- [Instructor] I'm gonna talk about a setting
in the surfacing tools, just an overall,
overarching sort of setting that exists
in a lot of the surfacing tools, it's called Alignment,
it's the Alignment method.
It's how things basically align to one another
as you create certain mesh surfaces,
or when you use a Swept or any of the other tools
that use multiple sections.
So, the Alignment is just that, how does a section
like this align with a section like that?
So now I'm going to go in
and use an example, Through Curves.
You have an Alignment under Through Curves,
you have an Alignment under Studio Surface,
you have Alignment under Swept.
They all use, again, multiple sections,
so how do those multiple sections align to one another?
So under Through Curves I'm gonna go down
and notice I have Alignment and I'm gonna
start off with Parameter, I'm gonna pick this section first,
again I get the little arrow, this is the direction
that the Alignment is going to take place.
So that's the first section, I'm gonna add a new set,
now I'm gonna add in this section,
and I want you to notice that as this makes a surface
or lots a surface in between these two,
I am using a Parameter, Alignment.
And what that means, let me hit OK here, just to create it.
This section here has two curved segments,
so if I double click on it, you'll notice that I have an arc
and an arc, I'm gonna finish.
I'm gonna go to the other section, double click on that,
same thing, one arc, two arcs.
So, parametrically the sections themselves are very similar.
Now, the way the Parameter Alignment works
is it looks at the parametrization of the sections,
now this is my start point,
start point to start point aligns.
Because this has two segments, this has two segments,
the next start or slash end point also aligns,
and then at the very end we have an Alignment as well,
and then it takes the patch in between.
Between this, and that, right?
Takes that patch and just fills it in with a surface,
does a really nice job, that is my Alignment.
Now, when I switch this from Parameter to Arc Length,
I'm gonna end up with a very different surface.
What I'm gonna do is I'm gonna simply select OK,
I'm gonna pick my surface and hide this for now,
okay so I'm just gonna hide that.
And then I'm gonna do exactly the same thing,
Through Curves but I'm gonna change my Alignment
to Arc Length, now you'll see I get a little alert,
Preserve Shape can only be used with Parameter,
that's this right over here, this is a warning
to let you know, that this is going to use
probably a bit more, not probably but,
definitely a bit more of the tolerance
to build the surface.
'Cause it's no longer building a perfect shape,
and you'll see why here in a moment.
So I'll just close that alert out, pick that,
second set, pick this, now you'll notice,
I no longer have that internal patch.
What the system does by Arc Length, is it looks
at the start and the end of each section
and then it uses a ratio from zero to 100%,
zero to 100% so the 50% mark on this section lofts
to the 50% mark on that section,
and the 25%, 75% so on and so forth.
So, that's what the Arc Length does, it's looking at each
complete section as a complete total Arc length,
from zero to 100.
So I'm gonna hit OK, I'm going to change the color on this
so we can do an overlay,
so you can really see the differences,
and we'll just pick a color, select OK.
I'm gonna go to the original Through Curves, and show that.
Now, I'm gonna rotate the part, and you can see
where those big differences occur.
Obviously the ends are just gonna line up,
but once you get away from those ends,
you can see that I have deviations,
and that's because of the nature of the way that those
sections are aligning.
Alright, so I'm gonna hide both of those,
I have another section, section two here, I'll show that,
and with that you'll notice that I have
three segments in this one.
Segment one, segment two, segment three.
I'm gonna go ahead and hide sketch one, for now,
and then I'm gonna do another Through Curves,
pick this, again make sure the arrows are pointing
in the same direction, if they don't, you'll get
the little ribbon, bow tie effect,
it'll tell ya it's self intersecting.
Again, you'll have to get into quantum physics
and a Singularity Mills to make this thing,
we really don't wanna do that.
So I'm just gonna reverse that,
and you can see here if I try using
a by Parameter and Preserve Shape what ends up happening
is the Parameter here in the middle,
of these two segments is lofting out to the middle
of this segment, this is coming in, this is coming in,
again it's at a percentage but,
because I have it by Parameter, I'm actually seeing
those segments that I'm preserving that shape.
So I'm keeping that edge as it lofts from one to the other.
Now, if I go in and change this to say, Arc Length,
you'll see there's a slight little change,
the Preserve Shape can't be used with Arc Length.
So what this does is it's kinda smoothing everything out,
to give you one big complete surface.
Now, again as a warning, these surfaces,
because of the nature of it right,
smoothing it out, washing over those
internal knots, Parameters can create very complex surfaces.
So, when you're doing this you wanna try
to get your sections to at least be similar.
You'll notice there's lots of Alignment methods,
you know, there's By Points, and Distances,
and Spines and all sorts of others.
But, these two are primarily what you're going
to deal with on a day to day basis.
If you can, the preference is to use by Parameter
and Preserve Shape, in this case this may not
be the brightest of ideas, where you may end up
with some additional patches that could potentially
cause issues later on, so this is where the Arc Length,
may be very useful.
Or even if you wanna keep it by Parameter,
and not necessarily use the Preserve Shape.
You can see, you can wash those out as well,
in this case with the by Parameter.
That's what Alignment stands for,
and again it's used in several tools,
the Studio Surface, you can see here the Through Curves.
You can also use that with the Swept tool as well,
so it's in a lot of places, so it's important
you at least understand, the difference between
Parameter, Arc Length, and the start and end points.