Import Splines With Tangency

Is there a way to force tangency at the ends of splines imported from
an IBL file?

Obviously, ProE permits tangency control when defining splines through
points. It seems it could do the same for imported splines.

Thanks for any assistance,
Dave

 

After you've created your curves from the .IBL or .IGS file, do
'Edit>Definition' and, with the Curves box checked, hit Done. You'll get the
'Edit Curves' menu manager with several menu items that could be of use,
though none directly allows setting end point tangencies. However, you can
select additonal spline points or trim/extend curves or even edit the data
file. I don't know, for sure, but one or more of these could give you that
kind of control. Adjust is also pretty powerful, if you can figure out how
to use it.

David Janes

 

Obviously, ProE permits tangency control when

Obviously it could but it probably assumes the curve
described by the points is what is intended. I would.
I'm not big on guessing games or typing. If you'll
describe goal and technique in at least as many words
I'll try to suggest something appropriate for the
situation or a more appropriate technique. Chances
are imposing a continuity condition will result in
unwanted curve oscillation.

One-size-fits-all answers adding to DJ's -
Independent Geometry Feature, Edit / Modify
CSys Offset Pts, Curve thru Pts / Whole Array.

 

There are other issues, as well. The first is that it's not at all clear,
from the IBL samples I have and have used to construct curves, that these
curves are splines and if not, then no end point conditions can be set. To
be certain that they were splines, it would be better to export the point
data from these curves and use that to import a point array, then create
curves as described above. Is that what the Independent Geometry Feature
does? Isn't that one of those things from REXX?

David Janes

 

They are unless the curve definition is two points. Then its
a line. That's documented in Help somewhere.

The Independent Geometry feature showed up in WF2 with the
addition of Scan-Tools to the FA license? It allows you to
copy or move standard model mode feature geometry into the
same environment used for Import Feature geometry manipulation.

 

Okay, well I'll have to try this with some IBL created geometry and see what
use can be made of it. Any "user friendliness" built in? Import Feature
editing is horrendous! And probably not what the OP is looking for.

David Janes

 

Import Feature editing is horrendous!

Personally, I find the Import Feature editing environment
satisfactory. It could be more friendly but, and often as not
this is the problem, if there's a substitute for working
knowledge of surface definition, structure, manipulation; I
haven't found it. I've patched up many megabytes of imported
model geometry in it. I do most of it manually. Tedious, time
consuming, effective to the extent the exported model quality
allows. I don't know that there are any shortcuts. I haven't
seen an auto healer that didn't suck, I'm talking over and above
minimal make-it-solid quality, on anything other than plane and
cylinder intersections with simple rounds. Maybe the twenty
grand + marvels. Out of my league.

The OP's situation would lead to an interface that's about
identical to that seen via Datum Curve / Edit Definition / Tweak,
with the addition of a Constraints drop down tab.

Try it, though. My opinions are my own. And though I haven't
heard enough to know, still suspect he doesn't want to add a
continuity constraint to a curve thru a fit point set. The task
wasn't described. For all I know he's tracing through a point
set to create an airfoil section or something equally inelegant.

 

Probably just my lack of experience with it. Like a lot of other things,
once you know it, it may seem 'easy'.

I actually have a lot of experience with surface construction and debugging,
but find the 'Edit>Definition' of imported features so totally obscure, I
probably dodn't try very hard. What are you supposed to do with the one
'Modify' icon you're presented with!?!
.....

Maybe, but he was trying to deal with IBL imported curves and there doesn't
seem to be much you can do with them, except through the MM interface that's
provided with 'Edit>Definition' as I described.

I guess I'm softening in my old age because I've usually prefaced answers to
questions like this with more questions, to gain definiton of the problem.
So, you're right, we're guessing. I guess wrong a lot and don't like to play
that game. Maybe we should make a pact to "nail" the OPs and find out
exactly what they want, what their situation is, what they've tried, i.e.,
get a more complete story, before we go out on a limb with an "educated"
guess. After all, the education was from other, 'similar' questions that may
not be similar at all. And, as an aid to that definition, I have been
pushing, here and with USENET, for making this a binary NG. I'm sure there'd
need to be a vote; tell me you hate/love the idea.

David Janes

 

Tedious. Time consuming. Effective. Satisfactory.
Easy and horrendous are both out of bounds in my book.
I get the willies when I hear 'friendly' applied to CAD.
My therapist thinks I've repressed memories of CAD childhood
abuse by mid range e-pederasts. I'm looking for a lawyer.
It may be the experiences left me with inappropriate
tolerance toward anything that works as advertised.

Help / Surfacing / Scan-Tools and you'll know as much about
it as I do. You can copy or move native feature geometry into
the environment to experiment with. I rarely use the, sorta
nifty, tool. The overwhelming bulk of import repair is cleaning
up or recreating nasty trim edges and aligning vertices, for
which it's no help. I do wish its control polyhedral display, or
some way of displaying knot spans, was available in standard
mode. Glaring omission in the analysis tools IMO (or glaring
omission in my knowledge of what's available?).

Probably my lack of scope showing but I can't imagine a reason to
do what OP wanted to do. Must have seemed like a good idea to
him, though, and he's got enough to go on. We'll probably never
know the secret behind the desire.

That's the cross an ethereal puzzle addict must bear.
Oh! Oh! Trim the curve and create a G1 or G2 transition.
I love this game!

Can you show me an unmoderated binary forum that's worth a
windfall fig for anything except downloading Fanny Does Fido
[1 of 82, 2 of 82, ... Fido's quite the performer] mpg's?
If there's a way around that I'd say go for it but I don't
really see the point. There are places to take discussions
that require data exchange to facilitate a solution and this
is the only Pro/E forum of it's kind in existence.

 

I'm still looking for a decent 'course' on this. Ideas? Tutorials?

Good point, so moderated first, then binary might make sense. Most
moderation is done with bots, anyway, and only posts to the moderator what
is in doubt.

If it were moderated and binary, it would still be, on USENET, the "only
Pro/E forum of it's kind in existence." Of course, by 'of its kind', you
might mean 'for texters only'. However, to my mind, what makes this unique
is not the text/binary business, but the fact that it's on USENET, that it's
a newsgroup. That, to me, is VERY important. Anyone on earth, with an
Internet connection and a news provider, can find us and find out about
Pro/e. Free! No stupid "registration". No lines, no waiting! Participation,
being there, weighing in, contributing, helping out around the place is the
only "requirement".

David Janes

 

Thanks for the discussion. I'm not familar with the Independent
Geometry feature, and I'm not sure what you mean by Import Feature.
Can you tell me where to go in the menu so I try it out?

I've imported the IBL file as datum curves. Edit Definition allows
some manipulation of the curve definition, but as far as I can tell
does not allow end conditions to be specified.

My workaround has been to scrap the IBL's and just read in the spline
points as Datum Points Offset from CSYS. Create spline through points
with appropriate tangency end conditions.

Dave

 

Could you use the IBL file for the point array definition? If not, where did
you get the points?

David Janes

 

This is probably more than you want to know but here's the entire
scope of the project:
1) Started with an existing model with a complex surface built using
Style Tool.
2) Saved style curves used to construct the surface as an IGES.
3) In a new model: create datum curves from file, using IGES.
4) Edit Definition (Redefine), Edit File brings up the control points
for the IGES curves in IBL format.
5) I then manipulated points in the IBL file (using Excel and some VBA
macros) to modify the surface. Several iterations were processed and
analyzed using FEA to meet a target mass and stiffness for the
feature.
6) This is where I tried to read in the modified IBL files but could
not figure out how to set the tangency end conditions. The original
IGES file had tangent splines, and when imported in step 4, the spines
are tangent. However, if you read the un-manipulated IBL generated in
Step 4 the curves are no longer tangent.

7) My work around was just to strip the IBL formatting from the IBL
file to create a "point file". Then use the Datum Point offset CSYS
feature, copy paste the point data from the point file. Then define
curves, through points with specified tangency end constraints.

 

snip...

Here, for some reason, possibly related to NG culture, we don't get enough
ramblers, those who tell us way MORE than we need to know. We, despite the
astronomical augmentation in capacity and speed, still pretend we're some
tightnit, close (and enclosed) little community of scientists working on
classified DoD projects, but needing a secure and cheaper-than-Ma-Bell
method of communicating conversational information quickly. So, short posts,
approximating telegraphic messages (with 'stops' in them) and short cut
communication with abbreviations, acronyms and anything else to make it more
like the telephonic in immediacy and speed. My way of saying no need to
apologize for what I asked for or for giving us the needed level of detail
that will help us dig into your problem. In fact, our usual complaint is
that we get too many questions on the order of "can i make a solid
protrusion in pro/e" to which we must inevitably answer "yes", since the
broadest, most vague questions receive the broadest, most contentless
answers. OTOH, the more pointed the question, the more precise (and to the
point) the answer.

Huh, why? From the start, where are you going with this, what are you trying
to accomplish? This is entirely missing in your presentation. Many of the
problems we encounter in this forum is misconceptions of how to get where
people want to go, and so they try to take bizarre, circuitous routes and
wind up at dead ends in the maze.

Again, why? For manipulation of curves/surfaces, you had one of the best
tools in the world ~ the Style feature. Don't see where you're going with
this but it seems like an extraordinarily roundabout way of getting there.
Maybe what is missing is a simple statement of "I am trying to get from HERE
to THERE" with enough detail of what 'here' and 'there' are to to form a
picture of the transition, the path, the process. So far, this seems
extraordinarily convoluted and unlike anything we've used or seen demo'd
before. Thus, I suspect you're "off the reservation" and lost, beating the
bush, hoping to find a familiar landmark. I can't provide you with one,
don't know where you are or where you're going. Spare no words on these
relevant subjects.

David Janes

 

Au contraire. That's exactly what's necessary to formulate relevant
suggestions.

The problem you are seeing is due to fact that ...

.... is a misconception. What you be looking at is the knot vector /
list or "fit" points; an incomplete curve definition. Thus the loss
of tangent direction.

I ~might~ do just as you are ... format pt list, crv thru pts.
I doubt, seriously, I'd worry with tangent direction. The curve
is good for reference only. If you have Scan-Tools look into Scan
Crv creation. I ~believe~ it would be precisely what you want for
Deviation Analysis references while you manipulate your existing ISDX
Style feature curves to match. Alternatively, you could just use
the point set for deviation references but that's not as nifty a deal
if I understand correctly.

If, for some reason, I actually wanted to reconstruct surfaces using
the import curves explicitly I believe I'd create the curves without
constraints, look at a curvature graph, apply constraints, look at
curve graph again.

Is this a class project? How "complex" are the surfaces you're
working with? A little more info ~might~ lead to some additional
refinements or alternatives, especially with regard to curve
creation / manipulation, if you want to investigate them.

 

Not a class project. Not terribly complex surfaces just a surface
blended from sections. The component is a turbine airfoil.

I'm not familar at all with Scan Tools - perhaps it's not in our
license.

I guess the bottom line is that you can't apply tangent conditions to
curves imported from an IBL?

If this is the case I'm satisfied with the curve through point method.
Any method that requires manually redefining the curves is not an
option in this case because I'm iterating through several designs to
reach an optimum solution. With the point through curve method I just
read in new points and the curves update including the tangency and
curvature constraints at the ends. In the end it took 2 days to run 15
models. Now that we've found a rough solution we will go back and
manually generate style curves to ensure smooth curvature in the
sections.

Thank you for all the help.

 

... Scan Tools - perhaps it's not in our license.

Help / Technical Support Info (for future reference).

I think that's a good assumption.

Sounds like a winner to me. Hope it goes well.