from laser scanning (for the surface) and CTI for the internals. Every component then went through a meticulous process whereby the design intent was created from these initial models. When complete this refined model allowed us to cast or machine a finished blade. It was not simple or cheap.

 

[Stupoty]

Have you tried meshlab ? Ive used that for cleaning some photogametry type scans.

Stu

 

[Dr.Al]

I think it's a hard problem to solve and I'd be very interested to hear if you manage!

I've had a little bit of success with fairly simple shapes using one of a couple of approaches:

1. Use Blender to reduce the number of triangles a bit (low poly, but not too low!), then essentially tracing the part in 3D CAD to make a nice model
2. Use (a trial of) Instep Studio to convert the STL to a STEP file. This is non-trivial, but when you can figure out how to make it work, it works really well. I wasn't getting consistent enough results to feel like it was worth buying. Note that if you do think of buying it, it seems to be on sale quite often, so sign up to the mailing list and be patient!

 

[daedalusminos]

It sounds like you want to scan something, modify the scanned object and then print? If that's the case, you use your scanned model as a 'guide' to creating a parametric model or use a polygon basher to modify the scanned model ....but in this case it sounds as though the scanned quality is poor so I'd go for the former.

 

[Dev]

The scan creates a point cloud or mesh that isn’t solid or airtight. You need to use a program like meshmixer, meshlab, blender etc

You _might_ be able to print the raw scan but at the very least I’d rinse it through netfab first.

 

[daedalusminos]

Also, to scan a full model, you need to scan the top, scan the bottom and merge the scans....the scanning software should take care of the alignment between the two

 

[sako243]

My only experience of it was a colleague used a oldish system about 5 years ago to model a component we had to adapt for our purposes. He scanned in the object, the point cloud was imported into a tool which converted it to something he could import into Solidworks. He then basically drew around it creating a new model, desperately trying not to adjust the view because rendering the initial point cloud took 9 hours (and that was on a monster machine built for this purpose).

He ended up at one point getting so frustrated at hitting the scroll wheel and writing off the computer until the next day that he took a mouse and physically cut out the wheel to stop it happening.

 

[Mark 2]

As above, I think you only use the mesh as a guide. This is the method used by those using sculpting (3d) techniques. You then build a mesh on top (remesh) in quads which can have more accuracy and easier to UV map. Unwrap is not needed here but quads are much easier to work with.
I'd imagine Blender would have a plugin

 

[ajlelectronics]

Thank you to all for your assistance. It would appear that this expensive scanner is not a lot of use to me then, as most of my interest lies in prototyping and re-engineering.

I can't even get 'er indoors to be a test model.

 

[cr500dom]

Scanning, despite what the sales people will tell you is not a “Magic wand”
It essentially just gives you a massive file size 3D dumb solid / surface to trace over.

I have a £25k handheld laser scanner here and 20+ years of high end CAD experience, I still can’t get proper useable data or short circuit the workflow

 

[Maker]

Fusion360 has some mesh tools, not sure if they're any good. You need a seriously powerful PC, I've got 16Gb of ram which I thought was a lot when I bought it, but I've got scanned meshes I can guarantee will make the computer crash if I open them.

 

[ajlelectronics]

Fusion360 has some mesh tools, not sure if they're any good. You need a seriously powerful PC, I've got 16Gb of ram which I thought was a lot when I bought it, but I've got scanned meshes I can guarantee will make the computer crash if I open them.

I started with an excessive spec and the only way to crash it is to turn a mesh into a solid in Design Spark Mechanical.

 

[ajlelectronics]

This is what I knocked up this morning without reference to the scan.

 

[ajlelectronics]

Fairly pleased with it, I just need to offer it up now.

 

[Mark 2]

I think you're on the right track there.
Take the measurements Where it absolutely needs to fit and fill in the rest.