Best Way To Process .stl Files From A 3D Scanner?

[anyoldname]

I have a project that needs to take the .stl files from a 3D scanner, import them into an NX model then use their geometry to perform boolean operations.

.stl files do not define a solid or surfaces, they are just a collection of points & triangular elements in space so they can't be used directly in a model. Therefore, the stl needs to be processed to form either a solid or a surface set that completely encloses a volume.

The best method we have so far is to import the .stl into Catia and process them with Catia's Quick Surface Recognition (QSR) module but this is very user intensive. Each surface section needs to be selected, given a type classification (plane, cylinder, sphere etc) then stretched to overlap its neighbouring surfaces. Once the same operation has been performed on the neighbouring surface, the surface sections can be merged together and an appropriate fillet radius added to the joined edge(s).

I once saw a demonstration of a software system called Rapidform, it was able to apply surfaces to complex .stl geometry in a much easier to use method, its approach was more like throughing a blanket over the point cloud. The operator had to give the software a few clues as to how the contours of the geometry flowed but after that the software could quickly generate a best fit surface through the point cloud.

Catia's QSR does have a Powerfit function that can fit a surface to contoured geometry but it only seems capable of doing this with relatively small sections of the model and the resulting surfaces don't join up particularly well.

Does anybody have any suggestions of a better method or know of any other software that would need less operator input to get the scanned stl to the point that NX can recognise it as a solid body?

I'm currently working in NX5 but will soon be moving to NX 7.5.

Thanks.

 

[JohnRBaker]

You can do pretty much that same thing with NX 5.0 (or NX 7.5) as you can with Catia.

NX supports the importing of .stl files as faceted representations and then using NX's 'Rapid Surfacing' tools, you can convert these facet models into b-rep models. However, you will need to purchase the Studio Design license to gain access to these advanced tools.

John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

To an Engineer, the glass is twice as big as it needs to be.

 

[bsideB]

Hi,
It all depends in the kind of geometry and accuracy you need.
It is not the same if your 3d is an organic shape or if it is a simple mechanical part.

It is also not necessary to convert the STL to a solid body to do boolean operations. There is an small and cheap software that can do this operation: Rhinoceros 3d.

For reverse engineering (STL 2 Surface) you can check Geomagic Studio, in my opinion one of the best. This software it is also able to perform STL boolean operations.

Greetings,
Dani.

 

[anyoldname]

Thanks for the tip bsideB, I will check out Rhino 3D, they offer a free trial so I'll download it and see what it can do.

Can I ask how you have used stl data with Rhino 3D? Ultimately I need to do a boolean subtract in my NX model. The geometry I'm working with is a scan of a waterjacket sand- core for a cylinder head casting, so the geometry is fairly complex with lots of contoured surfaces.

Does anybody have any other experience of using Rhino 3D (or any other package) to generate surfaces/solids from stl files?

We have Geomagic Qualify which is good for working with the stl scans but it can't generate surfaces.

Thanks.

 

[SDETERS]

this may be a terrible Idea but could you model something that is close to the stl file using the stl file as a reference. This way you can modify it later and or have a stable model to use later down the line?

 

[anyoldname]

SDETERS, I could do that but it would take months, an cylinder head water jacket has some pretty complex geometry so trying to replicate the stl with parametric features would take a really long time.

To put the complexity into context, I've designed components for pretty much all the systems in engines and regard a cylinder head water jacket as THE most difficult/complex piece of geometry in an engine.

 

[SDETERS]

Oh ok I did not know if it was a one part thing or a huge file sounds like huge complicated features. the complexiity of those heads and porting would not be fun to model from what I see on the manifold and engines of today.

 

[anyoldname]

FAO John R Barker,

Is "Design Studio" the full name of the module that contains the Rapid Surfacing tools? I've asked our IT dept what licences we have and received a long list of NX modules/applications that contains names such as Process Studio, Freeform Modelling (basic & advanced), Freeform Shape, Advanced Surface Analysis and many others but not "Studio Design".

Is there any easy way I could check what I have available from within NX? I'm on NX5 (soon to become NX7.5)

Thanks.

 

[JohnRBaker]

I believe that it would fall under the Advanced Freeform Modeling.

John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

To an Engineer, the glass is twice as big as it needs to be.

 

[Ranvh]

Dear anyoldname,

I would like to ask how you solved your problem of changing an STL file to a normal body in NX.

I am using NX 7.0 with an Academic partner licence.
The STL file I'm working on is a 3D scan of a very complex glider fuselage.

Thank you

 

[loki3000]

rhinoceros can do it more or less automatically and the trial version allows 25 saves...