Rhino V5 to Catia V5


#1

Hi

i would like the opinion of some Catia V5 surfacing guru. I just had a conversation with a master of class A surfacing on Catia V5 and his assessment was that Rhino to Catia in STP ( forget IGES it s crap we all know that ) the rhino surfaces are not that great. Work needs to be redone in some instances.
From my experience I didn t find it horrible. I was pretty satisfied ( maybe I m not as perfectionist as others or I m completely missing something) But are there any Catia V5 surfacing guru who sees that working with Rhino surfaces is not ideal ? and why exactly ?

I am aware of DATAKIT , by the way , however i am not willing to fork out more than a thousand euros for it.

thanks for your honest answers.

Alexandre


#2

Probably a garbage in = garbage out scenario. It is easy to create garbage in rhino without knowing it.


(Willem Derks) #3

I’ve seen garbage coming from Catia as well.
I think with any software you can create garbage to some extent. And there is always a distotion of information when porting from one system to another.

-Willem


#4

Yeah i Guess you guys are right. I also had in the past had to clean up catia surfaces before sending it to a cnc. Too many gaps. I guess i m a bit paranoid. But one thing i noticed is that exported rhino surfaces are broken in multiple surfaces in Catia, whereas Alias surfaces come out really nice in Catia. Yet they re all Nurbs surfaces.


(Marc Gibeault) #5

Hi Alex,
We could try a test comparing the same data trough STEP and DATAKIT.


#6

Salut Marc,

Agreed, i d like to look at the surfaces. I m surprised to hear that some experts in Catia say they need to rework rhino surfaces but are happy with Alias surfaces. They say rhino surfaces are broken down into much smaller ones in Catia.

Thanks

Alex


#7

Hello Alex,

We used Icem previously moving away from it due to the yearly maintenance costs, instead we purchased the Rhino plugins called VSR before they were purchased by Autodesk. We are also users of Catia, Unigraphics, Ideas and Creo.

Interestingly we used the VSR plugins to correct surface match imperfections on released automotive surface that were created in Catia version 2012 and our surface still displayed imperfections. We took our corrected surfaces into the 2014 version of Catia and there were no imperfections on the surfaces. This action was repeated with Step 203 and 214 and several flavors of Iges files, the results were identical. We sat with the automaker to display our dilemma as they direct our versions of software by contractual agreement, they could not explain it nor could they use the newer version of the software as their hands are tied also by corporate versioning. So they had to spend the time to smooth the surfaces directly in Catia 2012 before re-release. Food for thought…


#8

Very interesting comment. Truly appreciated.

Thanks

Alexandre


#9

CATIA V5 surfaces are not true NURBS. They act like NURBS but the math behind them is different. Rhino’s surfaces will often break apart at patch boundaries when exported to CATIA and vice versa. Otherwise I have had no problems using surfaces from either software when imported into the other other.

The older CATIA V4 was Bezier based and had a tolerance of just 0.0039 inches. Fixing gaps was a way of life using V4.


#10

Interesting observation, so do you think Alias and Catia surfaces are more alike? I m perplexed as to why Alias works so well with Catia, yet Alias is nurbs surfaces , or so it claims.

Thanks for your input


#11

Hi Alexandre

I’m not a Catia Surfaceing guru with NURBS, but I did some shape surface work for a company years ago. When I left we were on V5 R17 or R18 (?).
With Rhino/Grasshopper I played only on the trial-version more than a half year ago.

The good point on Rhino is the direct and easy modification of a NURBS surface like in Blender and the easy transformation of a curve or surface from one degree to an other.
The good point on Catia was/is the easy analyse of the curveture by a section through the surface. But in those time Catia had problem generate or keep a closed a highlevel non-uniform surface pipe with a kink or without a kink. Every time it broke up the pipe by an Iso-line.

An the momen I would go for Rhino for shape design so long Catia doesn’t convince me.

Ben


#12

Thanks for your input,

From my experience Catia is a pretty powerful tool, A lot of major manufacturing industries and many suppliers use Catia V5. My goal is to make Rhino and Catia surfaces be as seemless as possible, no gaps problems, no discontinuities etc…

. I have experience with Autodesk Shape Modeling plug in in Rhino, pretty amazing tool, it definitely needs to be part of Rhino’s modeling tool capabilities. Strive for single span surfaces using curve network for example.

Also there is the multiblend tool, again superior to the patch function in RHino.

Catia and Autodesk Shape Modeling seem to have a very similar way of building surfaces. No surprises since the Autodesk Shape Modeling was made by ex ICEM guys which became part of Catia V5.

My request for future versions of Rhino is to strive for single span surfacing tools, using lofts, curve network…

I hate on insisting this but Autodesk Shape Modeling is a hell of a plug in


(Rob McPherson) #13

Yes please!


#14

One more YES PLEASE!

Philip


(Rob McPherson) #15

…and let’s not forget a ‘Bezier patch only’ Fillet command too!


#16

To add even more confusion I found that if I used code to generate my CATIA surfaces they sometimes seemed to be of higher quality with fewer IGES export issues that the same surface made the traditional way.

I also wonder if the math is different between the GSD workbench and the Freestyle workbench.

As far as Alias I wonder if it is doing some repair work in the background.

CATIA version 2 through 4 seemed much more reliable for export/import than V5.


#17

I remember wHen i imported Catia V 4 to rhino v3 and then rhino v4 it was a nightmare. I would import surfaces broken down into tiny tiny ones and hundreds to clean up as well. Catia v5 improved because it was working on windows platform wHereas catia V4 was Unix based. Airbus had huge problems with the a380 design because the french were using v5 and germans were on v4. I wonder how Alias does it. Never heard people complain when importing in CatiaV 5.


#18

I found that to be true if I used CATIA surfaces that were from solids. I find that the CATIA explode function doesn’t work well for export purposes even today. I just spent some time rebuilding a loft some sent me that was made this way. Lots of tiny surfaces that I just used as the base for a whole new set of surfaces. What a mess.

The Gods of CATIA are probaby rolling on the floor laughing their heads off listening in on this conversation :slight_smile: