@0502880
I would have to look at your model to figure out why you have that surface flaw.
As to Class-A surfaces from T-Splines...it is completely possible but hard to achieve with "certain surfaces" and the current tools.
Not impossible just that it can be hard with the current toolset.
This is the reason I use a modeler and Topogun with T-Splines so often.
For Class-A surfaces your biggest enemy is surface tension and right now solving surface tension with T-Splines is completely trial and error.
By definition:
Class A surfaces is a term used in automotive design to describe a set of freeform surfaces of high efficiency and quality. Although, strictly, it is nothing more than saying the surfaces have curvature and tangency alignment - to ideal aesthetical reflection quality, many people interpret class A surfaces to have G2 (or even G3) curvature continuity to one another (see freeform surface modelling).
Class A surfacing is done using computer-aided industrial design applications. Class A surface modellers are also called "digital sculptors" in the industry. Industrial Designers develop their design styling through the A surface, the physical surface the end user can feel, touch, see etc.
What most people don't understand is the feel, touch, see part...in it's simplest this is all due to "surface tension"
When working on Class A surfaces your goal is to take a design and solve the "Surface tension equation" once you do you end up with a perfect surface in feel, touch and sight...etc
G2 and others try to do this in an automated way, so when your working without true G2 you have to go back to the old school methods.
Too many people now a days don't understand what's going on in the tools and rely way to much on the tools doing everything for them...this is a mistake in my opinion.
For instance how did they make cars before digital design?
Working in quads is actually the easy part of modeling with T-Splines.
My guess based on your render is your problem is feature topology flow or surface tension or a combination of them both.
The problem is in the math and as a designer you don't want to think about the math or how the tools are doing what they do, but the reality is if you don't understand the how and why of a tool you can't use it to 100% of it's capabilities. Once you understand the weak points and strong points of a tool you can develop a workflow and environment that's truly inspiring and rewarding.
Cheers
Phil Procario Jr.
Owner, Laser & CNC Creations
