Join Veejay Gahir for an in-depth discussion in this video Aligning surfaces, part of Alias Essential Training.
- So now let's take a look at aligning surfaces. So this is going to add some level of complexity now because we have an entity that has a U and V direction and it can be quite a complex align in some cases. So let's take a look at these two pieces of data here and I've switched my grids off for clarity because we're using some patch precision lines on these surfaces. Let's open up Align, and we're going to click Reset and we're going to use Edge first so let's pick the edge of this surface I'm going to pick the edge of this one here.
Now you'll notice by default Alias will snap to the extremes of those edges as you can see like this. Now we do have a marker here that allows me to drag these edges in so I can do what we call a partial match or a partial align. As soon as I do that you'll note that under Partial the check box appears. So if I uncheck this you'll notice it snaps out to the ends. If I click on Partial, it will snap back to a partial align. So let's do a Reset on this.
If I have Partial set from the beginning and I do the same operation what happens is it will be projected back normal to this edge and that's going to be the start point for our partial align but we can always go back and just tweak these edges like that. Okay, as we did with curves I can now opt this to G1 Continuity and again I can slide this slider down like this and I can also go to G2 and I can just use these sliders to just tweak that shape accordingly.
Now let's go back to G1. Now you'll notice one thing here if I click off Partial the complexity of this surface has jumped quite dramatically. Now we can control this to some degree by using this slider here, the Position Influence. We really want to try to keep the complexity of these surfaces down to a minimum to achieve the result that we're trying to obtain here. So with the Position Influence you'll notice it goes from zero to one and that's the only two options you have. If I slide it to one, what happens is that this slave surface tries to adopt the same complexity of the master surface.
Now the only thing is the Position Influence terminology is not really intuitive but really what it essentially does it tries to match continuity and the complexity to the master surface. So this is a really useful function to have to try to minimize the number of spans and degrees on your surface. So let's go to the top view now and you'll notice that if I pick this middle marker I can actually slide all of those control points in that whole hull in one go. If I pick on the end ones I can actually twist like this.
So again it gives you that level of control to achieve the shape that you're looking for. Also in this view here you can see that the Edges are aligned perfectly. So this Edge running off the master into the slave surface is a true tangent condition. Now this is what we call Transversal Tangency and it's a really good condition to have it's not essential but it is quite a desirable condition. If I click on this edge marker where it says Edge this is telling me that the edges are aligned as well. If I click on this marker you'll notice I do get another manipulator.
I'll click on this label and go into the manipulator this allows me now to skew those edges but you'll notice that the tangency marker is still green even if I'm skewing those edges. Well again, the tangency calculation is not a tangent vector from the edge here it's a normal vector so the normals can still be aligned and the tangent vectors from the edge of those surfaces can be off in a different angle and will still get tangency. So let's go back to Edge align like this and we're going to do a Reverts.
So we're still on the edge I'm going to pick this edge here and I can pick an isoparm and it will work just fine with an isoparm. We've got tangency again, we can manipulate these and on the internal portion here I could still work with the Position Influence. But you'll see here now the Position Influence is not doing as great a job as it was on the Edge. It's still reducing it if I had it to zero you can see that's quite a complex surface. This one is less complex but it's not as reduced as it was on the Edge because now we're doing an internal match to an isoparm so we are asking Alias to do a little bit more work in that respect.
So again we can add on Blending so we can go from G1 we can click on Blending and we can add another row like this. Okay, let's Revert that. Now again, with edge align just be careful because if we pick this edge here and we pick this edge sure enough it's going to try to align to this particular isoparm. So just be a little bit careful on the areas that you pick. Now let's do an internal match here so these are going from edge-to-edge which is fine but we want to look at another condition that we sometimes have to use which is this one here which is the Project option.
So now you can see how two surfaces one is sitting right underneath the other one and now we're going to go with the Project option. Let's leave it on G1. We're going to pick this edge here and if I pick on this edge here you'll notice that the boundary of the surface goes into this dotted effect. Now the reason for this is because if we look at our Vector Options we've picked View and View is not the best vector for us to use in this case here. We're going to switch to Zed and you'll notice in Zed now everything is back to a good condition. So again when you select Project just be careful on what Vector you're using to project in.
So now with Project we've projected straight up in the Zed direction and we've selected tangency but the first thing to note here is that we've lost our sliders for our first row of holes which is our tangency hole. We don't have the abilities to slide if we're doing an internal project. And also you'll note that we don't have the ability to skew either. So let's Revert that. Another option that we do have with Project is that we can pick this edge here and we can say Picked. Now I've got a vector setup which is this arrow here, I want to select my surface and now I'm going to pick my vector.
Alias is being forced now with that first row to project in this vector until it hits that surface and that's where it's going to start performing the tangency align. So again, with Position Influence we've lost the ability to do that because this is a very complex match and when you get to this level of complexity there's no way that we can actually reduce the end result. We don't have the ability to slide but we can increase to G2 go back to G1 and we can also add blending in like this.
So let's go back to G1 and let's go back to reverting this. Okay so let's take a look at another condition here. We've always been projecting from this short edge onto a larger surface which actually is an ideal condition, that should work just fine. What if we wanted to project this edge down to a smaller surface? Now again this is not a condition that you're going to do very often it's really bad practice but nevertheless, there is an option to correct that. The condition that you may have may not be as pronounced as this with such an overlap we might have just an overlap of maybe just maybe half a millimeter.
So what we can do now is go through the same operation we're going to Project, we're going to pick this edge here. Let's go back down in the Zed direction and now I want to pick internally into this surface. And you'll see right now that Alias comes up with this dotted edge which is telling us that it doesn't like this condition and its probably failed so we need to correct this. One way to do it is to use the Shrink to Fit command so if I Shrink to Fit, Alias will shrink that edge until it encompasses from one side to the other as you can see here.
Again we've lost the ability to slide the tangency hole but we can add Blending as you can see here like so. But again this is not a condition that you're going to be using very often so let's Revert that. Let's go back to the other direction which is this one to this surface here. Another very useful feature during this command is that we can go right down to the bottom and we can get some Specify Check information and Diagnostic Feedback, and Enable Proxy Display.
Proxy Display shows you where we've come from and where we're going to. Diagnostic Feedback, is giving some more numerical information about the condition that we have. But a really useful one here is this one here, Continuity Check Type. Now right now we're checking for position. I can force Alias to check for Tangency. I can force Alias to check for Curvature. Now just a point to note here if you are only doing a G0 align then you can't check for Tangency because it's going to fail.
If you're doing a tangency align there's no point in checking for Curvature because it will fail. So don't try to check for anything beyond what we're pushing here at the very top with the Continuity options. Okay, let's Revert that and let's come right out of that command. Let's take a look at this very simple scenario here. If I pick these two surfaces let's light up the control points. You can see what we have and let's do a quick exercise on using the Project command. So let's open up align and we're going to go ahead and do a tangency align.
We are going to Project so let's pick this first edge but you'll notice the first thing is that Alias is not allowing us to do that because we're back to our infamous periodic entity. So if we select this piece of data, ctrl + 5 it's a periodic entity. CAD systems don't like this so what we have to do here is we need to split this data up. So let's go to, Detach, let's pick one of these isoparms it doesn't matter which one and I'm going to hold my ctrl down, snap it to this point, space bar but I have to do this side as well, space bar.
Now ideally you should do these ones as well to make it into four pieces, so right down the center but for now we're just going to leave it as that. Let's go back to our Align command. Now in this case we're going to go G1, we're going to go Project, so let's pick this top surface and we're going to go with the Project, going to switch off Blending for now and let's Project in the Y direction. As you can see from the triad just in the bottom corner and we're going to select this surface here. So we've achieved tangency, it's green.
And we've affected the first row for position, and the second row for tangency and that's exactly what I expect. Let's Accept that and let's go back to the Align command. Okay, we're going to go back to G1, Project. Let's pick this edge here and we're going to Project in Y, take off Shrink to Fit, and let's pick this surface here, and again that's exactly what we expect. We're going to Accept that and let's select nothing. So what we've created is this dome effect.
Now let's go back to the Align command. Now we have to be very careful here if we continue on with G1 and I select this edge and I pick this surface here you'll see what's happened here with this surface it's now that Alias has had to flatten this surface effectively because the first row is position and the second row is tangency. And on this edge the first row was position and the second row was tangency. And we actually only had one, two, three, four rows to work with in the first place so I can't do tangency on both these rows the effect will be that this surface will be effectively flattened.
So let's Restore this and let's change this to just G0 or position. So let's go ahead now and pick this edge and we're going to go with G0 Project onto this surface like that. We're going to Accept that, let's go again, G0, Project, we're going to pick on this edge here, pick on this surface and that's the result we're looking for. So, let's press L, delete the locators, and let's do a quick shade on that.
So just be careful when you are using the Project command and you're using the Align command just be aware of how many rows of Cvs and Hulls that you do have in your particular part because whatever you slate for position will use one row, tangency will use another row, and curvature will use another row so if you're going to go with curvature you have to have at least three rows to achieve that type of curvature continuity.
- 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