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Re: The thread for silly Alias questions...

Postby eobet » April 22nd, 2010, 12:14 pm


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Great workaround, thank you!

Aargh! They changed the licensing to activation in 2011 even on the student version, and my account doesn't seem to work after I input my serial codes... I... hate... DRM... why companies should have more rights than you do is beyond me. Only legal customers ever get screwed, never ever pirates. Sigh.

Re: The thread for silly Alias questions...

Postby eobet » April 23rd, 2010, 9:15 am


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Ok, got the 2011 version now...

New feature is apparently that the non-proportional view scale works in perspective mode as well...

Which seems to have the effect that when using the view panel (as opposed to the new view cube), there is no way to reset it...

Legacy features are a wonderful thing, eh?

(PS. The reason I'm not using the view cube is that it hardly ever works in OS X... it rarely accepts my mouse clicks to rotate to a certain view, like top, etc... and some times the panel with the perspective toggle doesn't show up... it was the same in 2010, and it is still glitchy as hell in 2011.)

Re: The thread for silly Alias questions...

Postby eobet » April 23rd, 2010, 9:49 am


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Cyberdemon wrote:Heres a trick that should work for you too in a case like this:

If you duplicate your curves as an instance with the scale set to -1 in the axis you want to mirror you will create another curve. This curve will retain history and always be a perfect mirror image of your curve, and it should retain history no matter what you do to it.


Ok, so your workaround is great, until you encounter this:

I wanted to evaluate the curvature of a curve using the curve curvature tool to show it's curvature comb, however, Alias wouldn't let me. I discovered that the curve curvature tool sees the curve as a node, and not a curve. However, the object picker correctly identifies it as a curve. The curve in question has a duplicate instance, but it is NOT the instance that I am selecting, it is the original curve.

Create a curve away from the center plane, but put the pivot in the center. Duplicate it as an instance with scale -1 to mirror it across. Then create a skin between the curves. Use the curve curvature tool on the original curve. Note that it will identify the curve in the popup selection as a node instead, and won't let you evaluate it. Then use the object picker to pick the curve, and note how in the popup, it is now correctly identified as a curve.


Now, I guess I can work around that as well by evaluating the edge of the skin I made, but come on... a workaround for a workaround?

That's from a bug report I filed, btw... but... testing it now... it seems that I have to hide everything but the curves I want to see the comb on in order to activate the glitch, and that did not get included in my report... guess they won't be able to reproduce it and it won't get fixed... sigh...
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Re: The thread for silly Alias questions...

Postby eobet » April 23rd, 2010, 9:56 am


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Holy crap, the step size in the move cv tool doesn't work either in 2011!

How glitchy is this release?

How do they handle updates, I wonder? I haven't seen any service packs or anything to download for the previous 2010...

Guess I'm downgrading, I just hope 2010 can read my 2011 wire files.

Re: The thread for silly Alias questions...

Postby Cyberdemon » April 23rd, 2010, 12:57 pm

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As far as the curvature issue...really don't know.

If you want my real opinion it would be to model your geometry between two real curves, and just use the mirror function. In my workflow I never skin between 3 curves to begin with (I will either model to the center line, or I will model between the edges and pull CV's to get the surface where I want). My general rule of modelling is to use as few curves as possible and let your surfaces do the work. I don't have to care about history if I'm pulling the CV's of my surface edges.

And step size still works for me in 2011, not sure if this is a Mac issue or what.

Re: The thread for silly Alias questions...

Postby eobet » April 23rd, 2010, 1:47 pm


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The skin across three curves thing is a workflow that Majenta Academy taught, and they teach the workflow that the automobile industry uses, so I'm sticking to that. :)

Imo, it absolutely reduces the number of curves needed since, as I said, I don't have to build any ribs, unless I want to.

Step size issue is still driving me nuts, though.


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I learned that same workflow way way back in the day... '96 to be exact. things have changed alot in the software and the industry.

The problem with the workflow is that it creates a 3rd degree curve that is prone to curvature plot break at the span. you have to break history anyways to fix that or detach it down the center line if your only doing half the car.

the other limitation is that it does not allow you to add acceleration or tension to shape. again you have to break history to add it.

with that being said...building across the center line is the best way to get a fluid shape. Seriously try the OBJECT EDIT > SYMMETRIC MODELING it was made specifically for this.

Draft/Flange tool now has a "double sided" and "single surface" option. this helps create the section from the center line and then direct model the rest.

Re: The thread for silly Alias questions...

Postby eobet » April 24th, 2010, 7:41 am


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Hmm... this should perhaps now be moved to a "surfacing strategies" thread... but, I looked into symmetric modeling and it seems to be exactly the opposite of what I'm trying to accomplish...
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Re: The thread for silly Alias questions...

Postby Cyberdemon » April 25th, 2010, 10:19 am

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Maybe this is over simplified as an example, but why can't you build that surface with 2 curves (your two outside green edges) and either pull the CV's to build to the middle OR build your edge to your center and mirror it?

You're right - there is no reason to build those red curves when you can just pull some CV's to get there.

Re: The thread for silly Alias questions...

Postby eobet » April 26th, 2010, 4:58 am


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Well, I downgraded to 2010 again and the step size and old view panel is working great, so let's move away from surfacing talk (I'll create that thread too one day), and back to a silly question:

:)

http://aliasdesign.autodesk.com/learnin ... gy_136551/

I encountered this on a trimmed surface as well before, and now I even see it in the above tutorial in a picture halfway down the page... why on earth should I "ignore the wobbly bits" in the curvature comb, and why does it seem to happen after I trim a surface?

I thought Alias was accurate? ;)

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It is accurate. The reason he says ignore the wobbly bit is that curve he is evaluating is a trim intersection (do a duplicate curve on that trim edge, and you will see it is inherently nasty in order to maintain G0 continuity.

BUT you ignore it because that entire edge will be deleted and replaced by a fillet.

Trim edges are just nasty by their nature - it's why you want to avoid building geometry off trim edges whenever possible, and why many times when you see student work it looks horrendous with a billion isoparms, because they will trim a curve, and then create a surface between two trim edges instead of building a clean surface.


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its accurately showing you that the COS and trim edges are made with 3rd degree curves... they do that. it is smart to evaluate the intersection in this manner because its hard to predict the intersection when you have have 2 unrelated forms crossing each other. just look at the overall flow of the comb plots to make sure that you dont have inflections or S shapes that are not desired. Im guessing that is why she says to ignore the wobbles(the small ones) but still use this tool.

in 2011, the Curve fit algorithm(what COSs are based on) has been further optimized. This is visible with the "Curve Fit" tool and "project" with the options set to Curve & Curve Fit. this lets you build clean natural curves that you can control the tolerances to the surface or edge. Mainly used for Single span bezier modeling but useful in other situation too.

Re: The thread for silly Alias questions...

Postby eobet » April 28th, 2010, 10:37 am


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Thank you for your answers.

An interesting thing just happened for the first time for me. I seriously had to debate wether I should do a model in Solidworks or Alias. I ended up starting in Solidworks anyway, but got to a point where I really wanted to try for curvature continuity and just couldn't tweak it to match (and I also encountered a case where I really wanted the edge align of the fillets Alias provides), so I thought I'd have a go in Alias instead.

However, a possible new case of unwarranted loss of history appeared:

Whenever I use trim to divide a surface, that divided surface never has history.

So, is there another way to split a surface into two patches and retain history on both?

Or should I report this as well (since it now seems I actually got my first skin history bug confirmed)?

EDIT: While I'm asking newbie questions, I know that trim retains the CV hull of the original surface, while detach does not... but how do you force a trim to act like detach and recalculate the CV hull? I tried the rebuild surface tool, but it didn't seem to have the desired effect.

Re: The thread for silly Alias questions...

Postby Cyberdemon » April 28th, 2010, 11:58 am

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Not sure about how to divide and maintain history.

I think for the trim issue, you're looking for Trim Convert or the legacy Shrink to Trim plugin (access via the plugin manager). Both have slightly different use cases, play around with them and it will probably help you understand.

Re: The thread for silly Alias questions...

Postby eobet » May 3rd, 2010, 5:57 pm


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Simple one: How do you increase the number of U and V curvature combs across a surface in the Display panel?

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