how to import stl files

OpenR2

michael3424 said:

If I understand it correctly, an STL file is comprised of a large number of very small meshes which approximate the surface of the object modeled.  Can such objects be easily and accurately edited with Onshape's tools as they exist today?  In my experience with Geomagic Design (a parametric 3D CAD program) STL files were nearly impossible to revise and I'm wondering if that is just the nature of the STL beast in a 3D MCAD world or a reflection of my poor 3D MCAD skills.

If the former is true, I'd prefer that Onshape programming resources be focused in other areas.

I was my understanding that STL is just a huge array of individual triangles. It's just x,y,z , x,y,z , x,y,z , ... , ... , ...

The triangles could have been generated by sampling a surface ... which is usually called tessellation.
They could have been generated programmically by something like an openGL shader.
They could have be measured by something like laser scanning.

Reverse engineering the original surface from a tessellated surface is not often easy.
Constructing a quality surface from a scanned mesh is not always easy.
Making a 3D viewer that displays an STL file is VERY easy.

Basically the STL file is a one to one mapping of triangle primitives in OpenGL or DirectX.
There's a little work to be done if you want to optimize the individual triangles in a manner that helps the Graphics Card render them with the highest performance. You would want to get rid of redundant point coordinates by making them indexed. And you would want to organize them into trisets and trifans.

I think there is a huge return for being able to render STL in view only mode .... for very little investment.

andrew_troup

Hmmm -  I'm unconvinced that viewing (without the ability to extract geometry, or even measure the leading dimensions of underlying geometry) within an MCAD application like Onshape would be "huge" - but I can see it would be convenient (from a filing standpoint, for those using Onshape as a document container)

magret_dosey

michael3424 said:

If I understand it correctly, an STL file is comprised of a large number of very small meshes which approximate the surface of the object modeled.  Can such objects be easily and accurately edited with Onshape's tools as they exist today?  In my experience with Geomagic Design (a parametric 3D CAD program) STL files were nearly impossible to revise and I'm wondering if that is just the nature of the STL beast in a 3D MCAD world or a reflection of my poor 3D MCAD skills.

If the former is true, I'd prefer that Onshape programming resources be focused in other areas.

For large STL files, it's a bit hard to edit those files in Onshape's toolset; it works fine with small files. However, this is not the recommended way.

kevin_quigley

The ability to VIEW and Measure from scanned clouds, stls (as often scan systems export stl) is indeed very useful. This is exactly what we use our 3D scanner for..to create a kind of 3D sketch picture to enable us to rebuild a nurbs surface over. We use Rhino for this. SolidWorks Premium can do this through the Scanto3D add in but we chose not to upgrade to this, buying Rhino instead, and saving £1500 in the process...but that is another story.

The ability to import a STL to actually build into a solid to use is a waste of time. Kernels like parasolid are rubbish at handling facetted polygonal models. I personally dont think Onshape should pursue this approach. If they want to allow edits for imported stls then team up with Materialise and license the Magics tech (just like Autodesk have done with Nettfab recently...well, they bought them).

Give us the tools to model anything using nurbs based approaches or sub div interfaces to nurbs and allow importing, viewing, scaling and measuring from imported mesh formats (not just stl) and this covers 99% of the paying market.

honestly, if your output is stl for printing, there are far better (free) mesh tools around.

michael3424

kevin_quigley said:

honestly, if your output is stl for printing, there are far better (free) mesh tools around.

Thanks - that was my conclusion after trying to edit an STL file from Thingiverse in GeoMagic Design 

nav

kevin_quigley said:

The ability to VIEW and Measure from scanned clouds, stls (as often scan systems export stl) is indeed very useful. 

Yesterday we were given a demo on a handheld scanner, a part of one of our aircraft was scanned....STL format can`t ber imported to OS...bummer.

on edit :The stl file had to be repaired before being CAD ready in a 20K software...

not usable without repairing:

_Ðave_

+1 Yes, import into Onshape and the ability to make a drawing of stl would be very useful for me. 

brucebartlett

@nav do you plan to try and model this in Onshape? It would be very interesting to se if you could get a result with the Onshape loft command

nav

brucebartlett said:

@nav do you plan to try and model this in Onshape? It would be very interesting to se if you could get a result with the Onshape loft command

Hi bruce, we were just testing a 3D scanner, the part is already modeled in other CAD platform, what we found is that without a software to fix the mesh its impossible to use/modify in OS or similars.

joris_kofman

for applications such as free surface optimisation in mechanical engineering it would be great to be able to view an stl file in OS. Then the user would be able to model a new geometry using the STL file as a reference. Sort of like putting a picture into a sketch. This should be much easier to implement then the reverse engineering tools that some people are requesting, as all the hard decisions are made by people instead of software.

andrew_troup

@joris_kofman
OK, that makes so much sense it hurts 
The best sort of partnership between human and machine, each playing to their strength.
Muchos kudos.!

pete_yodis

joris_kofman said:

for applications such as free surface optimisation in mechanical engineering it would be great to be able to view an stl file in OS. Then the user would be able to model a new geometry using the STL file as a reference. Sort of like putting a picture into a sketch. This should be much easier to implement then the reverse engineering tools that some people are requesting, as all the hard decisions are made by people instead of software.

I like that idea as well @joris_kofman I also wonder if 3D scanners and accompanying software just skip the step to convert to surfaces, and we just use a point cloud as the "picture" or backdrop to design against.

kevin_quigley

Intersting you say that Pete. In the AEC sector the trend is to bring in the point cloud and use it within the model as a geometry element (as a point cloud). Today I upgraded to SolidWorks 2016 (we use the Pro version). It now includes Scanto3D, so it brings in point cloud formats and loads of mesh formats as well as native NextEngine 3D scan files. Nice.

maybe next year they will downgrade routing into pro as well 

pete_yodis

kevin_quigley said:

Intersting you say that Pete. In the AEC sector the trend is to bring in the point cloud and use it within the model as a geometry element (as a point cloud). Today I upgraded to SolidWorks 2016 (we use the Pro version). It now includes Scanto3D, so it brings in point cloud formats and loads of mesh formats as well as native NextEngine 3D scan files. Nice.

maybe next year they will downgrade routing into pro as well 

@kevin_quigley Yes, I can see a workflow that is no muss no fuss.  For those times when you just want a reference, and nothing more... why even have the hassle of converting to a mesh or a surface?  Minimalist.  It would then be nice to still be able to convert that point cloud at any point later if needed.  You could have your cake and eat it too, if you liked later.

Huh... Scanto3D is now in Pro?  For some reason I thought it always was.  Maybe they weren't selling enough Scanto3D seats.  How is the performance on those imported point clouds in Pro?

pete_yodis

pete_yodis said:

Huh... Scanto3D is now in Pro?  For some reason I thought it always was.  Maybe they weren't selling enough Scanto3D seats.  How is the performance on those imported point clouds in Pro?

@kevin_quigley
Ah... I'm in the office this morning and checked my SolidWorks install.  I have Premium and it's included there.

kevin_quigley

pete_yodis said:

Huh... Scanto3D is now in Pro?  For some reason I thought it always was.  Maybe they weren't selling enough Scanto3D seats.  How is the performance on those imported point clouds in Pro?

Fast!

pete_yodis

kevin_quigley said:

pete_yodis said:

How is the performance on those imported point clouds in Pro?

Fast!

@kevin_quigley Thanks for the feedback... Lends all the more reason then to not have to wade through the workflow of creating surfaces, if performance of the point cloud is fast - then a display of that cloud as reference is all some might really want.

I haven't messed with point clouds in my Premium seat of SolidWorks, but maybe I'll have to play around now.

andrew_troup

I'm not sure I see how a point cloud (displayed on a 2D monitor) could be much of use as a reference?

In my (admittedly limited) experience, they tend to convey shape about as well as a flock of starlings or a cloud of confetti.

ben_masefield

There is currently a Beta going on for people interested in testing & providing feedback on importing STL and similar poly based data (including CAE) into Onshape (Windows only for now). See this post:  https://forum.onshape.com/discussion/1953/have-you-ever-wanted-to-read-a-stl-file-into-onshape

kevin_quigley

andrew_troup said:

I'm not sure I see how a point cloud (displayed on a 2D monitor) could be much of use as a reference?

In my (admittedly limited) experience, they tend to convey shape about as well as a flock of starlings or a cloud of confetti.

We use two methods. One is visual, so you create the 3D surface over the point cloud as  a guide in the same way you use a 2D sketch picture...this is very easy to do if your CAD system has good 3D curve creation and editing tools (Rhino for example, and even SolidWorks now).

the second method is to use the point cloud to project onto for curve points or subdivision nodes. This is the technique we use in Modo and TSplines.

depending on your CAD system you can also create curves that intersect with the point cloud itself. Rhino has commands that do this and the scan software the NextEngine provide also does this (but not as well). I'm still experimenting with SolidWorks Scanto3D now that it cones with Pro!

andrew_troup

@kevin_quigley

I can certainly see what you describe being useful, but (rightly or wrongly) it seemed to me what was being suggested most recently in this thread was to merely display the point cloud, as we currently can with png/jpg etc

If the analogy was accurate, that would leave us with no ability to use the point cloud other than purely as a visual aid: no measure, snap, infer, project onto, convert to surface, shrinkwrap, or whatever.

A 2D graphic is useful in that scenario because edges within the graphic boundary are defined and unambiguous (independent of viewing angle), but I'm struggling to imagine how that could be the case for the sorts of point clouds I've ever worked with.

pete_yodis

kevin_quigley said:

Intersting you say that Pete. In the AEC sector the trend is to bring in the point cloud and use it within the model as a geometry element (as a point cloud).

@kevin_quigleyDo you know why the AEC sector is trending that way?

kevin_quigley

@pete_yodis Probably because a point cloud will come from a specialist contractor and has contractual value as the "existing or as built" data. Any CAD model is an interpretation not actual. If you are doing any job there is a difference between reality and the idealised 3D model. Often with a point cloud this is obvious (by overlaying the cloud onto the model, or doing a cloud overlay at different phases).

in fact we bought our NextEngine scanner for this very reason. 

We were designing an injection moulded cover for a ceramic plate. We were given the plate (no data available). We designed the cover, built a prototype and it fitted that plate perfectly. Problem was it didn't fit most others in the production sample! The production process was hand made so the tolerances were wide.

So I bought the scanner, scanned 25 samples, then overlayed the clouds in VX (which at the time we used and was one of the very few CAD systems that handles scan data). We then changed the design and used the overlayed clouds to show (visually) to the customer (a big UK supermarket) that their ideas would not work and the whole premise of their business plan was flawed. 

Didn't get any more work from them after that. Some people just don't like to be told their great plans are flawed, despite us saving them probably £100k in tooling and 10x that in a disastrous implementation. But hey, what do I know?

kevin_quigley

@andrew_troup Most decent systems that handle point clouds also allow measuring to points (or point tolerances as a dense scan picking up individuual points is tricky or irrelevant as you might pick up localised surface detail).

Rhino is also a great tool for this as its plug in architecture has some nice add ons for this. You can also create curves through a point cloud at a specific plane. Very handy.

more info here...
http://wiki.mcneel.com/rhino/reverseengineering

kevin_quigley

@andrew_troup Of course if you are serious about reverse engineering you need to invest in systems designed specifically for it. And these all cost £££££.

consider that a decent quality scanner will set you back £30-40k, apps like http://www.geomagic.com/en/products-landing-pages/re-designx-wrap come in at the prices to make your eyes water. But they do work well.

but for our use, maybe scanning a few times a year on a NextEngine, we make do with Rhino or Modo

chris_bottino

joris_kofman said:

for applications such as free surface optimisation in mechanical engineering it would be great to be able to view an stl file in OS. Then the user would be able to model a new geometry using the STL file as a reference. Sort of like putting a picture into a sketch. This should be much easier to implement then the reverse engineering tools that some people are requesting, as all the hard decisions are made by people instead of software.

Exactly, just like bringing a bitmap into a vector app to design over.... pretty useful.  And if OS isn't able to import .stl's - yet, disable the ability to import a blank tab please :-)

neobobkrause

I view my use of OnShape as one tool in an overall toolset. It can't simply exist in isolation and expect to thrive. As such, I also desperately need STL or OBJ import support in OnShape.

- Bob

henry_feldman

nestor_socas said:

 I've imported STL files today, they appear on the list, but can't see the image on screen!.  Anybody knows why?

You can import basically anything (like a pdf) into your studio, but that isn't part of your CAD model, it's just a document to go along with your model. Say you had a circuit diagram or spec sheet, that all members of a team need, it's handy to shove it up into OS so folks can get to it. However to be able to model with it, is a whole other ball of wax...

henry_feldman

michael3424 said:

andrew_troup said:

Those who have imported a complex STL file into Solidworks will probably recall just how frustrating and unproductive the result can be.

That was certainly my experience working with STLs from the maker community in GeoMagic Design.  In the end, it was easier to recreate the model from scratch in GMD than to work with the STL file.

Well, except my source polymeshes are from CT scans of patients. Makes it pretty hard to model from scratch (not that I couldn't model the complete skull I did yesterday, but damn that would be a lot of scans and weird planes and lofting...). Much easier to as the PACS system to segment out a polymesh surface with a given houndsfield unit (I did bone yesterday and skin as a second mesh) and let it grind for 10 minutes...

herb_langer

I would like the ability to import STL files also