Ken Versprille:

Q) What is the difference between uniform and chordal curves? I don’t know which one I should check and whether I can use both of them to create one or several surfaces.

A) This is only important on curves or surfaces with spans, they are two different mathematical methods of how the spans are internally distributed along the curve or surface in Alias
I find it odd that they would expose this to the user but the theory is, that one might give you a better result than the other depending on your geometry and as such they allow you to choose

Quite worthless in fact because it is an industry best practice to stick to either one, or the other! and I would highly advise to go for “Uniform” as it is the more stable and predictable of the two

Remember: if you stick to modeling single span as often as you can, you simply don’t have to worry about this! you can choose any of the two in a “Create CV/EP Curve” window and it doesn’t make any difference!

I’d still be dilligent and choose Uniform though in case you need to generate some spans later on, because like Square doesn’t have any option for Bezier so you may need to add some spans temporarily and remove them later, these spans should be more behaved with Uniform distribution and that will help you

http://wikihelp.autodesk.com/Alias/enu/2014/Help/0245-Alias_He245/0246-Alias_Co246/0267-Object_p267/0269-Paramete269

Q) Today I noticed that the tangent angle option in the square surface tool achieve sometimes smooth continuity of surface. How is that?

A) Tangent angle is a rediculously amazing option!! it’s not directly designed to give you smooth continuity across surface borders but I guess left to chance, it will sometimes, as in your case

Tangent angle ensures the angle between two surfaces at their common edge is consistent throughout. This can be a tricky subject to understand, but this will allow you to put a fillet on there that is consistent as well. The quality of your fillets are only as good as the quality of your primary surfaces and their theoretical intersections!

Otherwise if the angles are fluctuating your fillet will be like a trumpet i.e. go big, and small, and big, and small.. across your theoretical intersection. this phenomenon is highly undesirable

http://img.photobucket.com/albums/v252/Kev_Boy/Slide_0085_Full_zps1b16e4f7.jpg

http://img.photobucket.com/albums/v252/Kev_Boy/Slide_0086_Full_zpsd9e5a99f.jpg

http://img.photobucket.com/albums/v252/Kev_Boy/Slide_0089_Full_zpsefc5a622.jpg

http://img.photobucket.com/albums/v252/Kev_Boy/Slide_0090_Full_zps60111fdd.jpg

Q) In your creating and controlling curves NURBS curves tutorial, you achieve G4 curvature continuity. I am a bit confused by the curvature comb “language”. When the comb has a deep does it always describe a deep in the curve or the surface? I ask the question because when you achieve G3 in your video, the curve didn’t seem to have a deep.

A) I think your observation is a very good one, there’s a saying “there’s no free lunch in this world” and the same holds true for continuity. The higher the level of continuity you force a secondary curve/surface to achieve, the more room it needs to pull this off gracefully

Otherwise you end up with very tight radii (which are beyond ugly!) but there is no other way. if your start and end for that curve/surface are not far enough apart, you are forcing it to do this very smooooth G4 transition within a very narrow space, which will result in the peak radius being all bunched up, and it can have reversals in curvature etc… simple solution though: just give it more space, and it will work itself out

Actually a two part solution: make the ends of your primary crv’s/srfs begin to accelerate in curvature a bit before they terminate to their theoretical intersection, then do a tubular offset on that theoretical to trim them back, and make it big enough, well big! then create a new surface between the tangent edges and you will notice then you can achieve G4 and do so with the desired result

I have made a 14 min video about this! It is a LearningAlias Private release and is avail able to any paid up LearningAlias student. Just pay your subscription at

www.learningalias.co.uk

and then apart from getting access to loads of unique Alias Automotive training videos, you will be able to email Graham to get a live link to my G4 video tutorial.

Enjoy your Alias

Kevin de Smet

To Learn Alias Automotive to Industry Entry level has been made easier.

For student’s who have the objective of finding a CAD job in the near future, I still teach One to One students and all of these students get Automotive Modeling or Design/Modeling jobs, so it’s a great investment to make. The hourly rate is very high and there are vacancies in UK. France, Germany, Sweden, Spain, USA, Brazil etc. I can only take a maximum of 5-7 students at any one time. I teach all levels right up to Post Graduates. I have never had a Private student fail to get an Alias Automotive job (Companies include Ferrari, GM, Lotus, Opel, Audi Seat etc. ). If you wish to apply for a place, please email me with all your details.
Why not visit my website and take a look for your self?
Over 100 videos on many, many aspects of Learning Pro. Alias
I show you how to build a Complete Audi A5 Sportback (ext.) . Over 50 Videos on that alone !

Info. on Courses:

“Course #1”.

6 Months website access to all website based video tutorials, 167 Euros (215 USD equivalent Sept. 2012)

“Course #2”.

167 Euros (215 USD equivalent Sept. 2012) per month. You get your .wire reviewed by me every 15 days and you will receive : feedback, instruction, tips and advice from me personally. Access to all videos including my ” Private Student Training Videos”. You will build at least 3 complete automotive exteriors. The course also includes an intensive Reverse Engineering section, which required by most employers.

“#3 Full Pro. “Elite” Course”.

Fast Track Full Pro. “One to One” Course with weekly reviews and coaching 200-250 Euros (USD. 260-320 approx. Sept. 2012) per month. One to One Private tuition. You will receive specific geometry and meshes and modeling from me personally where required, to help you to complete your exteriors quickly to an Industry entry level standard. This means a bigger investment, but once in an Alias modeling job you will get back what you invested many times over and be able to work anywhere in the world

NB: Typically students pay 50% of the cost of the “Elite” course by monthly installments settling the balance over time,  once they have an Alias Automotive contract.

For more info,

Just register on my website and I’ll send you all the details
www.learningalias.co.uk

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If you are in the USA, just register and login, then go to Profile and you can pay your subscription with your US credit card. Absolutely no extra charges for currency conversion.

Regards

Graham Bullock B.Ed.(CNAA)Des.Tech.