Join Veejay Gahir for an in-depth discussion in this video Horizontal and vertical shaders, part of Alias Essential Training.
- In this video we're going to move on to some more analysis tools in the shader options. So, let's move on to diagnostic shader, and we're going to open this up. Now, this is a very rough concept model of the front portion of the vehicle so we have the hood and the front fenders. You can see here that this really is just a very quick concept. The next stage for this model would be to go back and rerun these fillets to make sure that we can reduce the density or the complexity of them. As is stands right now, it needs to be just rendered and obviously a design review to make sure that this is the correct theme that we're creating here.
So, again, purely for a visual sign-off. Then, we're going to go back in there and refine these surfaces. So what we can do here is we can select everything and we can switch off the Us and the Vs, just to simplify the visual perspective of that surface. So we looked at multicolor, and this is a multicolor surface shader. What I want to do here is go to Show Surface Orientation. So this is the first thing we should really do at this stage. So let's go to Surface Edit, Orientation, Set Surface Orientation.
Remember, just window over these like that to just change the orientation so that everything is going in the same direction from our view perspective, and that looks pretty good. Okay, let's jump into horizontal vertical shading. So, better known as zebra stripes, and in some CAD systems, it's also known as isophotes. You can see here in Alias, isophotes are split off into a separate shader. So with zebra stripes, again we are looking for surface discontinuities, so if I zoom into this area here, as I move my model, everything is being projected from my view perspective.
The camera and also these highlights. So, the first thing to note here is that we don't have a great quality along the edges here. So, again what we can do is go to Accurate, and we can also dial the tolerance down to .01. You'll notice that these will change in quality. Again, to increase a quality even more, if I get to this point here, you see that we still have some rough edges there. I can change this to .001. Okay, so that's a lot smoother around there now. Again, this is going to be a little bit more intensive on the processor.
So the idea is as I track this model like this, all I'm doing is rotating it. I'm just looking at the way these highlights are tracking across all those adjacent surfaces. I'm looking for imperfections. Now this is quite a wide band that we have here, so really it helps to identify issues. So, if we look at this area here, we actually have a gap between the hood and the fender and that's an intentional gap, so you can definitely see that these highlights are being picked up. It indicates a gap or a tangency error.
In this case, that's acceptable. What we're looking for here is a nice smooth transition over these surfaces. There shouldn't be any gaps, and there shouldn't be any tangency discrepancies. So what we can do here is we can change from black and white horizontal, we can also go to vertical. We can change the orientation of these stripes. So again, I can just move the model like so, and I'm just observing all the adjacent surfaces. I can also go to a color mode, horizontal and vertical.
I think in most cases, you'll choose the black and white to help analyze the surfaces. Now you can also switch the model off, so that we lose all the boundary indicators. Now we just have a smooth surface like this to look at. Let's put them back on. Don't worry about Limit Edge Length, I actually find that I get the best results just working with tolerance and accurate. Again, as we discussed earlier, we can change the color, so I can click on this, I can change the color like so.
We can also change the repeats. Now in this case here, if I wanted to have more repeats on there, I can just go and increase the repeats like this. That, in some cases will help you analyze the surfaces better, as I rotate like that. Now just a point to note here, if I go back to wireframe, and I pick this portion of that fender, I can actually apply it just to that selected portion. So you don't have to render everything. In some cases, it's better to do it this way. Or again, just use your layers and hide the entities that you're not going to use just to make your rendering a little bit quicker, and just analyze the areas that you're interested in at that time.
So, let's go back to wireframe, deselect, and I'm going to select everything again. So again, we've got ambient light and diffused light. Don't worry too much about those, that just changes the intensity of the actual texture itself as you can see. I find the best results just leave them as they are. Now one area that's very important is Lock Texture. Now you'll notice that these highlights are being projected from my viewpoint. So as I tumble the model, the highlights are being tracked across the model. What I can do, is I can lock the texture like this. In this case I've got to change my repeats right down.
Let's change them to let's say .001, like that. Actually that's a little bit too, go to .01. There we go. Now I've locked the texture now, so in this mode here as I tumble the model, the textures are being frozen onto that surface. It's almost like they've been painted on and applied. So what I can do is if I go to a left view, I can unlock, lock again, and now when I rotate, those textures have been applied in the side view and I can now just go in and analyze the end result without those textures moving.
So I could also do the same, I'd go to the front view, like so. I could lock like this, and I could also change to in this case, vertical. They're locked now, so as I rotate, nothing's going to move. Another option that you do have is if you unlock those textures, let's change these up to say something like, like this. I can go back to horizontal, and I can use my option, I'm just going to close down the control panel here.
If I open up these options on the right hand side here, I'm going to lock the View Azimuth/Elevation and I'm going to use my right mouse button. You can notice that it doesn't matter what I do with my right mouse button, it's only going to rotate in the Y axis. So now it allows me to just carefully just track down, and I'm just observing areas that are of concern to me. So I've actually locked the axis of rotation like this. I can zoom into this area. Again, one you release, you have to reinvoke that View Azimuth/Elevation.
Again, I can just track while I'm observing those surfaces. Again, in the right view, I can lock that elevation, and again, using my right mouse button, I'm just locking that rotation. So again, it gives me a more controlled end result as I'm viewing this. Go back to the home view. So in this case, what I'm going to do is I can always go back to my Link Lights and let's slide this up. With Link Lights, I can just change the light position like that.
Also I can change the Light Azimuth using the sliders, but I just find it's a lot easier just to use the slider like that. Again, that's using the horizontal vertical zebra stripes. Now if we jump over to isophotes, isophotes gives us another very similar result to the horizontal vertical stripes. Now in this case, it's a slightly different graphical representation. It's a thinner light, and it just gives us a slightly different result. So again, we can change the color, like this.
We'll go back to white in that case. In this case, the textures, we're going to use the camera viewpoint, like this. You can see it gives us a similar result, but these lines are a lot finer, so if some cases, it's better to analyze discrepancies. Now, to avoid confusion between these lines and our boundaries of surfaces, in this case it's a good idea again to just switch off the model. If we zoom in here, if you don't change your tolerances, let's say we use a tolerance of let's say .1.
You'll see that the edges look pretty rough, so if you do see that, don't immediately assume that the problem is in the surfaces. Just tweak your tolerances so that you get a really nice smooth result, like this. But again, remember to change them back when you're done with that. Okay, same thing with the horizontal vertical zebra stripes. We can go to our front view. We can, we can lock the textures like this. I'm rotating you with my left mouse button. If I want to lock the axis of rotation, just very simply click this icon here, right mouse button and now I can just rotate the model like so.
Front view, and I can go back into this option and let the highlights track as I tumble my model. Again, very similar, it's down to preference which one gives you the best result. In my opinion it's a good idea to use multiple ways of analyzing surfaces. Don't rely on just one analysis to say "Yep, that's good." or "It's Bad." Try to use a couple of them to at least get a different perspective using different textures.
- 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