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In this course, professional animator and director Lee Lanier shows how to create render passes in Autodesk Maya, recombine the passes in Adobe After Effects, and motion track the passes to live-action video footage that contains a moving camera or a moving character. The course covers both the Render Layer Editor and mental ray contribution pass systems. Additionally, 1- and 2-point motion tracking and match moving, stabilization, and 4-point corner pin tracking are discussed.
The next step to preparing the 3D model for rendering and eventual compositing is to match the lighting. I want to match the Maya lights to the lighting that's actually contained in the video footage, in other words, the real world lighting. So you can look at the footage and determine how many lights you have and what their functions are. And often when you discuss lighting, you talk about lights as it being the key light, or fill light, or a back light. Key light is the most intense light in the scene, it's your main light. The fill light is a secondary source. Often this is a weaker light and often this light is bounced off something like a wall.
The third light, which is sometimes there and sometimes not, is a backlight. That's a light that will be coming from behind the character or from behind the object. So let's take a look at the footage. So if I maximize this frame, here, I can see that the light is coming over her left shoulder. And I can tell that by the shadow on her nose, it's coming from high and from her left side, and that's the sun, because it was shot outside. So in order to create a sun, what I can do in Maya is use a directional light, because of the same type of parallel beams of lights. So I am going to create a directional light, Create > Lights > Directional Light.
Now, the icon is very small, but I can scale it up--and it won't affect the light quality--just so I can see it, and then it's just the matter of rotating it. Position does not matter for this light either. So I am going to rotate it so it comes from the same direction. Now, one thing you can do to help you figure this out is to go back to your Perspective view, go to Lighting menu, and switch to Use All Lights. You can see instantaneously that it starts to use the lights in the scene to give you more accurate shading. Now, the front of my spyglass is dark, which means I need to rotate the light some more to get it to creep around the front, something like this.
So at this point we can do a test render and see what it looks like. So I will scale down my Render view, and there it is. Now, I can use my Alt, or my Option, key and mouse buttons to scroll or zoom in, for instance, Alt to right-mouse button zooms in, and take a look. And there is the light in the front of this model. Now, the sun is creating a shadow like on her nose, so let's also create a shadow with this directional light. So with the directional light selected, I am going to go to the Attribute Editor and turn on Use Depth Map Shadows, and then I can re-render that and take a look, and there is a shadow.
Now, it might take some experimentation to find a good position for this to match your footage, and I did try a few different rotations, and I have some numbers here you can plug in. I came up with -58, 40, -26, and I'll re-render that, and there is the shadow. Now, one thing that's happening at this point is the parts that are in shadow are super dark. They are pretty much pitch-black, and that's not the same as the video footage where the dark area is not particularly dark. So I am going to lighten that up, and that's a really good place to add a second light, as a fill light.
So you want to create a fill light, in Maya you can use the ambient light. So I am going to create an ambient light. And position on this does matter because it's a combination of directional, omni-directional rays. So I will put it at the front side of the spyglass and maybe to the left, in other words, offset the directional light. And then I am going to render a smaller region. If you draw a region box, you can render that region by itself by clicking the Render Region button. You can see instantaneously that there is more light in that area now, it's definitely brighter. That's probably too bright. One thing I do have to deal with is the intensities of light, not only this light, but the key light also.
In fact, I should go back to the directional light and maybe increase that to make a little bit brighter, 1.5 in my Intensity. And then make the fill light dimmer, so I go back to Ambient Light and reduce that. And the rule of thumb for a fill light is generally you have at least half the intensity of the key. In fact, I can go even lower though, go to something like 0.3 to make it a little bit dimmer, and then I am going to render this area. And so we have the dark areas filled in a little bit and the front a little bit brighter, but not overly blown out in terms of brightness. At this point you notice that the shadows are very hard-edged.
And it might be nice to get a softer shadow because she has a soft shadow on her, like around the nose. So what I can do is go back to the Directional Light, go to the Attribute Editor then go to Depth Map section. The trick for a soft shadow, what that type of shadow is to have a small resolution and large filter size. So I can go straight to Filter Size and make that large number such as 18, keep the Resolution fairly small, at 512, render that region, and then get a softer shadow. So there is nice soft shadow. Now we have two lights so far, you can also place a third light as a backlight to get some light to sneak around the right side of the spyglass.
So what I can do for that is place a point light in there and the point light, the position definitely does matter. And we will put this behind the spyglass to the camera right side, some place like that. I don't want it to be too bright, so I am going to go back to that one and turn the Intensity down to, say, 0.2, and then render out a little region to test the right side. You can see it instantaneously has a little highlight right here. Now, again you have to experiment with the location. Now the location for that one I wound up with also, which is 24, 12, -13, and And I will render this region here, so it's giving me a little extra light in the right side here, and you can choose whether you want the highlight to appear or not.
Now, I do need to pay attention to the position of the ambient light also, because that will affect the lighting, even if it's subtle. So I do have a position on that too, that worked out, which is -6, 18, 23. Now all lights are rotated and positioned. Render one more time, and that's looking pretty good. So now we have worked out the lighting to match the video footage, we're ready to move on to next step, where we'll set up render passes to render out this model in separate pieces, which will be recombined in the composite.
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