continuity between surfaces in rhino

[mob]

Hello everyone
I have a doubt that it's been a long time since... and I try to explain it to you with examples.

in image 1 you see the sections of a session that I will build with the network command

In image 3 (the two does not exist :biggrin we see a particular of the surface that I obtain that I consider quite smooth and without particular discontinuity.

in image 4 I went to cut the frontal aprte of the surface and I go to reconstruct it with network command using the same sections first but setting tangence on the side to which is that of the surface.

in image 5 you see the new surface build, while in image 6 there is a first floor of the detail before. nothing clamorous, but you notice a small vein along the edge I used to build and that before, with the network command used throughout the surface, there was no.

Now... I wonder why.... it happened to me a thousand times, with the appearance of veins and hump but more obvious.
often modeling chairs maybe I have to go to change the surface of the seat in particular points, setting additional sections to better address the performance of the seat. So I have to cut them and rebuild them only at that point by hooking me to what remains of the first surface. in any case whether I use network with tangency or curvature set, whether you use a b-rail, whether you use the patch in case of 3 sides, or use other commands and then go to use it combines surfaces and then set the continuity I prefer....the result does not change... .

If I break the surface, this doesn't come back as when I build it with one command.
Is that normal?
solutions?
Thanks milla:finger:

 

[mariuss.r]

Hello everyone
I have a doubt that I've been abstaining for a long time... and try to illustrate it with examples.....cut



If I break the surface, this doesn't come back as when I build it with one command.
Is that normal?
solutions?
Thanks milla:finger:

The explanation depends on the parameters you used in building the surface.

you have imposed on rhino to create a surface with external edges that can differ +- a cent from the generating curves (the 4 edge curves)
and that the surface internally can differ of +- a tenth from the internal curves.

rhino therefore tries to build a surface as 'liscia' as possible in accordance with the parameters set

if the cut, which you have made of the surface, matches the position of an internal curve you will find that curve and edge trimming could have a discordance of +- 1 tenth (the parameters you set)
then in building the new ... have the shortness to use the edge of the trimmed surface and not the initial curve.

Remember cmq that even the curves on the edges can differ from the quarterly surface of +- 1 cent. (always for the parameters you set) and this condition could create "tensions".

a way to get "fluid" surfaces is to build them, trim them both along the edge that joins them for a width to taste and then "remember" them with a blend surface, to which you can apply a g2 continuity.

 

[mob]

Thank you very much. I think I understand... but first I try... and then I put another example.

cmq, let me understand a moment again: if in the parameters of the network I use values like 0.001 and more and more low, the surfaces will be as faithful to the construction sections?? ? but in any case... could tensions always be created unless the "truck" of the trim from both sides and the blend with g2?

 

[mob]

I ask in this regard another similar question...which concerns the unfaithful behaviour (by my fault it is clear eheh) of some commands.

in the attached pictures:

pictures 1 and 2: same chair before, I create the surface with the network

image 3 and 4: in the lower corner of the seat, if I make a 45° section known that this tends to thin out towards the extremes, which I do not want.

image 5: here's how I would like it to be the section at that point, similar to the trend of others.

I designed this last section, but how do I recreate the surface by including this section? What commands do I have to use?
if I begin to divide it into parts, I respond to the problem I mentioned in the previous post, that is parts that are not perfectly smooth (even if they give place to closed edges, I checked).