is MOI too weak to open a 50MB Step-File?

Next
 From:  mike (MIOHN)
5598.1 
Hi, I have problems to open a stp-file with 56 MB.
MOI seems to freese! Even after 3 Minutes no respond.

Any idear?

I need to convert this stp-file to obj with MOI.

regards
MIke
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  mattj (MATTJENN)
5598.2 
it just needs time. I regulary open 250mb files which take about 20 mins to open. Once open its very stable though.
matt
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  mike (MIOHN)
5598.3 
ahh o.k.
So I need to wait a bit longer!

thanks
Mike
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  Michael Gibson
5598.4 In reply to 5598.1 
Hi Mike, it's not unusual for it to take a while to load STEP files, 3 minutes is not nearly enough time to wait.

Also sometimes the size of the file on disk can be deceiving, if the file contains a large number of repeated instances that can balloon up the complexity at runtime by a lot.

If the file is heavier it's not a bad idea to change some of the view settings in MoI so that it will be generating a coarser display mesh instead of the default dense mesh, there is some information on that here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=5322.2

Coarser view settings will help to consume less memory and take less time generating the display meshes if there are any complex surfaces in the STEP file.

Also right now when MoI is busy loading any file the UI will appear frozen while it is crunching away on the file. If MoI is still using CPU in task manager it means it's still working and is not actually frozen. I am planning on tuning this up in v3 so that it will show a progress bar or something during the load instead of just looking frozen but right now that's just how it works.

- Michael
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  chrisd (CHRIS_DORDONI)
5598.5 In reply to 5598.4 
First I have to say that I don't have Moi yet, but I plan on getting it in the near future, so this question may come from my ignorance of Moi's export cabability.

Would the fact that it is a 56Mb nurbs file present a challenge to making a mesh that is optimized. I could see that translating to an OBJ that is enormous, paticularly since OBJ has no binary format?

Can Moi export an OBJ with quads?
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
 From:  Michael Gibson
5598.6 In reply to 5598.5 
Hi Chris,

> First I have to say that I don't have Moi yet, but I plan on getting it in the near future, so
> this question may come from my ignorance of Moi's export cabability.

I would definitely recommend giving the trial version a try, you can get a 30 day trial version from here:
http://moi3d.com/download.htm

With the trial version you'll be able to test the export yourself and see if it will be good for what you need or not.


> Would the fact that it is a 56Mb nurbs file present a challenge to making a mesh that is optimized.
> I could see that translating to an OBJ that is enormous, paticularly since OBJ has no binary format?

Yeah at 56Mb it's certainly something a lot more complex than just a model of a box. It will probably make a fairly large OBJ file, but a "large file" these days is not such a problem - we're not in an area of 1.44MB floppy disks anymore, something like a 300MB OBJ file is not usually a problem these days.

There is usually a pretty substantial increase in file size when converting a complex NURBS model into polygons, especially if you want it to look smooth since in order to make things look smooth with polygons you need to generate a whole bunch of little ones.


> Can Moi export an OBJ with quads?

It can export an OBJ with n-gons - it will be quads in internal areas of the surface and n-gons in areas where the surface has been trimmed - it basically starts out with quads on the base surface and then n-gons are formed where the surface has trimming information. This n-gon structure gives it a clean wireframe look but it is not the same as "all quads" output.

MoI is generally focused on producing an output mesh that will be used for rendering - if you're worrying about all quads that might mean that you're thinking of applying sub-d smoothing on to the mesh? If so then no - MoI's output is not intended to be used for sub-d smoothing, that really requires hand tuned topology and you will usually need to create a sub-d cage by hand in a sub-d modeling program and not as some automatic generated output. You can use the MoI output as a starting point for a retopology process though.

See here for some previous discussion:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4923.1


But if you want to generate a rendering, there is no need to have "all quads" for that anyway.


When you export a mesh from MoI (or other CAD programs too), it also exports vertex normals into the OBJ file and those vertex normals come from the original NURBS surface data from the CAD model, so things like all the polygons that make up a sphere piece have exact vertex normals from a sphere. So when those polygons are rendered they get shaded with those original surface normals and that makes the rendering look exactly the same as the original model.

So because of this you usually don't want to mess around with trying to additionally "smooth" the output, instead of making it smoother you would actually be deforming it and losing the accurate vertex normals in the process, making things worse instead of making them better. When you export out from MoI, all the smoothing information is basically already in the OBJ file in the vertex normals, you just render that directly and you get perfectly smooth looking shading. You really want to preserve that vertex normal information and not do anything that would cause it to get discarded.

Usually CAD models are in their precise shape already, with smooth surfaces in areas that are supposed to be smooth - so typically it is kind of a weird idea that you would want to "further smooth" the shape of the model - normally with CAD models that would disturb the precise shape of the model, things that were currently exactly spherical would get kind of melted to a somewhat different shape. So that kind of thing is not normally part of the process of what you do with models that you export from MoI.


It does not seem to be that unusual for someone who is coming from a sub-d modeling background to think that they must always apply sub-d smoothing to everything they're doing - but when you're rendering CAD data it's a different situation and you do not want to apply sub-d smoothing in that case, you just load the model and render it. Usually you don't go in and squish any individual points around since that will invalidate the vertex normals that are going to give the precise smooth shading to the rendering.


- Michael

EDITED: 13 Dec 2012 by MICHAEL GIBSON

  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged
 

Reply to All Reply to All