OBJ Import

GWS50

Please can you improve the OBJ import function. I have files that open in every other software that I have tried but all I get with Onshape is the document tab and a notification that the file has imported but NO tab (PArt studio) with the actual surfaces in it.

philip_thomas

GWS50 - Onshape will read OBJ and STL files and create a referenceable mesh as long as they are watertight.
Please note that because of the nature of faceted file formats (such as STL and OBJ), that there are no surfaces and no bodies (these file formats are simply a bucket of triangles).
Here is a video showing a use case - https://forum.onshape.com/discussion/4707/improvements-to-onshape-september-14th-2016/p1

I hope this helps.

GWS50

Thanks Philip, I think I've got the principle ( I have done a fair amount of work with STLs and OBJs) but what I don't understand is why other programs open the files and yet Onshape wont.
Why would this be?

philip_thomas

GWS50 - Would you please open a support ticket for that OBJ file. We are receiving similar notifications from others and we want to make sure that there isn't a bug we are not aware of. By opening a ticket, your name is added to the list of reporters and you will be notified directly via email when we figure out what the issue is. 
Thank you - Philip . . . 

GWS50

Many thanks Philip...will do

Marc_Miller

@philip_thomas   I don't understand why imported OBJ or STL files are required be watertight.  That feels a bit restrictive to me.  In most cases I would not care if it's watertight or not as I would just be using it for reference to model against or around.  What about 3d scans that are only of the pertinent side/section of something that you need to model up to?  Those are almost never watertight.  Or a model provided by someone that doesn't have great skills in providing you with a watertight model?  I mostly wouldn't care if the OBJ or STL had problems like reversed normals or duplicate faces/edges/verts as long as I could see the mesh in OS as a reference to model against.

I experimented importing several different OBJ and STL files the other day and had almost no luck at all.  Seems like OS is being overly picky about what it will actually display as a mesh.  I've submitted a ticket about it.

philip_thomas

@ye_2 care to weigh in on the requirements that a mesh be watertight? 

ye_2

We don't require watertight models, however, we do a strict validation of meshes before importing. You mentioned scan data. The common problems are self-intersecting and zero-area triangles. We're actively improving on our mesh imports. The data you provide can be helpful for our development. Thank you!

Marc_Miller

Thank you @ye_2 .  I was just surprised that OS wouldn't display models that other programs would display just fine, even if they were bad in some form.  OS might have good reasons for wanting/needing completely valid meshes for operations I'm not aware of, but for just modeling against shouldn't meshes with some errors still be ok to use?

philip_thomas

@Marc_Miller - please share a document containing the scanned data with support so that we can look at it.

Marc_Miller

Hi @philip_thomas.  I put in a support ticket the other day, Request #44321.
Also there's a shared document with some random files I'd tried to import in this thread:
https://forum.onshape.com/discussion/comment/23143
I don't have any scanned data to share at this time.

philip_thomas

Excellent - thank you.