View Full Version : ProE or large messy Iges rendering

03 March 2004, 03:16 PM
I'm doing some work for a company that is giving me ProE files that they exported in Iges format. I know that is the best format to use that ProE uses because it is pretty much straight NURBS data.
My problem is the models are very complex having wall thickness where it is not needed for rendering and a large number of the surfaces are trim surfaces where they don't need to be.

I can manage to usually get the filesize cut in half after a few hours of cleanup, but the renders, if they work at all, take very long. I can't even use MentalRay. It crashes right away.

When i render in Maya with maya software render, maya hangs, but the CPU monitor shows only 2percent activity. If it were juping to 100 percent alot I may give it a chance.

The first huge model I did, my solution was to batch render the frame. That worked. It still took a while, but I was expecting that.

I'm doing a new model now, and it is slightly smaller than the last. I have tried optimizing the scene size, deleting all history, curves, and anything that is not a camera, shader, light, or surface.
The renders before were finishing in about 20-30 minutes for 800x600 and they would finishe in 1h30min for 3200x2400 (print res).

I just wanted to check lighting so I am trying a render at 640x480. I have waited over 20minutes since batchrender wrote the file and it is still zero KB. The cpu is at a constant 100 percent, but it is just taking too long. This file is about 3/4 the size of the last large file I mentioned before.

Tessellation is also a bit of an issue, but for now I am finding photoshop to be the best fix for those issues. It would be great if I new a way, not in mental ray ,but it maya, to change the tesselation of all 1 degree surfaces, 3rd degree surfaces, and trim surfaces seperately without having to manually select them all first. There are thousands of surfaces in these files, so that would put me well over the budgeted time.

If anyone has any hints, tips or advice reguarding these issues please lend me a hand. I would appreciate it.

03 March 2004, 07:16 PM
?have you tried to apply mental ray approximation to it?

03 March 2004, 10:21 PM
try the attribute spreadsheet

03 March 2004, 07:53 AM
i had a similar problem when getting data from a CAD program (solid works for me).
the iges data really starts spoiling maya at a certain point.
as most of the 3d apps, maya is better in handling lower object counts with higher resolution.
so finally i ended up in converting the data in polytrans to polygons and was very happy with the result.
it is kind of tideous to find out the right settings in polytrans to get good geometry - especially since it took about 1 hour to convert the model.
so i would asks the CAD guys to give you some small exports of the complete model, that hold interesting data like very curved and very high detailed parts - with those you can fast do some tests.

also i recommend another format but iges for the file exchange.
the STEP file looked very good to me and worked great.

good luck


03 March 2004, 02:27 PM
STEP is the best if you can convert it to poly's because step understands solids information where as iges is just surfaces. So it tries to convert a solid model to surfaces and you get a hole heap of crazy patches trims etc etc....

03 March 2004, 02:32 PM
Thanks for the tip about the attribute spreadsheet. I wish it had ALL attributes that you could change. Sometimes I overlook the spreadsheet because it doesn't have everything. That would work fine, but I still would have to select every piece that is similar and adjust it accordingly. The other problem is, although two surfaces look the same they may have opposite U and V directions, so when you tesselate them the same it will cause horrible results with one direction.

As I had mentioned before, Mental Ray will not handle that much data. So, mental ray approximation will not work in this situation. I am very familiar with the tesselation in MR.

I was talking to a more experienced person at this jobsite and he suggested that I convert everything to Mesh (polygons). It makes the file size quite a bit larger, and somewhat less manageable, but the render times are faster. A render engine sees a polygon as a polygon no matter what from what I know. That made sense to me. I finally had the render before without Raytrace, and it took 20-30min. After the tedious conversion to polygons, the same size render took only 4.5min. What a huge difference.

Since I had moved the object I decided to convert all the objects directly in Maya. I have seen polytrans in use before, and it took about the same time, and I got to keep my shaders.

Polytrans seems good, but unless I need to keep animation data then I think Maya has quite a bit of control over translating the data. The only downside is that Of course, the polygons are not connected. I used the combine feature to keep the file size smaller, and I could probably keep it even smaller if I merge/weld the vertecies, but that just takes too long with such large objects.

Unless I stumble upon a better solution later converting to polys is the best for now. This job is nearly done. I'd still like to hear more for future jobs if anyone else has experience with large files in maya.

Thanks everyone

03 March 2004, 02:36 PM
Originally posted by andrewjohn81
Thanks for the tip about the attribute spreadsheet. I wish it had ALL attributes that you could change. Sometimes I overlook the spreadsheet because it doesn't have everything.

attribute spreadsheet holds all data.. it only depends on what you select.
e.g. selecting the transform node or selecting the shape will make a big difference.



03 March 2004, 09:51 PM
That makes sense alexx. I never thought of that before. Thanks for the tip.

I found another tip reguarding converting to Polygon Meshes. Those files use an enourmous amount of RAM. The machine had plenty, but it kept crashing and saying there wasn't enough memory to save. Turning off Undo fixed that problem. If you are use to undo, be careful and save often.

04 April 2004, 09:02 PM

I'm in the same line of work. I find a great fix is to import the igs file into rhino and re-export it as a maya-specific igs file. They offer a free demo with 30 exports. I usually have no problem with proe files, but i request all unneccesary geom to be hidden.

Another really helpful thing to pay attention to is the dos window that opens up when you render the file outside of maya. Frequently, little tiny pieces of the geometry dont make the conversion to igs smoothly, and it will totally jack your render. what you have to do is open the hypergraph and monitor the dos window. if it says things like " unable to find reasonable tesselation for Shape__12234" or whatever, you just punch the name into the hypergraph and delete the piece. make sure it's not a deletion you can't fix in photoshop. you might also want to hide 90% of your scene and see if that speeds things up by 90%.

if it doesnt, you might have a more systemic issue. I hope that isn't the case!

Good luck, and let me know how it goes...


here's my site: If you find you get over you head, and want to pass on a job, I'll pay you a 10% commission finders fee.

05 May 2004, 10:05 PM
I was having great problems exporting Rhino files. The client I was working with had a legit copy of Rhino, that is what they use there. I ended up using Sudio tools to import the ProE files because that works better with Maya.

I did find a few shapes that recieved the tesselation error in the dos window. One of the surfaces, however was the one of the main pieces. Is there an easy way to rebuild that. At the time I just remodeled the surface. if there is a simpler way I would love to know. some of the surfaces seemed to not even exist, so I deleted most of them. Does that really make the render time much longer if I get that error?

Hiding geometry never seems to make a difference for me. When you say I may have a systemic issue, what does that mean. I have that problem on any computer I use, both mac and PC (win2k pro).



as far as passing work your way, I am not allowed to do that because I work for a company that works for a company. It's complicated, but if it comes up I'll be sure to do that. Especially if it is on the East coast.

CGTalk Moderation
01 January 2006, 10:00 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.