Create Face, NGONS, and not able to fix

[lrsmithmi]

I'm working on a design where I want to create a plane faces and curves that I can edit. The route I've gone is to go into the splines modeling and creating a sketch with the curves and lines. Then I use the 'create-face' and I select were the lines intersect to create all the different faces. Its works, almost, expect for the top area ( in the attached photo ) though. It seems I have to select 4 points to create a face, or if I select polygon they overlap. It creates the face and looks good but I can't exit the due to an error with the form. Running the repair-body it shows what I think is a NGON ( 3) errors for the four faces at the top and the repair doesn't actually solve it. I want to keep a point there and googling and expirementing hasn't gotten me past this error. 

Any suggestions, tips on how to handle this would be appreciated.  

Thanks

Len

[Beyondforce]

Hi @lrsmithmi,

A screencast will be very helpful.

Ben,

[lrsmithmi]

Attached in a screencast of what I'm trying to do. this is how I created the faces on the rest of the model which works fine, I'm assuming because they are square. I did get this to work with 1 giant triangle but I want the four smaller triangles for some details later on.

[JDMather]

An actual file might be even more useful.

Often a better technique with "pinch point" geometry like that is to overbuild the surface and then trim it back to desired boundary.

I think Ed Eaton DiMonte Group Curvy Stuff tutorial covers this technique.

[PhilProcarioJr]

@lrsmithmi

How you create the geometry for things like this is completely dependent on how you plan to use the geometry and what your desired end form will look like.

I can tell you this you NEVER want triangles in your T-Spline control cage. Triangles are the lazy approach and lead to bad forms and an unstable working environment. The reason behind me saying this lies in the math involved in T-Splines. I know someone will probably disagree but I can tell you that I have over a thousand hours using T-Splines and the amount of problems you will encounter using them is astronomical. If you can show us what form your actually after we can help.

[lrsmithmi]

Phil,

Thanks basically I'm trying to create a plane/surface in that shape that I can then twist ( ala https://knowledge.autodesk.com/support/fusion-360/learn-explore/caas/screencast/Main/Details/0973244... ) Then from there I can thicken/extrude it and start to sculpt the surface more.

Thanks
Len

[lrsmithmi]

Thanks I'll take a look at that.

[PhilProcarioJr]

@lrsmithmi

You want to make your geometry all quads like this.