Hi Pilou, can you please post the file?

You should use the "Refit to tolerance" option if you want to get the minimal amount of control points on a wide selection of curves.

That will fit a line with 2 control points and a curve will be fit with more control points in curvy areas and less control points in flat areas.

If you want the minimal number of control points, then use that mode and not the "number of points" mode, because the number of points mode will just use exactly the number of points that you tell it.

- Michael

Hi Pilou,

> You don't obtain exactly the same result with the 2 examples

You mean between the 2 different modes?

But yes, of course you get different results with different modes - I mean if the different modes gave the exact same result, they could just be the same mode...


> PS Does it possible to have in the Browser : lines ?

There is not currently any way to have a "lines" entry in the browser.

- Michael

Hi Pilou,

> The cross is the same that my first post above: Lines+ arc circles

I'm sorry but I don't understand this - what do you mean by "The cross" ?

- Michael

Crossing message ;)
Image is above

Cross is the first figure of the sweep, second is circle

here the file 3Dm
http://piloumaison.weebly.com/uploads/3/6/2/0/3620514/overlapsed.3dm

Old Cross is that: new cross has only 20 Control points for have 2 points for a line!
Start / end so I can calculate (total =20) for all so the same for the circle

Hi Pilou, thanks for posting the file.

So I see in your file that you seem to be creating a sweep.

What are you trying to use the Rebuild command for in this case?

The Rebuild command is something that you would use to edit curves - in your case the sweep seems to be creating a proper result, and there is no need to use the Rebuild command as a separate step.

Could you maybe describe what kind of result you're trying to get different from the sweep that you already built?

- Michael

When I make a sweep with
cross with 20 Control points, Circle 12 Control Points = A
cross with 20 Control points, Circle 20 Control Points = B

A is slighty different of B despit of the fact that is the same Cross and Circle!
Just number of Control points are different for the circle!

I use Rebuild for give the same number of control points of the circle, (or any other figure)
I have build my cross for have just 2 control points for the straight lines!

Are you possibly worried about trying to create the same number of points in your cross shape as in the circle?

Why, though? It's not necessary to make the same number of control points between shapes when lofting or sweeping them.

It can be important to control the same number of segments between the curves to control how segment pieces match together in some cases (see this previous thread: http://moi3d.com/forum/index.php?webtag=MOI&msg=4227.1) - but note that "Number of segments" is not the same thing as "Number of control points".

If you use Edit > Separate on your cross curve, you will see that it breaks apart into 16 smaller segments which can then be selected individually - these are the segmented pieces of the curve. If you do that to the circle you will see there is only 1 segment in the circle.

That difference of 16 sub-segments compared to 1 sub-segment does not depend on how many control points there are in any of those pieces at all.

If you want to break a curve into smaller segments, you would use the Trim command on it to cut it up into pieces, you would not use the Rebuild command for that kind of task. You can use the Rebuild command to fuse segments together though - if for example you had a smooth curve that was made up of 100 little divided segment pieces you could run the Rebuild command on it to make it into just a single segment.

But it seems that you're worried about making an equal number of control points which is a much different thing than an equal number of segments...

- Michael

Hi Pilou,

> I use Rebuild for give the same number of control points
> of the circle, (or any other figure)

Why would you do this though? There is no need to make those curves have the same number of control points in them.

For matching segments of a one curve to another it is the number of segments that matters, not the number of control points.

Each segment in the cross piece will be matched to a fragment of the circle, this will happen no matter how many control points are in the circle or in the pieces of the cross.

If you want to control how a piece of the cross matches with the circle, then you need to use the Trim command to split the circle up into 16 pieces to match the 16 segments of the cross - to do this you would use the Trim command, not anything to do with control points.

- Michael

Also I don't see what is wrong with your sweep that you are trying to change - it seems like a good result already...

- Michael

< But it seems that you're worried about making an equal number of control points which is a much different thing than an equal number of segments...
seems yes :)

< Also I don't see what is wrong with your sweep that you are trying to change - it seems like a good result already.
yes they are good but seems they don't perfect overlap due my test of different number of Control points on the circle!

Have you maybe been using some sweep or lofting tools recently in a polygon modeling program, like some of those SketchUp plug-ins or something like that, where you might need to be concerned about the particular number of points in the curves?

That's a kind of different situation, because in a polygon modeler you don't have a real curve and the number of control points also basically controls the number of segments within the curve since they're just lines in between each control point.

In a NURBS modeler like MoI that's not the same kind of a case - the number of control points in the curve and the number of sub-segments the curve is made out of are separate things.

- Michael

Hi Pilou,

> yes they are good but seems they don't perfect overlap due
> my test of different number of Control on the circle!

If you want them to perfectly overlap, then you need to control the segmentation of the circle so that you will have a specific match for each piece of the cross to one piece of the circle.

So that means split the circle up into 16 segments using the Trim command - it doesn't have anything to do with making an equal number of control points!

- Michael

Yes seems that is my confusion but rich of learning for the circle (symetric figure)
It don't gives the same result following his number of Control points (over the 12 by default)!

And of course for segments / Control Points :)
Thx for All !

Hi Pilou,

> It don't gives the same result following his number
> of Control points (over the 12 by default)!

Yes, the "automatic segmentation" of the circle to match the 16 segments of the cross is slightly different between the original and the rebuilt circle.

That has to do with some various properties of the curve like its internal parameterization, you may also see a difference depending on which loft mode you use - either "Exact" or "Refit" for profiles.

But in either case if you want to control it specifically you can split the circle up into 16 pieces and that will then control how each piece of the cross maps to each piece of the circle. If the 2 curves have the same number of segments then it will match each segment to the other instead of doing an automatic segmentation of the circle.

- Michael

All seems very clear now :)