Join Veejay Gahir for an in-depth discussion in this video Surface primitives, part of Alias Essential Training.
- Let's get started with creating some surface data. So, I'm gonna go up to the Surface tab, right click on that. I'm gonna go to Create Sphere. Now, you'll notice with the options we're gonna leave them as the default options. So, create Surface, degree 3, 360 Sweep with 8 spans. And let's say go to that and I'm gonna select a point in space here and then let's just scale this up like so. And you'll notice in the Control panel we have a 3 by 3 degree surface and 8 by 4 spans.
If I select the surface and I click on Cv/Hulls a surface has a U and a V direction. Now, which is the U and V direction here? Well, I can see a V down here but it's not really clear if it's going this direction or that direction. Sometimes it's a little confusing, especially in a complex piece of data. So, let's select this data. Switch off the CVs and you'll notice down here in the display we have the option to check on U Isopalms and the Isopalms. So, if I uncheck the U you can see that the U isopalms are traveling radially around the sphere and the V isopalms are traveling from top to bottom.
So, this is another good indication of exactly how the CVs are distributed and which ways the U and V direction. By the way, if you switch both off you end up with just this representation of that sphere. It still is a sphere but if I go to Diagnostic Shading. Let's open this up and shade it, there it is. But for now we're gonna put our Us and Vs back on again. Now, if I select this data and put on the Cv/Hull I can change the complexity of this data. So, again, this is a starting point and I may want to increase the complexity but I may also want to reduce the complexity.
So, we can change the degrees or the spans just by holding this arrow down and I'mma take this back down to a five. Now, when I do that, Alias is gonna try its best to maintain the shape but if there is a deviation, it's gonna warn you and if you look at the prompt box at the top here, it's telling you that the deviation is two millimeters. So going from a complex shape to a less complex shape can be somewhat dangerous. If you like the result, you can accept. If you don't like it, you can just cancel. And you can also change the number of degrees. So, if I go from three to a six, again, the deviation has changed.
So, in some cases, reducing will cause an error. And in some cases, increasing will cause an error as well. So, let's cancel that. Let's go ahead and let's delete that data. Let's go back to the sphere again and this time let's change the Sweep to 180 degrees. And let's say go. Click in space, scale that up. And quite obviously, it's just done a one eighty sweep on that. It's created half a sphere. So, if I pick that (mumbling), ctrl + 5, let's see what information we can gather about this while your can change the Translation point, Rotation, and the Scale but that's pretty much it.
There's not a lot more we can do with this primitive. Okay, let's delete that. Let's move on now to Torus. So, let's look at the options for Torus. We have a Sweep option again. Absolute and we have a Major Radius and a Minor Radius that we can alter. Let's go with the default as it is and let's scale this up. So, again, we can see it's a 3 by 3, sixteen by eight spans. And this is the U spans and this is the V spans. So, if I go ahead and just switch off the Us you can see that those are the ones that are radial.
And those ones are tracking around the Torus. So, again, if we look at the CVs, not always easy to see which is the U and V direction. If we zoom in here, you can see quite clearly that this is the U direction and that is the V direction. So, let's select the data. Let's go to the ctrl + 5. Let's take a look at the data that we have here. Again, it's giving us some information and it's telling us that it's a PERIODIC entity. Typically a revolve as a primitive ends up being a PERIODIC entity. So, let's delete this.
Let's go back into Torus and let's just change the Major Radius to, let's say, .7, and we're gonna say go, click in space, and you can see now that that's changed the shape of that Torus. Now, once you've come out the command if you do want to change a shape now you have to use non-proportional scaling or scaling. Middle mouse button with the hot keys I can scale proportionally like this or I can go into a non-proportional scale, right mouse button will scale vertically, middle mouse button will scale in y, left mouse button will scale in the x like this.
Okay, so let's move on now the Cylinder. So, again, with the options, very simple. Degree 3, 360 Sweep, 8 Spans. Now, we have an option for Caps here. So, a cylinder has a cap. It can cap one end, it can cap both ends, you can cap neither one and just have purely a tube. So, let's go with the default as it is there now and we're gonna scale this up like this and let's just move it up. So, this cylinder is comprising of three separate components. We have a top piece here. We have a bottom piece.
And then we have the piece around the side. But when I select it it selects everything because it's grouped. Let's go up to Edit, Ungroup, and now if I select the middle portion and just say Move, I can move it out the way and then you can see those are the three components that make up a cylinder. So, in some cases, I like to just go ahead and group delete and I'll salvage this piece because that's a good starting point for me when I'm doing some of my surface modeling. But one thing to note here if I select this data, click on Cv/Hulls, you'll notice that we have a convergence point right at the center.
Now, CAD applications, even Inventor or (mumbling) or Pro E they don't like this kind of condition so this convergent point for CVs is great for concept modelling but it's certainly something to avoid sending in to an engineering application like Inventor. So, what we can do here is we can select this data and we can move it up and to eliminate that, very simply, what I tend to do is Attach, Detach, and I'm just gonna pick this edge, come in like this, spacebar, then I'm gonna select this middle piece and let's just delete that.
Now, this is a better piece to do but again, I would still split it into, maybe, four pieces before I start doing any kind of real engineering on that part. So, let's delete this. Let's go back into, now, the cone. So, with the cone, let's go with the default options, click in space, scale it up, and again, the cone this time is comprised of two separate pieces. Let's pick that, ctrl + u for ungroup, and now I can move this up. You can see, there are the two components for a cone.
So, let's just delete this portion here. But again, with a cone, be very careful when you use this. Don't send the information through in this condition. We have a convergence point where all the CVs are meeting at the top and again, not a great condition for engineering. So, let's delete this. Now, a cube, very, very simple. Either degree 1 or a degree 3. Let's click in space and let's scale this up. By the way, we can non-proportionally scale it too. When we've got it selected, ctrl + u to ungroup, and now we can go ahead, pick Object, let's pick one of these faces.
And we're gonna say Move, we'll pick up, and this one I'm pick in the x direction. This I'm just gonna separate. So, those are the six components that make up a cube. So, to just delete, spacebar, and let's look at the final one which is plane. Now, plane is the one that I use the most. It's a really useful command to get you started very quickly on surfacing. So, let's just click in space and we can scale to something like that, if not a non-proportional scale. If I put my Cv/Hull on, let's go ahead, select the entity.
I'm gonna Move, holding my alt, snap to the center, then I'm gonna pick alt, pick this hull, pick hill here, move vertically, then I can right mouse button and go straight into this hull and you can see very quickly you can start creating some very interesting geometry, and it's a good starting point for any surfacing project. So, planes are one of the most commonly used primitives in surfacing today. But again, you can salvage pieces of the other primitives as I've shown you before to get started.
- Manipulating views and entities
- Working with layers
- Creating curves
- Sweeping, extruding, revolving, offsetting, and blending surfaces
- Modifying geometry
- Moving, scaling, flipping, and rotating objects
- Trimming curves and surfaces
- Creating copies of objects
- Aligning, combining, and splitting objects
- Analyzing geometry
- Shading models