- [Instructor] Here I'm going to talk about
three operators.
Projection, Intersection, and Parallel Curve.
To get this file, you can either
download this from the exercise files,
or you can simply select on the function
if you have the help documentation loaded up for CATIA,
press the F1 key,
download the file, open it,
and get to work.
Go ahead and minimize that.
So, under projection,
you have a couple of different types.
Normal direction and along a direction.
If I select Normal,
here I'm going to specify what I want to project,
what's my support,
and I'm going to preview that.
You can see it takes the curve,
projects it down to the surface.
Now, this is along the surface normals, meaning
the direction of the surface at each one of these points
is driving how the curve is projected down.
So the surface normals are
creating this shape for that curve.
I'm going to select okay.
I'm going to perform another projection
and that curve, that surface,
but this time, I'm going to use Along a direction.
I'm going to use this curve back here
as my direction and preview that.
You can see I end up with something very different,
because now I'm forcing the direction
of that projection,
and the only thing the curve is doing at this point
is following this direction
and the surface doesn't drive anything
except for the final lay down of the curve.
It doesn't drive the direction of the projection.
Now, another way that I can
get a curve on a surface, as you see here,
or on a plane,
is I can use what's called Intersection.
With this, I need to set up a piece of
construction geometry.
So I'm just going to do an extrusion,
talk about that here in a bit.
We'll select the curve,
and in this case, you'll see the extrusion
is coming down through the surface,
and I want to use this curve
as my direction, as I did with the projection.
Select okay.
Now, if I come in, do an Intersect,
I want to intersect between this surface and this surface,
you'll see here, I can select a couple of elements,
what's going to intersect.
There's various options in here for
extrapolation or extending linear endpoints.
If I have, let's say, two lines
that are out in space,
and they're at angles to one another
and there's a vertex between
where the two lines would come together,
and you don't want to extend the lines out manually,
you can just turn these on
and it'll internally extrapolate that line out,
and lines are technically infinite.
So you can use these options for something like that.
In this case, I'm just going to use the extrude,
select okay, and here I have my intersection.
And you'll notice that I also have the projection.
Two different elements, and they are
pretty much nearly identical.
Let me go ahead and change the color of the projection.
So, as you can see,
projection's there, I just changed the color.
You don't really see anything until I hide the intersect.
The intersect is, basically,
laying over the top of the projection.
They're identical.
The difference between the two is,
when I drive a projection,
I can potentially go on a normal,
or as you saw, go in a line of direction,
and how the curve lays down on the surface,
based off of your tolerant modeling,
could be affected if I have a very complex shape.
Projections themselves
basically produce the curve
slightly different manner,
you may end up with a slightly different shape.
Again, it's based off of that tolerant modeling option
that we set at the very beginning.
So, depending on what you're doing,
you may want to do an intersect
versus a projection, and vice-versa.
Now that I have a curve on that surface,
I'm just going to go ahead and hide this extrude.
I'm going to go ahead and hide this curve.
I'm going to go use what's called a Parallel.
Now, Parallel is going to take a curve
on a surface, could be a plane as well,
and it's going to move the curve
along the surface.
So here, I'm going to pick my curve,
here I'm going to pick my surface.
I can determine the direction and the distance.
As you can see, as I parallel this out,
it stays constant along that parallel.
So any inside corner is going to shrink,
any outside corners are going to grow.
Select okay, there's my parallel.
Now, I'm going to double-click on my parallel
and there's an option down at the bottom
I do want to talk a little bit about.
It's called Both Sides,
and as you can see, I can have the parallel
go out to both sides.
I have various other options as well for smoothing.
Oftentimes, you get curves from someone,
they may be a little rough,
and you want to clean those curves up.
You can do what's called a Smoothing.
Based off of a tangency or a curvature,
you'll notice that as soon as I go
to one of the smoothing options,
I'm now building additional deviation.
Because as I smooth a curve, it necessarily means
it has to pull away from the original shape.
How much am I allowed to pull away?
Go careful with the smoothing option.
You don't want to up the deviation too much,
because you could end up with
undesirable results.
You also, in some cases, may need
to absolutely do the smoothing
in order to use the curve,
or in order to just actually get it to
parallel along the length of the actual surface.
So, they're there.
Be careful of the way you use them.
Again, every time you do something like this,
you're building an additional deviation
to the original input curves.
So, you have projection, intersection, parallel.
I use these tools a lot
in conjunction with one another.
Oftentimes, I do the intersect, do some parallels,
or, again, a projection,
and then do some parallels,
or I may have two curves out in space
that I want on a surface,
and I want to get the intersection of those two curves,
so I'll project the curves and then do an intersect
to get the intersection points.
These curves functions are very powerful.
You want to get very familiar with them.
They work in conjunction with one another very well.