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View Full Version : Converting LWO to IGES



rogerske
11-27-2006, 09:23 AM
I have a customer that needs to make a prototype of an object that I created for them in Lightwave and they are requesting an IGES model. I have downloaded several conversion tools but none of them seem to work because the Lightwave objects are faceted and IGES wants "Solid" models made from curves. Does anyone know how to solve this problem?

Wonderpup
11-27-2006, 11:07 AM
Polytrans may be able to do this- it certainly handles a lot of formats- worth checking out their site.

StereoMike
11-27-2006, 12:20 PM
oh, that's bad...
My pipeline is the other way around. The companies use catia, which can export to various "solid" formats as IGES etc.
The problem is (to my knowledge), that there's no easy conversion from solids to polys or subpatches.
It's like converting a subpatched model into polys, in LW you have to freeze it ,which makes it impossible to revert the process. You can't derive the original cage mesh from that freezed highpoly model.
In my case we freeze the solid data into VRML files, which looks very bad and requires alot of work afterwards, but till now it's the only thing that works for me.

btw, that's a general problem. We artists use software that don't need accurate models, it just has to look convincing.
Engineers use software that has to be perfectly accurate, cause they drive CNC machines etc with the data.
It's like birds and fishes. they live in different worlds.



Mike

BeeVee
11-28-2006, 03:31 AM
If they are making a prototype using a 3D printer, or super-CNC milling machine, then the format you want is STL (STereoLithography). Best of all, there's a freely available plug-in for the job here (http://www.chromecow.com).

B

voriax
11-28-2006, 05:55 PM
StereoMike said: "The problem is (to my knowledge), that there's no easy conversion from solids to polys or subpatches."

Converting from solids to polys is easy. It's converting polys to solids that is the problem. Once you go to polys, you can't go back ;). Usually if I'm bringing in a SolidWorks file to LW, it'll be output to STL format, then converted using Accutrans into LW format. There's the free STL import/export tools for LW, but Accutrans does it a lot faster.

IGES is like the good ol' DXF for solid modelling. It's mostly universal for cross-program CAD compatibility because it retains the accuracy and real-world measurement info from CAD programs. It's not limited by poly count because it relies on curves. It's never "frozen" into a set poly detail level. Our manufacturers in China request IGES files when they're making production moulds.

STL will do for a rapid prototype as long as the poly count is high enough.

A hint for making STL's for prototypes: switch off smooth shading in your perspective window. If you can see facets on the model there (relative to the actual model size), then you'll be able to see them on a rapid prototype.

PS: 3DS Max imports IGES files directly. 90% of my work is product visualisation and LW can't import IGES files directly :(

randomnumbers
11-29-2006, 01:21 AM
I did this, *a long time ago*, going from lwo to iges.
As I recall, I used rhino3D to make the conversion.
You have to be really tight with your modelling.
As long as your mesh is "water-tight", rhino can convert to a solid and export to iges.
You can download the full demo for free and you can save (I think) 25 times before the demo expires.

If you get stuck on this let me know and I can dig around in my archives and figure out how I forced Rhino to generate the IGES file.

Hope that helps.

Auger
11-29-2006, 07:32 AM
If you get stuck on this let me know and I can dig around in my archives and figure out how I forced Rhino to generate the IGES file.

Hope that helps.

If it's not too much trouble, I'd love to know how you did it randomnumbers. I had a client ask me to do it but I couldn't figure out how to make Rhino transform my lwo to a solid.

Thanks,

Jon

StereoMike
11-30-2006, 02:19 AM
http://www.geomagic.com/en/products/studio/
http://www.rapidformxor.com/

These both can build solids from 3D scans (poly meshes), but cause they give you a contact form if you click on purchase (contrary to just saying how much it costs), I think you have to really pay an arm and a leg to get it.

Mike

gristle
11-30-2006, 12:28 PM
http://www.geomagic.com/en/products/studio/
http://www.rapidformxor.com/

These both can build solids from 3D scans (poly meshes), but cause they give you a contact form if you click on purchase (contrary to just saying how much it costs), I think you have to really pay an arm and a leg to get it.

Mike

Yep, in fact I think those cost both arms and legs :)

An Iges file does not need to be closed into a solid. It depends on what you are doing with it. From what I remember Iges supports facets/polys (well, its own description of them, maybe it sees a poly as a surface?) so you should be able to take the file via Rhino as stated above. All depends on what the downstream need is -eg. is someone going to rebuild your model in a cad package and use yours as a reference?

I agree about the Iges import into Lightwave!!! 99% of my work is imported into Lightwave from Cad packages via Rhino. I guess if there was an importer Lightwave would have to convert the iges surface data into sub d patches?

voriax
11-30-2006, 06:14 PM
I agree about the Iges import into Lightwave!!! 99% of my work is imported into Lightwave from Cad packages via Rhino. I guess if there was an importer Lightwave would have to convert the iges surface data into sub d patches?

Now THAT would be sweeeeeet!
Would give us so much more freedom when dealing with CAD models.. so tired of dealing with high-poly STL exports! :grumpy:

StereoMike
12-01-2006, 03:11 AM
Yeah, but that seems to be the holy grail of format conversion...
I read that you still have to edit the conversed meshes and have some work during the conversion to get polys right into solids. Before I googled for it I even thought it's impossible to make a nurb mesh from a polygonal model. Think about the time you spend, figuring out how to get the creases and edges on the rigtht spot and in the right way on you subpatchmodel... these programs do it by themselves, very impressive.

btw, you can get demo versions of the aforementioned tools, if someone likes to dig into it, please post your experiences here :)

Mike