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# "Fill Surface" guidelines?

Genius

Fill Surface is magic feature, sometimes making difficult jobs of G2 filling irregular opennings very easy.

But very often it fails to work, and its use seems be a little like a lucky draw. I wonder whether there are some guidelines on its use.

Thanks!
18 REPLIES

# Re: "Fill Surface" guidelines?

Phenom
G2 is sometimes a tough nut to crack due to the existing geometry in which you're trying to fill. If it's modeled poorly, then you can bet the fill is going to be irregular.

Have you tried extracting the existing surfaces you wish to fill and extending then retrimming them (or better yet, Delete Edge on the edges you wish to fill), and then using Patch? I bet that won't always work due to the G2 you more than likely have in adjacent surfaces but it's worth a shot.

You also may have to extract isoparametric curves and try to build a 4 sided fill surface with TCM (Through Curve Mesh).

Additional details as to the nature of how you're using the Fill (imported geometry) or even a small image showing an example of the opening would help tremendously.
-Tim

# Re: "Fill Surface" guidelines?

Siemens Phenom

As you said, fill surface is a magical feature. but you can't force G2 continuity were it is not possible. If setting G2 on a specific side will cause the result to be self intersecting, the system will not let you create it. If G2 fails, then go to each edge in the list and change it to G1 or G0 to determine which location(s) are causing the problem.

As @TimF suggested an image showing the issue would help a lot.

Regards,
Abe

# Re: "Fill Surface" guidelines?

Genius

Hi @Abeinjapan @TimF  Thanks!

Let me show an example from my exercise:

Every face and curve in the model is G2. But Fill Surface fails to fill the opening with G2.

# Re: "Fill Surface" guidelines?

Siemens Phenom

The sharp corner areas are the reason G2 will not work. There is not enough space for the system to create G2 continuous patches in those corners without creating self intersections. With the definition you have, G1 is the best you can hope for. If you are able to remove the sharp coners, then you have a chance to get a G2 surface in the remaining area.

Regards,
Abe

# Re: "Fill Surface" guidelines?

Genius

Hi @Abeinjapan   Thanks!

Fill Surface works fine in the example below. The root cause of Fill failure seems not to be due to the sharp corners.

# Re: "Fill Surface" guidelines?

Siemens Phenom

In the OK case, the curvature of the surrounding surfaces is very different than the original case. In the OK case, the G2 curvature (basically spherical) continues in the same direction as the surrounding faces so the sharp corners don't matter. In the original case, because the surrounding surfaces are basically toroidal, in order to fit a G2 continuous surface, the curvature in the center of the fill surface will need to reverse itself. Then the sharp corners matter.

Regards,
Abe

# Re: "Fill Surface" guidelines?

Genius

Hi @Abeinjapan   Thanks!  I can't understand the difference very well.

# Re: "Fill Surface" guidelines?

Siemens Phenom

I hope this picture helps explain. Both red curves have G2 continuity with the surrounding curves.

Regards,
Abe

# Re: "Fill Surface" guidelines?

Genius

Hi @Abeinjapan  Thanks a lot for the series reply!