Some surfaces behaviour makes me confused

[Zaki]

Did anyone of you checked the surface modeling technique in Catia?? That is awesome dear. Catia has a lot of tools we always need to create A class surfaces.

 

[Jacoolo]

yea I saw some movies in Youtube

everything seem to be easy in this movies, however how close is it to reality? That is the question!

One thing, that catched my eye was when compare movies attached in Youtube - Catia vs Pro\e, Catia wins at Start.

So, Zaki, with that said, do You have any experience to share with us considering surfacing stuff?

 

[shankar_me]

Surface modelling in Catia is definetly easy and powerful. Well! In my opinion when comparing the surface modelling capabilities, Catia wins.

 

[Jacoolo]

taking youtube movies I can say - there is no doubt about that if You compare Pro\e ordinary surface capabilities with Catia`s offer. However I wonder how far ISDX is from Catia?

More - I suppose that some situations like 5 nd Boundary are common for all software. You have to seek workaround for them.

If A class is considered, then, well I can`t say a thing while I am far away from this stuff

finaly I have to give Catia second chance - the first I gave while my studies. I remind that time quite nice.

 

[Zaki]

Actually Jacek
Catia has a lot of tools that makes surface modeling comprehensive. We cant imagine in pro. I am in learning phase specially surface tools. I will share a lot soon in Catia forum. But you must need Catia seat.

 

[design-engine]

youtube compresses so much and all my videos are over 100 megs. I can't speak too much for Catia but my high level friends using Catia surfaces tell me that you often need ICEM to clean up the jacked surfaces in Catia. I did not see an example but maybe there are continuity issues? I do know that several interior groups use Catia to develop the auto interiors... even in the united states.


Edited by: design-engine

 

[Jacoolo]

yeah, Catia is "ugly bastard"

the point is some things looks really impressive. Lets`s take fill tool or fillet between surfaces. This looks amazing.

I saw in the weekend some new movies in youtube for Catia, I want to to try them now in Pro\e. However some are just not possible by the lack of such funcionality in Pro\e.

On another hand, some of them looks just to easy to deliver good result. There are some surfaces made by 3nd curve boundary, and I wonder if Catia manage such stuff better than Pro\e

however solving this case with only one feat with such goog result, push me to fall on the flour out of breath



in Pro\e You need some pre-defined curves to drive boundary conditions with right resluts. It can be done with one feat also but there is a problem with control points which are created due to the curve made from two rounds

 

[design-engine]

hey that is a design engine tutorial turned into Catia. I do that in one and 10 features to illustrate a point. Can you put the link so I can track that down...


Edited by: design-engine

 

[Jacoolo]

try here

http://www.youtube.com/watch?v=GHLQmfb4S74

or here

http://myweb.polyu.edu.hk/~mmdsham/model-f.htm - the source page of this info

 

[design-engine]

Chinese dude..... dick sham I have been dicked and scammed. No big deal i guess.... I subscribed to his posts.... He got a couple more of my models and turned them into Catia videos. Looks like I have been challenged to make some more videos.... like I don't have too much to do already.

I guess someone from our office uplaoded a WF1.0 video to youtube I did back in 2002 http://www.youtube.com/user/designengineeducatio I got to fix that URL tho.


Edited by: design-engine

 

[jeff4136]

we gonna gossip bout Tia or we gonna do some surfacin'?

2008-02-18_220357_prt0001--wf2--.prt.zip

 

[design-engine]

In Alias the A-Class guys in our office tease me in Pro/E because we cant get the geometry light enough to sit at the cool table (referencing GM auto designers using Alias. To meet the three rules of A-Class modeling you have to meet the g2 criteria by meeting the light reflections desirebale. 2. make it light as possible. By havening two tangent lines in your boundary surface there..... we using Pro/E fail that criteria. Part of the problem is Pro/ENGINEER itself.... lite enough .... light= less isoparms and PTC does not allow the isparms display. BTW isparms does not = isolines. Isolines are tangent lines and in software like Alias studio the isoparm display makes for the supper anal technically lite surfaces required to sit at the cool table at GM.

I am not on the surfacing technical committee but I have been graced with the honor to have two in my classes over the past year and home that thru them I can make a difference. I like not being on the committee so I can speak freely w/o disclosure.

I am preparing my talk for the international conference this year that nips this concept in the butt... for the users and the programmers at PTC. With WF4.0 we now get more control over the control vertices but I suspect not until WF6.0 will we have the ability to convert y=x^3 or 3rd degree curves to y=x^4 or higher math. Hell Rhino can do it and PTC programmers boast about programming Rhino on the weekend. (I love that boasting you know).

With Pro/E Wf1 thru 4.0 we only have the ability to convert to y=x^4 when we force the curve to the curvature continuity status. If you export to Rhino or Alias then you see an extra control verticy.

Jim... that model looks hot!

If you use a hi rez jpg (2500+ at 72dpi) in your room's reflection with realtime render 'ON' you get a better result than the low rez zebra stripes crap we got stuck with. The zebra stripes are in fact like a plastic gun unusable in war. If you zoom in the jaggy edges are as if the image PTC uses for the stipe is compressed or something. If you use the Alias Studio zebra stripe you get a fine crisp line that communicates much better.



Edited by: design-engine

 

[Jacoolo]

jeff amazing stuff - I mean the approach I like very much

I like most the results from 2nd group, I guess pic attached by You above comes from 3rd group, right?

I was trying to achieve same results some time ago(a month ago). I finaly did it but without g2 though



Bart

Can You clear the the difference between usage of Alias and Pro\e.

Do not get me wrong but sometime I feel lost reading Your posts. How accurate Pro\e is to use it as surfacing tool? I understand that You place Alias higher than Pro\e(it is understable for car industry i.e), but what then is the right place for Pro\e with its surfacing capabilities?

I would like to hear clear split how far Pro\e can be used, and what is the right place to start using Alias?

 

[Jacoolo]

jeff I am trying to figure your model out. Specialy those planes made after rounds - to be more precise what I mean, pic below



first - what advantage it gives when You mount them as normal to edge?

second - I suppose You relate angle in 3rd plane with evaluation feature(is it because the lack of BMX, which I suffer either?), but how without relations You control this by having a half of measured angle?

and in the end - how to set the config up to obtain Evaluation feature? I used to use this feat in the past, but forgot what should I put in config to see it in Insert > Model Datums >...

 

[Jacoolo]

ok, I`ve found it at last

allow_anatomic_features - set it to Yes

once again I got round I can rely on Synthesis tips ))

http://www.synthx.com/tom/sy_tip_0203.htm

 

[jeff4136]

> I like most the results from 2nd group,
> I guess pic attached by You above comes
> from 3rd group, right?


Uh huh. I, too, tend to favor the the 2nd group (Blends1) but it's
the more critical setup. With the trim boundaries I had there's a
pretty narrow range of 'foundation' blend extents and constraint
weights that will yield a nice final blend (Boundary Blend 4). I had
to fuss with it just to get dihedral angles below 1/10 degree. The
second blend set (Blends2) seems to be less critical to get something
'passable'. It can be simplified to two trim curve sketches instead
of the four I used.


What I wanted to demonstrate was the lack of 'free space' curves.
Sometimes they can help but more often than not, in my experience,
they make a mess of things. In most cases I ~think~ that if you
seem to need them you should first try to figure out what it is
about your technique or your boundary conditions that's keeping
you from getting good results and correct that.


It's worth noting, as well; those are 'simple case' scenarios shown.
Once 2nd direction boundaries are added it's a lot more complicated.
Trying to G2 constrain four boundaries sometimes just won't work out
no matter how you hold your mouth, threaten it, plead with it. Often
a much nicer surface and acceptable curvature continuity can be had
with two or three boundaries G1 constrained. All depends on the
bounding geometry.


... Just saw the new post. Past my bedtime so this'll be brief ...


I'm not sure there's any 'real' advantage to setting the planes up
that way. What I wanted was an average - split the difference -
sorta thing. It may actually improve things if it's swung a few
degrees one way or the other. I didn't take the time to try.
There's a feature relation on the middle plane; d71 = .5 * a1:fid_pln_angle.


No BMX. I'm cheaping it with Foundation Advantage. ;^)


I don't remember setting a config option but there are so many I've
read about, set and subsequently forgotten. I'll have to do some
research. You don't see Insert > Datum > Evaluate on your menu?

 

[design-engine]

I am really fighting with the Alias snobs in the our office and to push PTC at the same time. They so busy looking at SW that we loose ground in the A-Class realm.

This is the classic g2 workshop in Alias. Keep the
parameterization the same.. build the geometry in a
lite way.
http://www.proetools.com/courses/alias/level5.htm

I suggest taking an level one alias class or alternate to that a one week Pro/SURFACE ISDX class where 4 hrs are using Alias Studio.
I use Alias in the latter class to explain the strengths of rebuilding (rhino term) a curve higher or lower.
I have tried to explain this stuff as best I can in words... as you know I am challenged. You really got to see the the techniques in action. Come see my talk in Long Beach... alternate to that I will try to speak at an OHIO Pro/E user conference and another at the Badgerland Conference for practice within the next few months (so i don't sound like I am selling a class)

"I wish PTC would stop looking at little sister and focus on other more
advent guard software tools beyond their immediate competition like
Alias Studio." -me

For my talk at the 2008 international conference I
am going to explain what it takes to be a software tool at GM and
hopefully some of the PTC programmers take head so we can mature the
PTC platform into being even more of the killer app we did not know we
need until we learn how to wield it. To do this i will compare Alias
studio ability to convert the math of a curve upwards from a y=x^3 to
y=x^7 and back. Back and forth control and the further ability to be
able to control the internal CV's of the curve and surface at the
curvature level.

http://www.merriam-webster.com/dictionary/wield



<a href="http://www.proetools.com/courses/alias/level5.htm" target="_blank" target="_blank">
</a>


Edited by: design-engine

 

[jeff4136]

> Come see my talk in Long Beach...


For the benefit of us po' folk that can't walk to Long Beach;
how 'bout an example IGES or STEP?

 

[design-engine]

well.... an example in Pro/E exported from Alias would not do it since PTC does not allow isoparm display. Surfacing technical committee folk need to push that first.

I think Rhino displays isoparms tho so a 30 day free trile of that might work. I have Joel our Alias instructor coming to meet me at a cafe in an hour and Ill see what he can do to the discussion here.

To meet the criteria for an a-class surface= lightly created geometry - light reflects properly - meets the continuity wished for.


Edited by: design-engine

 

[jeff4136]

Bart,


> I think Rhino displays isoparms


Got Rhino and, yes, it does. I use it (via exported IGES) for surface
evaluation whenever surface quality is important.


> PTC does not allow isoparm display


True ... sorta. For those that might be interested; whenever you look at
surface curvature graphs or an offset analysis you are looking at isoparms
/ isocurves. The problem is the intervals are user specified and give no
indication of knot spans which is what's of interest. You ~can~ Collapse
a copy of a surface into an Independant Geometry Feature and view the
Control Vertices / Polyhedron using (menu: Edit /) Modify. That serves the
same purpose (e.g. evaluating density and uniformity) since there's a fixed
relationship between the number of CV's and number of knots, but it's not a
practical solution. ... Really, all PTC needs to do to satisfy me is add
an option to the Offset Analyis that displays isocurves at knot locations
vs. a uniform distribution across the surface. Dirt simple for them to do,
really. (I hear that in WF4 you can view the Control Polyhedron in model
mode. That won't serve my purpose as I doubt you can display it while
tweaking a Boundary Blend whereas you can display an Offset Analysis while
doing same.)


- - - -


Jacek, I see you found the option (same doc I'd read). Look, too, at
Insert / Advanced. There's some other stuff that shows up there when you
set the config option (none of which I have much use for but you might).


- - -


A little post script ... there seems to be some confusion about what isoparms
and isocurves are. I guess it depends on who's jargon / language your speaking
but I believe the term is (from Rhino Help):
---
Isoparametric curve
An isoparametric curve is a curve of constant U or V value on a surface.
Rhino uses isoparametric curves and surface edge curves to visualize the
shape of a NURBS surface. By default isoparametric curves are drawn at
knot locations. If the surface is a single knot-span surface like a
simple rectangular plane, isoparametric curves are drawn also in the
middle of the surface.
---



Edited by: jeff4136