Hi All

slightly strange result from a sweep.





Not knowing the maths , I would have guessed there is not much different between the corners sweep did create and the ones it failed to create. Is this a bug or is there some rule I have to keep in mind when sweeping? using version 2 trial.


Cheers, Steve

Must be some type of glitch in the autoplacement or mitering mechanism... You can get the results you want by removing the autoplacement and place your profile on the curve as it will sweep.



Wait for a more in depth look at it..

thanks BurrMan

Hi Steve, that is an odd result. I believe the problem basically stems from trying to make a tube that goes around a bend of the exact same radius.

That basically results in a surface that intersects itself, just kind of grazing itself right in this one point here:



Various mechanisms can behave unpredictably in the presence of self intersecting surfaces like that, so it's something that you generally want to avoid - if you use just a fraction of a smaller radius than those bends so there is at least a tiny clearance in those corner areas you will likely get a lot more predictable behavior.


Right now the surface is so close to bunching up and overlapping on itself in that area, and in some cases it seems to end up crossing over itself just a bit more than in other spots, that's what would lead to some slightly inconsistent looking behavior with some area happening to work ok and others maybe not.

All floating point mathematics that are done on the computer are subject to slight rounding errors so when you have a situation where it's just barely ok just the slightest difference in the sequence of numeric operations can possibly produce a result on one side of the fence or the other side.

- Michael

And the difference between the auto place and non-auto place probably has to do with where the seam of the circle happens to be located.

At any rate, if you use a circle of just a tiny bit smaller radius it will likely work better.

- Michael

Thanks Michael

Can you please explain what you mean by "where the seam of the circle happens to be located" new to 3D modelling and not sure what you mean.

(non-auto seemed to work every time I tried has long has I place the profile on a straight edge :) )

HI steve - re: "seam of the circle" - that's referring to the starting and ending point of the circle. A closed curve is formed basically the same as an open curve, just with the ending point of the curve touching the starting point of the curve.

The particular location of that start/end point will then have an influence on the similar seam edge of the closed tube that is then generated.

Just like a closed curve has the start and end on the same point, a surface that is closed in one direction like a tube or a cylinder has a "seam edge" where 2 edges of the surface come together.

- Michael

Michael

I just experienced something similar with sweep (see attached file). only red rail gave me straight and clear outcome.

THANKS. keep rolling.

REGARDS

Hi Mario, did you possibly attach the wrong file? That file seems to be a floorplan and elevation and there are about 2000 curves in the file so I'm not sure which ones in particular you are trying to sweep.

- Michael