Hi All,
Try to get this shape as clean as possible single surface without central pinching if possible tried various approaches and not getting it.
Any suggestions welcome.
thanks

Hi Alex, probably the best bet is something like the attached using Loft with Loft style = "loose".

You'll see something at the pole but it's just a display artifact from a low poly count there, make sure to do a higher density export to really see what the surface looks like:



Loose loft is usually the best way for these things but Network can also be workable if you add similar stations that progress towards a circle before it reaches the pole point. Basically you don't want a curve with different sized features like you have here with short corner areas, to slam directly down to a single point. It needs to sort of spread out to a circle before it comes down to a point.

- Michael

Hi Michael,

Thanks again for your help - the softening of central point with a circle is great tip and lofting also.

all the best

alex.

Hi Michael,

Further on this one trying to Boolean these shapes MOI just hangs in their and fails to complete. Managed to get it to boolean in Rhino any reason why OK in one and not the other.

thanks
alex

Hi Alex, the top and bottom surfaces of your cutting object there are extremely mangled surfaces with control points shooting far far away into space. The control points are so far off that they won't display in MoI in the normal display but if you do select all they will:





Many operations will be unpredictable on surfaces like that.

Was this maybe created by projective flow but with a base surface that had many areas that did not connect to the target object? Projective flow shoots out rays along the base surface and if those rays do not hit any piece of the target object it can make for bad results.

You'd probably need to do the projective flow with a smaller base plane, not one that sticks out past the target object along the outer areas.

- Michael

work in mm don't increase some problems of decimal point capacities or number of digits acceptable ?
not more easy to work without unity and transform at the end if needing?

Hi Pilou, the current unit system doesn't really have any effect on decimal point accuracy, unless it also causes you to use large or small numeric values.

For example if you make a line and put in a coordinate of x = 4.0 y = 3.0 for the start point of the line, the line will have those numeric values x = 4.0 and y = 3.0 no matter what unit system you have set.

The unit system is more like an additional label that says to someone how those numeric values are supposed to relate to real world measurements.

That's how it works in MoI anyway, it is true that some programs do it differently like SketchUp I think translates everything you enter into inches I think. That can then cause some problems like you are asking about.

But MoI does not alter numeric values that you enter unless you ask it to by giving a different unit system at the end when you type in a coordinate.

- Michael

ok :)

how many significant digits can be admissible ?
7 max in the right decimal point box
how many in the left part ?

Hi Michael,

How did you get to show the control points?

Yes in creating the flow deformation I usually copy and past the target surface and flatten that down to 0 depth and use that as the base mapping surface so in theory should be same size.

I just tried it by same process but I offset reduced the base surface and then used the flow command and then boolean difference and it all worked smoothly - thats another great tip.

Hi Pilou,

re:
> how many significant digits can be admissible ?
> 7 max in the right decimal point box
> how many in the left part ?

Well it's a bit complicated, there is not really a fixed limit on that.

The way floating point mathematics works on the computer allows for a floating point number to have a very wide range of values but larger values have less precision. Also precision is greater the closer you are to the origin.

To keep things the most robust and avoid arithmetic precision problems it's generally good to keep numeric values say not larger than 5000 and not smaller than say 0.05 or so. But those are not hard limits.

- Michael

Hi Alex,

re:
> How did you get to show the control points?

They'll show up if you turn on points and then do a "Select all". The extreme size probably messes with the depth buffering in the regular display.

- Michael

>> To keep things the most robust and avoid arithmetic precision problems it's generally good to keep numeric values say not larger than 5000 and not smaller than say 0.05 or so.

Perfect !