Hi niko, currently I don't have any specific plans for it.

Is there some particular reason why you are interested in it?

It requires denser geometry in order to go to higher continuities, and there is not really a direct simple visible difference like there is between G0, G1 and G2.

What do you think you would be gaining by a G4 Blend for example?

- Michael

Would it not help eliminate seams in more difficult blends?

Hi niko,

> Would it not help eliminate seams in more difficult blends?

No, not really - G3 and G4 are about equalizing "higher order" geometric properties where the blend surface touches the other surface edges.

The properties that they try to match are not really distinctly visible like a seam.

G2 means to have equal surface curvature where the surfaces touch. At this point there is already not any visible seam between them.

G3 means to have an equal "rate of change of curvature".

G4 means to have an equal "rate of change of the rate of change of curvature" - it's getting really very esoteric and removed from something actually visible to the eye at this point.

In addition, all of these things only make these properties equal right at the spot where the surfaces touch.

G3 and G4 require using a larger number of control points in the blend surface so there are some side effects from using them.


It's a very common misconception in the "Industrial design ultra cool surface styling" world that some higher continuity values like G4 are necessary.

It's better to have something like G2 where the shape is overall more evenly distributed throughout rather than something like G4 where the surface changes too quickly in just a close region nearby its edge. I mean the overall surface shaping is really more important than whether it's a G2 or a G4 type connection.

There has been a kind of "marketing bullet point list" arms race in this area for a while, something like G4 is a good example of something that looks nice on a marketing brochure and sounds like it should be better while it actually does not particularly serve a useful purpose.


If you draw a regular NURBS control point curve, it is actually only G2 itself between its different internal spans.


It's even likely that the G4 blend surfaces that you are talking about are only G4 where they touch the other surface but only G2 within different spans of the blend surface itself, because it's probably a cubic surface in the other direction than the blend edges.

- Michael

Got it, Thanx!!

MoI's new tool option??? G5 curvature!

G5 = Dynamic Curvature and rate of change.... The curve changes depending on how you look at it. :o

G6 = you realize there is no curve, it is only an illusion. You are at peace with the universe and you have achieved the highest level of continuity. ;)

- Michael

Bawahahaha....And there is NO UI for G6!

Personally, I want my blends to go to 11

I have to agree with this statement, when an Industrial designer with a bow tie is involve with a project you know your in trouble with getting your blends looking really, really nice.

I've mentioned this before about the definition of 'A' class surfacing that I've read; 'If the surface is smooth and pleasing to the eye, then it is an 'A' class surface.

Cheers

Hi Danny, I kind of vaguely remember that term "Class A surfaces" might have been introduced by the Gartner Group business analyst company, it seemed to me to be similar to a snake oil thing, kind of like "oh this $60,000 program running on this $60,000 SGI workstation is absolutely needed for this business because it does special Class A surfaces instead of ordinary plebeian low class surfaces"...

Of course some of the really specialized expensive surfacing software can do some other kinds of interesting things as well, which can be useful if you are obsessing about controlling how the reflections on a surface are shaped.

But G4 continuity doesn't have much to do with it really.

- Michael

Once moulds and/or production parts are polished, it doesn't really matter anyway... :)

>>>>Once moulds and/or production parts are polished, it doesn't really matter anyway... :) >>>>

Yeah, but Candides goes to 11!! lol